An ultrasensitive microfiber biosensor for fast detection of alpha-fetoprotein in human serum samples

Rapid detection of alpha-fetoprotein (AFP) as a tumor marker is crucial in early tumor screening and subsequent treatment processes. Low limit of detection (LoD) biosensors are essential for fast detecting the concentration of AFP. In this paper, an ultrasensitive microfiber biosensor integrated with fiber ring laser (FRL) system has been proposed and investigated for detecting the AFP in human serum samples within 30 min. The microfiber sensor was composed of a tapered seven-core optical fiber (TSCF), which was embedded into an FRL system to improve quality factor and thus enhance measurement accuracy. Experimental results show that the proposed microfiber biosensor has excellent specificity and good repeatability within AFP concentration range from 0.1 to 100 ng/mL in PBS buffer, and the LoD is as low as 0.042 ng/mL. Moreover, the detection performance of the proposed microfiber biosensor could effectively distinguish the concentrations of AFP in serum, and the results agree well with clinical examination detection. Therefore, the proposed microfiber biosensor has potential to be widely applied in clinical diagnosis.