The Construction of Liquid Crystal / Fluorescence Dual-Signal Immunosensor Based on DNA-Antibody Conjugate

A liquid crystal / fluorescence dual-signal immunosensor is developed for the sensitive detection of aflatoxin B1 (AFB1). Through click chemistry reaction, DNA probe is covalently conjugated to the antibody, constructing a detection system with liquid crystal (LC)/fluorescence dual-signal output capabilities. After co-incubation of DNA-antibody (Ab) conjugate, active DNA, and AFB1, the mixture is transferred to 96-well plates that have been pre-functionalized with AFB1 antigen for competitive binding. In the presence of AFB1, the separated supernatant can induce alignment changes in LC molecules, while the DNA-Ab complexes captured on the surface of 96-well plates can activate CRISPR/Cas12a to cleavage the ssDNA reporter, generating fluorescent signals. Notably, the active DNA demonstrated dual functionality. It can not only hybridize with DNA-antibody conjugate but also activate the CRISPR/Cas12a to cleavage the ssDNA reporter, generating fluorescent signals. As AFB1 concentrations increase, the reduced capture of DNA-Ab complexes on the 96-well plates leads to an increase in DNA and DNA-antibody complexes in the supernatant. It causes the LC image change from dark to bright, while the decreased capture of activator DNA results in the decrease of fluorescence signals. Overall, this dual-signal sensor exhibits high specificity, stability, and reproducibility, with simple operation enabling rapid AFB1 detection, it has the potential of application in real samples.