Biosensors for transaminase detection: Their diversity and trends – A comprehensive review

Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are organ-specific biomarkers for liver (cirrhosis, hepatitis) and heart (failure, infarction) diseases, as well as other conditions (preeclampsia, myopathy). Numerous biosensors have been developed to detect their activity or concentration, using various principles and materials. This review systematizes existing approaches to identify the most effective ones. Most single-analyte biosensors are electrochemical (mainly chronoamperometric), while dual-analyte systems are typically optical. Some use less common techniques like quartz crystal microbalance, photoreflectometry, or photocurrent spectroscopy. Bioselective materials are usually oxidase or dehydrogenase enzymes; rare examples involve autocatalysis or non-enzymatic elements. Immobilization is typically via covalent linking or adsorption. Enhancements include membranes, mediators, and nanomaterials. Despite active development, no AST or ALT biosensor has reached commercialization, likely due to technical and economic barriers such as limited analytical performance, insufficient selectivity in real samples, lack of portability, challenges with multi-analyte detection, non-invasive sampling, and absence of AI integration.