Direct glucose detection in whole blood by colorimetric assay based on glucose oxidase-conjugated graphene oxide/MnO2 nanozymes

Abstract

We herein report a facile approach for the preparation of horseradish peroxidase (HRP)-mimic glucose oxidase-conjugated graphene oxide/MnO₂ (GOD-GO/MnO₂) as new nanozyme to detect the glucose concentration in whole blood. The nano-sized of MnO₂ nanoparticles embedded in bovine serum albumin (BSA)-coated GO by in situ growth were evaluated focusing on the principle of HRP-mimic activity catalyzing the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide. Furthermore, we constructed dual sensing platforms based on the combination of a plasma separation pad and GOD-GO/MnO₂ for direct detection of glucose concentration in whole blood by colorimetric assay without blood sample pretreatment. As a proof-of-concept, a limit of detection of 3.1 mg dL⁻¹ for glucose was obtained with a wide linear quantification range from 25 mg dL⁻¹ to 300 mg dL⁻¹ through visual observation and quantitative analysis, suggesting potential clinical applications in blood glucose monitoring for diabetic patients.