A novel liquid crystal assay based on aptazyme-assisted bioprobe for ultra-sensitive monitoring of lead ion

The serious hazards of lead ion (Pb2+) to the human health has caused an importance to develop detection assays with high specificity and sensitivity. Here, a simple optical biosensing array was introduced for the colorimetric detection of ultra-low amounts of Pb2+ ion based on the cleavage activity of an aptazyme strand and long-range directional regularity of liquid crystal molecules (LCs). The presence of Pb2+ activated the cleavage function of the aptazyme strand that caused a break at 3'-part of the immobilized substrate strand on the modified glass platform. So, an alteration in the LCs' alignment from random to vertical state induced a change in the optical aspect of the biosensor platform from colored to dark. The LC-based biosensor could detect the ultra-trace values of Pb2+ as low as 0.84 aM. The successful determination of Pb2+ in some real samples, such as fish, tap water, and human serum, was achieved by the biosensor. The LC-based biosensor is promising for real-time environmental monitoring and food safety control.