Photoelectrochemical aptasensor based on nanocomposite of CdSe@SnS2 for ultrasensitive and selective detection of sulfamethazine

A photoelectrochemical (PEC) aptasensor based on CdSe@SnS 2 nanocomposite has been developed to detect sulfamethazine (SMZ). The introduction of CdSe into SnS 2 displayed an amplified PEC signal, which was higher than that of pure CdSe and SnS 2 , attributable to its enhanced light harvesting capacity and promoted PEC energy conversion efficiency. Due to the formation of specific non-covalent bonds, the SMZ-binding aptamer (SBA) has significant specificity and sensitivity. When SMZ was incubated on a CdSe@SnS 2 modified electrode fixed with aminated SBA, the formation of the SMZ/SBA complex increased the space resistance of electron transfer and hindered the electronic migration between the electrodes, resulting in a decrease in photocurrent. The greater the adsorbed amount on the SBA, the lower the photocurrent produced. Under optimized conditions the photocurrent response of MCH/SBA/CdSe@SnS 2 /FTO was inversely proportional to the SMZ concentration in the range 0.1 to 100 pM, with a detection limit (3 S/N) of 0.025 pM (at 0 V vs. Hg/HgCl). The recoveries ranged from 95.8 to 104% with relative standard deviations (RSDs)