Highly porous poly(l-lactic) acid nanofibers as a dual-signal paper-based bioassay platform for in vitro diagnostics

The portable, low-cost and sensitive biosensors are essential for in vitro diagnostics. Here, with a highly porous poly(l-lactic) acid nanofiber membrane (p-PLLA), an efficient and sensitive bioassay is created for biomarker detection, giving out colorimetric and fluorescence dual signals. A sensitivity-enhancing strategy is achieved based on the high porosity, loading capacity of p-PLLA and gold nanoparticles-based signal amplification. Through a sandwich immunoreaction strategy, the gold nanoparticle-labeled detector antibodies accumulate on the p-PLLA membrane and show a naked-eye-readable red spot starting from a cut-off value of the target biomarker. After adding goat anti-mouse IgG/FITC antibody (IgG-FITC), which is bound to the detector antibody, the concentration of the target biomarker can be accurately calculated by the differences in fluorescence intensity of IgG-FITC solution before and after the immunoreaction. When the liver cancer marker (α-fetoprotein) is used as a model analyte, this bioassay performs with excellent convenience and a high level of sensitivity. The preset visual color mutation point is 10 ng mL−1 (cut-off value) and the limit of detection is 0.17 pg mL−1. It shows good prospects of screening cancer biomarkers and point-of-care diagnostics applications.