Smartphone-Based Electrochemical Biosensors for Directly Detecting Serum-Derived Exosomes and Monitoring Their Secretion
Jing Su, Shixing Chen, Yanzhi Dou, Zhihan Zhao, Xiaolong Jia, Xianting Ding, Shiping Song
Abstract
Exosomes are potential biomarkers, which play an important role in early diagnosis and prognosis prediction of cancer-related diseases. Nevertheless, direct quantification of exosomes in biological fluid, especially in point-of-care tests (POCTs), remains extremely challenging. Herein, we developed a sensitive and portable electrochemical biosensor in combination with smartphones for quantitative analysis of exosomes. The improved double-antibody sandwich method-based poly-enzyme signal amplification was adopted to detect exosomes. We could detect as low as 7.23 ng of CD63-positive exosomes in 5 μL of serum within 2 h. Importantly, we demonstrated that the biosensor worked well with microliter-level serum and cell culture supernatant. The biosensor holds great potential for the detection of CD-63-expressing exosomes in early diagnosis of prostate disease because CD63-positive exosomes were less detected from the prostate patient serum. Also, the biosensor was used to monitor the secretion of exosomes with the drug therapy, showing a close relationship between the secretion of exosomes and the concentration of cisplatin. The biosensing platform provides a novel way toward POCT for the diagnosis and prognosis prediction of prostate disease and other diseases via biomarker expression levels of exosomes.