Rich-color visual genotyping of single-nucleotide polymorphisms based on platinum nanoparticle-induced etching of gold nanorods

摘要

Major technological challenges in point-of-care diagnostics are in the development of simple, fast, and inexpensive methods for high-throughput and multiplexed genotyping of single-nucleotide polymorphisms (SNPs). Herein, we develop a facile SNP detection platform based on platinum nanoparticles-induced etching of gold nanorods (AuNRs) by H_2O_2. The rVS-Ⅱ-1 (G>A) β-thalassemia mutation, as one of the most prevalent mutations in the Middle East, was used as a model disease. In the presence of H_2O_2, ferrous ion (Fe~(2+)) triggers a Fenton reaction with the catalytic decomposition of H_2O_2 into highly reactive hydroxyl (HO) and hydroperoxyl (HOO) radicals. These species etch AuNRs along the longitudinal axes to short AuNRs or even Au nanoparticles. For signaling SNPs, monobase-modified platinum nanoparticles (M-PtNPs) are hybridized to mutated sites of the duplex DNA. PtNPs catalyze the decomposition of H_2O_2 to water and oxygen, thus reducing the amount of H_2O_2 available for oxidative etching of AuNRs, and generating a series of distinct colors depending on the frequency of SNP in the target DNA. The frequency of SNP can be detected with the naked-eye or with UV-vis spectroscopy. The naked-eye detection limits of G-T and A-C mismatches are 17 and 15 pM, whereas UV-vis method responds linearly to these mismatches in the ranges from 10 to 200 pM and 5 to 120 pM with detection limits of 4 and 2 pM (3 a/slope), respectively. The present genosensor demonstrates a straightforward and easy-to-interpret method for naked-eye discrimination between PGR products of normal, heterozygous, and homozygous β-thalassemia-related mutation of β-hemoglobin.