Plasmonic and Photothermal Immunoassay via Enzyme-Triggered Crystal Growth on Gold Nanostars
Yahua Liu, Min Pan, Wenxiao Wang, Qunying Jiang, Fuan Wang, Dai-Wen Pang, and Xiaoqing Liu
DOI: 10.1021/acs.analchem.8b04517
Immunoassay is commonly used for the detection of disease biomarkers, but advanced instruments and professional operating are often needed with current techniques. The facile readout strategy for immunoassay is mainly limited to the gold nanoparti-cles-based colorimetric detection. Here, we show that photothermal nanoparticles can be applied for biosensing and immunoas-say with temperature as readout. We develop a plasmonic and photothermal immunoassay that allows straightforward readout by color and temperature based on crystal growth without advanced equipment. It is demonstrated that alkaline phosphatase-triggered silver deposition on the surface of gold nanostars causes large blue shift in the localized surface plasmon resonance of the nanosensor, accompanied with photothermal conversion efficiency changes. This approach also allows dual-readout of immunoassays with high sensitivity and great accuracy for the detection of prostate-specific antigen in complex samples. Our strategy provides a promising way for point-of-care testing and may broaden the applicability of programmable nanomaterials for diagnostics.