An AuNPs-based electrochemical aptasensor for the detection of 25-hydroxy vitamin D 3

Vitamin D 3 (VD 3 ) is the main form of vitamin D and an essential nutrient for maintaining human life. Currently, traditional methods for detecting 25-hydroxyvitamin D3(25(OH)D 3 ) are complex and expensive. In this study, we constructed an accurate, sensitive, simple, and cost-effective label-free biosensor based on an aptamer for the detection of 25(OH)D 3 . The aptamer-modified sulfhydryl adopted self-assembly as a way to stably immobilize at the glassy carbon electrode (GCE) surface modified by gold nanoparticles (AuNPs). Upon 25(OH)D 3 binding to the aptamer, the complexes inhibit electron transfer at the electrode surface, leading to reduced [Fe(CN) 6 ] 3−/4− redox peak current. Consequently, the quantity of 25(OH)D 3 that interacts with the electrode-bound aptamer correlates with the observed electric current response values. The Aptamer/AuNPs/GCE aptasensor achieved direct and highly sensitive detection of 25(OH)D 3 over a wide concentration range (1.0–1000 nM), with a limit of detection of 1.0 nM. At the same time, other molecules with a similar structure, such as 25(OH)D 2 , Vitamin D 3 , and Vitamin D 2 , had lower response interference than 25(OH)D 3 . Therefore, this biosensor has great potential to become a portable diagnostic device for 25(OH)D 3 . Graphic abstract