▎ 摘　　要

For maintaining the healthy metabolic status, vitamin D is a beneficial metabolite stored majorly in its pre-activated form, 25-hydroxyvitamin D-3 (25(OH)D-3). Due to its important role in bone strengthening, the study was planned to quantify 25(OH)D-3 levels in our blood. Quantification techniques for 25(OH)D-3 are costly thus requiring a need for a low cost, and sensitive detection methods. In this work, an economic, and sensitive sensor for the detection of 25(OH)D-3 was developed using aptamer and graphene oxide (GO). Aptamer is an oligonucleotide, sensitive towards its target, whereas, GO with 2D nanosheets provides excellent quenching surface. Aptamer labeled with fluorescein (5', 6-FAM) is adsorbed by pi-pi interaction on the GO sheets leading to quenching of the fluorescence due to Forster resonance energy transfer (FRET). However, in the presence of 25(OH)D-3, a major portion of aptamer fluorescence remains unaltered, due to its association with 25(OH)D-3. However, in the absence, aptamer fluorescence gets fully quenched. Fluorescence intensity quenching was monitored using fluorescence spectrophotometer and agarose gel based system. The limit of detection of 25(OH)D-3 by this method was found to be 0.15 mu g/mL whereas when GO-COOH was used, limit of detection was improved to 0.075 mu g/mL. Therefore, this method could come up as a new sensing method in the field of vitamin D detection.