Graphene quantum dot-gold hybrid nanoparticles integrated aptasensor for ultra-sensitive detection of vitamin D3 towards point-of-care application

Abstract Vitamin D is a sunshine vitamin required by the body for various physiological activities. Deficiency of vitamin D (≤29 ng mL−1) can cause dental diseases, sarcopenia, osteoporosis, depression, type 2 diabetes, cancer, etc. Additionally, elevated levels of vitamin D (>150 ng mL−1) can result in numerous infirmities such as anorexia, irregular heartbeat, hypercalcemia, fatigue, etc. Hence, a periodic detection can help maintain an appropriate level (≥30 ng mL−1) of vitamin D in blood serum. Conventional techniques used for the detection of vitamin D are expensive, time consuming, require skilled work force and a specialised laboratory. Herein, we report a portable electrochemical aptasensor for the detection of vitamin D3 using graphene quantum dot-gold (GQD-Au) hybrid nanoparticles. The developed aptasensor has a linear range of 1 nM – 500 nM, limit of detection (LOD) of 0.70 nM (0.28 ng mL−1), limit of quantification (LOQ) of 2.09 nM (0.84 ng mL−1), sensitivity of 0.90 Ω nM−1 mm−2 and a response time