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

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.