Highly sensitive label-free liquid crystal-based aptasensor to detect alpha-fetoprotein

In this study, a novel label-free optical aptasensor based on liquid crystals (LCs) for sensitive and specific alpha-fetoprotein (AFP) detection was developed. The modification parameters were optimised to limit the effect of the background signal and increase the sensitivity of the sensor. The AFP-specific aptamer was immobilised on the substrates using an APTES + GA bridge. The binding of AFP to its aptamer causes changes in the surface topography and disrupts the LC alignment. The orientational transition of LC could be observed, from dark to bright, using POM. The changes in the topography of the surfaces were confirmed by AFM, ellipsometry, and water contact angle measurements. Under optimal conditions, the proposed LC-based aptasensor exhibited optimal performance in AFP detection. The detection limit for AFP reached 12.62 pg mL⁻¹ in HEPES buffer and 18.65 pg mL⁻¹ in human serum, with the detection range from 20–800 mL⁻¹ for both the conditions. Owing to advantages such as simplicity, speed, and high sensitivity and specificity, the proposed label-free LC-based aptasensor has potential applications in the clinical diagnosis of various tumour markers.