title: Silver nanoparticle-enhanced fluorescence in microtransponder-based immuno- and DNA hybridization assays.
abstract: 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.
authors.affiliation: PharmaSeq, Inc, 11 Deer Park Dr., Suite 104, Monmouth Junction, NJ 08852, USA.
authors.forename: Ji
authors.initials: J
authors.lastname: Li
authors.forename: Zhuying
authors.initials: Z
authors.lastname: Wang
authors.forename: Ignacy
authors.initials: I
authors.lastname: Gryczynski
authors.forename: Wlodek
authors.initials: W
authors.lastname: Mandecki
mesh_terms: D004581:Electronics / Q000295:instrumentation; D005456:Fluorescent Dyes; D007118:Immunoassay / Q000379:methods*; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D012834:Silver / Q000737:chemistry*
chemical_list: D005456:Fluorescent Dyes; D012834:Silver
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