Optical Microfiber Coated with WS₂-Supported Gold Nanobipyramids: Ultrasensitive Detecting Prostate Cancer Extracellular Vesicles in Complex Human Samples

Ultrasensitive and rapid detection of single extracellular vesicles (EV) in complex biological samples requires a biosensor that possesses remarkable specificity, cost-effectiveness, and ease of use; however, this remains a big challenge owing to the small size and high heterogeneity of EV in samples. Although reported biosensors can detect biomarkers in complex biological samples, tedious preprocessing procedures, low sensitivity, and expensive and complicated production hinder their use in early-stage cancer diagnostics. To address these issues, an optical microfiber modified with WS2-supported gold nanobipyramid (Au NBPs) nanointerfaces for the ultrasensitive assay of prostate cancer (PC) exosomes is proposed. Owing to the strong localized surface plasmon resonance (LSPR) hotspots of the Au NBPs coupled with the WS2 nanointerface, the sensor could ultrasensitively detect exosomes with an ultralow limit of detection (LODs) of 23.5 particles mL(-1) in phosphate-buffered saline (PBS) solution and 570.6 particles mL(-1) in 10% serum. The LOD of 23.5 particles mL(-1) is two orders of magnitude lower than those reported for other cutting-edge techniques. Based on this sensing scheme, the sensor can distinguish PC serum from healthy serum, and successfully diagnose patients' whole blood by capturing and sizing a single bioparticle. This work presents a novel method for analyzing whole blood with ultrahigh sensitivity.