Fast and Ultrasensitive Visual Detection of Exosomes in Body Fluids for Point-of-Care Disease Diagnosis

Fast detection of low-concentration exosomes in body fluids is of great significance in understanding the pathogenesis and disease diagnosis but is quite a challenging work due to the complex matrix, tedious pretreatment, and relatively poor sensitivity without the aid of instruments. In this work, by simply using a filter membrane to enrich the exosomes at low concentrations and the use of CuS nanoparticles as labels, we were able to detect exosomes at concentrations as low as 2 × 103 particles/μL in a complex matrix by the naked eye. Due to its high sensitivity, specificity, and simplicity, it can be used for the diagnosis of direct prostate cancer via a 5 mL urine sample within 2 h without the use of any instrument. This method can also be applicable for the detection of other biological nanoparticles, such as viruses, at low concentrations in a complex matrix, offering a promising candidate for point-of-care disease diagnosis with low cost.