Next-generation transition metal nanozymes with peroxidase-mimetic activity for ultrasensitive colorimetric hydrogen...

Hydrogen peroxide (H₂O₂) is used in both biological and industrial processes, but at high concentrations, it can be toxic and detrimental to living organisms. So, its precise and accurate detection is important; however, conventional enzymatic detection technology has some shortcomings. Therefore, this review focuses on transition metal-based nanozymes that function as peroxidase mimics for the sensitive detection of H₂O₂ in colorimetric methods. The review evaluates the current approaches applied for increasing the selectivity using bimetallic alloys, hybrid nanostructures, and surface modifications, in conjunction with contact reduction mechanisms at the matrix-surface interface. It highlights the use of nanoparticles prepared from iron, copper, nickel, silver, gold, and cobalt due to their stability, cost-effectiveness, and flexibility. Even the most recent developments in research cannot address the current problems, which include oxidation susceptibility, material degradation, and the limited operational depth of real-world materials. Hence, this review provides insights into a portable microfluidics platform, smartphone-based analytical tools and AI-optimized nanozyme synthesis techniques to bridge the gap between laboratory proof-of-concept studies and industrial applications. This review also demonstrates sustainable sensing using eco-friendly nanoparticles developed from biomass resources by researchers. The adoption of biocompatibility standards alongside green manufacturing and multi-analyte detection systems will streamline the sensor operation in healthcare settings, environmental surveillance, and food safety analysis. The sensor development roadmap of H₂O₂ outlines the pathway by which material development takes an interdisciplinary approach and progresses toward large-scale production and commercialization of the sensor in the market.