A Simple Visual Strategy for Protein Detection Based on Oxidase-Like Activity of Silver Nanoparticles

Abstract

In this paper, we propose a simple and sensitive colorimetric sensing strategy for protein identification. The sensing array utilizes 3,3′,5,5′ tetramethylbenzidine (TMB) as the colorimetric sensing probe and three single-stranded (ss) DNA strands (15A, 15C, and 15T) as sensing elements. After adding protein, various interactions between DNA and protein result in differences in the amount of ssDNA remaining on the silver nanoparticles (AgNPs). It is well known that AgNPs have a strong catalytic ability toward the reaction between TMB and H2O2. Different amounts of ssDNA strands bound to AgNPs lead to diverse changes in the catalytic activity of AgNPs, which leads to different color and absorbance variations of the oxidized TMB solutions. These colorimetric responses as “fingerprints” were processed by linear discriminant analysis (LDA) to identify these target proteins. The sensing array can quantitatively identify lysozyme (Lys), Y-globin (Y-Glb), horseradish peroxidase (HRP), bovine liver peroxidase (Gat), trypsin (Try), human serum protein (HSA), pepsin (Pep), and ovalbumin (Alb) in the 1–400 nM, 1–1000 nM, 1–1000 nM, 50–700 nM, 1–400 nM, 1–400 nM, 1–700 nM, and 50–700 nM concentration ranges, respectively.