Spectrophotometric Determination of Glucose in Blood Based on the Catalytic Reaction of Copper Nanoparticles on Polydopamine Spheres

Copper nano particles were loaded on the surface of polydopamine spheres (PDA) by the hydrothermal method to give a composite of Cu@PDA which behave with activity of peroxidase and can catalyze the rapid oxidation of 3,3',5,5'-tetramethyl benzidine (TMB) by transforming from its colorless reduction form to its blue colored oxidation form, having its absorption maximum at 652 nm, and giving magnitude of absorbances measured related to the concentration of H₂O₂ in definite range. Applying this catalytic reaction in combination with the catalysis of oxidation reaction between oxygen and glucose to give H₂O₂ by glucoxydase (Gox), a spectrophotometric method for determination of glucose in blood samples was proposed. A definite amount of blood sample solution was added to 0.1 mol·L^-1 PBS (pH 4.0) containing 1.0 mg·L^-1 Cu@PDA, 4.0 g·L^-1 Gox and 0.5 mmol·L^-1 TMB and the total volume of the solution was made up to 10.0 mL. After standing for 10 min at 40 ℃, it was found that linear relationship between values of absorbance and concentration of glucose was kept in the range of 1.0-30.0 mmol·L^-1, with the detection limit (3S/N) of 0.3 mmol·L^-1. Samples of human blood were analyzed by the proposed method, giving results of glucose contents in consistency with those reported by the clinical laboratory of the hospital.