Polyethylene glycol–Brushite cement: A versatile platform for high-performance electrochemical biosensors

The combination of brushite (dicalcium phosphate dihydrate) and polyethylene glycol (PEG) provides a synergistic platform that integrates the biocompatibility and protein affinity of brushite with the antifouling properties and enzyme-stabilizing effects of PEG. This composite offers an ideal matrix for the development of electrochemical biosensors, enabling efficient enzyme immobilization while preserving catalytic activity. Here, we report the development of a novel electrochemical biosensor based on a PEG–brushite composite for the immobilization of glucose oxidase (GOx) as a model enzyme. The composite is obtained through a simple, rapidand reproducible procedure, yielding a homogeneous and stable colloidal system that enables efficient enzyme incorporation while preserving catalytic activity. The resulting biosensor displayed a wide linear range (1.8 × 10-6–1.2 × 10- 2 M), high sensitivity (50.5 mA⋅M- 1⋅cm- 2), low detection limit (1.7 × 10- 7 M), and rapid response (10 s) toward glucose detection.The biosensor was successfully applied for determination of glucose in clinical samples (artificial saliva and serum) as well as in a food matrix (grape juice), covering both millimolar and micromolar concentration ranges within a single sensing platform. Matrix effects were negligible, as evidence the recoveries values ranging from 93 to 110%. Furthermore, the PEG–brushite biosensor retained approximately 95% of its initial activity after 15 days of refrigerated storage, significantly outperforming brushite-only systems. Overall, these findings demonstrate that PEG–modified brushite provides enhanced stability and sensitivity, establishing this composite as a robust, biocompatible and versatile for practical glucose monitoring and a promising candidate for advanced enzyme-based electrochemical biosensors.