Porous Pt nanodendrites with exceptionally high oxidase-like mimic catalytic efficiency for ratiometric fluorescence sensing of ascorbic acid and acid phosphatase

In this study, three porous platinum nanodendrites (Pt NDs) with exceptionally high catalytic efficiencies were fabricated using a carbon-dot (CD)-mediated route. This study demonstrated that the as-prepared porous Pt NDs, such as the integration of a large number of small Pt nanozymes with excellent catalytic activity, exhibited larger sizes and higher oxidase-like catalytic efficiency. The highest K_cat value of the obtained porous Pt NDs was 8.61 × 10⁴ s⁻¹, which was 20-fold greater than that of HRP (K_cat = 4.3 × 10³ s⁻¹). A mechanistic study showed that superoxide radicals are likely key intermediates involved in oxidase-like catalysis. Furthermore, the porous Pt NDs exhibited excellent long-term and thermal stabilities and could be reused. Due to the exceptionally high oxide-like activity, the porous Pt NDs can catalyze the oxidation of ascorbic acid (AA) and o-phenylenediamine (OPD), forming two fluorescence emissions at 430 nm and 556 nm, respectively. A ratiometric fluorescence assay for AA and acid phosphatase (ACP) was established. The linear range for AA and ACP determination is 0.05–25 μmol·L⁻¹ and 0.1–30 U·L⁻¹, and the limit of detection was 0.036 μmol·L⁻¹ and 0.03 U·L⁻¹, respectively. Considering their high catalytic efficiency, this type of porous Pt NDs holds excellent potential for biosensor applications.