Aptamer-based chemiluminescent optical fiber immunosensor with enhanced signal amplification for ultrasensitive detection of tumor biomarkers

With the growing demand for early diagnosis of malignant tumor, ultrasensitive detection of cancer-related biomolecules with convenient operation is of great significance for timely treatment. In this study, we develop a robust and efficient analytical system, the aptamer-based chemiluminescent optical fiber immunosensor (aptamer-COFIS), for ultrasensitive detection of biomarkers. In the aptamer-COFIS system, target aptamer-primer probe is used as the bridge to combine antibody-antigen immunoreaction on the fiber surface with chemiluminescent signal amplification. The antibody-antigen (target)-aptamer sandwich-like reaction is coupled with rolling cycle amplification (RCA), which is capable to produce hundreds of binding sites to connect with the streptavidin-biotinylated horseradish peroxidase nanocomposites for signal amplification. Using prostate specific antigen (PSA), the most reliable and specific biomarker of prostate cancer, as the test sample, we show that the proposed strategy can greatly improve the sensor response with a wide linear range of 0.01-1000 pg/mL and an extremely low limit-of-detection of 3.2 fg/mL. Our results indicate that the proposed method presents high selectivity and good accuracy for ultrasensitive sensing biomarkers in complex clinical samples. Moreover, with additional advantages by using optical fiber as the ideal carrier of biorecognition elements and the transducer of chemiluminescent signal, the aptamer-COFIS system with a low-cost compact design is convenient for operation, making it suitable for cost-effective on-site and real time analysis of various biomarkers in early diagnosis of diseases.