Platinum Coordination Complex Nanozymes with Ligand-Modulated Peroxidase-like Activity for Sensitive Biosensing

Platinum-based coordination complexes show promise as nanozyme building blocks, yet their enzyme-like potential remains underexplored due to challenges in ligand engineering. Here, we develop ultrasmall platinum complex nanozymes by coordinating platinum with 6-aza-2-thiothymine (ATT), a pyrimidine-derived ligand, forming stable platinum–sulfur bonds (average size of 1.5 nm). Comprehensive spectroscopic and morphological analyses confirm that ATT stabilizes the complex while fine-tuning the platinum center’s electronic structure (Pt4+/Pt2+: 70.4%/29.6%). The resulting ATT-Pt exhibits superior peroxidase-like activity (137 U/mg), with Michaelis–Menten kinetic parameters for TMB (KM = 0.3026 mM, vmax = 5.79 × 10–8 M s–1) and H2O2 (KM = 1.046 mM, vmax = 9.26 × 10–8 M s–1), outperforming horseradish peroxidase and most reported platinum-based nanozymes in both catalytic efficiency and substrate affinity. Mechanistic studies reveal that ATT-Pt promotes efficient H2O2 activation and hydroxyl radical generation, mimicking natural enzyme pathways. Electrochemical analysis further demonstrates enhanced interfacial electron transfer, highlighting ligand engineering’s role in optimizing catalytic interfaces (linear range: 4–200 μM; LOD: 100 nM). Leveraging these properties, ATT-Pt enables ultrasensitive and selective colorimetric glucose detection, even with common interferents. This work establishes platinum coordination complexes as a versatile nanozyme platform and underscores ligand modulation as a key strategy for advancing biomedical applications.