Silver nanoprism etching-based plasmonic ELISA for the high sensitive detection of prostate-specific antigen

• Published in: Biosensors & bioelectronics 2015-07, Vol.69, p.128-134
• Main Authors: Liang, Jiajie, Yao, Cuize, Li, Xiuqing, Wu, Ze, Huang, Caihong, Fu, Qiangqiang, Lan, Caifeng, Cao, Donglin, Tang, Yong
• Format: Article
• Language: English
• Subjects: Antigens; Assaying; Biomarkers, Tumor - blood; Biosensors; ELISA; Enzyme-linked immunosorbent assay; Enzyme-Linked Immunosorbent Assay - instrumentation; Equipment Design; Equipment Failure Analysis; Etching; Humans; Male; Nanostructure; Plasmonic biosensor; Plasmonics; Prostate-Specific Antigen - blood; Prostatic Neoplasms - blood; Prostatic Neoplasms - diagnosis; Refractometry - instrumentation; Reproducibility of Results; Sensitivity and Specificity; Signal amplification; Silver; Silver - chemistry; Silver nanoprism; Surface Plasmon Resonance - instrumentation
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2015.02.026

Ultrasensitive and quantitative detection using simple and low-cost assays is critical in clinical diagnostics. In this report, we developed a triangular silver nanoprism (AgNPRs) etching-based plasmonic biosensor for the detection of cancer biomarkers. The triangular AgNPRs-based plasmonic biosensor is an enzyme-linked immunosorbent assay combined with the enzyme-mediated surface plasmon resonance (SPR) of triangular AgNPRs. Triangular AgNPRs uses the immune response of prostate-specific antigen (PSA) to trigger the glucose oxidase (GOx)-catalysed oxidation of glucose (Glu), producing hydrogen peroxide. Hydrogen peroxide acts as an oxidant to etch the triangular AgNPRs into smaller spherical silver nanoparticles, which is accompanied by a substantial blueshift of the SPR peak and a colourimetric blue-to-purple change that can be observed by the naked eye. The SPR peak shift enables the quantitative assessment of PSA due to the remarkable colour change. The triangular AgNPRs-based plasmonic ELISA approach exhibited a quasilinear response to logarithmic PSA concentrations in the range of 10fg/mL to 100pg/mL with a limit of detection (LOD) of 4.1fg/mL. In addition, the LOD of PSA in this approach exceeds that of the conventional HRP-based ELISA (1.25ng/mL) approach by more than 5 orders of magnitude. Patient serum samples from 16 donors were assayed with triangular AgNPRs-based plasmonic ELISA. The results from the triangular AgNPRs-based immunoassay and the time-resolved fluorescence immunoassay showed excellent correlation, and there were no significant differences in the quantified amounts of PSA. The triangular AgNPRs-based plasmonic ELISA approach has advantages (ultrasensitive, cost-effective, ease of operation) that are expected to be of great interest in diagnostics and to be suitable for a point-of-care test. •A novel plasmonic ELISA strategy for the detection of PSA.•Based on ELISA-mediated surface plasmon resonance buleshift of triangular silver nanoprism etching.•5 orders of magnitude improvements in sensitivity over a conventional ELISA.•This method was tested on sera sample from suspected cancer patients.•A potential method for clinic diagnosis and therapeutic monitoring of prostate cancer.