Background: The prostate-specific antigen (PSA) is one of the best markers for detecting prostate cancer. Rapid and real time recognition of PSA biomarker could be helpful in the early diagnosis and efficient treatment of prostate cancer. One of the usual methods to identify this biomarker is ELISA, which has a picomolar detection range but requires specialized personnel and also this technique is time-consuming and expensive. Methods: Cost-effective POC devices are great solutions because they are very cost-effective, sensitive and simple, do not require expert operators and have a high response time in a short time. With that in mind, in this work, a novel and simple label-free paper-based electrochemical immunosensor were designed by using conductive Ag-ink and designed directly by pen on paper technique on the surface of photographic paper, which is a suitable substrate for antibody immobilization, for rapid detection of PSA. Results: Based on the obtained results, under the optimum conditions, the synthesized Ag ink has a great substrate for antibody (Ab) and antigen (Ag) immobilization. The linear range was from 0.001 to 30 μg/L and the obtained low limite of quantification (LLOQ) was 0.001μg/L. This immunosensor also tested in human plasma samples, which had good analytical power. Conclusion: The proposed paper-based immunoassay could be a hopefully new and cheap tool for the diagnosis of other biomarkers.
Protocol to analyze circulating small non-coding RNAs by high-throughput RNA sequencing from human plasma samples
