In Situ Pt Staining Method for Simple, Stable, and Sensitive Pressure-Based Bioassays.

Pressure-based bioassays (PASS) integrate a molecular recognition process with a catalyzed gas generation reaction, enabling sensitive and portable quantitation of biomarkers in clinical samples. Using platinum nanoparticles (PtNPs) as a catalyst has significantly improved the sensitivity of PASS compared with protein enzyme-based detection. However, PtNPs are easily deactivated during storage or after being decorated with antibodies. Moreover, nonspecific adsorption of PtNPs on substrates has been a problem, resulting in significant backgrounds. To solve these problems of PtNP-based detection, we report a robust, simple, stable, and sensitive Pt staining method for PASS. Detection antibody-decorated gold nanoparticles (AuNPs) are used to perform enzyme-linked immunosorbent assay, followed by Pt staining to stain AuNPs with Ag and Pt bimetallic shells (Au@AgPtNPs), which endow AuNPs with catalytic activity. The concentration of targets can be quantitatively determined by measuring the pressure due to O2 gas (g) formed by the decomposition of H2O2 catalyzed by Au@AgPtNPs. C-reactive protein and avian influenza hemagglutinin 5 neuraminidase 1 can be quantitatively detected with detection limits of 0.015 and 0.065 ng/mL, respectively. The simple, stable, and sensitive properties of the Pt staining-based method will largely broaden the applications of PASS in clinical diagnosis and biomedicine.