Abstract
Melatonin (N-acetyl-5methoxytryptamine) plays an important role in the regulation of sleep cycles, immune functions and antioxidant capabilities. Various methods are used to determine melatonin concentration such as high-performance liquid chromatography (HPLC). However, this techniques is high-cost and not suitable for analyzing colloid samples such as milk. Enzyme-linked immunosorbent assay (ELISA) can be used for colloid samples but this is also expensive and time consuming. Thus, a fast and reliable method for melatonin detection was developed. Immunogenic melatonin was prepared by coupling melatonin with carrier protein as bovine serum albumin (BSA) using the Mannich reaction. After covalently bound with BSA, the melatonin-BSA coupling (Mel-BSA) was then used for rabbit immunization. The purified antibody was selected to construct a drop test immunoassay for melatonin detection. Under optimized condition, the limit of detection was shown to be 0.15 ng/mL with a turnaround time of about 20 minutes. This drop test immunoassay is a promising approach for development of a more rapid, robust and cost-effective tool for melatonin detection.
