Pt@Tei Nanozyme: An Antibiotic-Derived Peroxidase Mimic for Sensitive Smartphone-Based Glucose Biosensing

Developing cost-effective and highly active nanozymes compatible with accessible biosensing platforms remains a critical challenge for robust diagnostics. This study presents a facile and scalable method for synthesizing teicoplanin-stabilized platinum nanoparticles (Pt@Tei), utilizing the glycopeptide antibiotic teicoplanin as a unique stabilizer. Pt@Tei nanozymes exhibit potent peroxidase-mimetic activity, efficiently catalyzing the oxidation of chromogenic substrates (like 3,3',5,5'-tetramethylbenzidine (TMB)) in the presence of H₂O₂. The results indicate that the catalytic activity of Pt@Tei remained almost unchanged for at least 15 days, demonstrating the superiority of teicoplanin as a stabilizer. To demonstrate its application, we developed a sensitive smartphone-based colorimetric glucose biosensor. This assay integrates Pt@Tei nanozymes with glucose oxidase (GO_x) to initiate an enzymatic cascade: Glucose is first converted to gluconic acid, generating H₂O₂. The Pt@Tei then catalyzes the H₂O₂-dependent oxidation of TMB, producing a measurable color change. Key experimental conditions were optimized, achieving optimal performance at 37 °C and pH 5.0. Under these conditions, the Pt@Tei nanozyme demonstrated a limit of detection (LOD) for H₂O₂ of 0.177 μM. This system was further integrated into a paper-based analytical device (PAD). The PAD yielded a strong, quantifiable colorimetric signal in the red channel, directly proportional to the glucose concentration over the range of 0-10 mM (R² = 0.993), with a low glucose LOD of 0.385 mM. The platform exhibited excellent selectivity against common interfering analytes and high reproducibility (relative standard deviation (RSD) ≤ 4%). Critically, validation with goat serum samples showed strong agreement with a commercial meter and excellent spike recovery (98-102%), confirming their practical applicability. This work highlights teicoplanin as an effective stabilizer for nanozyme development and establishes a promising, accessible point-of-care platform for glucose monitoring.