Phase and composition selective superior cholesterol sensing performance of ZnO@ZnS nano-heterostructure and ZnS nanotubes

Abstract

Development of efficient enzyme-immobilized amperometric biosensor using nanostructure inorganic materials to estimate different biomolecules is an important research area in present frontier research. Here, the controlled synthesis of phase selective zinc oxide@zinc sulfide, zinc blend(ZB)/wurtzite (WZ), (ZnO@ZnSZB/ZnSWZ) through substitution reaction of corresponding ZnO nanorod using potassium ethyl xanthogenate as sulfur source under hydrothermal/solvothermal condition as well as corresponding ZnS nanotube through acetic acid leaching and evaluation of cholesterol sensing performance of the synthesized nanostructured modified electrode is presented. Potassium ethyl xanthogenate is used for controlled substitution reaction (sulfidation). Both the ZnO@ZnSZB nano-heterostructure and ZnSZB nanotubes based modified biosensor showed excellent amperometric cholesterol-sensing performance, over bare ZnO, ZnO@ZnSWZ heterostructure and ZnSWZ nanotube. ZnSZB nanotube showed highest sensitivity (598mAM−1cm−2) with a LOD of 0.44mM, whereas ZnO@ZnSZB nano-heterostructure showed reasonably good sensitivity 293mAM−1cm−2) with very low LOD of 0.08mM. The ZnSZB nanotube exhibits maximum sensitivity due to its relatively high surface area and easy electron transfer through its tubular channel. ZnO@ZnSZB nano-heterostructure showed low LOD due to its modified band structure which facilitate the electron transport to the detector. The sensing performance is superior to that of other literature reported sensors.