Electrochemical immunosensor based on poly(5-aminoindole) for cancer biomarker pentraxin-3 detection

Pentraxin-3 (PTX-3) plays a critical role in regulating inflammation, immune response, angiogenesis, and tissue remodeling. As a serum biomarker, it holds a potential in cancer diagnostics and monitoring. Elevated expression of PTX-3 has been found in various cancers, namely lung, prostate, gastric, breast, and hepatic cancers. Here, a PTX-3 immunosensor was fabricated by utilizing poly(5-aminoindole) (P5AIn) to increase the current response and the electroactive surface area (ESA). (3-Aminopropyl)triethoxysilane (APTES) was used as a linker and as an electron transfer enhancer. The developed PTX-3 immunosensor (BSA/anti-PTX-3/APTES/P5AIn/SPCE) shows excellent performance for PTX-3 detection in a wide concentration range from 0.0001 to 2000 ng/mL with the LOD of 0.012 pg/mL. Furthermore, the sensor possessed good reproducibility (%RSD = 0.78), a long shelf-life of at least 4 weeks (% RSD = 0.89), and high specificity to PTX-3. The fabricated PTX-3 immunosensor was demonstrated in the measurement of PTX-3 concentrations in real blood serums from gastric patients. It has been shown as a potentially promising portable sensor for cancer diagnostics and monitoring for cancer patients in remote areas with a low cost.