Polyelectrolyte-Coated Gold Magnetic Nanoparticles for Immunoassay Development: Toward Point of Care Diagnostics for Syphilis Screening

• Published in: Analytical chemistry (Washington) Vol. 85; no. 14; pp. 6688 - 6695
• Main Authors: Yang, Dong, Ma, Jianzhong, Zhang, Qinlu, Li, Ningning, Yang, Jiangcun, Raju, Paul Ananda, Peng, Mingli, Luo, Yanling, Hui, Wenli, Chen, Chao, Cui, Yali
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 16.07.2013
• Subjects: Antibodies; Antigens; Diagnostic software; Disease control; Gold; Immunoassay; Immunoassay - methods; Infectious diseases; Mass Screening - methods; Metal Nanoparticles; Nanoparticles; Particulate composites; Point-of-Care Systems; Polymers; Syphilis; Syphilis - blood; Syphilis - diagnosis; Thermogravimetric analysis; Treponema pallidum; Ultraviolet radiation
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac400517e

Immediate response for disease control relies on simple, inexpensive, and sensitive diagnostic tests, highly sought after for timely and accurate test of various diseases, including infectious diseases. Composite Fe3O4/Au nanoparticles have attracted considerable interest in diagnostic applications due to their unique physical and chemical properties. Here, we developed a simple coating procedure for gold magnetic nanoparticles (GMNs) with poly(acrylic acid) (PAA). PAA-coated GMNs (PGMNs) were stable and monodispersed and characterized by Fourier transform-infrared spectroscopy (FT-IR), transmission electron microscopy, UV–visible scanning spectrophotometry, thermogravimetric analysis, and Zetasizer methodologies. For diagnostic application, we established a novel lateral flow immunoassay (LFIA) strip test system where recombinant Treponema pallidum antigens (r-Tp) were conjugated with PGMNs to construct a particle probe for detection of anti-Tp antibodies. Intriguingly, the particle probes specifically identified Tp antibodies with a detection limitation as low as 1 national clinical unit/mL (NCU/mL). An ample pool of 1020 sera samples from three independent hospitals were obtained to assess our PGMNs-based LFIA strips, which exhibited substantially high values of sensitivity and specificity for all clinical tests (higher than 97%) and, therefore, proved to be a suitable approach for syphilis screening at a point-of-care test manner.