Weakly ionized gold nanoparticles amplify immunoassays for ultrasensitive point-of-care sensors

Affiliations

• Guangdong Provincial Key Laboratory of Advanced Biomaterials, Shenzhen Key Laboratory of Smart Healthcare Engineering, Department of Biomedical Engineering, Southern University of Science and Technology, No. 1088 Xueyuan Road, Nanshan District, Shenzhen, Guangdong 518055, P. R. China.
• Key Laboratory of Molecular Medicine and Biotherapy, the Ministry of Industry and Information Technology, School of Life Science, Beijing Institute of Technology, Beijing 100081, P. R. China.
• School of Mechatronical Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China.
• Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia.

PMID: 38985882 PMCID: PMC11235179 DOI: 10.1126/sciadv.adn5698

Abstract

Gold nanoparticle-based lateral flow immunoassays (AuNP LFIAs) are widely used point-of-care (POC) sensors for in vitro diagnostics. However, the sensitivity limitation of conventional AuNP LFIAs impedes the detection of trace biomarkers. Several studies have explored the size and shape factors of AuNPs and derivative nanohybrids, showing limited improvements or enhanced sensitivity at the cost of convenience and affordability. Here, we investigated surface chemistry on the sensitivity of AuNP LFIAs. By modifying surface ligands, a surface chemistry strategy involving weakly ionized AuNPs enables ultrasensitive naked-eye LFIAs (~100-fold enhanced sensitivity). We demonstrated how this surface chemistry-amplified immunoassay approach modulates nanointerfacial bindings to promote antibody adsorption and higher activity of adsorbed antibodies. This surface chemistry design eliminates complex nanosynthesis, auxiliary devices, or additional reagents while efficiently improving sensitivity with advantages: simplified fabrication process, excellent reproducibility and reliability, and ultrasensitivity toward various biomarkers. The surface chemistry using weakly ionized AuNPs represents a versatile approach for sensitizing POC sensors.