Rapid and portable detection of hepatocellular carcinoma marker alpha-fetoprotein using a droplet evaporation-based biosensor

The rapid and accurate detection of tumour markers in human serum is essential for the early screening and diagnosis of cancer. In this study, we develop a droplet evaporation-based biosensor for the detection of the tumour marker alpha-fetoprotein (AFP). The biosensor's mechanism relies on the evaporation of surfactant solutions containing varying concentrations of AFP on a hydrophobic plastic substrate, resulting in distinct dried droplet patterns with varying areas. Surfactant solutions containing myristoylcholine (Myr) produce large dried droplet patterns due to surface wetting. Upon the introduction of AFP, a complex is formed on magnetic beads (MBs) comprising AFP aptamer 1 (apt1), AFP, and a dual-functional single-stranded DNA that includes AFP aptamer 2 (apt2) and the acetylcholinesterase (AChE) aptamer. This interaction immobilizes AChE on the MBs through its specific binding to its aptamer. Notably, AChE hydrolyses Myr, leading to a reduction in the dried droplet pattern area, enabling AFP detection. This biosensor demonstrates high selectivity, stability, and repeatability for AFP, with a low detection limit of 1.27 ng/mL and a reliable linear detection range of 5-25 ng/mL. Additionally, it performs effectively in human serum sample tests. This approach offers a rapid, portable, and efficient method for AFP detection and holds significant potential for clinical applications in the early screening and diagnosis of cancer.