A nonenzymatic cholesterol sensor constructed by using porous tubular silver nanoparticles

Porous tubular silver (Ag) nanoparticles were successfully synthesized by electrodeposition of Ag into cadmium sulfide (CdS) modified porous anodic alumina (PAA) template and removal of CdS subsequently. Only the solid nanorods were obtained without CdS. The strong affinity between S^2- and Ag (I) caused preferential deposition of Ag on the pore walls to form tubular Ag. After removal of CdS, porous tubular Ag nanoparticles were obtained. This novel nanostructure was characterized by XRD, TEM, FESEM, EDS and nitrogen adsorption-desorption isotherms. Using porous tubular Ag nanoparticles modified glassy carbon electrode (GCE) as a working electrode, a good nonenzymatic cholesterol sensor was constructed, which showed markedly improved electrocatalytic activity toward cholesterol oxidation compared to that of solid Ag nanorods. Under optimal detection conditions, the constructed sensor had a linear response range of 2.8×10^-4M to 3.3×10^-2M and the detection limit was 1.8×10^-4M at a signal-to-noise ratio of 3. The biosensor showed an acceptable reproducibility, good stability and low interferences. To the best of our knowledge, it is the first example of a nonenzymatic cholesterol biosensor based on Ag nanoparticles. The experimental results demonstrated that porous tubular Ag nanoparticles provided a promising platform for rational design and fabrication of nonenzymatic cholesterol sensors.