A versatile biosensor for detecting Zn and Cu in Alzheimer's disease cells and acidic foods via RNA G-quadruplex hydrolysis.

Zinc (Zn) and copper (Cu) are essential micronutrients that also have the potential to act as pollutants, and their imbalance in the human body has been linked to neurodegenerative diseases, particularly Alzheimer's disease (AD). This study presents the development of a versatile RNAzyme-based biosensor capable of selectively detecting Zn and Cu in both Alzheimer's disease model cells and acidic food matrices. This biosensor is composed of a cyanine dye (SCY-5) and an artificially synthesized RNA G-quadruplex (G4). It functions through the specific binding of SCY-5 to G4s, the enzymatic hydrolysis of G4s by RNase T2, and the inhibition of RNase T2 activity by these metal ions. The biosensor effectively tracked variations in Zn and Cu levels within living AD cells, demonstrating a significant correlation between fluctuating metal ion concentrations and the severity of AD pathology. Additionally, it proved efficient in quantifying metal content in acidic foods. These findings highlight the biosensor's dual applicability in monitoring critical metal ion concentrations both in neurodegenerative disease research and in food safety, underscoring its potential as a valuable tool for environmental health and biomedical applications.