Silver nanoparticle-enhanced fluorescence in microtransponder-based immuno- and DNAhybridization assays

Ji Li, Zhuying Wang, Ignacy Gryczynski, Wlodek Mandecki

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


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.

Original languageEnglish
Pages (from-to)1993-2001
Number of pages9
JournalAnalytical and bioanalytical chemistry
Issue number5
StatePublished - Nov 2010


  • Hybridization
  • Microchip
  • Molecular diagnostics
  • Multiplex
  • Surface plasmon resonance


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