One-Dimensional Synergistic Core–Shell Nanozymes with Superior Peroxidase-like Activity for Ultrasensitive Colorimetric Detection of Blood Cholesterol

Abstract

In this paper, a simple and green strategy was proposed to fabricate one-dimensional core-shell Fe₃O₄@C/Ni nanocomposites. The rationally designed hybrid nanostructures notably exhibited an extremely excellent peroxidase-mimicking property, arising from the synergetic effects of Fe₃O₄, carbon, and Ni nanoparticles, along with the hollow and hierarchically porous nanostructures. Based upon the outstanding peroxidase-like activity and cholesterol oxidase cascade reaction, a label-free, ultrasensitive, and highly selective colorimetric assay for cholesterol determination has been developed. Under the optimized conditions, the colorimetric biosensor demonstrated a linear response to cholesterol ranging from 5 to 200 μM, with a relatively low detection limit of 0.17 μM. More importantly, cholesterol determination as low as 5 μM could be directly distinguished with the naked eye. In addition, we successfully determined the total cholesterol content in human serum samples with satisfactory accuracy and good precision. The Fe₃O₄@C/Ni nanocatalyst-based colorimetric biosensor provides great potential in point-of-care testing in disease diagnosis.