▎ 摘　　要

Vitamin D is a sunshine vitamin required by the body for various physiological activities. Deficiency of vitamin D (= 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 Omega nM(-1) mm(-2) and a response time < 1 min. The sensor shows high specificity towards vitamin D3, a good stability, shelf life of over 35 days and nearly 98% recovery with serum samples. The developed sensor has been in- tegrated with controlled electronics, thus establishing a portable prototype.