Iodine-Mediated Etching of Gold Nanorods for Plasmonic ELISA Based on Colorimetric Detection of Alkaline Phosphatase

Abstract

Here, we propose a plasmonic enzyme-linked immunosorbent assay (ELISA) based on highly sensitive colorimetric detection of alkaline phosphatase (ALP), which is achieved by iodine-mediated etching of gold nanorods (AuNRs). Once the sandwich-type immunocomplex is formed, the ALP bound on the polystyrene microwells will hydrolyze ascorbic acid 2-phosphate into ascorbic acid. Subsequently, iodate is reduced to iodine, a moderate oxidant, which etches AuNRs from rod to sphere in shape. The shape change of AuNRs leads to a blue-shift of longitudinal localized surface plasmon resonance. As a result, the solution of AuNRs changes from blue to red. Benefiting from the highly sensitive detection of ALP, the proposed plasmonic ELISA has achieved an ultralow detection limit (100 pg/mL) for human immunoglobulin G (IgG). Importantly, the visual detection limit (3.0 ng/mL) allows the rapid differential diagnosis with the naked eye. The further detection of human IgG in fetal bovine serum indicates its applicability to the determination of low abundance protein in complex biological samples.

Plasmonic colorimetric sensors based on etching and growth of noble metal nanoparticles: Strategies and applications

“…Drinking water, sea water, tap water (Zhang et al, 2015a(Zhang et al, , 2014a Enzyme-mediated etching (Liang et al, 2015a;Lin et al, 2016;Liu et al, 2013d;Saa et al, 2014;Xia et al, 2013;Yang et al, 2014;Zhang et al, 2017Zhang et al, , 2015b Inhibitor-mediated etching…”

Optical Nanoprobes for Ultrasensitive Immunoassay

“…In addition, we also reported a plasmonic ELISA based on colorimetric detection of alkaline phosphatase (ALP) through iodinemediated etching of gold nanorods (AuNRs) ( Figure 3C). 44 As the intermediate of the enzyme-triggered reaction, iodine etches AuNRs into Au(I) and leads to a blue-shift of the LSPR of AuNRs. The peak shift can be used for quantification of human immunoglobulin G (IgG), which was chosen as a model protein in this study.…”

Allochroic‐Graphene Oxide Linked 3D Oriented Surface Imprinting Strategy for Glycoproteins Assays

“…It meant that the sensitivity was improved by about three orders of magnitudes owing to the excellent recognition capacity of the antibody‐like OSI‐MNPs and high‐efficient allochroic merit of PBA‐AGO nanosheets. Furthermore, the performance of the AGO‐OSI was comparable to most of the state‐of‐the‐art plasmonic ELISA, shown in Table S2 in the Supporting Information. As of note, the limit for naked eye‐visible readout was as low as 2.5 ng mL −1 .…”