Development Of Heavy Ion Biosensor Based On Carbon Nitride Composite Nanomaterials

Heavy metal ions sensor having arisen a heated influence around the world,among quantities of techniques electrochemical detection can offer remarkable sensitivity, excellent selectivity and repeatability. Electrochemical biosensor has been widely considered as one of popular techniques to detect heavy metal ions, including enzymes, protein, and DNA sensor.In this article, two different kinds of electrochemical sensors are developed for the detection of cadmium:The first sensor which is highly sensitive and selective is modified by nanosheet graphitic carbon nitride (g-C3N4). The sensor modified by g-C3N4 nanosheet through calcination is based on glass carbon electrode, then uses differential pulse anodic stripping voltammetry (DPASV) measurement detecting Cd2+ in aqueous. The calibration curves for Cd2+ covered two ranges varying from 1 nM to 1μM and 1μM to 100μM. The limitation of detection (LOD) is estimated to be 0.5 nM for Cd2+,which is 53 times lower than the guideline values of drinking water given by the World Health Organization (WHO). As a result, the good repeatability and stability of the modified electrode is feasible for heavy metal detection in this work.(2) The second sensor is based on graphene and g-C3N4 nanosheets composite.In order to improve the performance of cadmium sensor, on the basis of first electrochemical sensor, we got composition of graphene and g-C3N4 nanosheets by hydrothermal method, then using the condensation between the carboxy on the graphene and the amino terminal of aptamer ssDNA specificity for Cd2+ built a selective electrochemical biosensor. Through the research, the optimal proportion for electrochemical biosensor of graphene and g-C3N4 nanosheets composite has been selected.In conclusion, in this work we have succeeded in building highly sensitive cadmium sensor using g-C3N4 nanosheets,and on this basis compounding graphene and g-C3N4 nanosheets composite and building a specific cadmium biosensor which provides a new direction and research basis to explore the idea for detecting heavy metal ions.