N-doped mesoporous carbon spheres/Pt–Pd nanocomposite-based amperometric biosensors for sensitive hydrogen peroxide and glucose detection in beverages and fruit juices

Accurate glucose detection in beverages and fruit juices is crucial for quality control and dietary management, particularly for individuals with diabetes. However, there remains a need for simple and highly sensitive glucose detection methods in complex juice matrices. In this work, a N-doped mesoporous carbon spheres (N-MCS)/platinum (Pt)-palladium (Pd) nanocomposite with good analytical performance has been synthesized through a facile one-step reduction method. This nanocomposite was modified onto a screen-printed electrode (SPE) along with glucose oxidase (GOx) to construct a glucose sensor (GOx/Pt-Pd/N-MCS/SPE). Owing to the good electrocatalytic activity of the N-MCS/Pt-Pd nanocomposite, the modified electrode showed significantly enhanced sensitivity toward H₂O₂, achieving a 480.5-fold improvement compared to bare SPEs. Under optimized conditions, the sensor demonstrates a linear detection range for glucose from 2 to 1001 μM, with a low limit of detection of 0.12 μM (S/N = 3) and a sensitivity of 48.6 μA mM^-1 cm^-2. Furthermore, the sensor demonstrated reliable performance in various real-world samples, including mineral water, milk, beverages, orange juices, tomato juices, and mixed orange-tomato juices, highlighting its strong potential for practical applications. Importantly, this amperometric sensor based on N-MCS/Pt-Pd provides a valuable method for detecting other biomolecules in complex food matrices.