Sample records for affibody molecule labeled

  1. Evaluation of maleimide derivative of DOTA for site-specific labeling of recombinant affibody molecules.

    Ahlgren, Sara; Orlova, Anna; Rosik, Daniel; Sandström, Mattias; Sjöberg, Anna; Baastrup, Barbro; Widmark, Olof; Fant, Gunilla; Feldwisch, Joachim; Tolmachev, Vladimir


    Affibody molecules are a new class of small (7 kDa) scaffold affinity proteins, which demonstrate promising properties as agents for in vivo radionuclide targeting. The Affibody scaffold is cysteine-free and therefore independent of disulfide bonds. Thus, a single thiol group can be engineered into the protein by introduction of one cysteine. Coupling of thiol-reactive bifunctional chelators can enable site-specific labeling of recombinantly produced Affibody molecules. In this study, the use of 1,4,7,10-tetraazacyclododecane-1,4,7-tris-acetic acid-10-maleimidoethylacetamide (MMA-DOTA) for 111 In-labeling of anti-HER2 Affibody molecules His 6-Z HER2:342-Cys and Z HER2:2395-Cys has been evaluated. The introduction of a cysteine residue did not affect the affinity of the proteins, which was 29 pM for His 6-Z HER2:342-Cys and 27 pM for Z HER2:2395-Cys, comparable with 22 pM for the parental Z HER2:342. MMA-DOTA was conjugated to DTT-reduced Affibody molecules with a coupling efficiency of 93% using a 1:1 molar ratio of chelator to protein. The conjugates were labeled with 111 In to a specific radioactivity of up to 7 GBq/mmol, with preserved binding for the target HER2. In vivo, the non-His-tagged variant 111 In-[MMA-DOTA-Cys61]-Z HER2:2395-Cys demonstrated appreciably lower liver uptake than its His-tag-containing counterpart. In mice bearing HER2-expressing LS174T xenografts, 111 In-[MMA-DOTA-Cys61]-Z HER2:2395-Cys showed specific and rapid tumor localization, and rapid clearance from blood and nonspecific compartments, leading to a tumor-to-blood-ratio of 18 +/- 8 already 1 h p.i. Four hours p.i., the tumor-to-blood ratio was 138 +/- 8. Xenografts were clearly visualized already 1 h p.i. PMID:18163536

  2. Direct comparison of {sup 111}In-labelled two-helix and three-helix Affibody molecules for in vivo molecular imaging

    Rosik, Daniel; Karlstroem, Amelie Eriksson [KTH Royal Institute of Technology, Division of Molecular Biotechnology, School of Biotechnology, Stockholm (Sweden); Orlova, Anna; Malmberg, Jennie; Varasteh, Zohreh [Uppsala University, Preclinical PET Platform, Uppsala (Sweden); Altai, Mohamed; Tolmachev, Vladimir [Uppsala University, Unit of Biomedical Radiation Sciences, Rudbeck Laboratory, Uppsala (Sweden); Sandstroem, Mattias [Uppsala University Hospital, Section of Medical Physics, Department of Oncology, Uppsala (Sweden)


    Radiolabelled Affibody molecules have demonstrated a potential for visualization of tumour-associated molecular targets. Affibody molecules (7 kDa) are composed of three alpha-helices. Recently, a smaller two-helix variant of Affibody molecules (5.1 kDa) was developed. The aim of this study was to compare two- and three-helix HER2-targeting Affibody molecules directly in vivo. The three-helix Affibody molecule ABY-002 and the two-helix Affibody molecule PEP09239 were labelled with {sup 111}In at the N-termini via DOTA chelator. Tumour-targeting properties were directly compared at 1 and 4 h after injection in mice bearing SKOV-3 xenografts with high HER2 expression and LS174T xenografts with low HER2 expression. The dissociation constants (K{sub D}) for HER2 binding were 78 pM for the three-helix Affibody molecule and 2.1 nM for the two-helix Affibody molecule. {sup 111}In-PEP09239 cleared more rapidly from the blood. In xenografts with high HER2 expression, the uptake of {sup 111}In-ABY-002 was significantly higher than that of {sup 111}In-PEP09239. The tumour-to-blood ratio was higher for {sup 111}In-PEP09239 at 4 h after injection, while there was no significant difference in other tumour-to-organ ratios. The tumour uptake of {sup 111}In-ABY-002 was eightfold higher than that of {sup 111}In-PEP09239 in xenografts with low expression. Tumour-to-blood ratios were equal in this case, but other tumour-to-organ ratios were appreciably higher for the three-helix variant. For tumours with high HER2 expression, two-helix HER2-targeting Affibody molecules can provide higher tumour-to-blood ratio at the cost of lower tumour uptake. In the case of low expression, both tumour uptake and tumour-to-organ ratios are appreciably higher for three-helix than for two-helix HER2-targeting Affibody molecules. (orig.)

  3. Radionuclide therapy of HER2-positive microxenografts using a 177Lu-labeled HER2-specific Affibody molecule.

    Tolmachev, Vladimir; Orlova, Anna; Pehrson, Rikard; Galli, Joakim; Baastrup, Barbro; Andersson, Karl; Sandström, Mattias; Rosik, Daniel; Carlsson, Jörgen; Lundqvist, Hans; Wennborg, Anders; Nilsson, Fredrik Y


    A radiolabeled anti-HER2 Affibody molecule (Z(HER2:342)) targets HER2-expressing xenografts with high selectivity and gives good imaging contrast. However, the small size (approximately 7 kDa) results in rapid glomerular filtration and high renal accumulation of radiometals, thus excluding targeted therapy. Here, we report that reversible binding to albumin efficiently reduces the renal excretion and uptake, enabling radiometal-based nuclide therapy. The dimeric Affibody molecule (Z(HER2:342))(2) was fused with an albumin-binding domain (ABD) conjugated with the isothiocyanate derivative of CHX-A''-DTPA and labeled with the low-energy beta-emitter (177)Lu. The obtained conjugate [CHX-A''-DTPA-ABD-(Z(HER2:342))(2)] had a dissociation constant of 18 pmol/L to HER2 and 8.2 and 31 nmol/L for human and murine albumin, respectively. The radiolabeled conjugate displayed specific binding to HER2-expressing cells and good cellular retention in vitro. In vivo, fusion with ABD enabled a 25-fold reduction of renal uptake in comparison with the nonfused dimer molecule (Z(HER2:342))(2). Furthermore, the biodistribution showed high and specific uptake of the conjugate in HER2-expressing tumors. Treatment of SKOV-3 microxenografts (high HER2 expression) with 17 or 22 MBq (177)Lu-CHX-A''-DTPA-ABD-(Z(HER2:342))(2) completely prevented formation of tumors, in contrast to mice given PBS or 22 MBq of a radiolabeled non-HER2-binding Affibody molecule. In LS174T xenografts (low HER2 expression), this treatment resulted in a small but significant increase of the survival time. Thus, fusion with ABD improved the in vivo biodistribution, and the results highlight (177)Lu-CHX-A''-DTPA-ABD-(Z(HER2:342))(2) as a candidate for treatment of disseminated tumors with a high level of HER2 expression. PMID:17363599

  4. Influence of macrocyclic chelators on the targeting properties of (68Ga-labeled synthetic affibody molecules: comparison with (111In-labeled counterparts.

    Joanna Strand

    Full Text Available Affibody molecules are a class of small (7 kDa non-immunoglobulin scaffold-based affinity proteins, which have demonstrated substantial potential as probes for radionuclide molecular imaging. The use of positron emission tomography (PET would further increase the resolution and quantification accuracy of Affibody-based imaging. The rapid in vivo kinetics of Affibody molecules permit the use of the generator-produced radionuclide (68Ga (T1/2=67.6 min. Earlier studies have demonstrated that the chemical nature of chelators has a substantial influence on the biodistribution properties of Affibody molecules. To determine an optimal labeling approach, the macrocyclic chelators 1,4,7,10-tetraazacylododecane-1,4,7,10-tetraacetic acid (DOTA, 1,4,7-triazacyclononane-N,N,N-triacetic acid (NOTA and 1-(1,3-carboxypropyl-1,4,7- triazacyclononane-4,7-diacetic acid (NODAGA were conjugated to the N-terminus of the synthetic Affibody molecule ZHER2:S1 targeting HER2. Affibody molecules were labeled with (68Ga, and their binding specificity and cellular processing were evaluated. The biodistribution of (68Ga-DOTA-ZHER2:S1, (68Ga-NOTA-ZHER2:S1 and (68Ga-NODAGA-ZHER2:S1, as well as that of their (111In-labeled counterparts, was evaluated in BALB/C nu/nu mice bearing HER2-expressing SKOV3 xenografts. The tumor uptake for (68Ga-DOTA-ZHER2:S1 (17.9 ± 0.7%IA/g was significantly higher than for both (68Ga-NODAGA-ZHER2:S1 (16.13 ± 0.67%IA/g and (68Ga-NOTA-ZHER2:S1 (13 ± 3%IA/g at 2 h after injection. (68Ga-NODAGA-ZHER2:S1 had the highest tumor-to-blood ratio (60 ± 10 in comparison with both (68Ga-DOTA-ZHER2:S1 (28 ± 4 and (68Ga-NOTA-ZHER2:S1 (42 ± 11. The tumor-to-liver ratio was also higher for (68Ga-NODAGA-ZHER2:S1 (7 ± 2 than the DOTA and NOTA conjugates (5.5 ± 0.6 vs.3.3 ± 0.6. The influence of chelator on the biodistribution and targeting properties was less pronounced for (68Ga than for (111In. The results of this study demonstrate that macrocyclic

  5. PET imaging of insulin-like growth factor type 1 receptor expression with a 64Cu-labeled Affibody molecule.

    Su, Xinhui; Cheng, Kai; Liu, Yang; Hu, Xiang; Meng, Shuxian; Cheng, Zhen


    The insulin-like growth factor 1 receptor (IGF-1R) serves as an attractive target for cancer molecular imaging and therapy. Previous single photon emission computerized tomography (SPECT) studies showed that the IGF-1R-targeting Affibody molecules (99m)Tc-ZIGF1R:4551-GGGC, [(99m)Tc(CO)3](+)-(HE)3-ZIGF1R:4551 and (111)In-DOTA-ZIGF1R:4551 can discriminate between high and low IGF-1R-expression tumors and have the potential for patient selection for IGF-1R-targeted therapy. Compared with SPECT, positron emission tomography (PET) may improve imaging of IGF-1R-expression, because of its high sensitivity, high spatial resolution, strong quantification ability. The aim of the present study was to develop the (64)Cu-labeled NOTA-conjugated Affibody molecule ZIGF-1R:4:40 as a PET probe for imaging of IGF-1R-positive tumor. An Affibody analogue (Ac-Cys-ZIGF-1R:4:40) binding to IGF-1R was site-specifically conjugated with NOTA and labeled with (64)Cu. Binding affinity and specificity of (64)Cu-NOTA-ZIGF-1R:4:40 to IGF-1R were evaluated using human glioblastoma U87MG cells. Small-animal PET, biodistribution, and metabolic stability studies were conducted on mice bearing U87MG xenografts after the injection of (64)Cu-NOTA-ZIGF-1R:4:40 with or without co-injection of unlabeled Affibody proteins. The radiosynthesis of (64)Cu-NOTA-ZIGF-1R:4:40 was completed successfully within 60 min with a decay-corrected yield of 75 %. (64)Cu-NOTA-ZIGF-1R:4:40 bound to IGF-1R with low nanomolar affinity (K D = 28.55 ± 3.95 nM) in U87MG cells. (64)Cu-NOTA-ZIGF-1R:4:40 also displayed excellent in vitro and in vivo stability. In vivo biodistribution and PET studies demonstrated targeting of U87MG gliomas xenografts was IGF-1R specific. The tumor uptake was 5.08 ± 1.07 %ID/g, and the tumor to muscle ratio was 11.89 ± 2.16 at 24 h after injection. Small animal PET imaging studies revealed that (64)Cu-NOTA-ZIGF-1R:4:40 could clearly identify U87MG tumors with good contrast at 1-24

  6. Preclinical evaluation of anti-HER2 Affibody molecules site-specifically labeled with 111In using a maleimido derivative of NODAGA

    Introduction: Affibody molecules have demonstrated potential for radionuclide molecular imaging. The aim of this study was to synthesize and evaluate a maleimido derivative of the 1,4,7-triazacyclononane-1-glutaric acid-4,7-diacetic acid (NODAGA) for site-specific labeling of anti-HER2 Affibody molecule. Methods: The maleimidoethylmonoamide NODAGA (MMA-NODAGA) was synthesized and conjugated to ZHER2:2395 Affibody molecule having a C-terminal cysteine. Labeling efficiency, binding specificity to and cell internalization by HER2-expressing cells of [111In-MMA-NODAGA-Cys61]-ZHER2:2395 were studied. Biodistribution of [111In-MMA-NODAGA-Cys61]-ZHER2:2395 and [111In-MMA-DOTA-Cys61]-ZHER2:2395 was compared in mice. Results: The affinity of [MMA-NODAGA-Cys61]-ZHER2:2395 binding to HER2 was 67 pM. The 111In-labeling yield was 99.6%±0.5% after 30 min at 60°C. [111In-MMA-NODAGA-Cys61]-ZHER2:2395 bound specifically to HER2-expressing cells in vitro and in vivo. Tumor uptake of [111In-MMA-NODAGA-Cys61]-ZHER2:2395 in mice bearing DU-145 xenografts (4.7%±0.8% ID/g) was lower than uptake of [111In-MMA-DOTA-Cys61]-ZHER2:2395 (7.5%±1.6% ID/g). However, tumor-to-organ ratios were higher for [111In-MMA-NODAGA-Cys61]-ZHER2:2395 due to higher clearance rate from normal tissues. Conclusions: MMA-NODAGA is a promising chelator for site-specific labeling of targeting proteins containing unpaired cysteine. Appreciable influence of chelators on targeting properties of Affibody molecules was demonstrated.

  7. A HER2-binding Affibody molecule labelled with {sup 68}Ga for PET imaging: direct in vivo comparison with the {sup 111}In-labelled analogue

    Tolmachev, Vladimir [Uppsala University, Division of Biomedical Radiation Sciences, Rudbeck Laboratory, Uppsala (Sweden); Uppsala University, Division of Nuclear Medicine, Department of Medical Sciences, Uppsala (Sweden); Velikyan, Irina [Uppsala University, Department of Biochemistry and Organic Chemistry, Uppsala (Sweden); GEMS PET Systems, GE Healthcare, Uppsala Applied Science Lab, Uppsala (Sweden); Sandstroem, Mattias [Uppsala University Hospital, Hospital Physics, Department of Oncology, Uppsala (Sweden); Orlova, Anna [Uppsala University, Division of Biomedical Radiation Sciences, Rudbeck Laboratory, Uppsala (Sweden)


    Overexpression of HER2 receptors is a prognostic and predictive biomarker in breast cancer and a number of other malignancies. Radionuclide molecular imaging of HER2 overexpression may influence patient management making treatment more personalized. Earlier, {sup 111}In-DOTA-Z{sub HER2:342-pep2} (ABY-002) Affibody molecule demonstrated excellent imaging of HER2-expressing xenografts in mice shortly after injection. The use of the positron-emitting nuclide {sup 68}Ga instead of {sup 111}In might increase both the sensitivity of HER2 imaging and accuracy of expression quantification. The goal of this study was to prepare and characterize {sup 68}Ga-labelled ABY-002. {sup 68}Ga labelling of ABY-002 was optimized. In vitro cell binding and procession of {sup 68}Ga-ABY-002 was evaluated. Biodistribution and tumour targeting of {sup 68}Ga-ABY-002 and {sup 111}In-ABY-002 was compared in vivo by paired-label experiments. ABY-002 was incubated with {sup 68}Ga at 90 C for 10 min resulting in a radiochemical labelling yield of over 95%. Capacity for specific binding to HER2-expressing cells was retained. In vivo, both {sup 68}Ga-ABY-002 and {sup 111}In-ABY-002 demonstrated specific targeting of SKOV-3 xenografts and high-contrast imaging. Background radioactivity in blood, lungs, gastrointestinal tract and muscle fell more rapidly for {sup 68}Ga-ABY-002 compared with {sup 111}In-ABY-002 favouring imaging shortly after injection. For {sup 68}Ga-ABY-002, a tumour uptake of 12.4 {+-} 3.8%ID/g and a tumour to blood ratio of 31 {+-} 13 were achieved at 2 h post-injection. {sup 68}Ga-ABY-002 is easy to label and provides high-contrast imaging within 2 h after injection. This makes it a promising candidate for clinical molecular imaging of HER2 expression in malignant tumours. (orig.)

  8. Influence of an aliphatic linker between DOTA and synthetic ZHER2:342 Affibody molecule on targeting properties of the 111In-labeled conjugate

    Introduction: Affibody molecules are small (∼6.5 kDa) scaffold proteins suitable for radionuclide imaging of tumor-associated molecular targets. Site-specific labeling of Affibody molecules made by peptide synthesis can be achieved by coupling a chelator to N-terminus in the last synthesis step. The goal of this study was to evaluate the influence of a 6-aminohexanoic linker between DOTA and ZHER2:342 on targeting properties of 111In-labeled conjugate. Methods: A DOTA-conjugated 6-aminohexanoic linker-containing variant of ZHER2:342 (ABY-003) was produced by peptide synthesis, and the in vitro binding affinity, specificity and cellular processing were evaluated. The biodistribution of 111In-ABY-003 in normal mice was compared to 111In-ABY-002 (DOTA-ZHER2:342-pep2) lacking the linker. Tumor-targeting properties of 111In-ABY-003 were evaluated in mice bearing HER2-expressing xenografts. Results: The dissociation constant of ABY-003 was in the low picomolar range, slightly higher than for ABY-002. 111In-ABY-003 bound specifically to HER2-expressing cells in vitro. The cellular retention was efficient but slightly worse than for 111In-ABY-002. In normal mice, the clearance of 111In-ABY-003 from blood and other tissues was slightly but significantly faster compared to 111In-ABY-002. Targeting of HER2-expressing xenografts by 111In-ABY-003 was receptor-specific. Due to faster clearance, the tumor-to-blood ratio for 111In-ABY-003 at 4 h postinjection was improved compared to 111In-ABY-002. The capacity of 111In-ABY-003 to visualize HER2-expressing tumors was confirmed by gamma camera imaging. Conclusions: A 6-aminohexanoic linker between the DOTA chelator and N-terminus of synthetic ZHER2:342 had a measurable effect on affinity, cellular retention of radioactivity and blood clearance. The linker might be used for modulation of targeting properties of Affibody molecules.

  9. Imaging of EGFR expression in murine xenografts using site-specifically labelled anti-EGFR 111In-DOTA-ZEGFR:2377 Affibody molecule: aspect of the injected tracer amount

    Overexpression of epidermal growth factor receptor (EGFR) is a prognostic and predictive biomarker in a number of malignant tumours. Radionuclide molecular imaging of EGFR expression in cancer could influence patient management. However, EGFR expression in normal tissues might complicate in vivo imaging. The aim of this study was to evaluate if optimization of the injected protein dose might improve imaging of EGFR expression in tumours using a novel EGFR-targeting protein, the DOTA-ZEGFR:2377 Affibody molecule. An anti-EGFR Affibody molecule, ZEGFR:2377, was labelled with 111In via the DOTA chelator site-specifically conjugated to a C-terminal cysteine. The affinity of DOTA-ZEGFR:2377 for murine and human EGFR was measured by surface plasmon resonance. The cellular processing of 111In-DOTA-ZEGFR:2377 was evaluated in vitro. The biodistribution of radiolabelled Affibody molecules injected in a broad range of injected Affibody protein doses was evaluated in mice bearing EGFR-expressing A431 xenografts. Site-specific coupling of DOTA provided a uniform conjugate possessing equal affinity for human and murine EGFR. The internalization of 111In-DOTA-ZEGFR:2377 by A431 cells was slow. In vivo, the conjugate accumulated specifically in xenografts and in EGFR-expressing tissues. The curve representing the dependence of tumour uptake on the injected Affibody protein dose was bell-shaped. The highest specific radioactivity (lowest injected protein dose) provided a suboptimal tumour-to-blood ratio. The results of the biodistribution study were confirmed by γ-camera imaging. The 111In-DOTA-ZEGFR:2377 Affibody molecule is a promising tracer for radionuclide molecular imaging of EGFR expression in malignant tumours. Careful optimization of protein dose is required for high-contrast imaging of EGFR expression in vivo. (orig.)

  10. In Vivo Imaging of Xenograft Tumors Using an Epidermal Growth Factor Receptor-Specific Affibody Molecule Labeled with a Near-infrared Fluorophore

    Haibiao Gong


    Full Text Available Overexpression of epidermal growth factor receptor (EGFR is associated with many types of cancers. It is of great interest to noninvasively image the EGFR expression in vivo. In this study, we labeled an EGFR-specific Affibody molecule (Eaff with a near-infrared (NIR dye IRDye800CW maleimide and tested the binding of this labeled molecule (Eaff800 in cell culture and xenograft mouse tumor models. Unlike EGF, Eaff did not activate the EGFR signaling pathway. Results showed that Eaff800 was bound and taken up specifically by EGFR-overexpressing A431 cells. When Eaff800 was intravenously injected into nude mice bearing A431 xenograft tumors, the tumor could be identified 1 hour after injection and it became most prominent after 1 day. Images of dissected tissue sections demonstrated that the accumulation of Eaff800 was highest in the liver, followed by the tumor and kidney. Moreover, in combination with a human EGFR type 2 (HER2-specific probe Haff682, Eaff800 could be used to distinguish between EGFR- and HER2-overexpressing tumors. Interestingly, the organ distribution pattern and the clearance rate of Eaff800 were different from those of Haff682. In conclusion, Eaff molecule labeled with a NIR fluorophore is a promising molecular imaging agent for EGFR-overexpressing tumors.

  11. HER2-Positive Tumors Imaged Within 1 Hour Using a Site-Specifically 11C-Labeled Sel-Tagged Affibody Molecule

    Wållberg, H; Grafström, J; Q. Cheng; Lu, L; Martinsson Ahlzén, HS; Samén, E; Thorell, JO; K. Johansson; Dunås, F; Olofsson, MH; Stone-Elander, S; Arnér, Elias S.J.; Ståhl, S


    A rapid, reliable method for distinguishing tumors or metastases that overexpress human epidermal growth factor receptor 2 (HER2) from those that do not is highly desired for individualizing therapy and predicting prognoses. In vivo imaging methods are available but not yet in clinical practice; new methodologies improving speed, sensitivity, and specificity are required. METHODS: A HER2-binding Affibody molecule, Z(HER2:342), was recombinantly fused with a C-terminal selenocystein...

  12. Cy5.5-labeled Affibody molecule for near-infrared fluorescent optical imaging of epidermal growth factor receptor positive tumors

    Miao, Zheng; Ren, Gang; Liu, Hongguang; Jiang, Lei; Cheng, Zhen


    Affibody protein is an engineered protein scaffold with a three-helical bundle structure. Affibody molecules of small size (7 kD) have great potential for targeting overexpressed cancer biomarkers in vivo. To develop an Affibody-based molecular probe for in vivo optical imaging of epidermal growth factor receptor (EGFR) positive tumors, an anti-EGFR Affibody molecule, Ac-Cys-ZEGFR:1907 (7 kD), is site-specifically conjugated with a near-IR fluorescence dye, Cy5.5-mono-maleimide. Using fluorescent microscopy, the binding specificity of the probe Cy5.5-ZEGFR:1907 is checked by a high-EGFR-expressing A431 cell and low-EGFR-expressing MCF7 cells. The binding affinity of Cy5.5-ZEGFR:1907 (KD) to EGFR is 43.6+/-8.4 nM, as determined by flow cytometry. For an in vivo imaging study, the probe shows fast tumor targeting and good tumor contrast as early as 0.5 h postinjection (p.i.) for A431 tumors, while MCF7 tumors are barely visible. An ex vivo imaging study also demonstrates that Cy5.5-ZEGFR:1907 has high tumor, liver, and kidney uptakes at 24 h p.i.. In conclusion, Cy5.5-ZEGFR:1907 shows good affinity and high specificity to the EGFR. There is rapid achievement of good tumor-to-normal-tissue contrasts of Cy5.5-ZEGFR:1907, thus demonstrating its potential for EGFR-targeted molecular imaging of cancers.

  13. Influence of an aliphatic linker between DOTA and synthetic Z{sub HER2:342} Affibody molecule on targeting properties of the {sup 111}In-labeled conjugate

    Tolmachev, Vladimir, E-mail: [Division of Biomedical Radiation Sciences, Department of Radiology, Oncology and Clinical Immunology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala (Sweden); Feldwisch, Joachim [Division of Biomedical Radiation Sciences, Department of Radiology, Oncology and Clinical Immunology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala (Sweden); Affibody AB, SE-112 51, Stockholm (Sweden); Lindborg, Malin; Baastrup, Barbro [Affibody AB, SE-112 51, Stockholm (Sweden); Sandstroem, Mattias [Hospital Physics, Department of Oncology, Uppsala University Hospital, Uppsala (Sweden); Orlova, Anna [Division of Biomedical Radiation Sciences, Department of Radiology, Oncology and Clinical Immunology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala (Sweden)


    Introduction: Affibody molecules are small ({approx}6.5 kDa) scaffold proteins suitable for radionuclide imaging of tumor-associated molecular targets. Site-specific labeling of Affibody molecules made by peptide synthesis can be achieved by coupling a chelator to N-terminus in the last synthesis step. The goal of this study was to evaluate the influence of a 6-aminohexanoic linker between DOTA and Z{sub HER2:342} on targeting properties of {sup 111}In-labeled conjugate. Methods: A DOTA-conjugated 6-aminohexanoic linker-containing variant of Z{sub HER2:342} (ABY-003) was produced by peptide synthesis, and the in vitro binding affinity, specificity and cellular processing were evaluated. The biodistribution of {sup 111}In-ABY-003 in normal mice was compared to {sup 111}In-ABY-002 (DOTA-Z{sub HER2:342-pep2}) lacking the linker. Tumor-targeting properties of {sup 111}In-ABY-003 were evaluated in mice bearing HER2-expressing xenografts. Results: The dissociation constant of ABY-003 was in the low picomolar range, slightly higher than for ABY-002. {sup 111}In-ABY-003 bound specifically to HER2-expressing cells in vitro. The cellular retention was efficient but slightly worse than for {sup 111}In-ABY-002. In normal mice, the clearance of {sup 111}In-ABY-003 from blood and other tissues was slightly but significantly faster compared to {sup 111}In-ABY-002. Targeting of HER2-expressing xenografts by {sup 111}In-ABY-003 was receptor-specific. Due to faster clearance, the tumor-to-blood ratio for {sup 111}In-ABY-003 at 4 h postinjection was improved compared to {sup 111}In-ABY-002. The capacity of {sup 111}In-ABY-003 to visualize HER2-expressing tumors was confirmed by gamma camera imaging. Conclusions: A 6-aminohexanoic linker between the DOTA chelator and N-terminus of synthetic Z{sub HER2:342} had a measurable effect on affinity, cellular retention of radioactivity and blood clearance. The linker might be used for modulation of targeting properties of Affibody molecules.

  14. Comparative evaluation of synthetic anti-HER2 Affibody molecules site-specifically labelled with 111In using N-terminal DOTA, NOTA and NODAGA chelators in mice bearing prostate cancer xenografts

    In disseminated prostate cancer, expression of human epidermal growth factor receptor type 2 (HER2) is one of the pathways to androgen independence. Radionuclide molecular imaging of HER2 expression in disseminated prostate cancer might identify patients for HER2-targeted therapy. Affibody molecules are small (7 kDa) targeting proteins with high potential as tracers for radionuclide imaging. The goal of this study was to develop an optimal Affibody-based tracer for visualization of HER2 expression in prostate cancer. A synthetic variant of the anti-HER2 ZHER2:342 Affibody molecule, ZHER2:S1, was N-terminally conjugated with the chelators DOTA, NOTA and NODAGA. The conjugated proteins were biophysically characterized by electrospray ionization mass spectroscopy (ESI-MS), circular dichroism (CD) spectroscopy and surface plasmon resonance (SPR)-based biosensor analysis. After labelling with 111In, the biodistribution was assessed in normal mice and the two most promising conjugates were further evaluated for tumour targeting in mice bearing DU-145 prostate cancer xenografts. The HER2-binding equilibrium dissociation constants were 130, 140 and 90 pM for DOTA-ZHER2:S1, NOTA-ZHER2:S1 and NODAGA-ZHER2:S1, respectively. A comparative study of 111In-labelled DOTA-ZHER2:S1, NOTA-ZHER2:S1 and NODAGA-ZHER2:S1 in normal mice demonstrated a substantial influence of the chelators on the biodistribution properties of the conjugates. 111In-NODAGA-ZHER2:S1 had the most rapid clearance from blood and healthy tissues. 111In-NOTA-ZHER2:S1 showed high hepatic uptake and was excluded from further evaluation. 111In-DOTA-ZHER2:S1 and 111In-NODAGA-ZHER2:S1 demonstrated specific uptake in DU-145 prostate cancer xenografts in nude mice. The tumour uptake of 111In-NODAGA-ZHER2:S1, 5.6 ± 0.4%ID/g, was significantly lower than the uptake of 111In-DOTA-ZHER2:S1, 7.4 ± 0.5%ID/g, presumably because of lower bioavailability due to more rapid clearance. 111In-NODAGA-ZHER2:S1 provided higher tumour

  15. Comparative evaluation of synthetic anti-HER2 Affibody molecules site-specifically labelled with {sup 111}In using N-terminal DOTA, NOTA and NODAGA chelators in mice bearing prostate cancer xenografts

    Malmberg, Jennie; Varasteh, Zohreh; Orlova, Anna [Uppsala University, Preclinical PET Platform, Department of Medicinal Chemistry, Uppsala (Sweden); Perols, Anna; Braun, Alexis; Eriksson Karlstroem, Amelie [AlbaNova University Centre, Division of Molecular Biotechnology, School of Biotechnology, KTH Royal Institute of Technology, Stockholm (Sweden); Altai, Mohamed; Tolmachev, Vladimir [Uppsala University, Unit of Biomedical Radiation Sciences, Rudbeck Laboratory, Uppsala (Sweden); Sandstroem, Mattias [Uppsala University Hospital, Section of Medical Physics, Department of Oncology, Uppsala (Sweden); Garske, Ulrike [Uppsala University Hospital, Department of Medical Sciences, Section of Nuclear Medicine, Uppsala (Sweden)


    In disseminated prostate cancer, expression of human epidermal growth factor receptor type 2 (HER2) is one of the pathways to androgen independence. Radionuclide molecular imaging of HER2 expression in disseminated prostate cancer might identify patients for HER2-targeted therapy. Affibody molecules are small (7 kDa) targeting proteins with high potential as tracers for radionuclide imaging. The goal of this study was to develop an optimal Affibody-based tracer for visualization of HER2 expression in prostate cancer. A synthetic variant of the anti-HER2 Z{sub HER2:342} Affibody molecule, Z{sub HER2:S1}, was N-terminally conjugated with the chelators DOTA, NOTA and NODAGA. The conjugated proteins were biophysically characterized by electrospray ionization mass spectroscopy (ESI-MS), circular dichroism (CD) spectroscopy and surface plasmon resonance (SPR)-based biosensor analysis. After labelling with {sup 111}In, the biodistribution was assessed in normal mice and the two most promising conjugates were further evaluated for tumour targeting in mice bearing DU-145 prostate cancer xenografts. The HER2-binding equilibrium dissociation constants were 130, 140 and 90 pM for DOTA-Z{sub HER2:S1}, NOTA-Z{sub HER2:S1} and NODAGA-Z{sub HER2:S1}, respectively. A comparative study of {sup 111}In-labelled DOTA-Z{sub HER2:S1}, NOTA-Z{sub HER2:S1} and NODAGA-Z{sub HER2:S1} in normal mice demonstrated a substantial influence of the chelators on the biodistribution properties of the conjugates. {sup 111}In-NODAGA-Z{sub HER2:S1} had the most rapid clearance from blood and healthy tissues. {sup 111}In-NOTA-Z{sub HER2:S1} showed high hepatic uptake and was excluded from further evaluation. {sup 111}In-DOTA-Z{sub HER2:S1} and {sup 111}In-NODAGA-Z{sub HER2:S1} demonstrated specific uptake in DU-145 prostate cancer xenografts in nude mice. The tumour uptake of {sup 111}In-NODAGA-Z{sub HER2:S1}, 5.6 {+-} 0.4%ID/g, was significantly lower than the uptake of {sup 111}In-DOTA-Z{sub HER2:S1

  16. {sup 68}Ga-DOTA-affibody molecule for in vivo assessment of HER2/neu expression with PET

    Kramer-Marek, Gabriela; Capala, Jacek [National Institutes of Health, National Cancer Institute, Bethesda, MD (United States); Shenoy, Nalini; Griffiths, Gary L. [National Institutes of Health, Imaging Probe Development Center, National Heart, Lung, and Blood Institute, Rockville, MD (United States); Seidel, Jurgen; Choyke, Peter [National Institutes of Health, Molecular Imaging Program, Center for Cancer Research, National Cancer Institute, Bethesda, MD (United States)


    Overexpression of HER2/neu in breast cancer is correlated with a poor prognosis. It may vary between primary tumors and metastatic lesions and change during the treatment. Therefore, there is a need for a new means to assess HER2/neu expression in vivo. In this work, we used {sup 68}Ga-labeled DOTA-Z{sub HER2:2891}-Affibody to monitor HER2/neu expression in a panel of breast cancer xenografts. DOTA-Z{sub HER2:2891}-Affibody molecules were labeled with {sup 68}Ga. In vitro binding was characterized by a receptor saturation assay. Biodistribution and PET imaging studies were conducted in athymic nude mice bearing subcutaneous human breast cancer tumors with three different levels of HER2/neu expression. Nonspecific uptake was analyzed using non-HER2-specific Affibody molecules. Signal detected by PET was compared with ex vivo assessment of the tracer uptake and HER2/neu expression. The {sup 68}Ga-DOTA-Z{sub HER2:2891}-Affibody probe showed high binding affinity to MDA-MB-361 cells (K{sub D} = 1.4 {+-} 0.19 nM). In vivo biodistribution and PET imaging studies demonstrated high radioactivity uptake in HER2/neu-positive tumors. Tracer was eliminated quickly from the blood and normal tissues, resulting in high tumor-to-blood ratios. The highest concentration of radioactivity in normal tissue was seen in the kidneys (227 {+-} 14%ID/g). High-contrast PET images of HER2/neu-overexpressing tumors were recorded as soon as 1 h after tracer injection. A good correlation was observed between PET imaging, biodistribution estimates of tumor tracer concentration, and the receptor expression. These results suggest that PET imaging using {sup 68}Ga-DOTA-Z{sub HER2:2891}-Affibody is sensitive enough to detect different levels of HER2/neu expression in vivo. (orig.)

  17. Evaluation of backbone-cyclized HER2-binding 2-helix Affibody molecule for In Vivo molecular imaging

    HONARVAR, HADIS; Jokilaakso, Nima; Andersson, Karl; Malmberg, Jennie; Rosik, Daniel; Orlova, Anna; Karlstrom, Amelie Eriksson; Tolmachev, Vladimir; Jarver, Peter


    Introduction Affibody molecules, small scaffold proteins, have demonstrated an appreciable potential as imaging probes. Affibody molecules are composed of three alpha-helices. Helices 1 and 2 are involved in molecular recognition, while helix 3 provides stability. The size of Affibody molecules can be reduced by omitting the third alpha-helix and cross-linking the two remaining, providing a smaller molecule with better extravasation and quicker clearance of unbound tracer. The goal of this st...

  18. Cellular studies of binding, internalization and retention of a radiolabeled EGFR-binding affibody molecule

    Nordberg, Erika [Rudbeck Laboratory, Department of Oncology, Radiology and Clinical Immunology, Biomedical Radiation Sciences, Uppsala University, SE-751 85 Uppsala (Sweden)], E-mail:; Friedman, Mikaela [Department of Molecular Biotechnology, AlbaNova University Center, Kungl Tekniska Hoegskolan (KTH), SE-106 91 Stockholm (Sweden); Goestring, Lovisa [Rudbeck Laboratory, Department of Oncology, Radiology and Clinical Immunology, Biomedical Radiation Sciences, Uppsala University, SE-751 85 Uppsala (Sweden); Affibody AB, PO Box 20137, SE-161 02 Bromma (Sweden); Adams, Gregory P. [Department of Medical Oncology, Fox Chase Cancer Center, Philadelphia, PA 19111 (United States); Brismar, Hjalmar [Department of Cell Physics, AlbaNova University Center, Kungl Tekniska Hoegskolan (KTH), SE-106 91 Stockholm (Sweden); Nilsson, Fredrik Y. [Rudbeck Laboratory, Department of Oncology, Radiology and Clinical Immunology, Biomedical Radiation Sciences, Uppsala University, SE-751 85 Uppsala (Sweden); Affibody AB, PO Box 20137, SE-161 02 Bromma (Sweden); Stahl, Stefan [Department of Molecular Biotechnology, AlbaNova University Center, Kungl Tekniska Hoegskolan (KTH), SE-106 91 Stockholm (Sweden); Glimelius, Bengt [Rudbeck Laboratory, Oncology, Radiology and Clinical Immunology, Uppsala University, SE-751 85 Uppsala (Sweden); Carlsson, Joergen [Rudbeck Laboratory, Department of Oncology, Radiology and Clinical Immunology, Biomedical Radiation Sciences, Uppsala University, SE-751 85 Uppsala (Sweden)


    Introduction: The cellular binding and processing of an epidermal growth factor receptor (EGFR) targeting affibody molecule, (Z{sub EGFR:955}){sub 2}, was studied. This new and small molecule is aimed for applications in nuclear medicine. The natural ligand epidermal growth factor (EGF) and the antibody cetuximab were studied for comparison. Methods: All experiments were made with cultured A431 squamous carcinoma cells. Receptor specificity, binding time patterns, retention and preliminary receptor binding site localization studies were all made after {sup 125}I labeling. Internalization was studied using Oregon Green 488, Alexa Fluor 488 and CypHer5E markers. Results: [{sup 125}I](Z{sub EGFR:955}){sub 2} and [{sup 125}I]cetuximab gave a maximum cellular uptake of {sup 125}I within 4 to 8 h of incubation, while [{sup 125}I]EGF gave a maximum uptake already after 2 h. The retention studies showed that the cell-associated fraction of {sup 125}I after 48 h of incubation was {approx}20% when delivered as [{sup 125}I](Z{sub EGFR:955}){sub 2} and {approx}25% when delivered as [{sup 125}I]cetuximab. [{sup 125}I]EGF-mediated delivery gave a faster {sup 125}I release, where almost all cell-associated radioactivity had disappeared within 24 h. All three substances were internalized as demonstrated with confocal microscopy. Competitive binding studies showed that both EGF and cetuximab inhibited binding of (Z{sub EGFR:955}){sub 2} and indicated that the three substances competed for an overlapping binding site. Conclusion: The results gave information on cellular processing of radionuclides when delivered with (Z{sub EGFR:955}){sub 2} in comparison to delivery with EGF and cetuximab. Competition assays suggested that [{sup 125}I](Z{sub EGFR:955}){sub 2} bind to Domain III of EGFR. The affibody molecule (Z{sub EGFR:955}){sub 2} can be a candidate for EGFR imaging applications in nuclear medicine.

  19. Increasing the Net Negative Charge by Replacement of DOTA Chelator with DOTAGA Improves the Biodistribution of Radiolabeled Second-Generation Synthetic Affibody Molecules.

    Westerlund, Kristina; Honarvar, Hadis; Norrström, Emily; Strand, Joanna; Mitran, Bogdan; Orlova, Anna; Eriksson Karlström, Amelie; Tolmachev, Vladimir


    A promising strategy to enable patient stratification for targeted therapies is to monitor the target expression in a tumor by radionuclide molecular imaging. Affibody molecules (7 kDa) are nonimmunoglobulin scaffold proteins with a 25-fold smaller size than intact antibodies. They have shown an apparent potential as molecular imaging probes both in preclinical and clinical studies. Earlier, we found that hepatic uptake can be reduced by the incorporation of negatively charged purification tags at the N-terminus of Affibody molecules. We hypothesized that liver uptake might similarly be reduced by positioning the chelator at the N-terminus, where the chelator-radionuclide complex will provide negative charges. To test this hypothesis, a second generation synthetic anti-HER2 ZHER2:2891 Affibody molecule was synthesized and labeled with (111)In and (68)Ga using DOTAGA and DOTA chelators. The chelators were manually coupled to the N-terminus of ZHER2:2891 forming an amide bond. Labeling DOTAGA-ZHER2:2891 and DOTA-ZHER2:2891 with (68)Ga and (111)In resulted in stable radioconjugates. The tumor-targeting and biodistribution properties of the (111)In- and (68)Ga-labeled conjugates were compared in SKOV-3 tumor-bearing nude mice at 2 h postinjection. The HER2-specific binding of the radioconjugates was verified both in vitro and in vivo. Using the DOTAGA chelator gave significantly lower radioactivity in liver and blood for both radionuclides. The (111)In-labeled conjugates showed more rapid blood clearance than the (68)Ga-labeled conjugates. The most pronounced influence of the chelators was found when they were labeled with (68)Ga. The DOTAGA chelator gave significantly higher tumor-to-blood (61 ± 6 vs 23 ± 5, p DOTA chelator. This study demonstrated that chelators may be used to alter the uptake of Affibody molecules, and most likely other scaffold-based imaging probes, for improvement of imaging contrast. PMID:27010700

  20. Site-specific labeling of affinity molecules for in vitro and in vivo studies

    Perols, Anna


    The thesis is focused on site-specific labeling of affinity molecules for different applications where two types of binding proteins, Affibody molecules and antibodies, have been used. For the purpose of improving the properties of Affibody molecules for in vivo imaging, novel bi-functional chelators for radiolabeling using the radionuclide 111In were evaluated. In a first study, two chelators denoted NOTA and DOTA, respectively, were separately conjugated via maleimide chemistry to a C-termi...

  1. Imaging of HER3-expressing xenografts in mice using a {sup 99m}Tc(CO){sub 3}-HEHEHE-Z{sub HER3:08699} affibody molecule

    Orlova, Anna; Rosestedt, Maria; Varasteh, Zohreh; Selvaraju, Ram Kumar [Uppsala University, Preclinical PET Platform, Department of Medicinal Chemistry, Uppsala (Sweden); Malm, Magdalena; Andersson, Ken; Staahl, Stefan; Loefblom, John [KTH Royal Institute of Technology, Division of Protein Technology, School of Biotechnology, Stockholm (Sweden); Altai, Mohamed; Honarvar, Hadis; Strand, Joanna; Tolmachev, Vladimir [Uppsala University, Division of Biomedical Radiation Sciences, Rudbeck Laboratory, Uppsala (Sweden)


    Human epidermal growth factor receptor type 3 (HER3) is a transmembrane receptor tyrosine kinase belonging to the HER (ErbB) receptor family. Membranous expression of HER3 is associated with trastuzumab resistance in breast cancer and the transition to androgen independence in prostate cancer. Imaging of HER3 expression in malignant tumors may provide important diagnostic information that can influence patient management. Affibody molecules with low picomolar affinity to HER3 were recently selected. The aim of this study was to investigate the feasibility of HER3 imaging using radiolabeled Affibody molecules. A HER3-binding Affibody molecule, Z{sub 08699}, with a HEHEHE-tag on N-terminus was labeled with {sup 99m}Tc(CO){sub 3} using an IsoLink kit. In vitro and in vivo binding specificity and the cellular processing of the labeled binder were evaluated. Biodistribution of {sup 99m}Tc(CO){sub 3}-HEHEHE-Z{sub 08699} was studied over time in mice bearing HER3-expressing xenografts. HEHEHE-Z{sub 08699} was labeled with {sup 99m}Tc(CO){sub 3} with an isolated yield of >80 % and a purity of >99 %. Binding of {sup 99m}Tc(CO){sub 3}-HEHEHE-Z{sub 08699} was specific to BT474 and MCF7 (breast cancer), and LS174T (colon cancer) cells. Cellular processing showed rapid binding and relatively quick internalization of the receptor/Affibody molecule complex (70 % of cell-associated radioactivity was internalized after 24 h). The tumor targeting was receptor mediated and the excretion was predominantly renal. Receptor-mediated uptake was also found in the liver, lung, stomach, intestine, and salivary glands. At 4 h pi, tumor-to-blood ratios were 7 ± 3 for BT474, and 6 ± 2 for LS174T xenografts. LS174T tumors were visualized by microSPECT 4 h pi. The results of this study suggest the feasibility of HER3-imaging in malignant tumors using Affibody molecules. (orig.)

  2. The influence of Bz-DOTA and CHX-A''-DTPA on the biodistribution of ABD-fused anti-HER2 Affibody molecules: implications for 114mIn-mediated targeting therapy

    Affibody molecules represent a novel class of high-affinity agents for radionuclide tumour targeting. Fusion of the Affibody molecules with an albumin-binding domain (ABD) enables modification of the blood kinetics of the Affibody molecules and reduction of the renal dose. 177Lu-CHX-A''-DTPA-ABD-(ZHER2:342)2, an anti-HER2 Affibody molecule-ABD fusion protein has earlier demonstrated promising results in treatment of HER2-expressing micro-xenografts in mice. The use of the in vivo generator 114mIn/114In as a label for ABD-fused Affibody molecules would create preconditions for efficient treatment of both micrometastases (due to conversion and Auger electrons of 114mIn) and bulky tumours (due to high-energy beta particles from the daughter nuclide 114In). The goal of this study was to investigate if different chelators influence the biodistribution of ABD-(ZHER2:342)2 and to find an optimal chelator for attachment of 114mIn to the Affibody molecule-ABD fusion protein. Isothiocyanate derivatives of Bz-DOTA and CHX-A''-DTPA were coupled to ABD-(ZHER2:342)2. The cellular processing of both conjugates was studied in vitro. The influence of chelators on the biodistribution was investigated in mice using double isotope (114mIn and 111In) labelling. The apparent affinity of CHX-A''-DTPA-ABD-(ZHER2:342)2 and Bz-DOTA-ABD-(ZHER2:342)2 to the extracellular domain of HER2 was similar, 13.5 and 15.0 pM, respectively. It was found that both conjugates were internalized by SKOV-3 cells. The use of CHX-A''-DTPA provided better cellular retention of the radioactivity, better tumour accumulation of radioactivity and better tumour to organ dose ratios than Bz-DOTA-ABD-(ZHER2:342)2. CHX-A''-DTPA is more suitable for 114mIn labelling of Affibody molecule-ABD fusion proteins for radionuclide therapy. (orig.)

  3. Radiolabeled Affibody-Albumin Bioconjugates for HER2 Positive Cancer Targeting

    Hoppmann, Susan; Miao, Zheng; Liu, Shuanglong; Liu, Hongguang; REN, GANG; Bao, Ande; Cheng, Zhen


    Affibody molecules have received significant attention in the fields of molecular imaging and drug development. However, Affibody scaffolds display an extremely high renal uptake, especially when modified with chelators and then labeled with radiometals. This unfavorable property may impact their use as radiotherapeutic agents in general and as imaging probes for the detection of tumors adjacent to kidneys in particular. Herein, we present a simple and generalizable strategy for reducing the ...

  4. In vivo targeting of HER2-positive tumor using 2-helix affibody molecules

    Ren, Gang; Webster, Jack M.; LIU, ZHE; Zhang, Rong; Miao, Zheng; Liu, Hongguang; Gambhir, Sanjiv S.; Syud, Faisal A.; Cheng, Zhen


    Molecular imaging of human epidermal growth factor receptor type 2 (HER2) expression has drawn significant attention because of the unique role of the HER2 gene in diagnosis, therapy and prognosis of human breast cancer. In our previous research, a novel cyclic 2-helix small protein, MUT-DS, was discovered as an anti-HER2 Affibody analog with high affinity through rational protein design and engineering. MUT-DS was then evaluated for positron emission tomography (PET) of HER2-positive tumor b...

  5. 抗人表皮生长因子受体2亲和体 ZHER2瞷342的18F 标记及靶向胃癌的示踪研究%Tracing investigation of targeting gastric cancer with 18F labeled anti-human epidermal growth factor receptor 2 specific affibody molecule ZHER2:342

    潘云云; 柏志成; 潘栋辉; 徐宇平; 杨润林; 王立振; 管文贤; 杨敏


    目的:探讨18 F标记抗人表皮生长因子受体2( HER2)亲和体探针在HER2过表达胃癌中的示踪作用。方法化学合成制备C末端含半胱氨酸的抗HER2亲和体 ZHER2瞷342,通过双功能螯合剂1,4,7-三氮杂环壬烷-1,4,7三乙酸的马来酰亚胺衍生物( NOTA-MAL)与巯基的加成反应合成NOTA-MAL-Cys59-ZHER2:342偶联物(简称偶联物),经18 FAl一步法定位标记制得新型HER2靶向分子探针18FAl-NOTA-MAL-Cys59ZHER2瞷342(简称探针),并经高效液相色谱法(HPLC)进行质量控制。构建NOD SCID鼠HER2高表达胃癌NCI N87移植瘤模型。进行体外细胞摄取、阻断、竞争结合实验和模型鼠micro PET显像以评价探针的靶向能力。结果18 F标记探针放化纯度>95%。细胞结合实验显示HER2过表达NCI N87细胞对18 F标记亲和体的摄取速度快,孵育15 min后接近摄取高峰,约(7.48±0.49)%ID。阻断HER2后,细胞对标记物的摄取水平显著下降,15 min 为(0.85±0.09)%ID (P<0.05),说明NCI N87对亲和体的摄取是通过HER2所特异性介导的。细胞竞争结合实验测得IC50为9.4 nM,说明探针与HER2结合亲和力高。 NOD SCID鼠micro PET显像肿瘤摄取高,30 min为(7.22±0.24)%ID/g。阻断组micro PET显像肿瘤摄取显著降低,1h为(2.56±0.11)%ID/g(P<0.05)。探针主要经肾脏排泄。结论新型探针标记方便,对HER2过表达胃癌靶向能力强。%Objective To investigate the effect of 18 F labeled anti-HER2 affibody probe on the targeting HER2 overexpressed human gastric cancer with micro PET imaging . Methods Anti-HER2 specific affibody ZHER2:342 was obtained from chemical synthesis routes .The bifunctional maleimide derivative of 1,4,7-Triazacyclononane-1,4,7-triacetic acid (NOTA) was coupled to thiol-group of cysteine of ZHER2:342 to form the chelator-peptide conjugation .Then the newly produced 18 F

  6. Imaging of platelet-derived growth factor receptor β expression in glioblastoma xenografts using affibody molecule 111In-DOTA-Z09591

    TOLMACHEV, VLADIMIR; Varasteh, Zohreh; HONARVAR, HADIS; Hosseinimehr, Seyed Jalal; Eriksson, Olof; Jonasson, Per; Frejd, Fredrik Y.; Abrahmsen, Lars; ORLOVA, ANNA


    The overexpression and excessive signaling of platelet-derived growth factor receptor β (PDGFRβ) has been detected in cancers, atherosclerosis, and a variety of fibrotic diseases. Radionuclide in vivo visualization of PDGFRβ expression might help to select PDGFRβ targeting treatment for these diseases. The goal of this study was to evaluate the feasibility of in vivo radionuclide imaging of PDGFRβ expression using an Affibody molecule, a small nonimmunoglobulin affinity protein. Methods The P...

  7. Labelled molecules, modern research implements

    Details of the synthesis of carbon 14- and tritium-labelled molecules are examined. Although the methods used are those of classical organic chemistry the preparation of carbon 14-labelled molecules differs in some respects, most noticeably in the use of 14CO2 which requires very special handling techniques. For the tritium labelling of organic molecules the methods are somewhat different, very often involving exchange reactions. The following are described in turn: the so-called Wilzbach exchange method; exchange by catalysis in solution; catalytic hydrogenation with tritium; reductions with borotritides. Some applications of labelled molecules in organic chemistry, biochemistry and pharmacology are listed

  8. EGFR-directed Affibody for fluorescence-guided glioma surgery: time-dose analysis (Conference Presentation)

    Ribeiro de Souza, Ana Luiza; Marra, Kayla; Gunn, Jason R.; Elliott, Jonathan T.; Samkoe, Kimberley S.; Paulsen, Keith D.; Draney, Daniel R.; Feldwisch, Joachim


    The key to fluorescence guided surgical oncology is the ability to create specific contrast between normal and glioma tissue. The blood brain barrier that limits the delivery of substances to the normal brain is broken in tumors, allowing accumulation of agents in the tumor interior. However, for a clinical success, imaging agents should be in the infiltrative edges to minimize the resection of normal brain while enable the removal of tumor. The aberrant overexpression and/or activation of EGFR is associated with many types of cancers, including glioblastoma and the injection of a fluorescent molecule targeted to these receptors would improve tumor contrast during fluorescence guided surgery. Affibody molecules have intentional medium affinity and high potential specificity, which are the desirable features of a good surgical imaging agent. The aim of this study was evaluate the brain/glioma uptake of ABY029 labeled with near-infrared dye IRDye800CW after intravenous injection. Rats were either inoculated with orthotopic implantations of U251 human glioma cell line or PBS (shams control) in the brain. The tumors were allowed to grow for 2-3 weeks before carrying out fluorescent tracer experiments. Fluorescent imaging of ex vivo brain slices from rats was acquired at different time points after infection of fluorescently labeled EGFR-specific affibody to verify which time provided maximal contrast tumor to normal brain. Although the tumor was most clearly visualized after 1h of IRDye800CW-labeled ABY029 injection, the tumor location could be identified from the background after 48h. These results suggest that the NIR-labeled affibody examined shows excellent potential to increase surgical visualization for confirmed EGFR positive tumors.

  9. The tritium labelling of organic molecules by heterogeneous catalytic exchange

    The influence of the temperature at 65 degree centigree and 120 degree centigree on the labelling of three organic molecules with tritium was studied. The compounds were: benzoic acid, de phenyl glyoxal and 2,3-tetramethylene-4-pantothenyl-7-oxo diacetin.The method employed was the heterogeneous catalytic exchange between tritiated water and the organic compound. The purification was made by thin-layer chromatography and the concentration, purity and specific activity of the products were determined by counting and ultraviolet techniques. The thermal stability and the radiolytic effects on labelled benzoic acid were also considered. (Author) 9 refs

  10. Multinuclear NMR of 15 N labelled organic molecules

    The paper presents the application of multinuclear NMR techniques to the study of 15 N labeled organic molecules. There are some important points of great interest in such type of research, namely, structure determination, i.e. location of the 15 N in molecule and determination of 15 N concentration in order to obtain quantitative results about the intramolecular short and long range interaction. Different NMR techniques were used in the study of 13 C, 1 H and 15 N. Obtaining the 15 N NMR signal imposes some special preparation of the spectrometer. First, we had to manage a very large spectral window (-400 to +1200 ppm) which makes difficult finding the signal. Secondly, in the condition of proton decoupling, in a very large band, a decrease of the signal can occur due to the NOE negative effect. To avoid this effect, other decoupling method, called 'inverse gated 1 H decoupling' was used. As a reference, for 15 N, we used CH3NO2, fixed at 0 ppm. In order to find the suitable spectral window we used the formamide (15 N). The results of obtaining the 15 N-labeled procaine are presented. (author)

  11. Technetium-99m Labelled Molecules for Hypoxia Imaging. Chapter 15

    In the field of diagnostic imaging, the concept of imaging hypoxia constitutes an important development and 99mTc labelled vectors have taken a long stride in this direction. Delineation of hypoxic cells amidst oxygenated cells has a strong bearing on treatment strategies and regimes, since hypoxic cells are normally resistant to therapy, thus having a direct influence on the extent of tumour propagation and malignant progression. Inherent drawbacks in the invasive methods currently available for measuring hypoxia led to the development of non-invasive modalities such as use of radiolabelled molecules for imaging hypoxia. In the chapter, an attempt is made to provide a comprehensive overview of 99mTc based radiopharmaceutical agents as well as a brief discussion of other radiolabelled agents that show considerable promise in diagnostic imaging of tumour hypoxia. The review also discusses the phenomenon of hypoxia, other non-invasive methods of detecting hypoxia currently available and the evolution of radiopharmaceuticals to image hypoxia. (author)

  12. Selective Chemical Labeling of Proteins with Small Fluorescent Molecules Based on Metal-Chelation Methodology

    Nobuaki Soh


    Site-specific chemical labeling utilizing small fluorescent molecules is a powerful and attractive technique for in vivo and in vitro analysis of cellular proteins, which can circumvent some problems in genetic encoding labeling by large fluorescent proteins. In particular, affinity labeling based on metal-chelation, advantageous due to the high selectivity/simplicity and the small tag-size, is promising, as well as enzymatic covalent labeling, thereby a variety of novel methods have been stu...

  13. Label-enhanced surface plasmon resonance applied to label-free interaction analysis of small molecules and fragments.

    Eng, Lars; Nygren-Babol, Linnéa; Hanning, Anders


    Surface plasmon resonance (SPR) is a well-established method for studying interactions between small molecules and biomolecules. In particular, SPR is being increasingly applied within fragment-based drug discovery; however, within this application area, the limited sensitivity of SPR may constitute a problem. This problem can be circumvented by the use of label-enhanced SPR that shows a 100-fold higher sensitivity as compared with conventional SPR. Truly label-free interaction data for small molecules can be obtained by applying label-enhanced SPR in a surface competition assay format. The enhanced sensitivity is accompanied by an increased specificity and inertness toward disturbances (e.g., bulk refractive index disturbances). Label-enhanced SPR can be used for fragment screening in a competitive assay format; the competitive format has the added advantage of confirming the specificity of the molecular interaction. In addition, label-enhanced SPR extends the accessible kinetic regime of SPR to the analysis of very fast fragment binding kinetics. In this article, we demonstrate the working principles and benchmark the performance of label-enhanced SPR in a model system-the interaction between carbonic anhydrase II and a number of small-molecule sulfonamide-based inhibitors. PMID:27325502

  14. A study on rhenium labelling for several small molecule ligands

    Objective: Several chemical reactions were studied with the theory of complex chemistry for finding out the objective law of rhenium labelling. Methods: Some kinds of ligands were complexed to rhenium, and the effects were observed in different reactive conditions. The results were analysed with the theories of chemical thermodynamics, chemical dynamics and structure chemistry. Results: 188Re-glucoheptonate (GH): in the condition of pH 2, SnCl2 1 mg, 30 min at room temperature, the labelling ratio was 85.9%. 188Re-methylene-diphosphonate (MDP): in the condition of pH 2, SnCl2 1mg, 30 min at room temperature, the labelling ratio was 85%. 188Re-MIBI: in the condition of pH 2, SnCl2 1 mg, 30 min at 100 degree C, the labelling ratio was 58%. 188Re-citric acid: in the condition of pH 2, SnCl2 1 mg, 30 min at room temperature, the labelling ratio was 92.1%. Conclusion: The theory generated from chemical experiments can be used to direct rhenium labelling and develop the application of rhenium in basic research and clinical diagnosis and therapy

  15. Semiconductor Quantum Rods as Single Molecule FluorescentBiological Labels

    Fu, Aihua; Gu, Weiwei; Boussert, Benjamine; Koski, Kristie; Gerion, Daniele; Manna, Liberato; Le Gros, Mark; Larabell, Carolyn; Alivisatos, A. Paul


    In recent years, semiconductor quantum dots have beenapplied with great advantage in a wide range of biological imagingapplications. The continuing developments in the synthesis of nanoscalematerials and specifically in the area of colloidal semiconductornanocrystals have created an opportunity to generate a next generation ofbiological labels with complementary or in some cases enhanced propertiescompared to colloidal quantum dots. In this paper, we report thedevelopment of rod shaped semiconductor nanocrystals (quantum rods) asnew fluorescent biological labels. We have engineered biocompatiblequantum rods by surface silanization and have applied them fornon-specific cell tracking as well as specific cellular targeting. Theproperties of quantum rods as demonstrated here are enhanced sensitivityand greater resistance for degradation as compared to quantum dots.Quantum rods have many potential applications as biological labels insituations where their properties offer advantages over quantumdots.

  16. Influence of quantum dot labels on single molecule movement in the plasma membrane

    Clausen, Mathias P.; Lagerholm, B. Christoffer


    Single particle tracking results are very dependent on the probe that is used. In this study we have investigated the influence that functionalized quantum dots (QDs) have on the recorded movement in single molecule tracking experiments of plasma membrane species in live cells. Potential issues in...... simultaneous investigations of different plasma membrane species in order to discriminate the effect of the label from differences in movement of the target molecules....

  17. Conformational dynamics of nucleic acid molecules studied by PELDOR spectroscopy with rigid spin labels

    Prisner, T. F.; Marko, A.; Sigurdsson, S. Th.


    Nucleic acid molecules can adopt a variety of structures and exhibit a large degree of conformational flexibility to fulfill their various functions in cells. Here we describe the use of Pulsed Electron-Electron Double Resonance (PELDOR or DEER) to investigate nucleic acid molecules where two cytosine analogs have been incorporated as spin probes. Because these new types of spin labels are rigid and incorporated into double stranded DNA and RNA molecules, there is no additional flexibility of the spin label itself present. Therefore the magnetic dipole-dipole interaction between both spin labels encodes for the distance as well as for the mutual orientation between the spin labels. All of this information can be extracted by multi-frequency/multi-field PELDOR experiments, which gives very precise and valuable information about the structure and conformational flexibility of the nucleic acid molecules. We describe in detail our procedure to obtain the conformational ensembles and show the accuracy and limitations with test examples and application to double-stranded DNA.

  18. Rapid localization of carbon 14-labeled molecules in biological samples by ion mass microscopy

    We report here on the ability of secondary ion mass spectrometry (SIMS) to provide rapid imaging of the intracellular distribution of 14C-labeled molecules. The validity of this method, using mass discrimination of carbon 14 atoms, was assessed by imaging the distribution of two molecules of well-known metabolism, [14C]-thymidine and [14C]-uridine, incorporated by human fibroblasts in culture. As expected, 14C ion images showed the presence of [14C]-thymidine in the nucleus of dividing cells, whereas [14C]-uridine was present in the cytoplasm as well as the nucleus of all cells, with a large concentration in the nucleoli. The time required to obtain the distribution images with the SMI 300 microscope was less than 6 min, whereas microautoradiography, the classical method for mapping the tissue distribution of 14C-labeled molecules, usually requires exposure times of several months. Secondary ion mass spectrometry using in situ mass discrimination is proposed here as a very sensitive method which permits rapid imaging of the subcellular distribution of molecules labeled with carbon 14

  19. Examples of the use of preparatory gas-chromatography in the manufacture of labelled molecules

    Gas chromatography is the most commonly used in the analysis of volatile products. Certain works mention its use for preparatory purposes. Since organic labelled-molecule preparations are usually made in respect of quantities of the order of 1-10 mmole, it has been possible to use gas chromatography with very little alteration for the purification of C14-labelled molecules and their separation from complex reaction mixtures. The apparatus employed is briefly described. The chromatography columns used (diam.: 9-12 mm, length: approx. 4-6 m) made it possible to separate labelled products with boiling-points of up to 180o C and in quantities of approximately 100 mg to 1 g. The fractions detected by a conventional conductivity-cell device were condensed in traps cooled by liquid nitrogen. The radioactivity was not measured at the same time, as an ionization chamber capable of operating at up to 200oC is still only at the research stage. In all cases, the vector gas was helium and the stationary phase support was usually 80 mesh ''celite 545''. Examples are given of applications to the purification of acetone 1-3-C14, benzene C414 methyl or ethyl acrylate 2-3-C14 and butadiene D6, and to the separation of a mixture of aromatic hydrocarbures. (author)

  20. Stable isotope labeling of glycoprotein expressed in silkworms using immunoglobulin G as a test molecule

    Yagi, Hirokazu [Nagoya City University, Faculty and Graduate School of Pharmaceutical Sciences (Japan); Nakamura, Masatoshi [National Institute of Agrobiological Sciences, Genetic Resources Conservation Research Unit, Genetic Resources Center (Japan); Yokoyama, Jun [Taiyo Nippon Sanso Corporation, Tsukuba Laboratories (Japan); Zhang, Ying; Yamaguchi, Takumi [National Institutes of Natural Sciences, Institute for Molecular Science and Okazaki Institute for Integrative Bioscience (Japan); Kondo, Sachiko [Nagoya City University, Faculty and Graduate School of Pharmaceutical Sciences (Japan); Kobayashi, Jun [Yamaguchi University, Department of Biological and Environmental Sciences, Faculty of Agriculture (Japan); Kato, Tatsuya; Park, Enoch Y. [Shizuoka University, Laboratory of Biotechnology, Research Institute of Green Science and Technology (Japan); Nakazawa, Shiori [Nagoya University, Sugashima Marine Biological Laboratory, Graduate School of Science (Japan); Hashii, Noritaka; Kawasaki, Nana [National Institute of Health Sciences, Division of Biological Chemistry and Biologicals (Japan); Kato, Koichi, E-mail: [Nagoya City University, Faculty and Graduate School of Pharmaceutical Sciences (Japan)


    Silkworms serve as promising bioreactors for the production of recombinant proteins, including glycoproteins and membrane proteins, for structural and functional protein analyses. However, lack of methodology for stable isotope labeling has been a major deterrent to using this expression system for nuclear magnetic resonance (NMR) structural biology. Here we developed a metabolic isotope labeling technique using commercially available silkworm larvae. The fifth instar larvae were infected with baculoviruses for co-expression of recombinant human immunoglobulin G (IgG) as a test molecule, with calnexin as a chaperone. They were subsequently reared on an artificial diet containing {sup 15}N-labeled yeast crude protein extract. We harvested 0.1 mg of IgG from larva with a {sup 15}N-enrichment ratio of approximately 80 %. This allowed us to compare NMR spectral data of the Fc fragment cleaved from the silkworm-produced IgG with those of an authentic Fc glycoprotein derived from mammalian cells. Therefore, we successfully demonstrated that our method enables production of isotopically labeled glycoproteins for NMR studies.

  1. Stable isotope labeling of glycoprotein expressed in silkworms using immunoglobulin G as a test molecule

    Silkworms serve as promising bioreactors for the production of recombinant proteins, including glycoproteins and membrane proteins, for structural and functional protein analyses. However, lack of methodology for stable isotope labeling has been a major deterrent to using this expression system for nuclear magnetic resonance (NMR) structural biology. Here we developed a metabolic isotope labeling technique using commercially available silkworm larvae. The fifth instar larvae were infected with baculoviruses for co-expression of recombinant human immunoglobulin G (IgG) as a test molecule, with calnexin as a chaperone. They were subsequently reared on an artificial diet containing 15N-labeled yeast crude protein extract. We harvested 0.1 mg of IgG from larva with a 15N-enrichment ratio of approximately 80 %. This allowed us to compare NMR spectral data of the Fc fragment cleaved from the silkworm-produced IgG with those of an authentic Fc glycoprotein derived from mammalian cells. Therefore, we successfully demonstrated that our method enables production of isotopically labeled glycoproteins for NMR studies

  2. Problems Associated with the Use of Labelled Molecules in Biology and Medicine. General Review

    A general review is given on problems associated with the use of labelled molecules in the life sciences. Three areas of interest were selected for discussion concerning: (a) the tracer molecule; (b) aspects of cellular metabolism; and (c) the toxicity of the incorporated isotopes. In respect of the tracer molecule, specificity of labelling (especially that with tritium), radiochemical purity, biological stability (particularly in the case of tritia ted precursors) and kinetic isotope effects are discussed. The paper also covers various aspects of cellular metabolism, such as the importance of cellular specificity of enzymes, the size of the ''soluble pool'', and control of pool equilibrium, as well as the implication of cell proliferation on isotope content, the relationship between cell cycle and radiosensitivity, factors influencing the duration of the cell cycle, problems of precursor availability and rate of cellular incorporation - including the contribution from precursor reutilization - and the importance of the geometry of the incorporated precursor. The discussion on the toxicity of incorporated isotopes gives an introduction to transmutation effects, aside from radiation effects and considers the transmutation effects of tritium, 14C, 35S and 32P. Attention is called to the possible biological implications of the Auger effect. (author)

  3. Fluorescent labeling of NASBA amplified tmRNA molecules for microarray applications

    Kaplinski Lauris


    Full Text Available Abstract Background Here we present a novel promising microbial diagnostic method that combines the sensitivity of Nucleic Acid Sequence Based Amplification (NASBA with the high information content of microarray technology for the detection of bacterial tmRNA molecules. The NASBA protocol was modified to include aminoallyl-UTP (aaUTP molecules that were incorporated into nascent RNA during the NASBA reaction. Post-amplification labeling with fluorescent dye was carried out subsequently and tmRNA hybridization signal intensities were measured using microarray technology. Significant optimization of the labeled NASBA protocol was required to maintain the required sensitivity of the reactions. Results Two different aaUTP salts were evaluated and optimum final concentrations were identified for both. The final 2 mM concentration of aaUTP Li-salt in NASBA reaction resulted in highest microarray signals overall, being twice as high as the strongest signals with 1 mM aaUTP Na-salt. Conclusion We have successfully demonstrated efficient combination of NASBA amplification technology with microarray based hybridization detection. The method is applicative for many different areas of microbial diagnostics including environmental monitoring, bio threat detection, industrial process monitoring and clinical microbiology.

  4. A study on labelling of bioactive molecules using 99mTc(CO)3(H2O)3+ precursor

    To radiolable bioactive molecules, we synthesized 99mTc precursor, 99mTc(CO)3(H2O)3+ with a low oxidation state (1). We evaluated the characteristics of bioactive molecules labeled with precursor using in vitro and in vivo study. The 99mTc(CO)3(H2O)3+ was synthesized by low pressure carbonylation (1 atm CO) of 99mTcO)4- in the presence of NaBH4 with high labeling yield (>98%) and stability up to 8 hrs. A prepared 99mTc(CO)3(H2O)3+ was reacted with common ligands for 99mTc labeling and amino acids to investigate labeling property of 99mTc(CO)3(H2O)3+. And we also assessed the biodistribution property of 99mTc(CO)3(H2O)3+-complexes in rabbit. 99mTc-tricarbonyl complexes with ligands for 99mTc labeling was also easily prepared and the properties of biodistribution differ between 99mTc-tricarbonyl labeling group and 99mTc labeling one. From these results, we concluded that 99mTc(CO)3(H2O)3+ and 99mTc-tricarbonyl complex is a potential precursor for the development of radiopharmaceuticals, especially for labeling of biomolecules

  5. Synthesis and study of the biodistribution of a new molecule labeled by technetium 99M

    Cytectrenes are stable complexes, neutral, low-weight molecular and lipophilic, that's allowing them to be able to cross the intact BBB. These piperidinic molecules are synthesized by atomic exchange between tricarbonyl technetium with the Fe-Cyclopentadienyl fragment. The labelling reaction is carried out classically in oil bath at a temperature of 150 C during one hour. The reaction can be optimized using microwave. The study of the biodistribution in rat of these complexes after there purification shows high cerebral uptake. Cytectrenes can be used as a potential cerebral radiotracers for the early diagnosis of neuropsychiatric diseases. Cytectrene are able to cross the BBB regarding there lipophilicity. These characteristic allow them to cross the membrane of the white cells and to be used us a potential agent for the diagnosis of infection. (Author). 44 refs

  6. Radiation protection problems in a laboratory for the labelling of molecules with carbon-11

    This paper shows that the qualities of carbon-11, especially its short half-life, which suit it so well for the labelling of radiopharmaceuticals prove to be a great handicap in the preparation of these substances. The operator has to make a fresh preparation for each examination and start with strong radioactivities (200 to 500 mCi) in order to obtain an adequate injected activity at the end of the process, the absorbed dose averaging 1.5 man-rem per manipulation at the fingertips. The development of an automatic preparation method involving as little manual interference as possible has halved the collective dose for twice the dose handled. The labelling of molecules used for diagnosis is now considered to take place under satisfactory radioprotection conditions. The fingertip irradiations are analysed in the light of CIPR recommendations, while regretting that in publication 26 this problem of partial external irradiation of the skin is not dealt with as clearly and precisely as before

  7. The use of radioactive cysteine methyl ester for labeling glycosylated molecules oxidized by periodate or neuraminidase plus galactose oxidase

    Treatment of rat lymph node cells with periodate or neuraminidase plus galactose oxidase initiates blast transformation and cell division of T lymphocytes. Either treatment introduces aldehyde functions onto glycosylated molecules of the plasma membrane. Reduction of the aldehydes with borohydride leads to a concentration-dependent inhibition of the mitogenic response. Cysteine methyl ester (Cys(Me], which can form a stable thiazolidine adduct with aldehydes, also inhibits mitogenesis in a concentration-dependent manner. Maximum inhibition is achieved at Cys(Me) concentrations about 10-fold lower than those required for borohydride (0.4 and 5 mM, respectively). [35S]Cys(Me) has been synthesized and compared with [3H]borohydride as a labeling reagent for molecules on the plasma membrane oxidized by periodate or neuraminidase plus galactose oxidase. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of labeled whole cell lysates or of crude membrane fractions prepared from labeled cells revealed that the same oxidized molecules are specifically labeled with both reagents. Homogenates of cells labeled with either radioactive reagent were fractionated by differential and isopycnic centrifugation. The fractions were analyzed for radioactivity and for a number of marker constituents localized in various subcellular organelles. Following treatment with either reagent, the radioactivity that was covalently incorporated into macromolecules was primarily associated with sedimentable components that distributed among the fractions like plasma membrane markers. When compared with [3H]borohydride, Cys(Me) offers several advantages as a surface labeling reagent for glycosylated plasma membrane molecules, chiefly the possibility of preparing reagents labeled with isotopes other than tritium, including those like 35S, which are much stronger radioactive emitters

  8. Label-free detection of protein molecules secreted from an organ-on-a-chip model for drug toxicity assays

    Morales, Andres W.; Zhang, Yu S.; Aleman, Julio; Alerasool, Parissa; Dokmeci, Mehmet R.; Khademhosseini, Ali; Ye, Jing Yong


    Clinical attrition is about 30% from failure of drug candidates due to toxic side effects, increasing the drug development costs significantly and slowing down the drug discovery process. This partly originates from the fact that the animal models do not accurately represent human physiology. Hence there is a clear unmet need for developing drug toxicity assays using human-based models that are complementary to traditional animal models before starting expensive clinical trials. Organ-on-a-chip techniques developed in recent years have generated a variety of human organ models mimicking different human physiological conditions. However, it is extremely challenging to monitor the transient and long-term response of the organ models to drug treatments during drug toxicity tests. First, when an organ-on-a-chip model interacts with drugs, a certain amount of protein molecules may be released into the medium due to certain drug effects, but the amount of the protein molecules is limited, since the organ tissue grown inside microfluidic bioreactors have minimum volume. Second, traditional fluorescence techniques cannot be utilized for real-time monitoring of the concentration of the protein molecules, because the protein molecules are continuously secreted from the tissue and it is practically impossible to achieve fluorescence labeling in the dynamically changing environment. Therefore, direct measurements of the secreted protein molecules with a label-free approach is strongly desired for organs-on-a-chip applications. In this paper, we report the development of a photonic crystal-based biosensor for label-free assays of secreted protein molecules from a liver-on-a-chip model. Ultrahigh detection sensitivity and specificity have been demonstrated.

  9. Kinetic and Equilibrium Binding Characterization of Aptamers to Small Molecules using a Label-Free, Sensitive, and Scalable Platform

    Chang, Andrew L.; McKeague, Maureen; Liang, Joe C.; Smolke, Christina D.


    Nucleic acid aptamers function as versatile sensing and targeting agents for analytical, diagnostic, therapeutic, and gene-regulatory applications, but their limited characterization and functional validation have hindered their broader implementation. We report the development of a surface plasmon resonance-based platform for rapid characterization of kinetic and equilibrium binding properties of aptamers to small molecules. Our system is label-free and scalable and enables analysis of diffe...

  10. Application of tritiated Schwartz' reagent (ZrCp2Cl3H) for labelling of macrocylic molecules

    The radiolabelling of macrocycles, such as the immunosuppressant fugimycin, is essential for receptor studies, radioimmuno assays and ADME studies. Through the use of Schwartz' Reagent, ZrCp2Cl3H, it is possible to introduce tritium into the vinylic position of a molecule, a site which is thought to be metabolically stable. The preparation of ZrCp2Cl3H as well as the results on the labelling of simpler model compounds will be discussed

  11. Site-specific labeling of proteins for single-molecule FRET by combining chemical and enzymatic modification

    Jager, M; Nir, E; Weiss, S


    An often limiting factor for studying protein folding by single-molecule fluorescence resonance energy transfer (FRET) is the ability to site-specifically introduce a photostable organic FRET donor (D) and a complementary acceptor (A) into a polypeptide chain. Using alternating-laser excitation and chymotrypsin inhibitor 2 as a model, we show that chemical labeling of a unique cysteine, followed by enzymatic modification of a reactive glutamine in an N-terminally appended substrate sequence r...

  12. A Novel Affibody-Auristatin E Conjugate With a Potent and Selective Activity Against HER2+ Cell Lines.

    Sochaj-Gregorczyk, Alicja M; Serwotka-Suszczak, Anna M; Otlewski, Jacek


    Targeted therapy is a new type of cancer treatment that most often uses biologically active drugs attached to a monoclonal antibody. This so called antibody-drug conjugate strategy allows the use of highly toxic substances that target tumor cells specifically, leaving healthy tissues largely unaffected. Over the last few years, antibody-drug conjugates have become a powerful tool in cancer treatment. We developed and characterized a novel cytotoxic conjugate against HER2 tumors in which the antibody has been substituted with a much smaller molecule: the affibody. The conjugate is composed of the ZHER2:2891 affibody that recognizes HER2 and a highly potent cytotoxic drug auristatin E. The ZHER2:2891 molecule does not contain cysteine(s) in its amino acid sequence. We generated 3 variants of ZHER2:2891, each containing a single cysteine to allow conjugation through the maleimide group that is present in the cytotoxic component. In 2 variants, we introduced single S46C and D53C substitutions. In the third variant, a short Drug Conjugation Sequence (DCS) containing a single cysteine was introduced at the C-terminus of ZHER2:2891, resulting in ZHER2:2891-DCS. The latter variant exhibited a significantly higher conjugation yield, and therefore its cytotoxicity has been studied more thoroughly. The ZHER2:2891-DCS-MMAE conjugate killed the HER2-overexpressing SK-BR-3 and MDA-MB-453 cells efficiently (IC50 values of 5.2 and 24.8 nM, respectively). The T-47-D and MDA-MB-231 cells that express normal levels of HER2 were significantly less sensitive to the conjugate (IC50 values of 135.6 and 161.5 nM, respectively). Overall, we have demonstrated for the first time that proteins other than antibodies/antibody fragments can be successfully combined with a linker-drug module, resulting in conjugates that eliminate cancer cells selectively. PMID:27227324

  13. PLLA-PEG-TCH-labeled bioactive molecule nanofibers for tissue engineering

    Chen J


    Full Text Available Jun Chen1,2, Beth Zhou1–3, Qi Li1,2, Jun Ouyang4, Jiming Kong2,4,5, Wen Zhong3,6, Malcolm MQ Xing1,2,4,71Department of Mechanical Engineering, Faculty of Engineering, University of Manitoba, Winnipeg, MB, Canada; 2Manitoba Institute of Child Health, Winnipeg, MB, Canada; 3Department of Textile Sciences, Faculty of Human Ecology, University of Manitoba, Winnipeg, MB, Canada; 4School of Basic Medical Science, Southern Medical University, Guangzhoug, China; 5Department of Human Anatomy and Cell Sciences, 6Department of Medical Microbiology, Faculty of Medicine, 7Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, MB, CanadaAbstract: By mimicking the native extracellular matrix, electrospun nanofibrous scaffolds (ENSs can provide both chemical and physical cues to modulate cell adherence and differentiation and to promote tissue regeneration while retaining bioresorbable and biocompatible properties. In this study, ENSs were developed to deliver multiple biomolecules by loading them into the core-sheath structure and/or by conjugating them to the nanofiber surfaces. In this work, poly(L-lactide-poly(ethylene glycol-NH2 and poly(L-lactide were emulsion electrospun into nanofibers with a core-sheath structure. A model drug, tetracycline hydrochloride, was loaded within the nanofibers. Amino and carboxyl reactive groups were then activated on the fiber surfaces using saturated water vapor exposure and base hydrolysis, respectively. These reactive groups allowed the surface of the ENS to be functionalized with two other bioactive molecules, fluorescein isothiocyanate- and rhodamine-labeled bovine serum albumins, which were used as model proteins. The ENSs were shown to retain their antimicrobial capacity after two functionalization reactions, indicating that multifunctional nanofibers can potentially be developed into functional wound dressings or periodontal membranes or used in more complicated

  14. Electrochemical immobilization of Fluorescent labelled probe molecules on a FTO surface for affinity detection based on photo-excited current

    Haruyama, Tetsuya; Wakabayashi, Ryo; Cho, Takeshi; Matsuyama, Sho-taro, E-mail: [Kyushu Institute of Technology, Department of Biological Functions and Engineering, Kitakyushu Science and Research Park, Hibikino, Kitakyushu, Fukuoka 808-0196 (Japan)


    Photo-excited current can be generated at a molecular interface between a photo-excited molecules and a semi-conductive material in appropriate condition. The system has been recognized for promoting photo-energy devices such as an organic dye sensitized solar-cell. The photo-current generated reactions are totally dependent on the interfacial energy reactions, which are in a highly fluctuated interfacial environment. The authors investigated the photo-excited current reaction to develop a smart affinity detection method. However, in order to perform both an affinity reaction and a photo-excited current reaction at a molecular interface, ordered fabrications of the functional (affinity, photo-excitation, etc.) molecules layer on a semi-conductive surface is required. In the present research, we would like to present the fabrication and functional performance of photo-excited current-based affinity assay device and its application for detection of endocrine disrupting chemicals. On the FTO surface, fluorescent pigment labelled affinity peptide was immobilized through the EC tag (electrochemical-tag) method. The modified FTO produced a current when it was irradiated with diode laser light. However, the photo current decreased drastically when estrogen (ES) coexisted in the reaction solution. In this case, immobilized affinity probe molecules formed a complex with ES and estrogen receptor (ER). The result strongly suggests that the photo-excited current transduction between probe molecule-labelled cyanine pigment and the FTO surface was partly inhibited by a complex that formed at the affinity oligo-peptide region in a probe molecule on the FTO electrode. The bound bulky complex may act as an impediment to perform smooth transduction of photo-excited current in the molecular interface. The present system is new type of photo-reaction-based analysis. This system can be used to perform simple high-sensitive homogeneous assays.

  15. [{sup 99m}Tc(CO){sub 3}]{sup +}-(HE){sub 3}-Z{sub IGF1R:4551}, a new Affibody conjugate for visualization of insulin-like growth factor-1 receptor expression in malignant tumours

    Orlova, Anna; Varasteh, Zohreh [Uppsala University, Preclinical PET Platform, Department of Medicinal Chemistry, Uppsala (Sweden); Hofstroem, Camilla; Graeslund, Torbjoern [Royal Institute of Technology, Division of Molecular Biotechnology, School of Biotechnology, Stockholm (Sweden); Strand, Joanna [Uppsala University, Division of Biomedical Radiation Sciences, Uppsala (Sweden); Sandstrom, Mattias [Uppsala University Hospital, Medical Physics, Department of Oncology, Uppsala (Sweden); Andersson, Karl [Uppsala University, Division of Biomedical Radiation Sciences, Uppsala (Sweden); Ridgeview Instruments AB, Uppsala (Sweden); Tolmachev, Vladimir [Uppsala University, Division of Biomedical Radiation Sciences, Uppsala (Sweden); Uppsala University, Biomedical Radiation Sciences, Rudbeck Laboratory, Uppsala (Sweden)


    Radionuclide imaging of insulin-like growth factor type 1 receptor (IGF-1R) expression in tumours might be used for selection of patients who would benefit from IGF-1R-targeted therapy. We have previously shown the feasibility of IGF-1R imaging using the Affibody molecule {sup 111}In-DOTA-His{sub 6}-Z{sub IGF1R:4551}. The use of {sup 99m}Tc instead of {sup 111}In should improve sensitivity and resolution of imaging, and reduce the dose burden to patients. We hypothesized that inclusion of a HEHEHE tag instead of a His{sub 6} tag in Z{sub IGF1R:4551} would permit its convenient purification using IMAC, enable labelling with [{sup 99m}Tc(CO){sub 3}]{sup +}, and improve its biodistribution. Z{sub IGF1R:4551} was expressed with a HEHEHE tag in the N terminus. The resulting (HE){sub 3}-Z{sub IGF1R:4551} construct was labelled with [{sup 99m}Tc(CO){sub 3}]{sup +}. Targeting of IGF-1R-expressing cells using [{sup 99m}Tc(CO){sub 3}]{sup +}-(HE){sub 3}-Z{sub IGF1R:4551} was evaluated in vitro and in vivo. (HE){sub 3}-Z{sub IGF1R:4551} was stably labelled with {sup 99m}Tc with preserved specific binding to IGF-1R-expressing DU-145 prostate cancer cells in vitro. In mice, [{sup 99m}Tc(CO){sub 3}]{sup +}-(HE){sub 3}-Z{sub IGF1R:4551} accumulated in IGF-1R-expressing organs (pancreas, stomach, lung and salivary gland). [{sup 99m}Tc(CO){sub 3}]{sup +}-(HE){sub 3}-Z{sub IGF1R:4551} demonstrated 3.6-fold lower accumulation in the liver and spleen than {sup 111}In-DOTA-Z{sub IGF1R:4551}. In NMRI nu/nu mice with DU-145 prostate cancer xenografts, the tumour uptake was 1.32 {+-} 0.11 %ID/g and the tumour-to-blood ratio was 4.4 {+-} 0.3 at 8 h after injection. The xenografts were visualized using a gamma camera 6 h after injection. [{sup 99m}Tc(CO){sub 3}]{sup +}-(HE){sub 3}-Z{sub IGF1R:4551} is a promising candidate for visualization of IGF-1R expression in malignant tumours. (orig.)

  16. Study of acetylcholine and barium receptors in the rat duodeno-jejunum by means of labelled molecules

    The purpose of this work is the determination of the number and the localization of Acetylcholine and Barium receptors in the rat intestine. We used 'radioactive labelled' drugs to reach a high sensitiveness of detection. So we were able to point out the number of 'effective' molecules of drugs, that is to say the only ones combining with receptors. With the aid of some assumptions, we determine on the one hand the receptors localization by an assessment of the drug penetration depth before reaching their level and on the other hand the number of these receptors. (author)

  17. Labeling of complex molecules with 18F, 13N, and 11C

    The overall objective during the period covered by this report was to develop a broad spectrum of radiopharmaceuticals labeled with short-lived cyclotron positron emitters, 11C, 13N and 18F. The goals of the program during the last year were: (1) to complete the modular automated system for important precursor production - formaldehyde, methyliodide, cyanide; (2) to perform animal studies with the 18F-glucose analogues 2FDG and 3FDG and measure the constants for both agents in different animals; and (3) to initiate the development of new fatty acid analogues for the myocardial imaging and metabolism. As part of a collaboration with other groups seeking new agents for myocardium and brain, 9-/sup 123m/Te-telluriumheptadecanoic acid as a myocardial imaging agent was studied. This compound could be used for designing new fatty acid analogues labeled with 11C and 18F that stay in the myocardium because of metabolic inhibition

  18. Dextran hydrogel coated surface plasmon resonance imaging (SPRi) sensor for sensitive and label-free detection of small molecule drugs

    Li, Shaopeng; Yang, Mo; Zhou, Wenfei; Johnston, Trevor G.; Wang, Rui; Zhu, Jinsong


    The label-free and sensitive detection of small molecule drugs on SPRi is still a challenging task, mainly due to the limited surface immobilization capacity of the sensor. In this research, a dextran hydrogel-coated gold sensor chip for SPRi was successfully fabricated via photo-cross-linking for enhanced surface immobilization capacity. The density of the dextran hydrogel was optimized for protein immobilization and sensitive small molecule detection. The protein immobilization capacity of the hydrogel was 10 times greater than a bare gold surface, and 20 times greater than an 11-mercaptoundecanoic acid (MUA) surface. Such a drastic improvement in immobilization capacity allowed the SPRi sensor to detect adequate response signals when probing small molecule binding events. The binding signal of 4 nM liquid-phase biotin to streptavidin immobilized on the dextran surface reached 435 RU, while no response was observed on bare gold or MUA surfaces. The dextran hydrogel-coated SPRi sensor was also applied in a kinetic study of the binding between an immunosuppressive drug (FK506) and its target protein (FKBP12) in a high-throughput microarray format. The measured binding affinity was shown to be consistent with reported literature values, and a detection limit of 0.5 nM was achieved.

  19. Preparation of nanocolloids based on modified DTPA molecule labeled with technetium-99M

    Full text: The method for preparation of new nanocolloid chemical systems based on modified diethylene triamine pentaacetic acid molecule has been elaborated in this work. Optimal method of sentinel lymph mode detection considers the use of colloid nanomaterials labled with technetium-99m for sintigraphic or radiometric detection of mode localization. The result of dynamic scintigraphic research showed that after being injected the substance is actively accumulated into lymphatic system

  20. Tetrairon(III) single-molecule magnet monolayers on gold: insights from ToF-SIMS and isotopic labeling.

    Totaro, Pasquale; Poggini, Lorenzo; Favre, Annaick; Mannini, Matteo; Sainctavit, Philippe; Cornia, Andrea; Magnani, Agnese; Sessoli, Roberta


    To work as magnetic components in molecular electronics and spintronics, single-molecule magnets (SMMs) must be reliably interfaced with metals. The organization on gold of a Fe4 SMM carrying two acetyl-protected thiol groups has been studied by exploiting the surface sensitivity of time-of-flight secondary ion mass spectrometry (ToF-SIMS), additionally powered by the use of an isotopic labeling strategy. Deposition from millimolar dichloromethane solutions results in a higher surface coverage and better packed monolayers as compared with previous protocols based on more diluted solutions. Fe4 complexes are chemically tethered to the surface via a single Au-S bond while they still contain an intact SAc group. PMID:25000391

  1. Studies on the development of 99mTc labelled serotonin receptor avid molecules

    Among the central nervous system (CNS) receptors, serotonin is reported to be very important with respect to the study of brain disorders. Hence this work focuses on serotonin. A summary of the studies that were carried out is given. These include: (a) standardization of the method of serotonin receptor preparation from rat brains and development of a radioreceptor assay using radio-iodinated serotonin, (b) standardization of the method of radio-iodination of serotonin using a tyrosylmethyl ester derivative of serotonin and the preparation of 14C labelled serotonin, (c) synthesis of the SNS tridentate ligand (following the procedure developed by the Democritos National Centre of Scientific Research (NCSR), Athens) and evaluation of a 99mTc complex formed with the tridentate SNS ligand and thiocresol for use as a CNS receptor imaging agent and (d) evaluation of the 99mTc complex formed with a SNS piperazine based tridentate ligand and a monodentate co-ligand (thiophenol obtained from NCSR). This limited study on brain uptake of the complex in rats showed that more structural modification of the ligand is required for preparation of a complex suitable for CNS receptor imaging. Also included is a design for synthesis of a novel complex based on the reported information on the 5-iodo-2-[(2-dimethyl)aminomethylphynoxy]benzyl alcohol compound, which is reported to have a binding affinity for serotonin re-uptake sites. (author)

  2. A laser scanner for imaging fluorophore labeled molecules in electrophoretic gels

    Fisk, D.J.; Sutherland, J.C. [Brookhaven National Lab., Upton, NY (United States). Biology Dept.


    A laser scanner for imaging electrophoretic gels was constructed and tested. The scanner incorporates a green helium-neon (HeNe) laser (543.5nm wavelength) and can achieve a spatial resolution of 19{micro}m. The instrument can function in two modes : snap-shot and finish-line. In snapshot mode, all samples are electrophoresed for the same time and the gel is scanned after completion of electrophoresis, while in finish-line mode, fluorophore labeled samples are electrophoresed for a constant distance and the image is formed as the samples pass under the detector. The resolving power of the finish-line mode of imaging is found to be greater than that of the snapshot mode of imaging. This laser scanner is also compared with a Charge Coupled Device (CCD) camera and in terms of resolving power is found to be superior. Sensitivity of the instrument is presented in terms of the minimum amount of DNA that can be detected verses its molecular length.

  3. Rapid method for radiofluorination of pyridine derivatives: Prosthetic groups for labelling bioactive molecules

    Ethyl 2-[18F]fluoro-4-pyridine and ethyl 6-[18F]fluoro-3-pyridine carboxylates were synthesized by catalyzed nucleophlic no-carrier-added radiofluorination. Treatment of the ethyl-2-(N,N,N-trimethylammonium)-4-pyridine- and ethyl-6-(N,N,Ntrimethylammonium)- 3-pyridine carboxylate.treflate precursors with radiofluoride and Kryptofix 2.2.2 in anhydrous acetonitrile at 95 deg. C provided these radiofluorinated intermediates with a greater than 90% radiochemical yield within 2 min reaction time. These intermediates served as precursors to obtain the activated N-succinimidyl 2-[18F]fluoro- 4-pyridine and 6-[18F]fluoro-3-pyridine carboxylate esters for efficient coupling to amine functions in bioactive molecules. This technique was used to radiofluorinate a model chemotactic peptide (N-Formyl-Nle-Leu-Phe-Nle-Tyr-Lys). Biodistribution studies in normal CBA/J mice revealed very rapid clearance through the renal system. (author)

  4. Some examples of the use of carbon 11-labelled molecules in medical research

    If a radioelement is to be useful for medical diagnosis it must: be an indicator of a normal or pathological biological process; have a half-life consistent with the duration of the biological phenomenon to be observed; emit a suitable radiation. Carbon 11 is one of the radionuclides which best satisfies these different requirements. It is shown how this radioelement, of 20-minute half-life, may be incorporated into psychotropic drugs and biologically useful molecules with enough speed to have an available radioactivity adequate for diagnostic examinations. Two examples are described, one concerning the metabolism of a neuroleptic, chlorpromazine-11C, the other the passage of methionine-11C through the blood brain barrier during a congenital disease, phenylketonuria

  5. Single Molecule 3D Orientation in Time and Space: A 6D Dynamic Study on Fluorescently Labeled Lipid Membranes.

    Börner, Richard; Ehrlich, Nicky; Hohlbein, Johannes; Hübner, Christian G


    Interactions between single molecules profoundly depend on their mutual three-dimensional orientation. Recently, we demonstrated a technique that allows for orientation determination of single dipole emitters using a polarization-resolved distribution of fluorescence into several detection channels. As the method is based on the detection of single photons, it additionally allows for performing fluorescence correlation spectroscopy (FCS) as well as dynamical anisotropy measurements thereby providing access to fast orientational dynamics down to the nanosecond time scale. The 3D orientation is particularly interesting in non-isotropic environments such as lipid membranes, which are of great importance in biology. We used giant unilamellar vesicles (GUVs) labeled with fluorescent dyes down to a single molecule concentration as a model system for both, assessing the robustness of the orientation determination at different timescales and quantifying the associated errors. The vesicles provide a well-defined spherical surface, such that the use of fluorescent lipid dyes (DiO) allows to establish a a wide range of dipole orientations experimentally. To complement our experimental data, we performed Monte Carlo simulations of the rotational dynamics of dipoles incorporated into lipid membranes. Our study offers a comprehensive view on the dye orientation behavior in a lipid membrane with high spatiotemporal resolution representing a six-dimensional fluorescence detection approach. PMID:26972111

  6. Synthetic and natural consensus design for engineering charge within an affibody targeting epidermal growth factor receptor.

    Case, Brett A; Hackel, Benjamin J


    Protein ligand charge can impact physiological delivery with charge reduction often benefiting performance. Yet neutralizing mutations can be detrimental to protein function. Herein, three approaches are evaluated to introduce charged-to-neutral mutations of three cations and three anions within an affibody engineered to bind epidermal growth factor receptor. These approaches-combinatorial library sorting or consensus design, based on natural homologs or library-sorted mutants-are used to identify mutations with favorable affinity, stability, and recombinant yield. Consensus design, based on 942 affibody homologs, yielded a mutant of modest function (Kd  = 11 ±4 nM, Tm  = 62°C, and yield = 4.0 ± 0.8 mg/L as compared to 5.3 ± 1.7 nM, 71°C, and 3.5 ± 0.3 mg/L for the parental affibody). Extension of consensus design to 10 additional mutants exhibited varied performance including a substantially improved mutant (Kd  = 6.9 ± 1.4 nM, Tm  = 71°C, and 12.7 ± 0.9 mg/L yield). Sorting a homolog-based combinatorial library of 7 × 10(5) mutants generated a distribution of mutants with lower stability and yield, but did identify one strongly binding variant (Kd  = 1.2 ± 0.3 nM, Tm  = 69°C, and 6.0 ± 0.4 mg/L yield). Synthetic consensus design, based on the amino acid distribution in functional library mutants, yielded higher affinities (P = 0.05) with comparable stabilities and yields. The best of four analyzed clones had Kd  = 1.7 ± 0.5 nM, Tm  = 68°C, and 7.0 ± 0.5 mg/L yield. While all three approaches were effective in creating targeted affibodies with six charged-to-neutral mutations, synthetic consensus design proved to be the most robust. Synthetic consensus design provides a valuable tool for ligand engineering, particularly in the context of charge manipulation. Biotechnol. Bioeng. 2016;113: 1628-1638. © 2016 Wiley Periodicals, Inc. PMID:26724421

  7. Cyclotron production of molecules labelled with short-lived radioisotopes β+ emitters (15O, 13N, 11C) and their clinical uses

    Clinical use of three short-lived radioisotopes: 15O, 13N and 11C is studied on two complementary aspects. A production and purification system is realized; detection instruments in medical use are studied. The production of labelled molecules with the three radiotracers 15O, 13N, 11C from the target bombardment with charged and accelerated particles was studied

  8. Single molecule resolution of the antimicrobial action of quantum dot-labeled sushi peptide on live bacteria

    Chen Jianzhu


    Full Text Available Abstract Background Antimicrobial peptides are found in all kingdoms of life. During the evolution of multicellular organisms, antimicrobial peptides were established as key elements of innate immunity. Most antimicrobial peptides are thought to work by disrupting the integrity of cell membranes, causing pathogen death. As antimicrobial peptides target the membrane structure, pathogens can only acquire resistance by a fundamental change in membrane composition. Hence, the evolution of pathogen resistance has been a slow process. Therefore antimicrobial peptides are valuable alternatives to classical antibiotics against which multiple drug-resistant bacteria have emerged. For potential therapeutic applications as antibiotics a thorough knowledge of their mechanism of action is essential. Despite the increasingly comprehensive understanding of the biochemical properties of these peptides, the actual mechanism by which antimicrobial peptides lyse microbes is controversial. Results Here we investigate how Sushi 1, an antimicrobial peptide derived from the horseshoe crab (Carcinoscorpius rotundicauda, induces lysis of Gram-negative bacteria. To follow the entire process of antimicrobial action, we performed a variety of experiments including transmission electron microscopy and fluorescence correlation spectroscopy as well as single molecule tracking of quantum dot-labeled antimicrobial peptides on live bacteria. Since in vitro measurements do not necessarily correlate with the in vivo action of a peptide we developed a novel fluorescent live bacteria lysis assay. Using fully functional nanoparticle-labeled Sushi 1, we observed the process of antimicrobial action at the single-molecule level. Conclusion Recently the hypothesis that many antimicrobial peptides act on internal targets to kill the bacterium has been discussed. Here, we demonstrate that the target sites of Sushi 1 are outer and inner membranes and are not cytosolic. Further, our findings

  9. Stable isotope labelling reveals that NaCl stress decreases the production of Ensifer (Sinorhizobium) arboris lipochitooligosaccharide signalling molecules.

    Penttinen, Petri; Räsänen, Leena A; Lortet, Gilles; Lindström, Kristina


    Ensifer (Sinorhizobium) arboris is a symbiont of salt-tolerant leguminous trees in the genera Acacia and Prosopis that are utilized in the prevention of soil erosion and desertification and in phytoremediation of salinized soil. Signalling between the plant and the rhizobia is essential for the formation of effective symbiosis that increases the success of reclaiming saline sites. We assessed the effect of salt stress on the growth and the production of lipochitooligosaccharide signalling molecules (LCOs) of S. arboris HAMBI 2361, an LCO-overproducing derivative of the S. arboris type strain HAMBI 1552. The strain tolerated NaCl up to 750 mM. To obtain both qualitative and quantitative information on the LCO production under salt stress, we devised a method where LCOs were differentially labelled by stable isotopes of nitrogen, (14)N and (15)N, and analysed by mass spectrometry. Under control conditions, the strain produced altogether 27 structural LCO variants. In 380 mM NaCl, 13 LCO variants were produced in detectable amounts, and six of these were reliably quantified, ranging from one-tenth to one-third of the non-stressed one. PMID:24256411

  10. Immunoassay of 5-methyltetrahydrofolate: use of 125I-labeled protein A as the tracer molecule for specific antibody

    A sensitive and specific solid-phase radioimmunoassay for 5-methyltetrahydrofolate (5-MTHFA) has been developed. 125I-Labeled staphylococcal Protein A (125I-PA) was used as the tracer molecule for rabbit IgG antibodies bound to 5-MTHFA immobilized on polyacrylamide beads. The dose-dependent inhibition of antibody binding by fluid-phase drug was reflected in decreased binding of 125I-PA. This inhibition, determined in the presence of known amounts of 5-MTHFA, served as the basis for quantification of 5-MTHFA in test samples. An early bleeding was relatively specific; 4.5 ng 5-MTHFA inhibited immune binding by 50% compared to 7700 ng folinic acid or 1200 ng tetrahydrofolate. Other folic acid analogs, including methotrexate, failed to inhibit significantly. The assay using a later bleeding was more sensitive since 1.6 ng 5-MTHFA gave 50% inhibition (detection limit 0.2 ng), but folinic acid cross-reacted significantly. Absorption with immobilized folinic acid markedly enhanced the specificity of this antiserum and resulted in a 15 to 20% increase in maximum inhibition by 5-MTHFA. The assay could be carried out in the presence of 0.025 ml human serum or urine without affecting the standard curve, and was used to determine levels of 5-MTHFA in serum of drug-treated rabbits

  11. Label-free electrochemical lead (II) aptasensor using thionine as the signaling molecule and graphene as signal-enhancing platform.

    Gao, Feng; Gao, Cai; He, Suyu; Wang, Qingxiang; Wu, Aiqun


    A label-free and highly sensitive electrochemical aptasensor for Pb(2+) was constructed using thionine (TH) as the signaling molecule and graphene (GR) as the signal-enhancing platform. The electrochemical sensing interface was fabricated by stepwise assembly of GR and TH on the lead (II) specific aptamer (LSA) modified electrode. Upon interaction with Pb(2+), the aptamer probe on the sensor underwent conformational switch from a single-stranded DNA form to the G-quadruplex structure, causing the GR with assembled TH released from the electrode surface into solution. As a result, the electrochemical signal of TH on the aptasensor was substantially reduced. Under the optimal experimental conditions, the attenuation of peak currents presented a good linear relationship with the logarithm of Pb(2+) concentrations over the range from 1.6×10(-13) to 1.6×10(-10)M. The detection limit was estimated to be 3.2×10(-14)M. The aptasensor also exhibited good regenerability, excellent selectivity, and acceptable reproducibility, indicating promising application in environment monitoring of lead. PMID:26913503

  12. The tritium labelling of organic molecules by heterogeneous catalytic exchange; El marcado de moleculas organicas con tritio por intercambio catalitico heterogeneo

    Angoso Marina, M.; Kaiser Ruiz del Olmo, F.


    The influence of the temperature at 65 degree centigree and 120 degree centigree on the labelling of three organic molecules with tritium was studied. The compounds were: benzoic acid, de phenyl glyoxal and 2,3-tetramethylene-4-pantothenyl-7-oxo diacetin.The method employed was the heterogeneous catalytic exchange between tritiated water and the organic compound. The purification was made by thin-layer chromatography and the concentration, purity and specific activity of the products were determined by counting and ultraviolet techniques. The thermal stability and the radiolytic effects on labelled benzoic acid were also considered. (Author) 9 refs.

  13. Enantiospecific C(sp3)-H activation catalyzed by ruthenium nanoparticles : application to isotopic labeling of molecules of biological interest.

    Taglang, Céline


    Isotopic labeling with deuterium and tritium is extensively used in chemistry, biology and pharmaceutical research.Numerous methods of labeling by isotopic exchange allow high isotopic enrichments but generally require harsh conditions (high temperatures, acidity). As a consequence, a general, regioselective and smooth labeling method that might be applicable to a wide diversity of substrates remains to develop. In the first part of this thesis, we demonstrated that the use of ruthenium nanop...

  14. A DNA-templated silver nanocluster probe for label-free, turn-on fluorescence-based screening of homo-adenine binding molecules.

    Park, Ki Soo; Park, Hyun Gyu


    A novel, label-free, turn-on fluorescence strategy to detect molecules that bind to adenine-rich DNA sequences has been developed. The probe employs DNA-templated silver nanoclusters (DNA-AgNCs) as the key detection component. The new strategy relies on the formation of non-Watson-Crick homo-adenine DNA duplex, triggered by strong interactions with homo-adenine binding molecules, which brings a guanine-rich sequence in one strand close to DNA-AgNCs located on the opposite strand. This phenomenon transforms weakly fluorescent AgNCs into highly emissive species that display bright red fluorescence. Finally, we have shown that the new fluorescence turn-on strategy can be employed to detect coralyne, the most representative homo-adenine binding molecule that triggers formation of a non-Watson-Crick homo-adenine DNA duplex. PMID:25441410

  15. Radioiodine and its labelled compounds

    Chemical characteristics and their nuclear characteristics, types of labelled molecules,labelling procedures, direct labelling with various oxidizing agents, indirect labelling with various conjugates attached to protein molecules, purification and quality control. Iodination damage.Safe handling of labelling procedures with iodine radioisotopes.Bibliography

  16. Analysis of the fluctuations of a single-tethered, quantum-dot labeled DNA molecule in shear flow

    Laube, K; Guenther, K; Mertig, M, E-mail: [Professur fuer Physikalische Chemie, Mess- und Sensortechnik, Technische Universitaet Dresden, 01062 Dresden (Germany)


    A novel technique for analyzing the conformational fluctuations of a single, surface-tethered DNA molecule by fluorescence microscopy is reported. Attaching a nanometer-sized fluorescent quantum dot to the free end of a {lambda}-phage DNA molecule allows us to study the fluctuations of a native DNA molecule without the mechanical properties being altered by fluorescent dye staining. We report on the investigation of single-tethered DNA in both the unperturbed and the shear flow induced stretched state. The dependence of the observed fractional extension and the magnitude of fluctuations on the shear rate can be qualitatively interpreted by Brochard's stem-and-flower model. The cyclic dynamics of a DNA molecule is directly observed in the shear flow experiment.

  17. The synthesis of multifunctional nanoparticles conjugated with anti-Her2 affibody and monomethylauristatin E

    Pala, Katarzyna; Jakimowicz, Piotr; Cyranka-Czaja, Anna; Otlewski, Jacek


    Conjugation of bioactive xenobiotics with innert particles often improves their efficacy and/or specificity. In this work we designed superparamagnetic ferric oxide nanoparticles (NPs) conjugated with a strong cytotoxic drug, monomethylauristatin E (MMAE), and evaluated their potential against cancer cells. Cytotoxicity tests showed that the conjugate was at least twice as toxic as the free drug. We then studied the cytotoxic potential of the conjugate at an elevated temperature achieved due to the superparamagnetic properties of the NPs, finding no enhancement of cytotoxicity in comparison with that at 37 °C. Next, multifunctional NPs containing MMAE and a targeting agent were synthesized. The targeting agent was the ZHer2:342 affibody specific to Her2 receptor. The selectivity and effectiveness of the conjugates was evaluated using SK-BR3 (Her2-positive) and U-87 MG (a negative control) cell lines. The multifunctional NPs selectively decrease of the viability of the SK-BR3 cells, showing their specificity towards cells overexpressing the Her2 receptor.

  18. Transport and fate of labelled molecules after application of 14C-gibberellic acid to the young leaves of tomato plants

    After application of 14C-GA3 to the distal leaflet of young leaves (2.5 cm long) of tomato plants, labelled molecules are exported by the donor leaflet. In the first stage, the transport was basipetal, and preferably took place in the tissues of foliar traces; the tracers moved toward the roots at an average speed greater than 4 cm.h-1. One part of the tracers seemed to accumulate in the elongating internodes, whereas a more important part went into the vessels and then was driven upwards to the leaves by the transpiration stream. A high concentration of tracers was localized in the extremity of some leaflets. The guttated fluid contained labelled molecules having for the most part a Rsub(t) value similar or nearly similar to the Rsub(f) value of GA3 according to the solvent systems. The exportation of 14C, which was at first very low, continued during the development of the donor leaf

  19. Ultra-sensitive DNA assay based on single-molecule detection coupled with fluorescent quantum dot-labeling and its application to determination of messenger RNA

    Li Li [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Li Xincang [School of Life Sciences, Shandong University, Jinan 250100 (China); Li Lu [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Wang Jinxing [School of Life Sciences, Shandong University, Jinan 250100 (China); Jin Wenrui, E-mail: [School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)


    An ultra-sensitive single-molecule detection (SMD) method for quantification of DNA using total internal reflection fluorescence microscopy (TIRFM) coupled with fluorescent quantum dot (QD)-labeling was developed. In this method, the target DNA (tDNA) was captured by the capture DNA immobilized on the silanized coverslip blocked with ethanolamine and bovine serum albumin. Then, the QD-labeled probe DNA was hybridized to the tDNA. Ten fluorescent images of the QD-labeled sandwich DNA hybrids on the coverslip were taken by a high-sensitive CCD. The tDNA was quantified by counting the bright spots on the images using a calibration curve. The LOD of the method was 1 x 10{sup -14} mol L{sup -1}. Several key factors, including image acquirement, fluorescence probe, substrate preparation, noise elimination from solutions and glass coverslips, and nonspecific adsorption and binding of solution-phase detection probes were discussed in detail. The method could be applied to quantify messenger RNA (mRNA) in cells. In order to determine mRNA, double-stranded RNA-DNA hybrids consisting of mRNA and corresponding cDNA were synthesized from the cellular mRNA template using reverse transcription in the presence of reverse transcriptase. After removing the mRNA in the double-stranded hybrids using ribonuclease, cDNA was quantified using the SMD-based TIRFM. Osteopontin mRNA in decidual stromal cells was chosen as the model analyte.

  20. Enantio-specific C(sp3)-H activation catalyzed by ruthenium nanoparticles: application to isotopic labeling of molecules of biological interest

    Isotopic labeling with deuterium and tritium is extensively used in chemistry, biology and pharmaceutical research. Numerous methods of labeling by isotopic exchange allow high isotopic enrichments but generally require harsh conditions (high temperatures, acidity). As a consequence, a general, regioselective and smooth labeling method that might be applicable to a wide diversity of substrates remains to develop. In the first part of this thesis, we demonstrated that the use of ruthenium nanoparticles, synthesized by Pr. Bruno Chaudret's team (INSA Toulouse), allowed the mild (2 bar of deuterium gas at 55 C), effective and selective H/D exchange reaction of a large variety of nitrogen-containing compounds, such as pyridines, indoles and primary, secondary and tertiary alkyl amines. The usefulness and the efficiency of this novel methodology was demonstrated by the deuteration of eight nitrogen-containing molecules of biological interest without altering their chemical and stereochemical properties. However, the conservation of the original stereochemistry of an activated chiral C-H center remains a major issue. We studied the reactivity of RuNP(at)PVP on different categories of nitrogen-containing substrates (amines, aminoacids and peptides) in water or in organic solvents. Our results showed that C-H activation of chiral carbons C(sp3) took place efficiently, selectively and, in all cases, with total retention of configuration. The wide range of applications of this procedure was demonstrated by the labeling of three chiral amines, fourteen aminoacids, three aromatic amino esters and four peptides. Moreover, our collaboration with Pr. Romuald Poteau's team (INSA Toulouse) led to the identification of two mechanisms by ab initio simulation in agreement with our experimental results: the σ-bond metathesis mechanism and the oxidative addition mechanism. These two mechanisms imply two vicinal ruthenium atoms leading to the formation an original

  1. Screening small-molecule compound microarrays for protein ligands without fluorescence labeling with a high-throughput scanning microscope

    Fei, Yiyan; Landry, James P.; Sun, Yungshin; Zhu, Xiangdong; Wang, Xiaobing; Luo, Juntao; Wu, Chun-Yi; Lam, Kit S.


    We describe a high-throughput scanning optical microscope for detecting small-molecule compound microarrays on functionalized glass slides. It is based on measurements of oblique-incidence reflectivity difference and employs a combination of a y-scan galvometer mirror and an x-scan translation stage with an effective field of view of 2 cm×4 cm. Such a field of view can accommodate a printed small-molecule compound microarray with as many as 10,000 to 20,000 targets. The scanning microscope is...

  2. Single molecule super-resolution imaging of proteins in living Salmonella enterica using self-labelling enzymes.

    Barlag, Britta; Beutel, Oliver; Janning, Dennis; Czarniak, Frederik; Richter, Christian P; Kommnick, Carina; Göser, Vera; Kurre, Rainer; Fabiani, Florian; Erhardt, Marc; Piehler, Jacob; Hensel, Michael


    The investigation of the subcellular localization, dynamics and interaction of proteins and protein complexes in prokaryotes is complicated by the small size of the cells. Super-resolution microscopy (SRM) comprise various new techniques that allow light microscopy with a resolution that can be up to ten-fold higher than conventional light microscopy. Application of SRM techniques to living prokaryotes demands the introduction of suitable fluorescent probes, usually by fusion of proteins of interest to fluorescent proteins with properties compatible to SRM. Here we describe an approach that is based on the genetically encoded self-labelling enzymes HaloTag and SNAP-tag. Proteins of interest are fused to HaloTag or SNAP-tag and cell permeable substrates can be labelled with various SRM-compatible fluorochromes. Fusions of the enzyme tags to subunits of a type I secretion system (T1SS), a T3SS, the flagellar rotor and a transcription factor were generated and analysed in living Salmonella enterica. The new approach is versatile in tagging proteins of interest in bacterial cells and allows to determine the number, relative subcellular localization and dynamics of protein complexes in living cells. PMID:27534893

  3. Mineralization of 14C-labelled aromatic pesticide molecules in Egyptian soils under aerobic and anaerobic conditions

    The mineralization of 2,4-D, carbofuran and pirimiphos-methyl in Egyptian soils was studied over a period of 90 days. Laboratory studies under aerobic and anaerobic conditions were conducted using 14C-ring labelled pesticides. Under anaerobic conditions 10-14% of applied ring labelled 2,4-D mineralized during 90 days with no significant variations due to soil type. Under aerobic conditions, 2,4-D mineralized more readily in clay soil to reach 29-34% of applied dose within 90 days. In clay loam soil, 14C-carbofuran and 14C-pirimiphos-methyl mineralized at a rather slow rate to reach 12-14% and 12-13% of applied dose in 90 days, respectively under aerobic conditions. Generally, soils repeatedly treated with pesticides gave a slightly lower percentage of mineralization than control soils. In all studies, the soil extractable pesticide residues decreased with time and the bound residues gradually increased. The highest binding affinity of about 26-29% was observed with 2,4-D in clay soil under aerobic conditions in 90 days. Carbofuran, and pirimiphos-methyl, on the other hand, had lower binding capacity that did not exceed 16% of applied radioactivity. (author)

  4. Label-free liquid crystal biosensor for L-histidine: A DNAzyme-based platform for small molecule assay.

    Liao, Shuzhen; Ding, Huazhi; Wu, Yan; Wu, Zhaoyang; Shen, Guoli; Yu, Ruqin


    We have developed a novel DNAzyme-based liquid crystal (LC) biosensor with high sensitivity for L-histidine, which is based on L-histidine-mediated formation of DNA duplexes by cleaving DNAzyme using L-histidine, resulting in a remarkable optical signal. Firstly, an optimal amount of capture probe is bound to the glass slide, which changes the surface topology as little as possible and shows a zero-background for the sensing system. When the DNAzyme molecule is cleaved by the target, L-histidine, a partial substrate strand is produced, which in turn can hybridize with the capture probe, forming a DNA duplex. The DNA duplexes induce LC molecules to undergo a homeotropic-to-tiled transition, obtaining a remarkable optical signal. The results show that the DNAzyme-based LC biosensor is highly sensitive to L-histidine with a detection limit of 50nM. Compared with previously reported multi-step amplified methods, this newly designed assay system for L-histidine has no amplified procedures with comparable sensitivity. This method is an unprecedented example of DNAzyme-based LC biosensor for small molecules, which has potential to offer a DNAzyme-based LC model used in various targets. PMID:26765528

  5. Labeling of complex molecules with 18F, 13N, and 11C. Progress report, March 1, 1981-February 28, 1982

    The overall objective during the period covered by this report was to develop a broad spectrum of radiopharmaceuticals labeled with short-lived cyclotron produced positron emitters, 11C, 13N and 18F. The progress report of this year will summarize work done in the last three years. The goals of the program during the last three years were: to build and complete the transport system to Nuclear Medicine; to complete the modular automated system for important precursor production: formaldehyde, methyliodide, cyanide; to perform animal studies with the 18F-glucose analogs 2FDG and 3FDG and measure the rate constants and glucose metabolic rates derived from the Sokoloff model for both agents in different animal species; to initiate the development of new fatty acid analogs for myocardial imaging and metabolism; and to develop syntheses for 18F and 11C sugar analogs

  6. Expression profile of vascular cell adhesion molecule-1 (CD106) in inflammatory foci using rhenium-188 labelled monoclonal antibody in mice.

    Kairemo, K J; Strömberg, S; Nikula, T K; Karonen, S L


    Rhenium (Re)-188 is a generator (W-188/Re-188) produced high energy beta-emitter suitable for radionuclide therapy (T1/2 is 16.9 hrs and Emax 2.1 MeV (range 11 mm)). We have labelled monoclonal antibody (MAb) raised against vascular cell adhesion molecule-1 (VCAM-1) with Re-188 using glucoheptonate chelation technique and SnCl2 as reducing agent. The labelling efficiency, free perrhenate and reduced Re were controlled with thin layer chromatography and the purification of Re-188-MoAbs was performed using gel filtration. Our results indicate that Re-188-labelled antibodies remain in vitro stable and the labelling purity is > 90%. We also have applied these Re-188-MoAbs for detection of inflammatory disease in a mouse. The effective half-lives of organs of interest after an injection of Re-188-anti-VCAM1 were as follows: blood 5.2 hr, kidney 4.7 hr, and liver 9.6 hr. Re-188-anti-VCAM-1 was found to accumulate mainly in kidney and liver. One hour after the injection, the kidney contained in average as high as 12.5% and the liver 2.8 ID/g tissue. After 6 hr, the kidney contained 5.5% ID/g and the liver 2.6% ID/g. At 24 hr, the kidney uptake was 0.5% ID/g and the liver uptake 0.8% ID/g, respectively. The inflamed foci, subcutaneous lesions in the footpad skin, were visualized using gamma camera. From the distribution data the uptakes in the inflamed foci as follows: at 1 hr 2.18 (inflammation) and 1.72% ID/g (control), at 6 hr 1.42 (inflammation) and 0.85% ID/g (control), and at 24 hr 0.17 (inflammation) and 0.084% ID/g (control), respectively. Anti-VCAM-1 MAb showed better targeting as compared to control MoAbs in inflammation (caused by E.coli lipoplysaccaride). In conclusion, Re-188 is suitable for MAb labelling, and MAb against VCAM-1 may be used for detection of local inflammatory disease. PMID:9762472

  7. Direct and in vitro observation of growth hormone receptor molecules in A549 human lung epithelial cells by nanodiamond labeling

    Cheng, C.-Y.; Perevedentseva, E.; Tu, J.-S.; Chung, P.-H.; Cheng, C.-L.; Liu, K.-K.; Chao, J.-I.; Chen, P.-H.; Chang, C.-C.


    This letter presents direct observation of growth hormone receptor in one single cancer cell using nanodiamond-growth hormone complex as a specific probe. The interaction of surface growth hormone receptor of A549 human lung epithelial cells with growth hormone was observed using nanodiamond's unique spectroscopic signal via confocal Raman mapping. The growth hormone molecules were covalent conjugated to 100nm diameter carboxylated nanodiamonds, which can be recognized specifically by the growth hormone receptors of A549 cell. The Raman spectroscopic signal of diamond provides direct and in vitro observation of growth hormone receptors in physiology condition in a single cell level.

  8. Chelator-Accelerated One-Pot ‘Click’ Labeling of Small Molecule Tracers with 2-[18F]Fluoroethyl Azide

    Erik Årstad


    Full Text Available 2-[18F]Fluoroethyl azide ([18F]FEA can readily be obtained by nucleophilic substitution of 2-azidoethyl-4-toluenesulfonate with [18F]fluoride (half-life 110 min, and has become widely used as a reagent for ‘click’ labeling of PET tracers. However, distillation of [18F]FEA is typically required, which is time-consuming and unpractical for routine applications. In addition, copper(I-catalyzed cycloaddition of [18F]FEA with non-activated alkynes, and with substrates containing labile functional groups, can be challenging. Herein, we report a highly efficient and practical ligand-accelerated one-pot/two-step method for ‘click’ labeling of small molecule tracers with [18F]FEA. The method exploits the ability of the copper(I ligand bathophenanthrolinedisulfonate to accelerate the rate of the cycloaddition reaction. As a result, alkynes can be added directly to the crude reaction mixture containing [18F]FEA, and as cyclisation occurs almost immediately at room temperature, the reaction is tolerant to labile functional groups. The method was demonstrated by reacting [18F]FEA with a series of alkyne-functionalized 6-halopurines to give the corresponding triazoles in 55–76% analytical radiochemical yield.

  9. Determination of human IgG by solid substrate room temperature phosphorescence immunoassay based on an antibody labeled with nanoparticles containing Rhodamine 6G luminescent molecules

    Jia-Ming, Liu; hui, Zhu Guo; Aihong, Wu; Pingping, Li; Huanhuan, Xu; Li, Long-Di; Liu, Zhen-bo


    Luminescent silicon dioxide nanoparticles (R-SiO 2) with size of 50 nm containing Rhodamine 6G (R) were synthesized by sol-gel method. In the presence of Pb(Ac) 2 as a heavy atom perturber, the particle can emit intense and stable room temperature phosphorescence signal of R, respectively, on polyamide membrane, with the λexmax/λemmax=470/635 nm for R. Our research indicates that the specific immune reaction between goat-anti-human IgG antibody labeled with R-SiO 2 and human IgG can be carried on polyamide membrane quantitatively, and the phosphorescence intensity was enhanced after the immunoreactions. Thus, a new method of solid substrate room temperature phosphorescence immunoassay (SS-RTP-IA) for the determination of human IgG was established basing on antibody labeled with the nanoparticles containing binary luminescent molecules. The linear range of this method is 0.0624-20.0 pg spot -1 of human IgG (corresponding concentration, 0.156-50.0 ng mL -1; sample volume, 0.40 μL spot -1). The regression equations of working curves are Δ Ip = 88.16. + 16.79m IgG (pg spot -1) (485/646 nm, r = 0.9997). Detection limits calculated by 3Sb/k are 0.017 pg spot -1. For samples containing 0.156 and 50.0 ng mL -1 of IgG, we measured repeatedly for 11 times, RSDs are 3.9 and 2.8%, respectively. This method is sensitive, accurate and of high precision.

  10. Targeting, bio distributive and tumor growth inhibiting characterization of anti-HER2 affibody coupling to liposomal doxorubicin using BALB/c mice bearing TUBO tumors.

    Akhtari, Javad; Rezayat, Seyed Mahdi; Teymouri, Manouchehr; Alavizadeh, Seyedeh Hoda; Gheybi, Fatemeh; Badiee, Ali; Jaafari, Mahmoud Reza


    Human epidermal growth factor receptor 2 (HER2) is overexpressed in 20-30% of breast cancer tumors. In the current investigation, we exploited such a feature and utilized an anti-HER2 affibody (ZHER2:477) in combination with a pegylated liposomal doxorubicin (PLD) for concurrent passive and active targeting of HER2 overexpressing TUBO tumor, using BALB/c mice. It was determined that the affibody coupled liposomes (affisomes) was capable of increasing doxorubicin (Dox) delivery to HER2+ cells (SK-BR-3 and TUBO cells), while transferring drug similarly as low as naïve PLD to HER2- MDA-MB-231 cells. This also resulted in selectively enhance cytotoxicity. The veracity of targeting was further assessed utilizing DiD lipophilic tracer model liposomes via competition assay. An approximated 10 ligand/liposome integration caused Dox delivery at 50% of maximal delivery capacity (Kd). Such integration did not alter Dox release in vitro, while it affected the serum clearance profile. Affibody integration to PLD increased drug concentration in tumor and led to significantly further augmentation of drug in liver and spleen compared to those of PLD. Overall, such differences led to prolonging the mice life spans as compared to PLD. PMID:27039149

  11. Novel Chemical Strategies for Labeling Small Molecule Ligands for Androgen, Progestin, and Peroxisome Proliferator-Activated Receptors for Imaging Prostate and Breast Cancer and the Heart

    Summary of Progress The specific aims of this project can be summarized as follows: Aim 1: Prepare and evaluate radiolabeled ligands for the peroxisome proliferator-activated receptor γ (PPARγ), a new nuclear hormone receptor target for tumor imaging and hormone therapy. Aim 2: Prepare steroids labeled with a cyclopentadienyl tricarbonyl technetium or rhenium unit. Aim 3: Prepare and evaluate other organometallic systems of novel design as ligand mimics and halogenated ligands for nuclear hormone receptor-based tumor imaging. As is described in detail in the report, we made excellent progress on all three of these aims; the highlights of our progress are the following: (1) we have prepared the first fluorine-18 labeled analogs of ligands for the PPARγ receptor and used these in tissue distribution studies in rats; (2) we have developed three new methods for the synthesis of cyclopentadienyltricarbonyl rhenium and technetium (CpRe(CO)3 and CpTc(CO)3) systems and we have adapted these to the synthesis of steroids labeled with these metals, as well as ligands for other receptor systems; (3) we have prepared a number of fluorine-18 labeled steroidal and non-steroidal androgens and measured their tissue distribution in rats; (4) we have prepared iodine and bromine-labeled progestins with high progesterone receptor binding affinity; and (5) we have prepared inorganic metal tricarbonyl complexes and steroid receptor ligands in which the metal tricarbonyl unit is an integral part off the ligand core

  12. Food Labels

    ... How Can I Help a Friend Who Cuts? Food Labels KidsHealth > For Teens > Food Labels Print A ... have at least 95% organic ingredients. continue Making Food Labels Work for You The first step in ...

  13. Preparation, characterization and magnetic behavior of a spin-labelled physical hydrogel containing a chiral cyclic nitroxide radical unit fixed inside the gelator molecule.

    Takemoto, Yusa; Yamamoto, Takayuki; Ikuma, Naohiko; Uchida, Yoshiaki; Suzuki, Katsuaki; Shimono, Satoshi; Takahashi, Hiroki; Sato, Nobuhiro; Oba, Yojiro; Inoue, Rintaro; Sugiyama, Masaaki; Tsue, Hirohito; Kato, Tatsuhisa; Yamauchi, Jun; Tamura, Rui


    An optically active amphiphilic nitroxide radical compound [(S,S,R)-], which contains a paramagnetic (2S,5S)-2,5-dimethyl-2,5-diphenylpyrrolidine-N-oxyl radical group fixed in the inner position together with a hydrophobic long alkyl chain and a hydrophilic (R)-alanine residue in the opposite terminal positions, was found to serve as a low-molecular-weight gelator in H2O to give rise to a spin-labelled physical hydrogel. Characterization of the hydrogel was performed by microscopic (SEM, TEM and AFM) techniques, XRD and SAXS measurements, and IR, UV and CD spectroscopies. The gel-sol transition temperature was determined by EPR spectral line-width (ΔHpp) analysis. Measurement of the temperature dependence of relative paramagnetic susceptibility (χrel) for the hydrogel and sol phases was achieved by means of the double-integration of VT-EPR spectra. PMID:26073537

  14. Determination of human IgG by solid substrate room temperature phosphorescence immunoassay based on an antibody labeled with nanoparticles containing dibromofluorescein luminescent molecules

    Luminescent silicon dioxide nano-particles with size of 20 nm, which containing dibromofluorescein (D) were synthesized by sol-gel method (symbolized by D-SiO2).The particles can emit intense and stable room temperature phosphorescence signal on polyamide membrane when Pb(Ac)2 was used as a heavy atom perturber. The λexmax/λemmax was 457/622 nm. Our research indicated that the specific immune reaction between goat-anti-human IgG antibody labeled with D-SiO2 and human IgG could be carried out on polyamide membrane quantitatively, and the phosphorescence intensity of the particle was enhanced after the immunoreactions. Thus a new method of solid substrate room temperature phosphorescence immunoassay (SS-RTP-IA) for the determination of human IgG was established basing on antibody labeled with the D-SiO2 nanoparticles. The linear range of this method was 0.0624-20.0 pg human IgG spot-1 (corresponding concentration: 0.156-50.0 ng ml-1, the sample volume: 0.40 μl spot-1) with a limit of detection (LD) as 0.018 pg spot-1, and the regression equation of working curve was ΔIp = 7.201 mIgG (pg spot-1) + 82.57. Samples containing 0.156 and 50.0 ng ml-1 of IgG were measured repeatedly for 11 times and R.S.D.s were 4.1 and 3.4%, respectively. Results showed that this method had the merits as sensitive, accurate and precise

  15. Radiation dosimetry and first therapy results with a {sup 124}I/{sup 131}I-labeled small molecule (MIP-1095) targeting PSMA for prostate cancer therapy

    Zechmann, Christian M.; Afshar-Oromieh, Ali; Mier, Walter [University Hospital Heidelberg, Department of Nuclear Medicine, Heidelberg (Germany); Armor, Tom; Joyal, John [Molecular Insight Pharmaceuticals, Boston, MA (United States); Stubbs, James B. [Radiation Dosimetry Systems RDS, Inc., Apharetta, GA (United States); Hadaschik, Boris [University Hospital Heidelberg, Department of Urology, Heidelberg (Germany); Kopka, Klaus [Division Radiopharmaceutical Chemistry, DKFZ, Heidelberg (Germany); Debus, Juergen [University Hospital Heidelberg, Department of Radiation Oncology, Heidelberg (Germany); Babich, John W. [Molecular Insight Pharmaceuticals, Boston, MA (United States); Cornell University, Division of Radiopharmacy, Department of Radiology, New York, NY (United States); Haberkorn, Uwe [University Hospital Heidelberg, Department of Nuclear Medicine, Heidelberg (Germany); Clinical Cooperation Unit Nuclear Medicine, DKFZ, Heidelberg (Germany)


    Since the prostate-specific membrane antigen (PSMA) is frequently over-expressed in prostate cancer (PCa) several PSMA-targeting molecules are under development to detect and treat metastatic castration resistant prostate cancer (mCRPC). We investigated the tissue kinetics of a small molecule inhibitor of PSMA ((S)-2-(3-((S)-1-carboxy-5-(3-(4-[{sup 124}I]iodophenyl)ureido)pentyl)ureido) pentan edioicacid; MIP-1095) using PET/CT to estimate radiation dosimetry for the potential therapeutic use of {sup 131}I-MIP-1095 in men with mCRPC. We also report preliminary safety and efficacy of the first 28 consecutive patients treated under a compassionate-use protocol with a single cycle of {sup 131}I-MIP-1095. Sixteen patients with known prostate cancer underwent PET/CT imaging after i.v. administration of {sup 124}I-MIP-1095 (mean activity: 67.4 MBq). Each patient was scanned using PET/CT up to five times at 1, 4, 24, 48 and 72 h post injection. Volumes of interest were defined for tumor lesions and normal organs at each time point followed by dose calculations using the OLINDA/EXM software. Twenty-eight men with mCRPC were treated with a single cycle of {sup 131}I-MIP-1095 (mean activity: 4.8 GBq, range 2 to 7.2 GBq) and followed for safety and efficacy. Baseline and follow up examinations included a complete blood count, liver and kidney function tests, and measurement of serum PSA. I-124-MIP-1095 PET/CT images showed excellent tumor uptake and moderate uptake in liver, proximal intestine and within a few hours post-injection also in the kidneys. High uptake values were observed only in salivary and lacrimal glands. Dosimetry estimates for I-131-MIP-1095 revealed that the highest absorbed doses were delivered to the salivary glands (3.8 mSv/MBq), liver (1.7 mSv/MBq) and kidneys (1.4 mSv/MBq). The absorbed dose calculated for the red marrow was 0.37 mSv/MBq. PSA values decreased by >50 % in 60.7 % of the men treated. Of men with bone pain, 84.6 % showed complete or

  16. Wasteful Labeling

    Mahenc, Philippe


    The role of labeling is to solve the adverse selection problem caused by unsubstantiated claims from firms. The problem however is likely to remain unsolved if the labeling agency is not trustworthy.The agency can be suspected to divert the fees charged for labeling from their primary purpose of collecting information in order to raise excessive revenue. This paper addresses this issue and shows that labeling may be wasteful if the agency is likely to be untrustworthy. To award firms green la...

  17. Label and Label-Free Detection Techniques for Protein Microarrays

    Amir Syahir


    Full Text Available Protein microarray technology has gone through numerous innovative developments in recent decades. In this review, we focus on the development of protein detection methods embedded in the technology. Early microarrays utilized useful chromophores and versatile biochemical techniques dominated by high-throughput illumination. Recently, the realization of label-free techniques has been greatly advanced by the combination of knowledge in material sciences, computational design and nanofabrication. These rapidly advancing techniques aim to provide data without the intervention of label molecules. Here, we present a brief overview of this remarkable innovation from the perspectives of label and label-free techniques in transducing nano‑biological events.

  18. Nutrition Labeling

    Grunert, Klaus G


    because consumers will avoid products that the label shows to be nutritionally deficient, but also because food producers will try to avoid marketing products that appear, according to the label, as nutritionally problematic, for example, because of a high content of saturated fat or salt. Nutrition......Nutrition labeling refers to the provision of information on a food product’s nutritional content on the package label. It can serve both public health and commercial purposes. From a public health perspective, the aim of nutrition labeling is to provide information that can enable consumers...... to make healthier choices when choosing food products. Nutrition labeling is thus closely linked to the notion of the informed consumer, that chooses products according to their aims, on the basis of the information at their disposal. Because many consumers are assumed to be interested in making healthy...

  19. Nutrition Labeling

    Metzger, Lloyd E.

    Nutrition labeling regulations differ in countries around the world. The focus of this chapter is on nutrition labeling regulations in the USA, as specified by the Food and Drug Administration (FDA) and the Food Safety and Inspection Service (FSIS) of the United States Department of Agriculture (USDA). A major reason for analyzing the chemical components of foods in the USA is nutrition labeling regulations. Nutrition label information is not only legally required in many countries, but also is of increasing importance to consumers as they focus more on health and wellness.

  20. Expression of apoptotic nuclei by ultrastructural terminal deoxyribonucleotidyl transferase mediated dUTP nick end labeling and detection of FasL, caspases and PARP protein molecules in cadmium induced acute alveolar cell injury

    Cadmium causes cellular damage but the exact mechanism of apoptosis in cadmium induced acute lung injury is not clear. We investigated the sequential expression of apoptotic nuclei and detected related molecules in tissue of cadmium-induced acute lung injury. Forty Sprague-Dawley rats were sacrificed at days 1, 3, 7 and 10 after intra-tracheal cadmium injection (2.5 mg/kg). Light microscopic, ultrastructural terminal deoxyribonucleotidyl transferase mediated dUTP nick end labeling (TUNEL), and Western blot analysis for detection of FasL, Bid, cytochrome c, caspase 3 and PARP were carried out. Apoptosis occurred at day 1, and markedly decreased at days 3, 7 and 10 (11.8, 2.8, 0.9, 0.5%, respectively) determined by light microscopy and TUNEL assay. Ultrastructural TUNEL revealed two patterns of nuclear morphology according to the apoptotic stage. One pattern showed chromatin fragmentation and apoptotic nuclear body formation. The other pattern had bleb formation in the chromatin, budding with projection out to the nuclear membranes, fragmentation, segregation of chromatin clumps and apoptotic body formation. Western blot analysis showed prominent expression of FasL at days 1 and 3. Expression of Bid, cytochrome c and caspase 3 were prominent at day 1 compared to days 3, 7 and 10. PARP cleavage was prominent at day 1. In conclusion, intra-tracheal cadmium injection showed active alveolar cell apoptosis at day 1. Ultrastructural TUNEL showed various expressions according to the apoptotic nuclear stage. These studies suggest that cadmium-induced alveolar cell apoptosis is mediated by FasL and caspase-dependent mitochondrial apoptosis pathways

  1. Atoms, molecules & elements

    Graybill, George


    Young scientists will be thrilled to explore the invisible world of atoms, molecules and elements. Our resource provides ready-to-use information and activities for remedial students using simplified language and vocabulary. Students will label each part of the atom, learn what compounds are, and explore the patterns in the periodic table of elements to find calcium (Ca), chlorine (Cl), and helium (He) through hands-on activities.

  2. Protein aggregation and degradation during iodine labeling and its consequences for protein adsorption to biomaterials

    Holmberg, Maria; Jensen, Karin Bagger Stibius; Ndoni, Sokol;


    the CAT method, and higher amounts of fragmentation are observed for CAT-labeled IgG molecules relative to unlabeled IgG molecules as well as to IgG molecules labeled using the Iodo-Gen method. These results show that the widely applied method of radioisotope labeling for quantitative assessment of...

  3. Radioactively labelled porphyrin derivatives

    Radioactive labelling of guanidine bearing tetraphenylporphyrin and Dy-texaphyrin with 166Ho and 90Y is described. UV-VIS absorption spectrometry was used to describe porphyrin and texaphyrin, including their behaviour over a wide pH range. This technique also provided preliminary information about the complexation of holmium and yttrium with porphyrin and texaphyrin. The labelling yield of the macrocyclic molecules depends on the pH of the reaction mixture, metal-to-ligand ratio and time of incubation. The optimum reaction conditions for the formation of radioactive complexes of porphyrin and texaphyrin were determined by thin layer chromatography combined with beta activity measurement. The ability of porphyrin derivatives to bind anions was also examined. Our experiments were focused on perrhenate ion (ReO4-) because radiopharmaceuticals labeled with 186Re and 188Re play an important role in the therapy of many tumorous diseases. The possibility of using the ReO4- anion directly for labeling without reduction to a lower oxidation state can simplify considerably the preparation of the radiotherapeutic pharmaceuticals. Neither UV-Vis spectrometry nor TLC gave evidence of any incorporation of the ReO4- anion into the porphyrin ring

  4. A small-molecule dye for NIR-II imaging

    Antaris, Alexander L.; Chen, Hao; Cheng, Kai; Sun, Yao; Hong, Guosong; Qu, Chunrong; Diao, Shuo; Deng, Zixin; Hu, Xianming; Zhang, Bo; Zhang, Xiaodong; Yaghi, Omar K.; Alamparambil, Zita R.; Hong, Xuechuan; Cheng, Zhen; Dai, Hongjie


    Fluorescent imaging of biological systems in the second near-infrared window (NIR-II) can probe tissue at centimetre depths and achieve micrometre-scale resolution at depths of millimetres. Unfortunately, all current NIR-II fluorophores are excreted slowly and are largely retained within the reticuloendothelial system, making clinical translation nearly impossible. Here, we report a rapidly excreted NIR-II fluorophore (~90% excreted through the kidneys within 24 h) based on a synthetic 970-Da organic molecule (CH1055). The fluorophore outperformed indocyanine green (ICG)--a clinically approved NIR-I dye--in resolving mouse lymphatic vasculature and sentinel lymphatic mapping near a tumour. High levels of uptake of PEGylated-CH1055 dye were observed in brain tumours in mice, suggesting that the dye was detected at a depth of ~4 mm. The CH1055 dye also allowed targeted molecular imaging of tumours in vivo when conjugated with anti-EGFR Affibody. Moreover, a superior tumour-to-background signal ratio allowed precise image-guided tumour-removal surgery.

  5. Photoisomerisable molecules

    Peris Fajarnes, Eduardo Víctor; Mata Martínez, José Antonio; Márquez Linares, Francisco Manuel; Sabater Picot, María José


    [EN] The invention relates to a molecule comprising at least one carbon-carbon double bond which is substituted by at least one cyclopentadienyl-metal-cyclopentadienyl complex, having the cis/trans isomerisation property, in a reversible manner in response to the absorption of light. Preferably, the rest of the molecule comprises a dendrimer of any generation, advantageously of the polypropylenimine octaamine type. The inventive molecule can be used as a molecular switch and in various differ...

  6. Food labels

    Selsøe Sørensen, Henrik; Clement, Jesper; Gabrielsen, Gorm


    The food industry develops tasty and healthy food but fails to deliver the message to all consumers. The consumers’ background knowledge is essential for how they find and decode relevant elements in the cocktail of signs which fight for attention on food labels. In this exploratory study, we find...... evidence for dividing consumers into two profiles: one relying on general food knowledge and another using knowledge related to signpost labels. In a combined eyetracking and questionnaire survey we analyse the influence of background knowledge and identify different patterns of visual attention for the...... two consumer profiles. This underlines the complexity in choosing and designing the ‘right’ elements for a food package that consumers actually look at and are able to make rational use of. In spite of any regulation of food information provided by authorities, consumers will still be confronted with...

  7. Environmental Labeling

    Andrea Podhorsky


    This paper studies how information disclosed by voluntary environmental labels creates incentives for firms to invest in environmentally-friendly production technologies. I develop a model with differentiated products and imperfectly-informed consumers. Consumers care about the environmental characteristics of goods (for example, how they were produced), but cannot directly observe these product characteristics. Firms differ in their abilities to develop "clean" technologies, but have no ince...

  8. Use of 3-[18F]fluoropropanesulfonyl chloride as a prosthetic agent for the radiolabelling of amines: Investigation of precursor molecules, labelling conditions and enzymatic stability of the corresponding sulfonamides

    Reik Löser


    Full Text Available 3-[18F]Fluoropropanesulfonyl chloride, a recently proposed prosthetic agent for fluorine-18 labelling, was prepared in a two-step radiosynthesis via 3-[18F]fluoropropyl thiocyanate as an intermediate. Two benzenesulfonate-based radiolabelling precursors were prepared by various routes. Comparing the reactivities of 3-thiocyanatopropyl nosylate and the corresponding tosylate towards [18F]fluoride the former proved to be superior accounting for labelling yields of up to 85%. Conditions for a reliable transformation of 3-[18F]fluoropropyl thiocyanate to the corresponding sulfonyl chloride with the potential for automation have been identified. The reaction of 3-[18F]fluoropropanesulfonyl chloride with eight different aliphatic and aromatic amines was investigated and the identity of the resulting 18F-labelled sulfonamides was confirmed chromatographically by comparison with their nonradioactive counterparts. Even for weakly nucleophilic amines such as 4-nitroaniline the desired radiolabelled sulfonamides were accessible in satisfactory yields owing to systematic variation of the reaction conditions. With respect to the application of the 18F-fluoropropansulfonyl group to the labelling of compounds relevant as imaging agents for positron emission tomography (PET, the stability of N-(4-fluorophenyl-3-fluoropropanesulfonamide against degradation catalysed by carboxylesterase was investigated and compared to that of the analogous fluoroacetamide.

  9. A systematic investigation of differential effects of cell culture substrates on the extent of artifacts in single-molecule tracking.

    Laura C Zanetti-Domingues

    Full Text Available Single-molecule techniques are being increasingly applied to biomedical investigation, notwithstanding the numerous challenges they pose in terms of signal-to-noise ratio issues. Non-specific binding of probes to glass substrates, in particular, can produce experimental artifacts due to spurious molecules on glass, which can be particularly deleterious in live-cell tracking experiments. In order to resolve the issue of non-specific probe binding to substrates, we performed systematic testing of a range of available surface coatings, using three different proteins, and then extended our assessment to the ability of these coatings to foster cell growth and retain non-adhesive properties. Linear PEG, a passivating agent commonly used both in immobilized-molecule single-molecule techniques and in tissue engineering, is able to both successfully repel non-specific adhesion of fluorescent probes and to foster cell growth when functionalized with appropriate adhesive peptides. Linear PEG treatment results in a significant reduction of tracking artifacts in EGFR tracking with Affibody ligands on a cell line expressing EGFR-eGFP. The findings reported herein could be beneficial to a large number of experimental situations where single-molecule or single-particle precision is required.

  10. Enumerating molecules.

    Visco, Donald Patrick, Jr. (, . Tennessee Technological University, Cookeville, TN); Faulon, Jean-Loup Michel; Roe, Diana C.


    This report is a comprehensive review of the field of molecular enumeration from early isomer counting theories to evolutionary algorithms that design molecules in silico. The core of the review is a detail account on how molecules are counted, enumerated, and sampled. The practical applications of molecular enumeration are also reviewed for chemical information, structure elucidation, molecular design, and combinatorial library design purposes. This review is to appear as a chapter in Reviews in Computational Chemistry volume 21 edited by Kenny B. Lipkowitz.

  11. Labelling and biological evaluation of therapeutic radiopharmaceuticals

    The paper describes research aimed at developing radiolabelled agents using 'bone seeking' molecules and peptides as the target specific moieties. For the study of bone seeking molecules, hydroxyethylene diphosphonate (HEDP) and dimercaptosuccinic acid (DMSA) (V) were labelled with 188Re. For peptide radiolabelling, 99mTc and 111In were used as the diagnostic radioisotopes, and 90Y was used as the therapeutic radioisotope. The labelling yielded agents with high radiochemical purity. The labelled compounds - 188Re- HEDP, 188Re-DMSA(V), 111In-DOTATOC, 99mTc-HYNIC-TATE, 90Y-DOTATOC and 90Y-DOTATATE - were evaluated in mice, rats and healthy beagle dogs. All compounds were also tested in dogs with spontaneous tumours as pathological models. Biodistribution studies showed that the molecules accumulated in their respective target cells. Spontaneous tumours in dogs offered a unique opportunity to investigate the diagnostic utility and therapeutic behaviour of the radiopharmaceuticals. (author)

  12. Fluorescent labels and their use in separations

    Mathies, Richard A.; Glazer, Alexander; Ju, Jingyue


    Compositions are provided comprising sets of fluorescent labels carrying pairs of donor and acceptor dye molecules, designed for efficient excitation of the donors at a single wavelength and emission from the acceptor in each of the pairs at different wavelengths. The different molecules having different donor-acceptor pairs can be modified to have substantially the same mobility under separation conditions, by varying the distance between the donor and acceptor in a given pair. Particularly, the fluorescent compositions find use as labels in sequencing nucleic acids.

  13. Issues in Data Labelling

    Cowie, Roddy; Cox, Cate; Martin, Jeam-Claude; Batliner, Anton; Heylen, Dirk; Karpouzis, Kostas; Cowie, Roddy; Pelachaud, Catherine; Petta, Paolo


    Labelling emotion databases is not a purely technical matter. It is bound up with theoretical issues. Different issues affect labelling of emotional content, labelling of the signs that convey emotion, and labelling of the relevant context. Linked to these are representational issues, involving time

  14. 99mTc: Labeling Chemistry and Labeled Compounds

    Alberto, R.; Abram, U.

    This chapter reviews the radiopharmaceutical chemistry of technetium related to the synthesis of perfusion agents and to the labeling of receptor-binding biomolecules. To understand the limitations of technetium chemistry imposed by future application of the complexes in nuclear medicine, an introductory section analyzes the compulsory requirements to be considered when facing the incentive of introducing a novel radiopharmaceutical into the market. Requirements from chemistry, routine application, and market are discussed. In a subsequent section, commercially available 99mTc-based radiopharmaceuticals are treated. It covers the complexes in use for imaging the most important target organs such as heart, brain, or kidney. The commercially available radiopharmaceuticals fulfill the requirements outlined earlier and are discussed with this background. In a following section, the properties and perspectives of the different generations of radiopharmaceuticals are described in a general way, covering characteristics for perfusion agents and for receptor-specific molecules. Technetium chemistry for the synthesis of perfusion agents and the different labeling approaches for target-specific biomolecules are summarized. The review comprises a general introduction to the common approaches currently in use, employing the N x S4-x , [3+1] and 2-hydrazino-nicotinicacid (HYNIC) method as well as more recent strategies such as the carbonyl and the TcN approach. Direct labeling without the need of a bifunctional chelator is briefly reviewed as well. More particularly, recent developments in the labeling of concrete targeting molecules, the second generation of radiopharmaceuticals, is then discussed and prominent examples with antibodies/peptides, neuroreceptor targeting small molecules, myocardial imaging agents, vitamins, thymidine, and complexes relevant to multidrug resistance are given. In addition, a new approach toward peptide drug development is described. The section

  15. Succesful labelling schemes

    Juhl, Hans Jørn; Stacey, Julia


    It is usual practice to evaluate the success of a labelling scheme by looking at the awareness percentage, but in many cases this is not sufficient. The awareness percentage gives no indication of which of the consumer segments that are aware of and use labelling schemes and which do not. In the...... spring of 2001 MAPP carried out an extensive consumer study with special emphasis on the Nordic environmentally friendly label 'the swan'. The purpose was to find out how much consumers actually know and use various labelling schemes. 869 households were contacted and asked to fill in a questionnaire....... 664 households returned a completed questionnaire. There were five answering categories for each label in the questionnaire: * have not seen the label before. * I have seen the label before but I do not know the precise contents of the labelling scheme. * I have seen the label before, I do not know...

  16. Synthesizing labeled compounds

    A metabolic study is presented of the chemical reactions provided by isotopic labeling and NMR spectroscopy. Synthesis of 13C-labeled D-glucose, a 6-carbon sugar, involves adding a labeled nitrile group to the 5-carbon sugar D-arabinose by reaction with labeled hydrogen cyanide. The product of this reaction is then reduced and hydrolyzed to a mixture of the labeled sugars. The two sugars are separated by absorption chromotography. The synthesis of 13C-labeled L-tyrosine, an amino acid, is also presented

  17. Fluorescent Labeling of Plasmid DNA and mRNA: Gains and Losses of Current Labeling Strategies.

    Rombouts, K; Braeckmans, K; Remaut, K


    Live-cell imaging has provided the life sciences with insights into the cell biology and dynamics. Fluorescent labeling of target molecules proves to be indispensable in this regard. In this Review, we focus on the current fluorescent labeling strategies for nucleic acids, and in particular mRNA (mRNA) and plasmid DNA (pDNA), which are of interest to a broad range of scientific fields. By giving a background of the available techniques and an evaluation of the pros and cons, we try to supply scientists with all the information needed to come to an informed choice of nucleic acid labeling strategy aimed at their particular needs. PMID:26670733

  18. Mental Labels and Tattoos

    Hyatt, I. Ralph


    Discusses the ease with which mental labels become imprinted in our system, six basic axioms for maintaining negative mental tattoos, and psychological processes for eliminating mental tattoos and labels. (RK)

  19. Pesticide Product Label System

    U.S. Environmental Protection Agency — The Pesticide Product Label System (PPLS) provides a collection of pesticide product labels (Adobe PDF format) that have been approved by EPA under Section 3 of the...

  20. On Online Labeling with Polynomially Many Labels

    Babka, Martin; Bulánek, Jan; Cunat, Vladimír; Koucky, Michal; Saks, Michael


    In the online labeling problem with parameters n and m we are presented with a sequence of nkeys from a totally ordered universe U and must assign each arriving key a label from the label set {1,2,…,m} so that the order of labels (strictly) respects the ordering on U. As new keys arrive it may be...... necessary to change the labels of some items; such changes may be done at any time at unit cost for each change. The goal is to minimize the total cost. An alternative formulation of this problem is the file maintenance problem, in which the items, instead of being labeled, are maintained in sorted order in...... are known that use O(n logn) relabelings. A matching lower bound was claimed in [7]. That proof involved two distinct steps: a lower bound for a problem they call prefix bucketing and a reduction from prefix bucketing to online labeling. The reduction seems to be incorrect, leaving a (seemingly...

  1. Group specific internal standard technology (GSIST) for simultaneous identification and quantification of small molecules

    Adamec, Jiri; Yang, Wen-Chu; Regnier, Fred E


    Reagents and methods are provided that permit simultaneous analysis of multiple diverse small molecule analytes present in a complex mixture. Samples are labeled with chemically identical but isotopically distince forms of the labeling reagent, and analyzed using mass spectrometry. A single reagent simultaneously derivatizes multiple small molecule analytes having different reactive functional groups.

  2. Gold Nanoparticle Labels Amplify Ellipsometric Signals

    Venkatasubbarao, Srivatsa


    The ellipsometric method reported in the immediately preceding article was developed in conjunction with a method of using gold nanoparticles as labels on biomolecules that one seeks to detect. The purpose of the labeling is to exploit the optical properties of the gold nanoparticles in order to amplify the measurable ellipsometric effects and thereby to enable ultrasensitive detection of the labeled biomolecules without need to develop more-complex ellipsometric instrumentation. The colorimetric, polarization, light-scattering, and other optical properties of nanoparticles depend on their sizes and shapes. In the present method, these size-and-shape-dependent properties are used to magnify the polarization of scattered light and the diattenuation and retardance of signals derived from ellipsometry. The size-and-shape-dependent optical properties of the nanoparticles make it possible to interrogate the nanoparticles by use of light of various wavelengths, as appropriate, to optimally detect particles of a specific type at high sensitivity. Hence, by incorporating gold nanoparticles bound to biomolecules as primary or secondary labels, the performance of ellipsometry as a means of detecting the biomolecules can be improved. The use of gold nanoparticles as labels in ellipsometry has been found to afford sensitivity that equals or exceeds the sensitivity achieved by use of fluorescence-based methods. Potential applications for ellipsometric detection of gold nanoparticle-labeled biomolecules include monitoring molecules of interest in biological samples, in-vitro diagnostics, process monitoring, general environmental monitoring, and detection of biohazards.

  3. Fluorescent RNA labeling using self-alkylating ribozymes.

    Sharma, Ashwani K; Plant, Joshua J; Rangel, Alexandra E; Meek, Kirsten N; Anamisis, April J; Hollien, Julie; Heemstra, Jennifer M


    The ability to fluorescently label specific RNA sequences is of significant utility for both in vitro and live cell applications. Currently, most RNA labeling methods utilize RNA-nucleic acid or RNA-protein molecular recognition. However, in the search for improved RNA labeling methods, harnessing the small-molecule recognition capabilities of RNA is rapidly emerging as a promising alternative. Along these lines, we propose a novel strategy in which a ribozyme acts to promote self-alkylation with a fluorophore, providing a robust, covalent linkage between the RNA and the fluorophore. Here we describe the selection and characterization of ribozymes that promote self-labeling with fluorescein iodoacetamide (FIA). Kinetic studies reveal a second-order rate constant that is on par with those of other reactions used for biomolecular labeling. Additionally, we demonstrate that labeling is specific to the ribozyme sequences, as FIA does not react nonspecifically with RNA. PMID:24896502

  4. Deuterium labeled cannabinoids

    Complex reactions involving ring opening, ring closure and rearrangements hamper complete understanding of the fragmentation processes in the mass spectrometric fragmentation patterns of cannabinoids. Specifically labelled compounds are very powerful tools for obtaining more insight into fragmentation mechanisms and ion structures and therefore the synthesis of specifically deuterated cannabinoids was undertaken. For this, it was necessary to investigate the preparation of cannabinoids, appropriately functionalized for specific introduction of deuterium atom labels. The results of mass spectrometry with these labelled cannabinoids are described. (Auth.)

  5. Labelling Fashion Markets

    Aspers, P.


    The present article discusses how an ethical and environmental labelling system can be implemented in fashion garment markets. Consumers act in markets that provide them with more information than their limited cognitive capacity allows them to handle. Ethical and environmental labelling in markets characterized by change, such as the fashion garment market, makes decision-making even more complicated. The ethical and environmental labelling system proposed here is designed to alleviate firms...

  6. Blood cell labelling

    The labelling of blood cells in vitro for subsequent in vivo studies was one of the earliest applications of radioactive tracers in clinical medicine and laid the foundations for many important contributions to the advancement of knowledge of human blood cell pathophysiology. The characteristics required for satisfactory clinical studies, the mechanisms of cell labelling, the problems of radiation or chemical damage to the labelled cells and some examples of modern clinical applications are described and discussed. (Author)

  7. Labelling of live cells using fluorescent aptamers: binding reversal with DNA nucleases

    Terazono Hideyuki; Anzai Yu; Soloviev Mikhail; Yasuda Kenji


    Abstract A reversible cell labelling method has been developed for non-destructive and non-invasive cell labelling and purification. Our method uses high affinity single strand DNA (ssDNA) aptamers against surface exposed target molecules on cells. The aptamers are subsequently removed from the cell surface using DNase nuclease treatment. We exemplified our method by labelling human acute lymphoblastic leukemia cells with Qdot-ssDNA aptamers, and restoring them to the label-free condition by ...

  8. On labelled compounds nomenclature

    Different approaches of major labelled compounds producers to their nomenclature in technical and commercial documentation are discussed. Some draft options of a standard technical guide document for labelled compounds nomenclature rules are suggested. Such a document after due discussion by the experts will serve to unification of the labelled compounds nomenclature within the frame of the CMEA member-countries co-operation in this field. The suggested options are based on the general recommendations by the International Union of Pure and Applied Chemistry and incorporate some more accurate definitions originating from the labelled compounds production and application experience

  9. Bone marrow origin of Ia molecules purified from epidermal cells

    Using radiation bone marrow chimeras, we have shown that Ia molecules purified from epidermal cell preparations of the mouse reflect the Ia phenotype of the bone marrow donor. This result strongly suggests that Ia molecules are synthesized by a bone-marrow-derived cell in the epidermis. Furthermore, results of peptide map analysis of immunoprecipitated biosynthetically labeled Ia suggest that the Ia molecules found in skin are identical to those found on B lymphocytes. These results support biochemical as well as serologic identity

  10. Single Molecule Raman Detection of Enkephalin on Silver Colloidal Particles

    Kneipp, Katrin; Kneipp, Holger; Abdali, Salim; Berg, Rolf W.; Bohr, Henrik


    Raman signal the enkephalin molecules have been attached to silver colloidal cluster structures. The experiments demonstrate that the SERS signal of the strongly enhanced ring breathing vibration of phenylalanine at 1000 cm-1 can be used as “intrinsic marker” for detecting a single enkephalin molecule...... and for monitoring its diffusion on the surface of the silver colloidal cluster without using a specific label molecule....

  11. Tomography of epidermal growth factor receptor binding to fluorescent Affibody in vivo studied with magnetic resonance guided fluorescence recovery in varying orthotopic glioma sizes

    Holt, Robert W.; Demers, Jennifer-Lynn H.; Sexton, Kristian J.; Gunn, Jason R.; Davis, Scott C.; Samkoe, Kimberley S.; Pogue, Brian W.


    The ability to image targeted tracer binding to epidermal growth factor receptor (EGFR) was studied in vivo in orthotopically grown glioma tumors of different sizes. The binding potential was quantified using a dual-tracer approach, which employs a fluorescently labeled peptide targeted to EGFR and a reference tracer with similar pharmacokinetic properties but no specific binding, to estimate the relative bound fraction from kinetic compartment modeling. The recovered values of binding potential did not vary significantly as a function of tumor size (1 to 33 mm3), suggesting that binding potential may be consistent in the U251 tumors regardless of size or stage after implantation. However, the fluorescence yield of the targeted fluorescent tracers in the tumor was affected significantly by tumor size, suggesting that dual-tracer imaging helps account for variations in absolute uptake, which plague single-tracer imaging techniques. Ex vivo analysis showed relatively high spatial heterogeneity in each tumor that cannot be resolved by tomographic techniques. Nonetheless, the dual-tracer tomographic technique is a powerful tool for longitudinal bulk estimation of receptor binding.

  12. Stable isotopes labelled compounds

    The catalogue on stable isotopes labelled compounds offers deuterium, nitrogen-15, and multiply labelled compounds. It includes: (1) conditions of sale and delivery, (2) the application of stable isotopes, (3) technical information, (4) product specifications, and (5) the complete delivery programme

  13. Labeling and Delinquency.

    Adams, Mike S.; Robertson, Craig T.; Gray-Ray, Phyllis; Ray, Melvin C.


    Index comprised of six contrasting descriptive adjectives was used to measure incarcerated youths' perceived negative labeling from the perspective of parents, teachers, and peers. Results provided partial support for hypothesis that juveniles who choose a greater number of negative labels will report more frequent delinquent involvement. Labeling…

  14. Comparative study of fixation of Co57 labelled bleomycin, labelled gallium citrate and Hg197 labelled mercury chloride, benign or malignant pulmonary lesions

    Over the last ten years, numerous labelled molecules have been used in lung diseases, in order to attempt definite localisation of primary or secondary carcinoma. Three of these substances are now used: cobalt 57-labelled bleomycin, Hg197Cl2 and Ga67 citrate. A study of 34 patient with malignant or tuberculous lung disease with definite diagnosis, permitted demonstration of the fact that the highest uptake, or the best images, were obtained with labelled bleomycin. However, the long period of Co57 limits its indications in young subjects and, in these cases, HgCl2 is indicated

  15. Label Fusion Strategy Selection

    Nicolas Robitaille


    Full Text Available Label fusion is used in medical image segmentation to combine several different labels of the same entity into a single discrete label, potentially more accurate, with respect to the exact, sought segmentation, than the best input element. Using simulated data, we compared three existing label fusion techniques—STAPLE, Voting, and Shape-Based Averaging (SBA—and observed that none could be considered superior depending on the dissimilarity between the input elements. We thus developed an empirical, hybrid technique called SVS, which selects the most appropriate technique to apply based on this dissimilarity. We evaluated the label fusion strategies on two- and three-dimensional simulated data and showed that SVS is superior to any of the three existing methods examined. On real data, we used SVS to perform fusions of 10 segmentations of the hippocampus and amygdala in 78 subjects from the ICBM dataset. SVS selected SBA in almost all cases, which was the most appropriate method overall.

  16. OR Specimen Labeling.

    Zervakis Brent, Mary Ann


    Mislabeled surgical specimens jeopardize patient safety and quality care. The purpose of this project was to determine whether labeling surgical specimens with two patient identifiers would result in an 80% reduction in specimen labeling errors within six months and a 100% reduction in errors within 12 months. Our failure mode effects analysis found that the lack of two patient identifiers per label was the most unsafe step in our specimen handling process. We piloted and implemented a new process in the OR using the Plan-Do-Check-Act conceptual framework. The audit process included collecting data and making direct observations to determine the sustainability of the process change; however, the leadership team halted the direct observation audit after four months. The total number of surgical specimen labeling errors was reduced by only 60% within six months and 62% within 12 months; therefore, the goal of the project was not met. However, OR specimen labeling errors were reduced. PMID:26849982

  17. Nutrition Facts: Reading the Label

    ... My Go4Life Get Free Stuff Be a Partner Nutrition Facts: Reading the Label Reading labels can help ... of information on their labels or packaging about nutrition and food safety. Product dates . You might see ...

  18. Radioactive labelled orgotein

    The preparation and use of radioactively labelled orgotein, i.e. water-soluble protein congeners in pure, injectable form, is described. This radiopharmaceutical is useful in scintigraphy, especially for visualization of the kidneys where the orgotein is rapidly concentrated. Details of the processes for labelling bovine orgotein with sup(99m)Tc, 60Co, 125I or 131I are specified. The pharmaceutical preparation of the labelled orgotein for intravenous and parenteral administration is also described. Examples using either sup(99m)TC or 125I-orgotein in scintiscanning dogs' kidneys are given. (UK)

  19. Photoactivatable protein labeling by singlet oxygen mediated reactions.

    To, Tsz-Leung; Medzihradszky, Katalin F; Burlingame, Alma L; DeGrado, William F; Jo, Hyunil; Shu, Xiaokun


    Protein-protein interactions regulate many biological processes. Identification of interacting proteins is thus an important step toward molecular understanding of cell signaling. The aim of this study was to investigate the use of photo-generated singlet oxygen and a small molecule for proximity labeling of interacting proteins in cellular environment. The protein of interest (POI) was fused with a small singlet oxygen photosensitizer (miniSOG), which generates singlet oxygen ((1)O2) upon irradiation. The locally generated singlet oxygen then activated a biotin-conjugated thiol molecule to form a covalent bond with the proteins nearby. The labeled proteins can then be separated and subsequently identified by mass spectrometry. To demonstrate the applicability of this labeling technology, we fused the miniSOG to Skp2, an F-box protein of the SCF ubiquitin ligase, and expressed the fusion protein in mammalian cells and identified that the surface cysteine of its interacting partner Skp1 was labeled by the biotin-thiol molecule. This photoactivatable protein labeling method may find important applications including identification of weak and transient protein-protein interactions in the native cellular context, as well as spatial and temporal control of protein labeling. PMID:27220724

  20. Clinical applications of cells labelling

    Blood cells labelled with radionuclides are reviewed and main applications are described. Red blood cell labelling by both random and specific principle. A table with most important clinical uses, 99mTc labelling of RBC are described pre tinning and in vivo reduction of Tc, in vitro labelling and administration of labelled RBC and in vivo modified technique. Labelled leucocytes with several 99mTc-complex radiopharmaceuticals by in vitro technique and specific monoclonal s for white cells(neutrofiles). Labelled platelets for clinical use and research by in vitro technique and in vivo labelling

  1. Radioiodine labelling of insulin using dimethylsulfoxide as a labelling-aid

    Using dimethylsulfoxide (DMSO) as a labelling aid, insulin 126I of radioimmunoassay use has been effectively prepared. A small amount of DMSO was added to usual labelling mixture and the reaction time was controlled. The labelled insulin obtained in such a way showed improved bindabilities to the antibody and thus expressed larger dose-gradients in the plots of standard dose-response curves even though the labelling rate was decreased to some extent. However, by extending the reaction time to about 1 min, average labelling yield of 30% could be obtained. The average increase of bindability (B/F) in definite antiserum dilution was 2.5 comparing with 1.5 obtained in the absence of DMSO. Thus, the net bindability increase was 70% of those obtained in the absence of DMSO. By means of NMR spectrometry, it has been confirmed that the DMSO in the labelling mixture is converted to dimethylsulfone by chloramine-T. The results, generally agreed with the Stagg's postulation, were discussed in view of a competitive oxidation of DMSO with disulfide linkages of the insulin molecule by the chloramine-T. (author)

  2. FDA Online Label Repository

    U.S. Department of Health & Human Services — The drug labels and other drug-specific information on this Web site represent the most recent drug listing information companies have submitted to the Food and...

  3. Like your labels?

    Field, Michele


    The descriptive “conventions” used on food labels are always evolving. Today, however, the changes are so complicated (partly driven by legislation requiring disclosures about environmental impacts, health issues, and geographical provenance) that these labels more often baffle buyers than enlighten them. In a light-handed manner, the article points to how sometimes reading label language can be like deciphering runes—and how if we are familiar with the technical terms, we can find a literal meaning, but still not see the implications. The article could be ten times longer because food labels vary according to cultures—but all food-exporting cultures now take advantage of our short attention-span when faced with these texts. The question is whether less is more—and if so, in this contest for our attention, what “contestant” is voted off. PMID:21539053

  4. Stereoselective synthesis of stable-isotope-labeled amino acids

    Unkefer, C.J.; Martinez, R.A.; Silks, L.A. III [Los Alamos National Laboratory, NM (United States); Lodwig, S.N. [Centralia College, WA (United States)


    For magnetic resonance and vibrational spectroscopies to reach their full potential, they must be used in combination with sophisticated site-specific stable isotope labeling of biological macromolecules. Labeled amino acids are required for the study of the structure and function of enzymes and proteins. Because there are 20 common amino acids, each with its own distinguishing chemistry, they remain a synthetic challenge. The Oppolzer chiral auxiliary provides a general tool with which to approach the synthesis of labeled amino acids. By using the Oppolzer auxiliary, amino acids can be constructed from several small molecules, which is ideal for stable isotope labeling. In addition to directing the stereochemistry at the {alpha}-carbon, the camphorsultam can be used for stereo-specific isotope labeling at prochiral centers in amino acids. By using the camphorsultam auxiliary we have the potential to synthesize virtually any isotopomer of all of the common amino acids.

  5. Certified Rule Labeling

    Nagele, Julian; Zankl, Harald


    The rule labeling heuristic aims to establish confluence of (left-)linear term rewrite systems via decreasing diagrams. We present a formalization of a confluence criterion based on the interplay of relative termination and the rule labeling in the theorem prover Isabelle. Moreover, we report on the integration of this result into the certifier CeTA, facilitating the checking of confluence certificates based on decreasing diagrams for the first time. The power of the method is illustrated by ...

  6. Labelling of Vincamine derivatives

    Tritium labelled Vincamine and ethyl apovincaminate (Cavinton) have been prepared on the bases of known stereospecific synthesis. High specific activity compounds were obtained by the catalytic tritiation of appropriate unsaturated starting compounds. When the structure of the unsaturated starting compounds was changed (even rather for from the reaction centre) instead of the catalytic addition of tritium a specific hydrogen-tritium exchange reaction was found to be the main labelling process

  7. Labelling of electricity

    This comprehensive report for the Swiss Federal Office of Energy (SFOE) presents a possible course of action to be taken to provide a means of declaring the sources of electrical power, as is foreseen in the draft of new Swiss electricity market legislation. The report presents the basic ideas behind the idea and defines the terms used such as labelling, certificates and declarations. Also, the legal situation in the European Union and in Switzerland is examined and a quantitative overview of electricity production and consumption is presented. Suggestions for a labelling scheme are made and some of the problems to be expected are looked at. The report also presents a series of examples of labelling schemes already implemented in other countries, such as Austria, Great Britain, Sweden and Germany. Tradable certificates and tracking systems are discussed as are initial quality labels like the Swiss 'Naturemade' label for green power. A concrete recommendation for the declaration and labelling of electricity in Switzerland is presented and various factors to be considered such as import/export, pumped storage, distribution losses, small-scale producers as well as the time-scales for introduction are discussed

  8. A comparison of two 99Tcm leucocyte labelling techniques

    Full text: 111In-oxine labelled leucocytes are routinely used for the diagnosis of various inflammatory conditions. The search for a good 99Tcm labelling agent continues in order to prevent the radio-toxicity effects to lymphocytes caused by the high radiation dose from 111In decay. 99Tcm-HMPAO, a lipophilic, neutral molecule, has a leucocyte labelling mechanism similar to that of 111In-oxine (Passive Diffusion).Granulocytes are preferentially labelled with 99Tcm-HMPAO. Another method for labelling leucocytes with 99Tcm has been achieved with the polycationic, hydrophilic molecule, Modified Poly-lysine (MPL). Most mammalian cells have negatively charged surfaces which electrostatically attract cationic 99Tcm-MPL. Surface adsorption followed by internalisation by endocytosis leads to cell labelling. The entire mechanism is termed non-specific adsorptive endocytosis. The aim of this study was to compare the in vitro stability of the 99Tcm-leucocyte label prepared with 99Tcm-MPL to that prepared with 99Tcm-HMPAO. Leucocytes were isolated from venous blood using the 2% methyl cellulose sedimentation method. Half of the leucocytes were incubated in 99Tcm-HMPAO (1.5 GBq, 1 mL) for 15 minutes, the remaining leucocytes were incubated in 99Tcm- MPL (1.5 GBq, 1 mL) for 45 minutes. The labelling stability of the leucocytes was determined by incubation at room temperature in serum for 120 minutes. 99Tcm-MPL labels all components of the leucocyte population equally well and its improved labelling efficiency and stability may have application in studying the trafficking of T-lymphocytes in adoptive immunotherapy. Copyright (2000) The Australian and New Zealand Society of Nuclear Medicine Inc

  9. Streaming Label Learning for Modeling Labels on the Fly

    You, Shan; Xu, Chang; Wang, Yunhe; Xu, Chao; Tao, Dacheng


    It is challenging to handle a large volume of labels in multi-label learning. However, existing approaches explicitly or implicitly assume that all the labels in the learning process are given, which could be easily violated in changing environments. In this paper, we define and study streaming label learning (SLL), i.e., labels are arrived on the fly, to model newly arrived labels with the help of the knowledge learned from past labels. The core of SLL is to explore and exploit the relations...

  10. Eco-labelling, competition and environment: Endogenization of labelling criteria

    Ben Youssef, Adel; Lahmandi-Ayed, Rim


    This paper suggests a modelling of the labelling procedure consistent with empirical observations, that allows the endogenous calculation of labelling criteria. The authority in charge of the labelling program chooses the level of labelling criteria so as to maximise the social surplus, anticipating competition between firms in environmental qualities and prices. While accounting simply for the informational role of labels, this model allows to understand observed behavior such as firms' igno...

  11. A simple synthesis of [sup 13]C[sub 6]-labelled flavone and 5-methoxyflavone

    Ares, J.J.; Wehmeyer, K.R. (Procter and Gamble Co., Cincinnati, OH (United States))


    The [sup 13]C[sub 6]-labelled molecules, flavone and 5-methoxyflavone, with the carbon-13 label at all six carbons of the aromatic B ring, have been prepared for use as internal standards in isotope dilution-mass spectrometry. The key step involves addition of a labelled benzoyl group to the methyl group of a hydroxyacetophenone, forming a 1,3-diketone. Overall yields from [sup 13]C[sub 6]-benzoic acid were 38% for the labelled flavone and 45% for the labelled 5-methoxyflavone. (Author).

  12. On online labeling with polynomially many labels

    Babka, M.; Bulánek, Jan; Čunát, V.; Koucký, Michal; Saks, M.

    Berlin : Springer, 2012 - (Epstein, L.; Ferragina, P.), s. 121-132 ISBN 978-3-642-33089-6. - (Lecture Notes in Computer Science. 7501). [20th Annual European Symposium on Algorithms (ESA 2012). Ljubljana (SI), 10.09.2012-12.09.2012] R&D Projects: GA ČR GAP202/10/0854; GA AV ČR IAA100190902 Institutional support: RVO:67985840 Keywords : online labeling * file maintenance problem * lower bounds Subject RIV: BA - General Mathematics

  13. European consumers and nutrition labelling

    Wills, Josephine M.; Grunert, Klaus G.; Celemín, Laura Fernández;


    Nutrition labelling of food in Europe is not compulsory, unless a nutrition or health claim is made for the product. The European Commission is proposing mandatory nutrition labelling, even front of pack labelling with nutrition information. Yet, how widespread is nutrition labelling in the EU...

  14. Genetic algorithms for map labeling

    Dijk, Steven Ferdinand van


    Map labeling is the cartographic problem of placing the names of features (for example cities or rivers) on the map. A good labeling has no intersections between labels. Even basic versions of the problem are NP-hard. In addition, realistic map-labeling problems deal with many cartographic constr

  15. Off-Label Drug Use

    ... Your Local Offices Close + - Text Size Off-label Drug Use What is off-label drug use? In the United States new drugs are ... unapproved use of a drug. Is off-label drug use legal? The off-label use of FDA- ...

  16. Radio labeling with preassigned frequencies.


    A radio labeling of a graph G is an assignment of pairwise distinct, positive integer labels to the vertices of G such that labels of adjacent vertices differ by at least $2$. The radio labeling problem (RL) consists in determining a radio labeling that minimizes the maximum label that is used (the so-called span of the labeling). RL is a well-studied problem, mainly motivated by frequency assignment problems in which transmitters are not allowed to operate on the same frequency channel. We c...

  17. CD molecules 2005: human cell differentiation molecules

    Zola, H.; Swart, B.; Nicholson, I.; Aasted, B.; Bensussan, A.; Boumsell, L.; Buckley, C.; Clark, G.; Drbal, Karel; Engel, P.; Hart, D.; Hořejší, Václav; Isacke, C.; Macardle, P.; Malavasi, F.; Mason, D.; Olive, D.; Saalmüller, A.; Schlossman, S.F.; Schwartz-Albiez, R.; Simmons, P.; Tedder, T.F.; Uguccioni, M.; Warren, H.


    Roč. 106, č. 9 (2005), s. 3123-3126. ISSN 0006-4971 Institutional research plan: CEZ:AV0Z5052915 Keywords : CD molecules * leukocyte antigen Subject RIV: EC - Immunology Impact factor: 10.131, year: 2005

  18. Radioactive labelling of peptidic hormones

    The labelling of peptidic hormones requires stability, specificity and sensitivity of the label. Introduction of a radioactive atome is one way to satisfy these criteria. Several processes have been described to prepare radioactive TRF: synthesis of the peptide with labelled aminoacids or introduction of the label into the hormone. In that approach, tritium can be substituted in the imidazole ring, via precursors activating the proper carbon. Monoiodo TRF leads essentially to tritium labelling of the 5 positions whereas monoazo TRF allows the preparation of 3H TRF labelled in the 2 positions. Di-substituted TRF leads to labelling into the 2 and 5 carbons. Labelled analogs of TRF can be prepared with labelled iodine; further developments of peptide labelling, will be presented. In particular, the homolytic scission of the C-iodine, bond by photochemical activation. The nascent carbon radical can be stabilized by a tritiated scavenger. This approach eliminates the use of heavy metal catalysts

  19. Single Molecule Fluorescence Measurements of Ribosomal Translocation Dynamics

    Chen, Chunlai; Stevens, Benjamin; Kaur, Jaskarin; Cabral, Diana; Liu, Hanqing; Wang, Yuhong; Zhang, Haibo; Rosenblum, Gabriel; Smilansky, Zeev; Goldman, Yale E.; Cooperman, Barry S.


    We employ single-molecule fluorescence resonance energy transfer (smFRET) to study structural dynamics over the first two elongation cycles of protein synthesis, using ribosomes containing either Cy3-labeled ribosomal protein L11 and A- or P-site Cy5-labeled tRNA or Cy3 and Cy5 labeled tRNAs. Pre-translocation (PRE) complexes demonstrate fluctuations between classical and hybrid forms, with concerted motions of tRNAs away from L11 and from each other when classical complex converts to hybrid ...

  20. Synthesis of labeled compounds

    Intermediate compounds labeled with 13C included methane, sodium cyanide, methanol, ethanol, and acetonitrile. A new method for synthesizing 15N-labeled 4-ethylsulfonyl-1-naphthalene-sulfonamide was developed. Studies were conducted on pathways to oleic-1-13C acid and a second pathway investigated was based on carbonation of 8-heptadecynylmagnesium bromide with CO2 to prepare sterolic acid. Biosynthetic preparations included glucose-13C from starch isolated from tobacco leaves following photosynthetic incubation with 13CO2 and galactose-13C from galactosylglycerol-13C from kelp. Research on growth of organisms emphasized photosynthetic growth of algae in which all cellular carbon is labeled. Preliminary experiments were performed to optimize the growth of Escherichia coli on sodium acetate-13C

  1. Fluorine-18 labelled compounds

    The work presented in this thesis deals with the problems involved in the adaption of reactor-produced fluorine-18 to the synthesis of 18F-labelled organic fluorine compounds. Several 18F-labelling reagents were prepared and successfully applied. The limitations to the synthetic possibilities of reactor-produced fluoride-18 become manifest in the last part of the thesis. An application to the synthesis of labelled aliphatic fluoro amino acids has appeared to be unsuccessful as yet, although some other synthetic approaches can be indicated. Seven journal articles (for which see the availability note) are used to compose the four chapters and three appendices. The connecting text gives a survey of known 18F-compounds and methods for preparing such compounds. (Auth.)

  2. Semantic Role Labeling

    Palmer, Martha; Xue, Nianwen


    This book is aimed at providing an overview of several aspects of semantic role labeling. Chapter 1 begins with linguistic background on the definition of semantic roles and the controversies surrounding them. Chapter 2 describes how the theories have led to structured lexicons such as FrameNet, VerbNet and the PropBank Frame Files that in turn provide the basis for large scale semantic annotation of corpora. This data has facilitated the development of automatic semantic role labeling systems based on supervised machine learning techniques. Chapter 3 presents the general principles of applyin

  3. Chemiluminescent Labeled Organic Reagents and Their Use in Analysis of Organic Compounds

    Hummelen, Jan C.; Wynberg, Hans


    Thermochemically induced luminescence is generated in a fluorescent labeled organic compound containing a covalently bonded fluorescent label which is a polycyclic aromatic radical having at least three linearly fused benzene rings and capable of being excited to a fluorescent electronic excited state by energy transfer from an energy donor molecule or radical having an electronic excited state, by a process comprising generating an energy donor radical or molecule by a thermochemical reactio...

  4. Design and synthesis of tracers labelled with a short-lived positron emitting

    Positron emission tomography (PET) is currently used widely as a non-invasive tool for dynamic studies of regional in vivo biochemistry in biomedical research as well as in medical diagnosis. Its advance has increased the demand for labeled tracers and stimulated the search for synthetic strategies for rapid synthesis of tracer molecules labeled with short-lived radionuclides. The paper deals with various topics in this field with emphasis on the design and the synthesis of interesting radiolabeled tracer molecules. It first discusses requirements for the design of labeled tracer molecules. Important factors in selecting an appropriate tracer molecule for PET study include the type of radionuclide to be used, position for labeling, and appropriate stereochemical configuration. The report then discusses position specific labeling for studies of metabolism, kinetic isotopic effects in PET, multiple isotopic labeling for non-invasive validation of metabolism, synthetic strategies for labeling tracer molecules with short-lived radionuclides, and creation of chirality by asymmetric organic and enzyme catalyzed synthesis. (N.K.)

  5. Formation of Ultracold Molecules

    Cote, Robin [Univ. of Connecticut, Storrs, CT (United States)


    Advances in our ability to slow down and cool atoms and molecules to ultracold temperatures have paved the way to a revolution in basic research on molecules. Ultracold molecules are sensitive of very weak interactions, even when separated by large distances, which allow studies of the effect of those interactions on the behavior of molecules. In this program, we have explored ways to form ultracold molecules starting from pairs of atoms that have already reached the ultracold regime. We devised methods that enhance the efficiency of ultracold molecule production, for example by tuning external magnetic fields and using appropriate laser excitations. We also investigates the properties of those ultracold molecules, especially their de-excitation into stable molecules. We studied the possibility of creating new classes of ultra-long range molecules, named macrodimers, thousand times more extended than regular molecules. Again, such objects are possible because ultra low temperatures prevent their breakup by collision. Finally, we carried out calculations on how chemical reactions are affected and modified at ultracold temperatures. Normally, reactions become less effective as the temperature decreases, but at ultracold temperatures, they can become very effective. We studied this counter-intuitive behavior for benchmark chemical reactions involving molecular hydrogen.

  6. Labeling of herbicide femesafen

    5-[2-chroo-4-(trifluoromethyl ) phenoxy]-N-(methyl sulphonyl )-2-niorobenzamide [femesafen] was labeled by six steps. Radio-chemical yield was 19.15%. TLC analysis of the final product showed that the radiochemical purity is not less than 99%. (authors)

  7. Waisda?: video labeling game

    Hildebrand, M.; Brinkerink, M.; Gligorov, R.; Steenbergen, M. van; Huijkman, J.; Oomen, J.


    The Waisda? video labeling game is a crowsourcing tool to collect user-generated metadata for video clips. It follows the paradigm of games-with-a-purpose, where two or more users play against each other by entering tags that describe the content of the video. Players score points by entering the sa

  8. Understanding Food Labels

    ... girls Eating healthy at restaurants Special food issues Vegetarian eating Eating for strong bones Quiz: Food Facts Links to more information girlshealth glossary home Home Nutrition Healthy eating for girls Understanding food labels Understanding ...

  9. Stabilization of labelled compounds

    This invention concerns a composition including a labelled compound, and the vitamin B 12. This vitamin gives a red colour to the solution and stabilize it radiochemically, allowing to transport the solution at ambient temperature and a storage at 4 degrees celsius. (N.C.). 5 refs

  10. Genetic algorithms for map labeling

    Dijk, Steven Ferdinand van


    Map labeling is the cartographic problem of placing the names of features (for example cities or rivers) on the map. A good labeling has no intersections between labels. Even basic versions of the problem are NP-hard. In addition, realistic map-labeling problems deal with many cartographic constraints, which pose more demands on how the labels should be placed in relation to their surroundings. For example, a label is preferably placed above and to the right of a city. These two aspects (comb...

  11. Trapping molecules on chips

    Santambrogio, Gabriele


    In the last years, it was demonstrated that neutral molecules can be loaded on a microchip directly from a supersonic beam. The molecules are confined in microscopic traps that can be moved smoothly over the surface of the chip. Once the molecules are trapped, they can be decelerated to a standstill, for instance, or pumped into selected quantum states by laser light or microwaves. Molecules are detected on the chip by time-resolved spatial imaging, which allows for the study of the distribution in the phase space of the molecular ensemble.

  12. Light-up properties of complexes between thiazole orange-small molecule conjugates and aptamers

    Pei, Renjun; Rothman, Jeffrey; Xie, Yuli; Stojanovic, Milan N.


    The full understanding of dynamics of cellular processes hinges on the development of efficient and non-invasive labels for intracellular RNA species. Light-up aptamers binding fluorogenic ligands show promise as specific labels for RNA species containing those aptamers. Herein, we took advantage of existing, non-light-up aptamers against small molecules and demonstrated a new class of light-up probes in vitro. We synthesized two conjugates of thiazole orange dye to small molecules (GMP and A...

  13. Spin labels. Applications in biology

    The main applications of spin labels in the study of biomembranes, enzymes, nucleic acids, in pharmacology, spin immunoassay are reviewed along with the fundamentals of the spin label method. 137 references. (author)

  14. Use the Nutrition Facts Label

    ... Features Spokespeople News Archive eNewsletters Calendar Use the Nutrition Facts Label You can help your family eat ... to some of their favorite foods. Use the Nutrition Facts label found on food packages to make ...

  15. Labeling lake water with tritium

    Frederick, B.J.


    A method of packaging tritiated water in a manner that facilitates safe handling in environmental labeling operations, and procedures followed in labeling a large body of water with a small volume of tritiated water are described. ?? 1963.

  16. Physics of Polymers under Nanoscopic Confinement: a Single Molecule Study

    Keshavarz, M.


    Physicist Masoumeh Keshavarz studied the thermal motion of a fluorescently labelled, individual “reporter” polymer molecule, surrounded and entangled by a gel of similar but unlabelled polymers. Owing to their extreme length and stiffness, it is possible to follow the shape and the motion of the rep

  17. Food Labels Tell the Story!

    ... My World From the Label to the Table! Food Labels Tell the Story! What is in food? Food provides your body with all of the ... your food choices. Nutrition Facts—the Labels on Food Products Beginning in 1994, the US government began ...

  18. Isotopically labelled benzodiazepines

    This paper reports on the benzodiazepines which are a class of therapeutic agents. Improvements in the analytical methodology in the areas of biochemistry and pharmacology were significant, particularly in the application of chromatographic and spectroscopic techniques. In addition, the discovery and subsequent development of tritium and carbon-14 as an analytical tool in the biological sciences were essentially post-world war II phenomena. Thus, as these new chemical entities were found to be biologically active, they could be prepared in labeled form for metabolic study, biological half-life determination (pharmacokinetics), tissue distribution study, etc. This use of tracer methodology has been liberally applied to the benzodiazepines and also more recently to the study of receptor-ligand interactions, in which tritium, carbon-11 or fluorine-18 isotopes have been used. The history of benzodiazepines as medicinal agents is indeed an interesting one; an integral part of that history is their use in just about every conceivable labeled form

  19. Nomenclature for labelled compounds

    This paper report on isotopically labelled compounds. The first indexing system for isotopically labelled organic compounds is generally credited to Boughton and named after him. An extension of his principles for designating compounds containing hydrogen isotopes has been part of the Chemical Abstracts Service index nomenclature system for many years. After close on five years labor the IUPAC sponsored Commission on Nomenclature of Organic Chemistry presented in 1979 their findings on Isotopically Modified Compounds. The system codified in their rules provides for recognition of various types of isotopic modification and is therefore of more general applicability. Concurrently the rules for the nomenclature of isotopically modified inorganic compounds are developed. These are to be seen as supplementing and extending the guidelines laid down in the IUPAC Inorganic Nomenclature Rules already published

  20. Labelling, Deviance and Media

    Greer, C.


    Labelling theory is a perspective that emerged as a distinctive approach to criminology during the 1960s, and was a major seedbed of the radical and critical perspectives that became prominent in the 1970s. It represented the highpoint of an epistemological shift within the social sciences away from positivism – which had dominated criminological enquiry since the late-1800s – and toward an altogether more relativistic stance on the categories and concepts of crime and control. It inspired a ...

  1. Eco-labelling

    Kuna-Marszałek, Anetta


    Considering environmental protection requirements in business operations may, in the long run, determine if a lasting comparative advantage can be achieved. That is why our textbook, rich in case studies, identifies not only the threats a business may pose to the environment but stresses the ways of reducing its negative impact. It discusses, among other things, the concept of corporate social responsibility, environmental management systems, methods and the importance of eco-labelling goods ...

  2. Myocardial arterial spin labeling

    Kober, Frank; Jao, Terrence; Troalen, Thomas; Nayak, Krishna S.


    Arterial spin labeling (ASL) is a cardiovascular magnetic resonance (CMR) technique for mapping regional myocardial blood flow. It does not require any contrast agents, is compatible with stress testing, and can be performed repeatedly or even continuously. ASL-CMR has been performed with great success in small-animals, but sensitivity to date has been poor in large animals and humans and remains an active area of research. This review paper summarizes the development of ASL-CMR techniques, c...

  3. Optical detection of single non-absorbing molecules using the surface plasmon of a gold nanorod

    Zijlstra, Peter; Orrit, Michel


    Current optical detection schemes for single molecules require light absorption, either to produce fluorescence or direct absorption signals. This severely limits the range of molecules that can be detected, because most molecules are purely refractive. Metal nanoparticles or dielectric resonators detect non-absorbing molecules by a resonance shift in response to a local perturbation of the refractive index, but neither has reached single-protein sensitivity. The most sensitive plasmon sensors to date detect single molecules only when the plasmon shift is amplified by a highly polarizable label or by a localized precipitation reaction on the particle's surface. Without amplification, the sensitivity only allows for the statistical detection of single molecules. Here we demonstrate plasmonic detection of single molecules in realtime, without the need for labeling or amplification. We monitor the plasmon resonance of a single gold nanorod with a sensitive photothermal assay and achieve a ~ 700-fold increase in ...

  4. Stearic acid spin labels in lipid bilayers: insight through atomistic simulations.

    Stimson, Lorna; Dong, Lei; Karttunen, Mikko; Wisniewska, Anna; Dutka, Małgorzata; Róg, Tomasz


    Spin-labeled stearic acid species are commonly used for electron paramagnetic resonance (EPR) studies of cell membranes to investigate phase transitions, fluidity, and other physical properties. In this paper, we use large-scale molecular dynamics simulations to investigate the position and behavior of nitroxide spin labels attached to stearic acid molecules in dipalmitoylphosphatidylcholine (DPPC) bilayers. The results of these studies are potentially very important for the interpretation of EPR spectra, which rely on assumptions about the position of the label in the membrane. Additionally, we investigate the effect of chirality and ionization of the carboxyl group of the label. For a non-ionized species, we observe that spin-label molecules are even able to make flip-flop transitions between the leaflets of the bilayer. Such transitions have been previously observed only in very rare cases in molecular simulations. PMID:17929861

  5. Linerless label device and method

    Binladen, Abdulkari


    This apparatus and method for applying a linerless label to an end user product includes a device with a printer for printing on a face surface of a linerless label, and a release coat applicator for applying a release coat to the face surface of the label; another device including an unwinder unit (103) to unwind a roll of printed linerless label; a belt (108); a glue applicator (102) for applying glue to the belt; a nip roller (106) for contacting and applying pressure to the face surface of the linerless label such that the glue on the belt transfers to the back surface of the linerless label; at least one slitting knife 105) positioned downstream the belt and a rewinder unit (104) positioned downstream the slitting knife; and a third device which die cuts and applies the linerless label to an end user object.

  6. Label-Guided Graph Exploration with Adjustable Ratio of Labels

    Zhang, Meng; Tang, Jijun


    The graph exploration problem is to visit all the nodes of a connected graph by a mobile entity, e.g., a robot. The robot has no a priori knowledge of the topology of the graph or of its size. Cohen et al. \\cite{Ilcinkas08} introduced label guided graph exploration which allows the system designer to add short labels to the graph nodes in a preprocessing stage; these labels can guide the robot in the exploration of the graph. In this paper, we address the problem of adjustable 1-bit label guided graph exploration. We focus on the labeling schemes that not only enable a robot to explore the graph but also allow the system designer to adjust the ratio of the number of different labels. This flexibility is necessary when maintaining different labels may have different costs or when the ratio is pre-specified. We present 1-bit labeling (two colors, namely black and white) schemes for this problem along with a labeling algorithm for generating the required labels. Given an $n$-node graph and a rational number $\\rh...

  7. Single Molecule DNA Detection with an Atomic Vapor Notch Filter

    Uhland, Denis; Widmann, Matthias; Lee, Sang-Yun; Wrachtrup, Jörg; Gerhardt, Ilja


    The detection of single molecules has facilitated many advances in life- and material-sciences. Commonly, it founds on the fluorescence detection of single molecules, which are for example attached to the structures under study. For fluorescence microscopy and sensing the crucial parameters are the collection and detection efficiency, such that photons can be discriminated with low background from a labeled sample. Here we show a scheme for filtering the excitation light in the optical detection of single stranded labeled DNA molecules. We use the narrow-band filtering properties of a hot atomic vapor to filter the excitation light from the emitted fluorescence of a single emitter. The choice of atomic sodium allows for the use of fluorescent dyes, which are common in life-science. This scheme enables efficient photon detection, and a statistical analysis proves an enhancement of the optical signal of more than 15% in a confocal and in a wide-field configuration.

  8. Electron correlation in molecules

    Wilson, S


    Electron correlation effects are of vital significance to the calculation of potential energy curves and surfaces, the study of molecular excitation processes, and in the theory of electron-molecule scattering. This text describes methods for addressing one of theoretical chemistry's central problems, the study of electron correlation effects in molecules.Although the energy associated with electron correlation is a small fraction of the total energy of an atom or molecule, it is of the same order of magnitude as most energies of chemical interest. If the solution of quantum mechanical equatio

  9. Artifacts in single-molecule localization microscopy.

    Burgert, Anne; Letschert, Sebastian; Doose, Sören; Sauer, Markus


    Single-molecule localization microscopy provides subdiffraction resolution images with virtually molecular resolution. Through the availability of commercial instruments and open-source reconstruction software, achieving super resolution is now public domain. However, despite its conceptual simplicity, localization microscopy remains prone to user errors. Using direct stochastic optical reconstruction microscopy, we investigate the impact of irradiation intensity, label density and photoswitching behavior on the distribution of membrane proteins in reconstructed super-resolution images. We demonstrate that high emitter densities in combination with inappropriate photoswitching rates give rise to the appearance of artificial membrane clusters. Especially, two-dimensional imaging of intrinsically three-dimensional membrane structures like microvilli, filopodia, overlapping membranes and vesicles with high local emitter densities is prone to generate artifacts. To judge the quality and reliability of super-resolution images, the single-molecule movies recorded to reconstruct the images have to be carefully investigated especially when investigating membrane organization and cluster analysis. PMID:26138928

  10. Labeling of virus components for advanced, quantitative imaging analyses.

    Sakin, Volkan; Paci, Giulia; Lemke, Edward A; Müller, Barbara


    In recent years, investigation of virus-cell interactions has moved from ensemble measurements to imaging analyses at the single-particle level. Advanced fluorescence microscopy techniques provide single-molecule sensitivity and subdiffraction spatial resolution, allowing observation of subviral details and individual replication events to obtain detailed quantitative information. To exploit the full potential of these techniques, virologists need to employ novel labeling strategies, taking into account specific constraints imposed by viruses, as well as unique requirements of microscopic methods. Here, we compare strengths and limitations of various labeling methods, exemplify virological questions that were successfully addressed, and discuss challenges and future potential of novel approaches in virus imaging. PMID:26987299

  11. Labelled compounds. (Pt. B)

    Since the end of World War II there has been a tremendous increase in the number of compounds that have been synthesized with radioactive or stable isotopes. They have found application in many diverse fields, so much so, that hardly a single area in pure and applied science has not benefited. Not surprisingly it has been reflected in appearance of related publications. The early proceedings of the Symposia on Advances in Trace Methodology were soon followed by various Euratom sponsored meetings in which methods of preparing and storing labelled compounds featured prominently. In due course a resurgence of interest in stable isotopes, brought about by their greater availability (also lower cost) and partly by development of new techniques such as gas chromatography - mass spectrometry (gc-ms), led to the publication of proceedings of several successful conferences. More recently conferences dealing with the synthesis and applications of isotopes and isotopically labelled compounds have been established on a regular basis. In addition to the proceedings of conferences and journal publications individuals left their mark by producing definitive texts, usually on specific nuclides. Only the classic two volume publication of Murray and Williams (Organic syntheses with isotopes, New York 1985), now over 30 years old and out of print, attempted to do justice to several nuclides. With the large amount of work that has been undertaken since then it seems unlikely that an updated edition could be produced. The alternative strategy was to ask scientists currently active to review specific areas and this is the approach adopted in the present series of monographs. In this way it is intended to cover the broad advances that have been made in the synthesis and applications of isotopes and isotopically labelled compounds in the physical and biomedical sciences. (author). refs.; figs.; tabs

  12. Trace fluorescent labeling for protein crystallization

    Pusey, Marc, E-mail:; Barcena, Jorge; Morris, Michelle; Singhal, Anuj; Yuan, Qunying; Ng, Joseph [iXpressGenes Inc., 601 Genome Way, Huntsville, AL 35810 (United States)


    The presence of a covalently bound fluorescent probe at a concentration of <0.5% does not affect the outcome of macromolecule crystallization screening experiments. Additionally, the fluorescence can be used to determine new, not immediately apparent, lead crystallization conditions. Fluorescence can be a powerful tool to aid in the crystallization of proteins. In the trace-labeling approach, the protein is covalently derivatized with a high-quantum-yield visible-wavelength fluorescent probe. The final probe concentration typically labels ≤0.20% of the protein molecules, which has been shown to not affect the crystal nucleation or diffraction quality. The labeled protein is then used in a plate-screening experiment in the usual manner. As the most densely packed state of the protein is the crystalline form, then crystals show as the brightest objects in the well under fluorescent illumination. A study has been carried out on the effects of trace fluorescent labeling on the screening results obtained compared with nonlabeled protein, and it was found that considering the stochastic nature of the crystal nucleation process the presence of the probe did not affect the outcomes obtained. Other effects are realised when using fluorescence. Crystals are clearly seen even when buried in precipitate. This approach also finds ‘hidden’ leads, in the form of bright spots, with ∼30% of the leads found being optimized to crystals in a single-pass optimization trial. The use of visible fluorescence also enables the selection of colors that bypass interfering substances, and the screening materials do not have to be UV-transparent.

  13. Waisda?: video labeling game

    Hildebrand, Michiel; Brinkerink, M.; Gligorov, R.; Steenbergen, Van; Huijkman, J.; Oomen, J.


    The Waisda? video labeling game is a crowsourcing tool to collect user-generated metadata for video clips. It follows the paradigm of games-with-a-purpose, where two or more users play against each other by entering tags that describe the content of the video. Players score points by entering the same tags as one of the other players. As a result each video that is played in the game is annotated with tags that are anchored to a time point in the video. Waisda? has been deployed in two projec...

  14. From Label to Practice

    Byrkjeflot, Haldor; Strandgaard, Jesper; Svejenova, Silviya


    This article examines the process of creation of new Nordic cuisine (NNC) as a culinary innovation, focusing on the main stages, actors, and mechanisms that shaped the new label and its practices and facilitated its diffusion in the region and internationally. Fast-paced diffusion was possible...... because NNC was conceived as an identity movement, triggered by active involvement of entrepreneurial leaders from the culinary profession, high-profile political supporters, legitimating scientists, disseminating media, and interpreting audiences. It was facilitated by three mechanisms: First, the use of...

  15. Labeled bile acids

    A general short procedure for the introduction of 13C to the side chain of bile acids is described. Suitable (Z)-pregn-17(20)-enes are key intermediates, while the isotope is introduced by an ene reaction with [1,2,3-13C3]-methyl propiolate. For the labeling with tritium, the unlabeled product of the ene synthesis, a Δsup(5,16,22)-triene was saturated selectively at 16,17 and 22,23 with tritium gas. (author)

  16. A Food Labeling

    ... " ﻗﺎﻧﻮن اﻟﺒﻄﺎﻗﺎت واﻟﺘﻮﻋﻴﺔ اﻟﻐﺬاﺋﻴﺔ " [ Nutrition Labeling and Education Act ... ﻟﻠﻌﺼﻴﺮ اﻟﻤﻜﻮن ﺑﺈﺿﺎﻓﺔ اﻟﻤﺎء إﻟﻰ ﺧﻼﺻﺔ ﻣﺮآﺰة : ﻳﺠﺮى اﻟﺤﺴﺎب ﻣﻦ ﺟﺪول Brix ﻓﻲ 21 CFR 101.30(h)(1) ...

  17. Towards Multi Label Text Classification through Label Propagation

    Shweta C. Dharmadhikari


    Full Text Available Classifying text data has been an active area of research for a long time. Text document is multifaceted object and often inherently ambiguous by nature. Multi-label learning deals with such ambiguous object. Classification of such ambiguous text objects often makes task of classifier difficult while assigning relevant classes to input document. Traditional single label and multi class text classification paradigms cannot efficiently classify such multifaceted text corpus. Through our paper we are proposing a novel label propagation approach based on semi supervised learning for Multi Label Text Classification. Our proposed approach models the relationship between class labels and also effectively represents input text documents. We are using semi supervised learning technique for effective utilization of labeled and unlabeled data for classification. Our proposed approach promises better classification accuracy and handling of complexity and elaborated on the basis of standard datasets such as Enron, Slashdot and Bibtex.

  18. Electron-molecule collisions

    Takayanagi, Kazuo


    Scattering phenomena play an important role in modern physics. Many significant discoveries have been made through collision experiments. Amongst diverse kinds of collision systems, this book sheds light on the collision of an electron with a molecule. The electron-molecule collision provides a basic scattering problem. It is scattering by a nonspherical, multicentered composite particle with its centers having degrees of freedom of motion. The molecule can even disintegrate, Le., dissociate or ionize into fragments, some or all of which may also be molecules. Although it is a difficult problem, the recent theoretical, experimental, and computational progress has been so significant as to warrant publication of a book that specializes in this field. The progress owes partly to technical develop­ ments in measurements and computations. No less important has been the great and continuing stimulus from such fields of application as astrophysics, the physics of the earth's upper atmosphere, laser physics, radiat...

  19. Single molecules and nanotechnology

    Vogel, Horst


    This book focuses on recent advances in the rapidly evolving field of single molecule research. These advances are of importance for the investigation of biopolymers and cellular biochemical reactions, and are essential to the development of quantitative biology. Written by leading experts in the field, the articles cover a broad range of topics, including: quantum photonics of organic dyes and inorganic nanoparticles their use in detecting properties of single molecules the monitoring of single molecule (enzymatic) reactions single protein (un)folding in nanometer-sized confined volumes the dynamics of molecular interactions in biological cells The book is written for advanced students and scientists who wish to survey the concepts, techniques and results of single molecule research and assess them for their own scientific activities.

  20. CNN: Single-label to Multi-label

    Wei, Yunchao; Xia, Wei; Huang, Junshi; Ni, Bingbing; Dong, Jian; Zhao, Yao; Yan, Shuicheng


    Convolutional Neural Network (CNN) has demonstrated promising performance in single-label image classification tasks. However, how CNN best copes with multi-label images still remains an open problem, mainly due to the complex underlying object layouts and insufficient multi-label training images. In this work, we propose a flexible deep CNN infrastructure, called Hypotheses-CNN-Pooling (HCP), where an arbitrary number of object segment hypotheses are taken as the inputs, then a shared CNN is...

  1. Optothermal Molecule Trap

    Duhr, Stefan; Braun, Dieter


    Thermophoresis moves molecules along temperature gradients, typically from hot to cold. We superpose fluid flow with thermophoretic molecule flow under well defined microfluidic conditions, imaged by fluorescence microscopy. DNA is trapped and accumulated 16-fold in regions where both flows move in opposite directions. Strong 800-fold accumulation is expected, however with slow trapping kinetics. The experiment is equally described by a three-dimensional and one-dimensional analytical model. ...

  2. Modeling the effects of labeling

    Juhl, Hans Jørn; Fjord, Thomas Ahle; Poulsen, Carsten Stig

    A new approach to evaluate the consequences of labeling is presented and applied to test the potential effect of a label on fresh fish. Labeling effects on quality perceptions and overall quality are studied. The empirical study is based on an experimental design and nearly 500 respondents partic...... participated in an in home test. The results indicate that catch time alone is not enough to work as an efficient predictor of actual perceived quality.......A new approach to evaluate the consequences of labeling is presented and applied to test the potential effect of a label on fresh fish. Labeling effects on quality perceptions and overall quality are studied. The empirical study is based on an experimental design and nearly 500 respondents...

  3. Edge colouring by total labellings

    Brandt, Stephan; Rautenbach, D.; Stiebitz, M.;


    We introduce the concept of an edge-colouring total k-labelling. This is a labelling of the vertices and the edges of a graph G with labels 1, 2, ..., k such that the weights of the edges define a proper edge colouring of G. Here the weight of an edge is the sum of its label and the labels of its...... two endvertices. We define χ (G) to be the smallest integer k for which G has an edge-colouring total k-labelling. This parameter has natural upper and lower bounds in terms of the maximum degree Δ of G : ⌈ (Δ + 1) / 2 ⌉ ≤ χ (G) ≤ Δ + 1. We improve the upper bound by 1 for every graph and prove χ (G...

  4. Visualization of DNA molecules in time during electrophoresis

    Lubega, Seth


    For several years individual DNA molecules have been observed and photographed during agarose gel electrophoresis. The DNA molecule is clearly the largest molecule known. Nevertheless, the largest molecule is still too small to be seen using a microscope. A technique developed by Morikawa and Yanagida has made it possible to visualize individual DNA molecules. When these long molecules are labeled with appropriate fluorescence dyes and observed under a fluorescence microscope, although it is not possible to directly visualize the local ultrastructure of the molecules, yet because they are long light emitting chains, their microscopic dynamical behavior can be observed. This visualization works in the same principle that enables one to observe a star through a telescope because it emits light against a dark background. The dynamics of individual DNA molecules migrating through agarose matrix during electrophoresis have been described by Smith et al. (1989), Schwartz and Koval (1989), and Bustamante et al. (1990). DNA molecules during agarose gel electrophoresis advance lengthwise thorough the gel in an extended configuration. They display an extension-contraction motion and tend to bunch up in their leading ends as the 'heads' find new pores through the gel. From time to time they get hooked on obstacles in the gel to form U-shaped configurations before they resume their linear configuration.

  5. Synthesis and properties of differently charged chemiluminescent acridinium ester labels.

    Natrajan, Anand; Sharpe, David


    Chemiluminescent acridinium dimethylphenyl esters containing N-sulfopropyl groups in the acridinium ring are highly sensitive, hydrophilic labels that are used in automated immunoassays for clinical diagnostics. Light emission from these labels is triggered with alkaline peroxide in the presence of a cationic surfactant. At physiological pH, N-sulfopropyl acridinium esters exist as water adducts that are commonly referred to as pseudobases. Pseudobase formation, which results from addition of water to the zwitterionic N-sulfopropyl acridinium ring, neutralizes the positive charge on the acridinium nitrogen and imparts a net negative charge to the label due to the sulfonate moiety. As a consequence, N-sulfopropyl acridinium ester conjugates of small molecule haptens as well as large molecules such as proteins gain negative charges at neutral pH. In the current study, we describe the synthesis and properties of two new hydrophilic acridinium dimethylphenyl ester labels where the net charge in the labels was altered. In one label, the structure of the hydrophilic N-alkyl group attached to the acridinium ring was changed so that the pseudobase of the label contains no net charge. In the second acridinium ester, two additional negative charges in the form of sulfopropyl groups were added to the acridinium ring to make this label's pseudobase strongly anionic. Chemiluminescence measurements of these labels, as well as their conjugates of an antibody with a neutral pI, indicate that acridinium ester charge while having a modest effect on emission kinetics has little influence on light output. However, our results demonstrate that acridinium ester charge can affect protein pI, apparent chemiluminescence stability and non-specific binding of protein conjugates to microparticles. These results emphasize the need for careful consideration of acridinium ester charge in order to optimize reagent stability and performance in immunoassays. In the current study, we observed that

  6. HaloTag protein-mediated specific labeling of living cells with quantum dots

    Quantum dots emerge as an attractive alternative to small molecule fluorophores as fluorescent tags for in vivo cell labeling and imaging. This communication presents a method for specific labeling of live cells using quantum dots. The labeling is mediated by HaloTag protein expressed at the cell surface which forms a stable covalent adduct with its ligand (HaloTag ligand). The labeling can be performed in one single step with quantum dot conjugates that are functionalized with HaloTag ligand, or in two steps with biotinylated HaloTag ligand first and followed by streptavidin coated quantum dots. Live cell fluorescence imaging indicates that the labeling is specific and takes place at the cell surface. This HaloTag protein-mediated cell labeling method should facilitate the application of quantum dots for live cell imaging

  7. Limitations of Label-Free Sensors in Serum Based Molecular Diagnostics

    Varma, Manoj M


    Immunoassay formats applicable for clinical or point-of-care diagnostics fall into two broad classes. One which uses labeled secondary antibodies for signal transduction and the other which does not require the use of any labels. Comparison of the limits of detection (LoD) reported by these two sensing approaches over a wide range of detection techniques and target molecules in serum revealed that labeled techniques achieve 2-3 orders of magnitude better LoDs. Further, a vast majority of commercial tests and recent examples of technology translations are based on labeled assay formats. In light of this data, it is argued that extension of traditional labeled approaches and enhancing their functionality may have better clinical impact than the development of newer label-free techniques.

  8. Aggregating Labels in Crowdsourcing Data

    Priisalu, Maria; Grey, Francois; Segal, Ben


    Project Specification Crowdsourcing is gaining popularity in academia with the launch of crowdsourcing platforms such as Crowdcrafting [Lombraña, 2015] and GeoTagX [UNOSAT, 2015]. There have been a number of proposed algorithms for the aggregation of true labels and a confusion matrix from crowdsourced labels for ordinal, nominal and binary labels. The work here consists of an implementation of the Dawid Skene [Dawid 1979] adaptation of the Expectation Maximization algorithm [D...

  9. Classification and Labelling for Biocides

    Rubbiani, Maristella


    CLP and biocides The EU Regulation (EC) No 1272/2008 on Classification, Labelling and Packaging of Substances and Mixtures, the CLP-Regulation, entered into force on 20th January, 2009. Since 1st December, 2010 the classification, labelling and packaging of substances has to comply with this Regulation. For mixtures, the rules of this Regulation are mandatory from 1st June, 2015; this means that until this date classification, labelling and packaging could either be carried out according to D...

  10. Co-Labeling for Multi-View Weakly Labeled Learning.

    Xu, Xinxing; Li, Wen; Xu, Dong; Tsang, Ivor W


    It is often expensive and time consuming to collect labeled training samples in many real-world applications. To reduce human effort on annotating training samples, many machine learning techniques (e.g., semi-supervised learning (SSL), multi-instance learning (MIL), etc.) have been studied to exploit weakly labeled training samples. Meanwhile, when the training data is represented with multiple types of features, many multi-view learning methods have shown that classifiers trained on different views can help each other to better utilize the unlabeled training samples for the SSL task. In this paper, we study a new learning problem called multi-view weakly labeled learning, in which we aim to develop a unified approach to learn robust classifiers by effectively utilizing different types of weakly labeled multi-view data from a broad range of tasks including SSL, MIL and relative outlier detection (ROD). We propose an effective approach called co-labeling to solve the multi-view weakly labeled learning problem. Specifically, we model the learning problem on each view as a weakly labeled learning problem, which aims to learn an optimal classifier from a set of pseudo-label vectors generated by using the classifiers trained from other views. Unlike traditional co-training approaches using a single pseudo-label vector for training each classifier, our co-labeling approach explores different strategies to utilize the predictions from different views, biases and iterations for generating the pseudo-label vectors, making our approach more robust for real-world applications. Moreover, to further improve the weakly labeled learning on each view, we also exploit the inherent group structure in the pseudo-label vectors generated from different strategies, which leads to a new multi-layer multiple kernel learning problem. Promising results for text-based image retrieval on the NUS-WIDE dataset as well as news classification and text categorization on several real-world multi

  11. The radioactive labeling of monocytes

    With the aim of studying a possible relationship between circulating monocytes and Sternberg-Reed cells investigations were started on the specific labeling of monocytes. In this thesis the literature on the pertinent data has been reviewed and a series of experiments on the monocyte labeling procedure has been described. The principles of cell labeling with radioactive compounds were discussed. 1. Total separation of the particular cell population to be labeled and subsequent labeling with a non-specific radiopharmaceutical. 2. Specific cell labeling in a mixture of cell types based on a well defined affinity of the cell under study for the radiopharmaceutical used. Next the radionuclides that can be used for cell labeling purposes were discussed with special attention for 111In and its chelates. The principles of radiodosimetry were also discussed shortly. This section was focussed on the radiation dose the labeled cells receive because of the intracellular localized radioactivity. The radiation burden is high in comparison to amounts of radiation known to affect cell viability. A newly developed method for labeling monocytes specifically by phagocytosis of 111In-Fe-colloid without apparent loss of cells was described in detail. (Auth.)

  12. The stereoconfiguration of newly formed molecules of bis(monoacylglycero)phosphate in BHK cells.

    Joutti, A


    Newly formed molecules of bis(monoacylglycero)phosphate (known also as lysobisphosphatidic acid), which were labeled with 32Pi in cultured BHK cells during relatively short pulses, were subjected to stereoanalysis. In contrast to the high proportion of sn-1-glycerophosphate residues in the bulk of the bis(monoacylglycero)phosphate molecules, the newly formed molecules were rich in sn-3-glycerophosphate residues. PMID:508774

  13. 76 FR 75809 - Prior Label Approval System: Generic Label Approval


    ... the type of packaging material on which the label is printed; n. Brand name changes, provided that... poultry products will take effect January 1, 2012 (75 FR 82148, Dec. 29, 2010). These mandatory features..., location, and indication of final color. To obtain sketch label approval, domestic meat and...

  14. Laser labeling, a safe technology to label produce

    Laser labeling of fruits and vegetables is an alternative means to label produce. Low energy CO2 laser beams etch the surface showing the contrasting underlying layer. These etched surfaces can promote water loss and potentially allow for entry of decay organisms. The long-term effects of laser labe...

  15. Interaction between a "processed" ovalbumin peptide and Ia molecules

    Buus, S; Colon, S; Smith, C;


    The binding of 125I-labeled immunogenic peptides to purified Ia molecules in detergent solution was examined by equilibrium dialysis. We used the chicken ovalbumin peptide ovalbumin-(323-339)-Tyr, which is immunogenic in the BALB/c mouse and restricted to I-Ad. 125I-labeled ovalbumin-(323-339)-Tyr...... I-Ak but not to I-Ek, I-Ad, or I-Ed. Thus, a specific interaction between Ia and antigen that correlates with the major histocompatibility complex restriction was demonstrated, strongly arguing in favor of a determinant selection hypothesis for such restriction....

  16. Synthesis of tritium-labeled vitamin A and its analogs

    Metabolic and pharmacologic studies of Vitamin A and its analogs related to the prevention of lung cancer and other epithelial cancers required tritium-labeled Vitamin A analogs and β-carotene at high specific activity. Syntheses of some of the isomers were therefore developed in the laboratory, as described in the paper. The advantages of the scheme shown are that : 1. Tritiums are introduced into the molecule by catalytic hydrogenation, thus affording high specific activity. 2. It uses an allylic rearrangement of tritiated vinyl-β-ionol to C15-phosphonium salt, which is condensed with C5-nitrile to give C20-skeleton of retinonitrile. 3. It permits the development of milder methods to convert tritium-labeled retinaldehyde, as a common intermediate, to the other retinoids (i.e., retinoic acid, retinol, and retinyl acetate). Furthermore, tritium-labeled all-trans-β-carotene, an important carotenoid, has been obtained from the retinaldehyde

  17. Radio-labelled humic materials in migration studies

    Humic- and fulvic acids are able to complex polyvalent metal ions, e.g. radionuclides, leading to soluble complexes of significant strength, thereby decreasing the sorption of these compounds to soils and sediments. The interaction of humic materials with radionuclides may significantly influence the availability and transport of the latter in the environment. Typically, studies along these lines have focussed almost exclusively on the radionuclides, whereas the actual role of the humic material has been elucidated only indirectly. In order directly to study the behavior of the naturally occurring organic macro-molecules in relation to the environmental fate of radionuclides, radio-labelled humic- and fulvic acids can advantageously be applied. Radio-labels such as 14C and 125I have successfully been covalently incorporated in humic- and fulvic-acids. Labelling of humic substances as well as preliminary migration studies are discussed

  18. Tetraphenylporphyrin as a protein label for triple detection analytical systems.

    Konopińska, Kamila; Pietrzak, Mariusz; Mazur, Radosław; Malinowska, Elżbieta


    Porphyrins and metalloporphyrins are promising new protein labels that can be detected using multiple techniques; improving the reliability of the analysis and broadening the range of the linear response. Here, we investigate the potential of 5,10,15,20-tetraphenyl-21H,23H-porphyrin (Tpp) as a hybrid protein label. The electrochemical and optical properties of porphyrin conjugated with bovine serum albumin (BSA), chicken egg albumin (CEA) and immunoglobulin G (IgG) were determined and optimal conditions for Tpp-protein conjugation established. Model conjugates of carboxylated Tpp with BSA and short peptides were characterized using differential pulse voltammetry, UV-Vis spectrophotometry and spectrofluorimetry. These results reveal that Tpp is a promising molecule to be used in a triple detection protein labelling system. PMID:27441235

  19. Magnetic labelled HRP-polymer nanoparticles: A recyclable nanobiocatalyst

    Khosravi Arezoo


    Full Text Available In this paper, the reusability and process stability of nano-reengineered horseradish peroxidase was investigated in fluorescence based sensing system for hydrogen peroxide determination as a model application. To this end, dendron macromolecules were attached to enzyme surface through bio-conjugation techniques. The resulted enzyme-polymer nanoparticles, with average size of 14(±2 nm, showed significant life time and thermal stability. For enzyme recovery and reusability purposes, the enzyme-polymer nanoparticles were labelled with magnetic nanoparticles with a labelling yield of 90%. These labelled enzyme molecules showed significant process stability up to 7 recycling period in a model sensing system. A linear calibration curve was obtained over the hydrogen peroxide concentrations ranging from 5×10-8 mol L-1 to 1×10-5 mol L-1 with detection limit of 1.3×10-9 mol L-1 for the sensing system under the optimal conditions.

  20. Oxygen labelled CO2

    Tests were carried out as to whether additional information concerning pulmonary gas exchange could be obtained from the application of oxygen labelled carbon dioxide. Single breath experiments were performed on two healthy subjects with 0.1 percent C16O18O and 2.8 percent C18O2 in the inspiratory gas. Breath-hold time was varied between 0.5-20s in different experiments. The 18O-concentration of the end-expired gas bi-exponentially decreased with increasing breath-hold time. The high and low rate constants 4s-1 and 0.12s-1 for C18O2 and 2.5s-1 and 0.87s-1 for C16O18O were derived, respectively. These results, together with model calculations, suggest: 1) the rapid disappearance of C18O2 from the alveolar space is primarily limited by diffusion, so that this isotopic species can be applied to quantify pulmonary diffusing conditions; 2) the lower disappearance rate of C16O18O is caused by a lower equilibration kinetics in blood, so that this isotopic species offers a possibility to study carbonic anhydrase activity of the red cells in vivo; 3) the slow phase of label decay is influenced by both alveolar dead space and carbonic anhydrase activity of the pulmonary tissues. Pathological dead spaces are expected to be sensitively detectable by C16O18O as well as by C18O2. (author). 4 refs.; 4 figs

  1. Towards single molecule switches.

    Zhang, Jia Lin; Zhong, Jian Qiang; Lin, Jia Dan; Hu, Wen Ping; Wu, Kai; Xu, Guo Qin; Wee, Andrew T S; Chen, Wei


    The concept of using single molecules as key building blocks for logic gates, diodes and transistors to perform basic functions of digital electronic devices at the molecular scale has been explored over the past decades. However, in addition to mimicking the basic functions of current silicon devices, molecules often possess unique properties that have no parallel in conventional materials and promise new hybrid devices with novel functions that cannot be achieved with equivalent solid-state devices. The most appealing example is the molecular switch. Over the past decade, molecular switches on surfaces have been intensely investigated. A variety of external stimuli such as light, electric field, temperature, tunneling electrons and even chemical stimulus have been used to activate these molecular switches between bistable or even multiple states by manipulating molecular conformations, dipole orientations, spin states, charge states and even chemical bond formation. The switching event can occur either on surfaces or in break junctions. The aim of this review is to highlight recent advances in molecular switches triggered by various external stimuli, as investigated by low-temperature scanning tunneling microscopy (LT-STM) and the break junction technique. We begin by presenting the molecular switches triggered by various external stimuli that do not provide single molecule selectivity, referred to as non-selective switching. Special focus is then given to selective single molecule switching realized using the LT-STM tip on surfaces. Single molecule switches operated by different mechanisms are reviewed and discussed. Finally, molecular switches embedded in self-assembled monolayers (SAMs) and single molecule junctions are addressed. PMID:25757483

  2. Chains, clusters, inclusion compounds, paramagnetic labels, and organic rings

    Zanello, P


    The role of stereochemistry to elucidate reaction patterns and physico-chemical properties in topical subjects ranging from inorganic to organic chemistry are treated in the fifth and final volume of this series. Detailed accounts are given to study: chaining in polyphosphates, electron-transfers in carbonyl clusters, inclusion of organometallic molecules in cyclodextrins, stereochemistry of paramagnetic metal complexes by labeling with nitroxyl radicals, stereocontrol in organic syntheses assisted by inorganic complexes.

  3. Physical activation of molecules

    A brief review of processes of physical activation of molecules on the basis of phenomena of electronic and vibrational excitation, electron polarization is presented. Consideration is given to activation by electron impact, photo-, magneto- and mechanoactivation, as well as to radiation activation, proceeding under the effect of high-power radiations (102-107 eV). The character of disturbance of molecules, participating in chemical reactions, under the effect of different types of ionizing radiation (α-particles, electrons, γ-quanta etc.) is discussed

  4. In silico labeling reveals the time-dependent label half-life and transit-time in dynamical systems

    Maiwald Thomas


    Full Text Available Abstract Background Mathematical models of dynamical systems facilitate the computation of characteristic properties that are not accessible experimentally. In cell biology, two main properties of interest are (1 the time-period a protein is accessible to other molecules in a certain state - its half-life - and (2 the time it spends when passing through a subsystem - its transit-time. We discuss two approaches to quantify the half-life, present the novel method of in silico labeling, and introduce the label half-life and label transit-time. The developed method has been motivated by laboratory tracer experiments. To investigate the kinetic properties and behavior of a substance of interest, we computationally label this species in order to track it throughout its life cycle. The corresponding mathematical model is extended by an additional set of reactions for the labeled species, avoiding any double-counting within closed circuits, correcting for the influences of upstream fluxes, and taking into account combinatorial multiplicity for complexes or reactions with several reactants or products. A profile likelihood approach is used to estimate confidence intervals on the label half-life and transit-time. Results Application to the JAK-STAT signaling pathway in Epo-stimulated BaF3-EpoR cells enabled the calculation of the time-dependent label half-life and transit-time of STAT species. The results were robust against parameter uncertainties. Conclusions Our approach renders possible the estimation of species and label half-lives and transit-times. It is applicable to large non-linear systems and an implementation is provided within the PottersWheel modeling framework (

  5. Comparison of labels for Carafate in a gastric ulcer model

    The purpose of this study was to evaluate three radiolabels for the drug Carafate (basic aluminum sucrose octasulfate), which, when ingested orally, is believed to coat gastric ulcers and protect them from digestive enzymes to promote healing. In order to study the mode of action and residence time in the stomach using external imaging, a gamma-emitting label which is truly bound to the molecule is needed. Carafate has been radiolabeled with Se-75, In-111 (both chemically incorporated into the molecule) and with Tc-99m-HSA which physically adheres to Carafate. In the presence of stomach acid, Carafate polymerizes; when the labeled Carafates were mixed in vitro with 0.1N HCl, >90% of the radio-activity was associated with the polymer in the case of Se-75 and Tc-99m, but the In-111 label was less stable (25-35% bound to polymer). The three labeled preparations were administered orally to rats with gastric ulcers, and the transit of each was followed by gamma camera imaging. Gamma camera images confirmed radioactivity remaining at the ulcer site after unbound material had emptied from the stomach, and the focal activity persisted for >5 hours. The stomachs were then removed, washed and dissected at 5.5 hours and in vitro measurements of ulcer crater: normal stomach tissue radioactivity ratios averaged 15.4, 6.3, and 5.6 for the Se-75, In-111, and Tc-99m-HSA labels, respectively. Biodistribution studies of oral Se-75-Carafate in rats and pigs indicated that very little is absorbed from the GI tract and the distribution is similar to that of C-14-Carafate. It is concluded that Se-75 is the best marker for Carafate of these three gamma-emitting labels and Se-75-Carafate is suitable for studying the kinetics of the drug Carafate in human subjects

  6. Meat and Poultry Labeling Terms

    ... Food Standards and Labels: The Facts Labeling and Marketing Information [ Top of Page ] OVEN PREPARED: Product is fully cooked and ready to eat. [ Top of Page ] YOUNG TURKEY: Turkeys of either sex that are less than 8 months of age according to present regulations. [ Top of Page ] Last ...

  7. Nutrition Marketing on Food Labels

    Colby, Sarah E.; Johnson, LuAnn; Scheett, Angela; Hoverson, Bonita


    Objective: This research sought to determine how often nutrition marketing is used on labels of foods that are high in saturated fat, sodium, and/or sugar. Design and Setting: All items packaged with food labels (N = 56,900) in all 6 grocery stores in Grand Forks, ND were surveyed. Main Outcome Measure(s): Marketing strategy, nutrient label…

  8. [Investigation of the microstructure of biological systems by triplet label].

    Kotel'niko, A I; Kuznetsov, S N; Fogel', V R; Likhtenshteĭn, G I


    A method for investigating the microstruct and dynamics of biological systems by means of triplet-excited molecules is suggested. The method is based on the phenomenon of triplet excitation disactivation by exchange-resonance triplet-triplet energy transfer to the acceptor or by intercombination conversion induced by interaction of an excited molecule with a paramagnetic center. The disactivation efficiency was measured by registrating the phosphorescense decay kinetics. The interaction of the triplet label eosin isothiocyanate, covalently coupled with albumine, lysozyme, sarcoplasmic reticulum membrane and Ca-Mg-dependent sarcoplasmic reticulum ATPase, with O2, the stable nitroxide radicals and ions of Mn2+ was investigated to analyse the potentialities of this method. As a model system the eosin phosphorescence quenching by the same quenchers in glycerine-aguaous solutions was studied. The method permits to investigate the microviscosity and microstructure of biological objects in the label attached region on interaction of the label with a sound-quencher with constants being 10(4) divided by 10(9) M-1 sec-1 and to measure the lateral diffusion of molecules in highly viscosity media (10 divided by 10(5) santypuas). PMID:223037

  9. A Better Carbon Footprint Label

    Thøgersen, John; Nielsen, Kristian S.


    expected, price and carbon footprint were negatively related to choice. Further, participants preferred organic to non-organic coffee and certification by a public authority. The effect of the carbon label is significantly stronger the more environmentally concerned the consumer is. Using colors to...... indicate relative carbon footprint significantly increases carbon label effectiveness. Hence, a carbon footprint label is more effective if it uses traffic light colors to communicate the product's relative performance.......Based on insights from behavioral economics, it is suggested to extend carbon footprint labeling with information about relative performance, using the well-known “traffic light” color scheme to communicate relative performance. To test this proposition, the impact of a carbon footprint label on...

  10. Sublinear distance labeling for sparse graphs

    Alstrup, Stephen; Dahlgaard, Søren; Knudsen, Mathias Bæk Tejs; Porat, Ely

    A distance labeling scheme labels the $n$ nodes of a graph with binary strings such that, given the labels of any two nodes, one can determine the distance in the graph between the two nodes by looking only at the labels. A $D$-preserving distance labeling scheme only returns precise distances be...

  11. 21 CFR 201.71 - Magnesium labeling.


    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Magnesium labeling. 201.71 Section 201.71 Food and... LABELING Labeling Requirements for Over-the-Counter Drugs § 201.71 Magnesium labeling. (a) The labeling of over-the-counter (OTC) drug products intended for oral ingestion shall contain the magnesium...

  12. Prebiologically Important Interstellar Molecules

    Kuan, Y.-J.; Huang, H.-C.; Charnley, S. B.; Tseng, W.-L.; Snyder, L. E.; Ehrenfreund, P.; Kisiel, Z.; Thorwirth, S.; Bohn, R. K.; Wilson, T. L.


    Understanding the organic chemistry of molecular clouds, particularly the formation of biologically important molecules, is fundamental to the study of the processes which lead to the origin, evolution and distribution of life in the Galaxy. Determining the level of molecular complexity attainable in the clouds, and the nature of the complex organic material available to protostellar disks and the planetary systems that form from them, requires an understanding of the possible chemical pathways and is therefore a central question in astrochemistry. We have thus searched for prebiologically important molecules in the hot molecular cloud cores: Sgr B2(N-LMH), W51 e1/e2 and Orion-KL. Among the molecules searched: Pyrimidine is the unsubstituted ring analogue for three of the DNA and RNA bases. 2H-Azirine and Aziridine are azaheterocyclic compounds. And Glycine is the simplest amino acid. Detections of these interstellar organic molecular species will thus have important implications for Astrobiology. Our preliminary results indicate a tentative detection of interstellar glycine. If confirmed, this will be the first detection of an amino acid in interstellar space and will greatly strengthen the thesis that interstellar organic molecules could have played a pivotal role in the prebiotic chemistry of the early Earth.

  13. Atoms, Molecules, and Compounds

    Manning, Phillip


    Explores the atoms that govern chemical processes. This book shows how the interactions between simple substances such as salt and water are crucial to life on Earth and how those interactions are predestined by the atoms that make up the molecules.

  14. Exotic helium molecules

    We study the photo-association of an ultracold cloud of magnetically trapped helium atoms: pairs of colliding atoms interact with one or two laser fields to produce a purely long range 4He2(23S1-23P0) molecule, or a 4He2(23S1-23S1) long range molecule. Light shifts in one photon photo-association spectra are measured and studied as a function of the laser polarization and intensity, and the vibrational state of the excited molecule. They result from the light-induced coupling between the excited molecule, and bound and scattering states of the interaction between two metastable atoms. Their analysis leads to the determination of the scattering length a = (7.2 ± 0.6) ruling collisions between spin polarized atoms. The two photon photo-association spectra show evidence of the production of polarized, long-range 4He2(23S1-23S1) molecules. They are said to be exotic as they are made of two metastable atoms, each one carrying a enough energy to ionize the other. The corresponding lineshapes are calculated and decomposed in sums and products of Breit-Wigner and Fano profiles associated to one and two photon processes. The experimental spectra are fit, and an intrinsic lifetime τ = (1.4 ± 0.3) μs is deduced. It is checked whether this lifetime could be limited by spin-dipole induced Penning autoionization. This interpretation requires that there is a quasi-bound state close to the dissociation threshold in the singlet interaction potential between metastable helium atoms for the theory to match the experiment. (author)

  15. OMG: Open Molecule Generator

    Peironcely Julio E


    Full Text Available Abstract Computer Assisted Structure Elucidation has been used for decades to discover the chemical structure of unknown compounds. In this work we introduce the first open source structure generator, Open Molecule Generator (OMG, which for a given elemental composition produces all non-isomorphic chemical structures that match that elemental composition. Furthermore, this structure generator can accept as additional input one or multiple non-overlapping prescribed substructures to drastically reduce the number of possible chemical structures. Being open source allows for customization and future extension of its functionality. OMG relies on a modified version of the Canonical Augmentation Path, which grows intermediate chemical structures by adding bonds and checks that at each step only unique molecules are produced. In order to benchmark the tool, we generated chemical structures for the elemental formulas and substructures of different metabolites and compared the results with a commercially available structure generator. The results obtained, i.e. the number of molecules generated, were identical for elemental compositions having only C, O and H. For elemental compositions containing C, O, H, N, P and S, OMG produces all the chemically valid molecules while the other generator produces more, yet chemically impossible, molecules. The chemical completeness of the OMG results comes at the expense of being slower than the commercial generator. In addition to being open source, OMG clearly showed the added value of constraining the solution space by using multiple prescribed substructures as input. We expect this structure generator to be useful in many fields, but to be especially of great importance for metabolomics, where identifying unknown metabolites is still a major bottleneck.

  16. Bacterial invasion reconstructed molecule by molecule

    Werner, James H [Los Alamos National Laboratory


    We propose to visualize the initial stages of bacterial infection of a human host cell with unmatched spatial and temporal resolution. This work will develop a new capability for the laboratory (super-resolution optical imaging), will test unresolved scientific hypotheses regarding host-pathogen interaction dynamics, and leverages state of the art 3D molecular tracking instrumentation developed recently by our group. There is much to be gained by applying new single molecule tools to the important and familiar problem of pathogen entry into a host cell. For example, conventional fluorescence microscopy has identified key host receptors, such as CD44 and {alpha}5{beta}1 integrin, that aggregate near the site of Salmonella typhimurium infection of human cells. However, due to the small size of the bacteria ({approx} 2 {micro}m) and the diffraction of the emitted light, one just sees a fluorescent 'blob' of host receptors that aggregate at the site of attachment, making it difficult to determine the exact number of receptors present or whether there is any particular spatial arrangement of the receptors that facilitates bacterial adhesion/entry. Using newly developed single molecule based super-resolution imaging methods, we will visualize how host receptors are directed to the site of pathogen adhesion and whether host receptors adopt a specific spatial arrangement for successful infection. Furthermore, we will employ our 3D molecular tracking methods to follow the injection of virulence proteins, or effectors, into the host cell by the pathogen Type III secretion system (TTSS). We expect these studies to provide mechanistic insights into the early events of pathogen infection that have here-to-fore been technically beyond our reach. Our Research Goals are: Goal 1--Construct a super-resolution fluorescence microscope and use this new capability to image the spatial distribution of different host receptors (e.g. CD44, as {alpha}5{beta}1 integrin) at the

  17. Biomedical applications of single molecule detection

    Kelso, D. M.


    The search for increased sensitivity of bio-analytical techniques has recently shifted from signal generation to detection. While enzyme amplifiers and chemiluminescent reporters developed by chemists over the last two decades gradually moved detection limits to the attomol level, it has taken engineers only a few years to reach single- molecule sensitivity with the development of new instrumentation. A number of different approaches have successfully achieved single-molecule fluorescence detection including confocal and near-field scanning optical microscopy, photon-counting cameras, fluorescence- correlation and time-gated spectroscopy. They detect labels immobilized on substrates, diffusing in solution and flowing in electro-osmotic and hydrodynamically focused streams. Biotechnology has created numerous application s for single- molecule detection. In research labs, it can dramatically increase the rate of DNA sequencing, screen libraries for products of directed evolution, and characterize compounds in drug discovery programs. In medical diagnostics, ultra- sensitive detection technologies can be used for genetic screening, detection of infectious diseases, or multi- analyte profiles. It can be applied to immunoassays as well as DNA or RNA hybridization assays.

  18. Synthesis of coumarin or ferrocene labeled nucleosides via Staudinger ligation

    Kois Pavol


    Full Text Available Abstract Background Reaction of azides with triaryl phosphines under mild conditions gives iminophosphoranes which can react with almost any kind of electrophilic reagent, e.g. aldehydes/ketones to form imines or esters to form amides. This so-called Staudinger ligation has been employed in a wide range of applications as a general tool for bioconjugation including specific labeling of nucleic acids. Results A new approach for the preparation of labeled nucleosides via intermolecular Staudinger ligation is described. Reaction of azidonucleosides with triphenylphosphine lead to iminophosphorane intermediates, which react subsequently with derivatives of coumarin or ferrocene to form coumarin or ferrocene labeled nucleosides. Fluorescent properties of coumarin labeled nucleosides are determined. Conclusion New coumarin and ferrocene labeled nucleosides were prepared via intermolecular Staudinger ligation. This reaction joins the fluorescent coumarin and biospecific nucleoside to the new molecule with promising fluorescent and electrochemical properties. The isolated yields of products depend on the structure of azidonucleoside and carboxylic acids. A detailed study of the kinetics of the Staudinger ligation with nucleoside substrates is in progress.

  19. How to Read a Nutrition Facts Label

    Full Text Available ... Under Control Figuring Out Food Labels Healthy Food Shopping If My Child Has Food Allergies, What Should ... for Parents Figuring Out Food Labels Smart Supermarket Shopping Figuring Out Fat and Calories Food Labels Contact ...

  20. Single-molecule denaturation mapping of DNA in nanofluidic channels

    Reisner, Walter; Larsen, Niels Bent; Silahtaroglu, Asli;


    Here we explore the potential power of denaturation mapping as a single-molecule technique. By partially denaturing YOYO (R)-1-labeled DNA in nanofluidic channels with a combination of formamide and local heating, we obtain a sequence-dependent "barcode" corresponding to a series of local dips and...... peaks in the intensity trace along the extended molecule. We demonstrate that this structure arises from the physics of local denaturation: statistical mechanical calculations of sequence-dependent melting probability can predict the barcode to be observed experimentally for a given sequence....... Consequently, the technique is sensitive to sequence variation without requiring enzymatic labeling or a restriction step. This technique may serve as the basis for a new mapping technology ideally suited for investigating the long-range structure of entire genomes extracted from single cells....

  1. A systematization of spectral data on the methanol molecule

    Akhlyostin, A. Yu.; Voronina, S. S.; Lavrentiev, N. A.; Privezentsev, A. I.; Rodimova, O. B.; Fazliev, A. Z.


    Problems underlying a systematization of spectral data on the methanol molecule are formulated. Data on the energy levels and vacuum wavenumbers acquired from the published literature are presented in the form of information sources imported into the W@DIS information system. Sets of quantum numbers and labels used to describe the CH3OH molecular states are analyzed. The set of labels is different from universally accepted sets. A system of importing the data sources into W@DIS is outlined. The structure of databases characterizing transitions in an isolated CH3OH molecule is introduced and a digital library of the relevant published literature is discussed. A brief description is given of an imported data quality analysis and representation of the results obtained in the form of ontologies for subsequent computer processing.

  2. Labelling GM-free Products

    Punt, Maarten; Venus, Thomas; Wesseler, Justus


    Food suppliers in the EU must comply with labelling regulations for genetically modified organisms (GMOs). However, excluded from mandatory labelling are food products derived from animals fed with GM feed (mainly GM soybean in the EU). Because of this labelling exemption, consumers are unable to...... limited. The results indicate that for switching to ‘GM-free’ production, long-term effects such as the creation of a positive image or differentiation from competitors are more important for dairy companies than short-term effects such as higher sales or profit....

  3. Sustainability labels on food products

    Grunert, Klaus G; Hieke, Sophie; Wills, Josephine


    This study investigates the relationship between consumer motivation, understanding and use of sustainability labels on food products (both environmental and ethical labels), which are increasingly appearing on food products. Data was collected by means of an online survey implemented in the UK...... types of information available on food labels or as use inferred from the results of a choice-based conjoint analysis. Hierarchical regression indicated that use is related to both motivation and understanding, and that both motivation, understanding and use are affected by demographic characteristics...

  4. New labels for radiation therapy

    Kubota, Susumu; Mukai, Minoru; Kato, Hirotoshi (National Inst. of Radiological Sciences, Chiba (Japan))


    In simulating radiotherapy, the bone and trachea identified by plain X-P and the other organs, such as the esophagus and bladder, outlined by contrast medium have so far been used as labels. However, irradiation with a high therapeutic ratio is required for an intracorporeal insertion of artificial labels that are identified by X-ray fluoroscopy. For this purpose, metal clips and seed dummies are available, although they cause artifacts in CT scans. Therefore, the authors are using an acupuncture needle and lipiodol for tracing as new artificial labels, since both are identified by X-ray fluoroscopy and CT scan and create few artifacts. (J.P.N.).

  5. New labels for radiation therapy

    In simulating radiotherapy, the bone and trachea identified by plain X-P and the other organs, such as the esophagus and bladder, outlined by contrast medium have so far been used as labels. However, irradiation with a high therapeutic ratio is required for an intracorporeal insertion of artificial labels that are identified by X-ray fluoroscopy. For this purpose, metal clips and seed dummies are available, although they cause artifacts in CT scans. Therefore, the authors are using an acupuncture needle and lipiodol for tracing as new artificial labels, since both are identified by X-ray fluoroscopy and CT scan and create few artifacts. (J.P.N.)

  6. Are radiogallium-labelled DOTA-conjugated somatostatin analogues superior to those labelled with other radiometals?

    Gallium-68 is a metallic positron emitter with a half-life of 68 min that is ideal for the in vivo use of small molecules, such as [68Ga-DOTA,Tyr3]octreotide, in the diagnostic imaging of somatostatin receptor-positive tumours. In preclinical studies it has shown a striking superiority over its 111In-labelled congener. The purpose of this study was to evaluate whether third-generation somatostatin-based, radiogallium-labelled peptides show the same superiority. Peptides were synthesised on solid phase. The receptor affinity was determined by in vitro receptor autoradiography. The internalisation rate was studied in AR4-2J and hsst-HEK-transfected cell lines. The pharmacokinetics was studied in a rat xenograft tumour model, AR4-2J. All peptides showed high affinities on hsst2, with the highest affinity for the GaIII-complexed peptides. On hsst3 the situation was reversed, with a trend towards lower affinity of the GaIII peptides. A significantly increased internalisation rate was found in sst2-expressing cells for all 67Ga-labelled peptides. Internalisation into HEK-sst3 was usually faster for the 111In-labelled peptides. No internalisation was found into sst5. Biodistribution studies employing [67Ga-DOTA,1-Nal3]octreotide in comparison to [111In-DOTA,1-Nal3]octreotide and [67Ga-DOTA,Tyr3]octreotide showed a significantly higher and receptor-mediated uptake of the two67Ga-labelled peptides in the tumour and somatostatin receptor-positive tissues. A patient study illustrated the potential advantage of a broad receptor subtype profile radiopeptide over a high-affinity sst2-selective radiopeptide. This study demonstrates that 67/68Ga-DOTA-octapeptides show distinctly better preclinical, pharmacological performances than the 111In-labelled peptides, especially on sst2-expressing cells and the corresponding animal models. They may be excellent candidates for further development for clinical studies. (orig.)

  7. Molecules without electrons

    Electrons are the glue that holds the atoms in molecules together. Without them the positive charges of nuclei would repel each other, and the world would be a much simpler place. But in the quest to gain control over matter at a fundamental level, physicists in Russia and Canada have come up with a way of binding charged nuclei without any electrons. Instead the researchers use intense laser light. (U.K.)

  8. Single Molecule Mechanochemistry

    Li, Shaowei; Zhang, Yanxing; Ho, Wilson; Wu, Ruqian; Ruqian Wu, Yanxing Zhang Team; Wilson Ho, Shaowei Li Team

    Mechanical forces can be used to trigger chemical reactions through bending and stretching of chemical bonds. Using the reciprocating movement of the tip of a scanning tunneling microscope (STM), mechanical energy can be provided to a single molecule sandwiched between the tip and substrate. When the mechanical pulse center was moved to the outer ring feature of a CO molecule, the reaction rate was significantly increased compared with bare Cu surface and over Au atoms. First, DFT calculations show that the presence of CO makes the Cu cavity more attractive toward H2 Second, H2 prefers the horizontal adsorption geometry in the Cu-Cu and Au-Cu cavities and no hybridization occurs between the antibonding states of H2 and states of Cu atoms. While H2 loses electrons from its bonding state in all three cavities, the filling of its anti-bonding state only occurs in the CO-Cu cavity. Both make the CO-Cu cavity much more effectively to chop the H2 molecule. Work was supported by the National Science Foundation Center for Chemical Innovation on Chemistry at the Space-Time Limit (CaSTL) under Grant No. CHE-1414466.

  9. Photonic Molecule Lasers Revisited

    Gagnon, Denis; Dumont, Joey; Déziel, Jean-Luc; Dubé, Louis J.


    Photonic molecules (PMs) formed by coupling two or more optical resonators are ideal candidates for the fabrication of integrated microlasers, photonic molecule lasers. Whereas most calculations on PM lasers have been based on cold-cavity (passive) modes, i.e. quasi-bound states, a recently formulated steady-state ab initio laser theory (SALT) offers the possibility to take into account the spectral properties of the underlying gain transition, its position and linewidth, as well as incorporating an arbitrary pump profile. We will combine two theoretical approaches to characterize the lasing properties of PM lasers: for two-dimensional systems, the generalized Lorenz-Mie theory will obtain the resonant modes of the coupled molecules in an active medium described by SALT. Not only is then the theoretical description more complete, the use of an active medium provides additional parameters to control, engineer and harness the lasing properties of PM lasers for ultra-low threshold and directional single-mode emission. We will extend our recent study and present new results for a number of promising geometries. The authors acknowledge financial support from NSERC (Canada) and the CERC in Photonic Innovations of Y. Messaddeq.

  10. NIR fluorescent silica nanoparticles as reporting labels in bioanalytical applications

    Patonay, Gabor; Henary, Maged; Chapman, Gala; Emer, Kyle; Crow, Sydney


    The use of the NIR spectral region (650-900 nm) for bioanalytical and biomedical analyses is advantageous due to the inherently lower background interference in biological matrices and the high molar absorptivities of NIR chromophores. There are several different groups of NIR fluorescing dye are available for bioanalytical applications. One of these groups, NIR carbocyanines are increasingly used in analytical, bioanalytical and medical applications. These dyes can be used as reporter labels for sensitive bioanalytical use, such as immunochemistry. Due to the spectroscopic sensitivity of NIR carbocyanines for polarity changes in the microenvironment fluorescence quantum yield can vary significantly dependent on the microenvironment. NIR dyes can have relatively low fluorescent quantum yields as compared to visible fluorophores, especially in aqueous buffers but the lower quantum yield is compensated for by a much higher molar absorptivity. The fluorescence intensity of NIR reporting labels can significantly be increased by enclosing several dye molecules in silica nanoparticles. Incorporation of NIR dyes in silica nanoparticles creates a unique challenge as these dyes can be unstable under certain chemical conditions present during silica nanoparticles syntheses. In addition, self quenching may also become a problem for carbocyanines at higher a concentrations that typically found inside of NIR dye loaded silica nanoparticles. Dyes possessing high Stokes' shift can significantly reduce this problem. NIR carbocyanines are uniquely positioned for achieving this goal using a synthetic route that substitutes meso position halogens in NIR fluorescent carbocyanines with a linker containing amino moiety, which can also serve as a linker for covalently attaching the dye molecule to the nanoparticle backbone. The resulting silica nanoparticles can contain a large number of NIR dyes dependent on their size. For example some NIR fluorescent silica nanoparticle labels