Ag[at]SiO sub(2)-entrapped hydrogel microarray: a new platform for a metal-enhanced fluorescence-based protein assay

We developed a novel protein-based bioassay platform utilizing metal-enhanced fluorescence (MEF), which is a hydrogel microarray entrapping silica-coated silver nanoparticles (Ag[at]SiO sub(2)). As a model system, different concentrations of glucose were detected using a fluorescence method by seque...

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Bibliographic Details
Published in:Analyst (London) 2015-05, Vol.140 (10), p.3375-3383
Main Authors: Jang, Eunji, Kim, Minsu, Koh, Won-Gun
Format: Article
Language:English
Subjects:
Assaying
Devices
Enzymes
Fluorescence
Glucose
Hydrogels
Platforms
Silicon dioxide
Online Access:Get full text
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Summary:We developed a novel protein-based bioassay platform utilizing metal-enhanced fluorescence (MEF), which is a hydrogel microarray entrapping silica-coated silver nanoparticles (Ag[at]SiO sub(2)). As a model system, different concentrations of glucose were detected using a fluorescence method by sequential bienzymatic reaction of hydrogel-entrapped glucose oxidase (GOX) and peroxidase (POD) inside a hydrogel microarray. Microarrays based on poly(ethylene glycol)(PEG) hydrogels were prepared by photopatterning a solution containing PEG diacrylate (PEG-DA), photoinitiator, enzymes, and Ag[at]SiO sub(2). The resulting hydrogel microarrays were able to entrap both enzymes and Ag[at]SiO sub(2) without leaching and deactivation problems. The presence of Ag[at]SiO sub(2) within the hydrogel microarray enhanced the fluorescence signal, and the extent of the enhancement was dependent on the thickness of silica shells and the amount of Ag[at]SiO sub(2). Optimal MEF effects were achieved when the thickness of the silica shell was 17.5 nm, and 0.5 mg mL super(-1) of Ag[at]SiO sub(2) was incorporated into the assay systems. Compared with the standard hydrogel microarray-based assay performed without Ag[at]SiO sub(2), more than a 4-fold fluorescence enhancement was observed in a glucose concentration range between 10 super(-3) mM and 10.0 mM using hydrogel microarray entrapping Ag[at]SiO sub(2), which led to significant improvements in the sensitivity and the limit of detection (LOD). The hydrogel microarray system presented in this study could be successfully combined with a microfluidic device as an initial step to create an MEF-based micro-total-analysis-system ( mu -TAS).
ISSN:0003-2654
1364-5528
DOI:10.1039/c5an00251f