# Bimetallic Au–Ag Nanoclusters as a Photo‐Responsive Oxidase‐Like Nanozyme for Antioxidant Detection and Intracellular Redox Analysis

## TL;DR

Gold-silver nanoclusters act as light-activated enzyme mimics to detect antioxidants and track redox changes in cells, offering a fast and reagent-free diagnostic tool.

## Contribution

First demonstration of bimetallic Au–Ag nanoclusters as photo-responsive oxidase-like nanozymes for antioxidant detection and intracellular redox analysis.

## Key findings

- AuAgNCs catalyze thiamine oxidation under visible light, generating peroxyl radicals for antioxidant detection.
- The platform enables rapid, reagent-free detection of antioxidants and measurement of total antioxidant capacity in biofluids and products.
- AuAgNCs allow dynamic tracking of intracellular redox changes in normal and steatotic hepatocyte models.

## Abstract

Bimetallic nanoclusters (NCs) hold promise as catalytic materials, yet their potential as enzyme mimics remains largely unexplored. Here, we report the first demonstration that gold–silver nanoclusters (AuAgNCs) function as photo‐responsive oxidase‐like nanozymes. Under visible‐light irradiation, AuAgNCs catalyze thiamine oxidation via a Type I photosensitization pathway, predominantly generating physiologically relevant peroxyl radicals (ROO•). The AuAgNCs outperform monometallic analogs, achieving enhanced catalytic efficiency with lower Km and higher v
max than previously reported nanozymes. Utilizing these capabilities, we established a rapid (<6 min), reagent‐free platform that enables: (i) selective detection of diverse physiological antioxidants, (ii) quantitative assessment of total antioxidant capacity (TAC) in simulated biofluids and consumer products, and (iii) dynamic tracking of intracellular redox alterations in normal and steatotic hepatocyte models. This versatile platform addresses critical limitations of conventional assays by employing in situ‐generated biologically relevant radicals and high specificity for antioxidant detection, while offering mechanistic insight, operational simplicity, and broad applicability. Our findings expand the functional landscape of bimetallic nanoclusters, establishing them as powerful redox‐active nanozymes for biomedical diagnostics, antioxidant evaluation, and redox biology.

Gold–silver nanoclusters act as light‐activated enzyme mimics that generate peroxyl radicals, oxidizing thiamine into a fluorescent product. Antioxidants block this conversion, providing the basis for rapid, reagent‐free detection and accurate measurement of total antioxidant capacity in fluids and products. The platform also tracks redox changes in liver cells, offering a simple tool for biomedical diagnostics and antioxidant evaluation.© 2026 WILEY‐VCH GmbH