Abstract:

Objective Excessive hydrogen peroxide (H₂O₂) can cause cardiovascular diseases, neurodegenerative diseases, diabetes complications, arthritis and other diseases. H₂O₂ detection is conducive to physiological disease monitoring, production process optimization, product quality improvement, and environmental monitoring. The existing biosensors have some drawbacks such as low sensitivity, poor selectivity and complicated technology. Therefore, it is of great significance to develop an H₂O₂ sensor with simple manufacturing processes and excellent performance.

Method A copper layer was constructed on the carbon fiber surface by chemical copper plating, and the copper-loaded carbon fiber was immersed in 0.1 mg/mL horseradish peroxidase (HRP) solution for in-situ growth of organic/inorganic nanoflowers. The morphological structure and chemical structure of the modified carbon fiber were investigated. The cyclic voltammetry and current response curves were measured to verify the capability of the modified carbon fiber for H₂O₂ detection. Furthermore, the specificity of HRP/Cu₃(PO₄)₂/carbon fiber was studied.

Results A uniform copper layer was successfully deposited on the carbon fiber surface through chemical copper plating at room temperature for 30-60 min. Subsequently, the copper-coated carbon fiber was immersed in a phosphate-buffered saline (PBS) solution containing 0.1 mg/mL HRP. The copper could be oxidized into copper ions, which first chelated with the amide groups of HRP to form a crystal nucleus and then bound with phosphate ions in a buffer solution to achieve crystal growth. As the process continued, the grains gradually aggregated, forming petal-like structures that eventually developed into a hierarchical flower-like morphology. The prepared carbon fiber electrode with HRP/Cu₃(PO₄)₂ organic/inorganic nanoflowers showed excellent electrocatalytic performance. The HRP/Cu₃(PO₄)₂/carbon fiber exhibited a sensitive current response to H₂O₂ within a concentration range of 0.1 to 2 mmol/L, and it showed a good linear response to H₂O₂ with a correlation coefficient R² of 0.999, a sensitivity of 146.3 μA/(mmol·L^-1·cm) and a low detection limit of 0.441 μmol/L. Additionally, The electrode has no current response to potential interfering substances such as glucose, NaCl, KCl, ascorbic acid and urea, demonstrating it has excellent anti-interference capabilities.

Conclusion The HRP/Cu₃(PO₄)₂/carbon fiber H₂O₂ electrochemical sensor was prepared by in-situ organic/inorganic nanoflowers growth on the highly conductive carbon fiber surface at room temperature. This method is simple, cost-effective, and environmentally friendly. The modified carbon fiber demonstrated excellent electrocatalytic performance. It exhibited a good linear relationship in the concentration range of H₂O₂ from 0.1 to 2 mmol/L with a linear correlation coefficient R² of 0.999, a sensitivity of 146.3 μA/(mmol·L^-1·cm) and the detection limit of 0.441 μmol/L. In addition, the electrode has no current response to potential interfering substances such as glucose, NaCl, KCl, ascorbic acid, and urea, highlighting its excellent anti-interference capabilities. These results indicated its potential for highly selective and sensitive detection of H₂O₂ in complex biological and environmental samples.

Key words: organic/inorganic nanoflower, in-situ growth method, carbon fiber, hydrogen peroxide, horseradish peroxidase, electrochemistry, biosensor