Portable kits based on L-arginine modified Cu-CuFe2O4 with superior peroxidase-like activity for colorimetric detection of cholesterol and glucose in human serum

At-home monitoring of key blood indicators, including cholesterol and glucose, is vital for point-of-care chronic condition management. In this work, portable kits based on L-arginine modified Cu-CuFe 2 O 4 nanoparticles (Cu-CuFe 2 O 4 @L-Arg NPs) were fabricated for colorimetric determination of glucose and cholesterol in human serum. Cu-CuFe 2 O 4 @L-Arg NPs with superior peroxidase-like activities were synthesized via a straightforward hydrothermal approach. The accelerated electron transfer process of Cu 0 and its role as an electron donor contributed to excellent catalytic activity of Cu-CuFe 2 O 4 @L-Arg toward 3,3’,5,5’-tetramethylbenzidine (TMB). Portable kits include glucose oxidase or cholesterol oxidase, phosphate buffer solution (PBS) pH 7.0, Cu-CuFe 2 O 4 @L-Arg, PBS pH 4.0 and TMB. Among the enzyme-like reactions, Cu-CuFe 2 O 4 @L-Arg catalyzes the conversion of H 2 O 2 into hydroxyl radicals (•OH), which subsequently oxidize the TMB substrate to yield a blue-colored product. The signal intensities of the blue products were proportional to H 2 O 2 , which was produced in the cholesterol or glucose systems. This method achieves linear detection of free cholesterol from 5 µM to 1.2 mM, exhibiting a low LOD of 1 µM, and was validated by obtaining recoveries of 97-103.5% for total cholesterol in human serum analyses. The method enabled the linear quantification of glucose from 50 to 1500 µM with a limit of detection (LOD) of 5 µM, and recoveries in human serum ranged from 96% to 102.8%. The portable kits, characterized by low cost, visual readout, high specificity, and long-term stability, demonstrate considerable potential for self-monitoring devices for key clinical biomarkers. Graphical