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Li J.,PharmaSeq, Inc. | Wang Z.,PharmaSeq, Inc. | Wang Z.,GenScript Inc. | Gryczynski I.,University of North Texas Health Science Center | Mandecki W.,PharmaSeq, Inc.
Analytical and Bioanalytical Chemistry | Year: 2010

The aim of this study is to improve assay sensitivity in common solid-phase bioassay configurations as the result of using silver nanoparticles. The solid phase was provided by numerically indexed, silicon-based electronic chips, microtransponders (p-Chips) that have previously been used in multiplexed assays. Assay configurations investigated included an ELISA-type immunoassay and a DNA hybridization assay. The surface of p-Chips was derivatized with the silver island film (SIF) and a polymer, and then characterized with AFM and SEM. Silver nanoparticle sizes were in the range of 100 to 200 nm. Four fluorophores were tested for fluorescence enhancement; namely, green fluorescent protein, phycoerythrin, Cy3 and Alexa Fluor 555. We consistently observed significant fluorescence enhancement and sensitivity improvement in the p-Chip-based assays: the sensitivity in the cytokine IL-6 immunoassay was 4.3 pg/ml, which represented a 25-fold increase over the method not involving a SIF; and 50 pM in the hybridization assay, a 38-fold increase. The greatest enhancement was obtained for p-Chip surfaces derivatized first with the polymer and then coated with SIF. In conclusion, we show that the SIF-p-Chip-based platform is a highly sensitive method to quantify low-abundance biomolecules in nucleic acid-based assays and immunoassays. © 2010 Springer-Verlag. Source

Kalwat M.A.,Indiana University | Wiseman D.A.,Indiana University | Luo W.,GenScript Inc. | Wang Z.,Indiana University | Thurmond D.C.,Indiana University
Molecular Endocrinology | Year: 2012

The plasma membrane soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) protein syntaxin (Syn)4 is required for biphasic insulin secretion, although how it regulates each phase remains unclear. In a screen to identify new Syn4-interacting factors, the calcium-activated F-actin-severing protein gelsolin was revealed. Gelsolin has been previously implicated as a positive effector of insulin secretion, although a molecular mechanism to underlie this function is lacking. Toward this, our in vitro binding studies showed the Syn4-gelsolin interaction to be direct and mediated by the N-terminal Ha domain (amino acid residues 39-70) of Syn4. Syn4-gelsolin complexes formed under basal conditions and dissociated upon acute glucose or KCl stimulation; nifedipine blocked dissociation. The dissociating action of secretagogues could be mimicked by expression of the N-terminal Ha domain of Syn4 fused to green fluorescent protein (GFP) (GFP-39-70). Furthermore, GFP-39-70 expression in isolated mouse islet and clonal MIN6 β-cells initiated insulin release in the absence of appropriate stimuli. Consistent with this, the inhibitory GFP-39-70 peptide also initiated Syn4 activation in the absence of stimuli. Moreover, although MIN6 β-cells expressing the GFP-39-70 peptide maintained normal calcium influx in response to KCl, KCl-stimulated insulin secretion and the triggering pathway of insulin secretion were significantly impaired. Taken together, these data support a mechanistic model for gelsolin's role in insulin exocytosis: gelsolin clamps unsolicited soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE)-regulated exocytosis through direct association with Syn4 in the absence of appropriate stimuli, which is relieved upon stimulus-induced calcium influx to activate gelsolin and induce its dissociation from Syn4 to facilitate insulin exocytosis. © 2012 by The Endocrine Society. Source

GenScript Corporation | Date: 2006-04-06

Detection reagents for scientific or medical research use.

GenScript Corporation | Date: 2007-03-23

Reagents for scientific or medical research use.

GenScript Corporation | Date: 2009-06-02

Chemical test kits comprised of lysis buffer and enzyme for generation of DNA for sequencing or cloning for laboratory or research use.

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