Carbon dots-modified chitosan based electrochemical biosensing platform for detection of vitamin D

Here in, a carbon dots (CDs)-modified chitosan (CH) based biosensing platform was fabricated for vitamin D2 detection. Carbon dots were synthesized through microwave pyrolysis method, and characterized with transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and UV/VIS spectroscopy. Chitosan (1%) solution was prepared in acetic acid (1%) solution and followed by the addition of CDs to prepare the carbon dots-chitosan (CD-CH) composite. A thin film of CD-CH composite was prepared onto ITO glass substrate (CD-CH/ITO) by drop casting method. Surface of the composite film was characterized by atomic force microscopy, static contact angle measurement and cyclic voltammetry. CD-CH/ITO surface was further modified with immobilization of vitamin D2 antibody (Ab-VD2) and bovine serum albumin (BSA) to prepare BSA/Ab-VD2/CD-CH/ITO bioelectrode. Electrochemical response of the bioelectrode towards vitamin D2 antigen (Ag-VD2) was carried out by differential pulse voltammetry. The biosensing electrode showed linearity within the range 10-50 ng mL−1 of Ag-VD2 concentration. The sensitivity was found to be 0.2 μA ng−1 mL cm−2, LOD was 1.35 ng mL−1, and the biosensor had a shelf-life of about 25 days.