Copper-Based MOF Derivative with Enhanced Electrocatalytic Activity for Highly Sensitive and Ultrafast Detection of Salivary Glucose

Currently, invasive blood-testing methods that are widely employed for diabetes monitoring present issues including discomfort, infection risks, and delayed wound healing, which lead to poor patient compliance, creating a demand for noninvasive testing methods, including saliva-based testing. However, the implementation of saliva glucose monitoring is hindered by the necessity of achieving high sensitivity, accuracy, and rapid response times. Precise atom regulation in metal-organic frameworks (MOFs) is poised to create fast, highly sensitive, and specific electronic interfaces, enabling ultrafast sensing methods, based on which a noninvasive glucose MOF derived Cu-CuO/C sensor is proposed. The sensor employs Cu-CuO/C composites, utilizing the properties of oxygen vacancies to enhance the catalytic oxidation activity of glucose, enabling high sensitivity and rapid response. Finite element simulations revealed that the synergy between the carbon substrate and Cu-CuO heterojunction optimized charge transfer and mass transport pathways, significantly improving sensor performance. Additionally, theoretical calculations demonstrated that the Cu-CuO/C electrode effectively lowers the Gibbs free energy barrier, facilitating glucose oxidation by promoting the desorption of intermediates and enhancing electrocatalytic activity. Experimental validation of the sensor performance revealed an extremely fast response time (0.3 s) and high sensitivity (919.86 μA·mM^-1·cm^-2), with a detection range from 0.001 to 7.33 mM (<i>R</i>² = 0.997). Selectivity tests and real sample tests in artificial and human saliva further confirmed the sensor's reliability in practical applications. Finally, Cu-CuO/C was immobilized onto screen-printed electrodes, resulting in a portable biosensor that was validated for rapid glucose detection in portable instruments, paving the way for wearable real-time continuous monitoring devices.