A CRISPR/Cas12a-powered liquid crystal aptasensor for point-of-care detection of prostate-specific antigen for early-stage cancer diagnosis

Abstract

Herein, an ultrasensitive aptasensor was developed for monitoring prostate-specific antigen (PSA) levels for the first time by incorporating the catalytic activity of CRISPR/Cas12a assembly and directional orientation of liquid crystal (LC) molecules. In the absence of PSA, the specific aptamer was hybridized with crRNA segment of the CRISPR/Cas12a assembly, which activated it for cleaving the ssDNA strand on the sensing substrate. This resulted in a dark background of the sensing substrate. While the assembly was unable to cleave the ssDNA sequence in the presence of PSA, due to forming the PSA-aptamer hybrid and disabling the enzymatic assembly, visualizing the colorful polarized sensing substrate. By changing the polarized background of the LC aptasensor from murky to multicolored, PSA could be detected ranging from 1 ag mL⁻¹-1 pg mL⁻¹ and 1 pg mL⁻¹-1 ng mL⁻¹ with a detection limit of 0.28 ag mL⁻¹. With the potency to determine PSA in the spiked human serum samples with the recovery amounts of 97.87–99.57 %, the CRISPR/Cas12a-powered LC aptasensor is a reliable test kit for cancer screening. This was also confirmed by comparing the results obtained from the LC aptasensor with those of ELISA analysis for human serum samples of some patients. Being ultrasensitive, cost-effective, label-free, and user-friendly, the aptasensor can be an efficient future portable gadget for early-stage cancer monitoring.