Hollow NiCoP/PBA heterojunction engineered laser-induced graphene electrode for non-invasive dynamic tracking of salivary glucose

Abstract

Non-invasive salivary glucose (Glu) monitoring offers a promising alternative for diabetes management, yet its core challenge lies in the design of ultrasensitive sensing materials. In this study, a hollow NiCo PBA nanocage (H-NiCo PBA) was synthesized by selective etching of NiCo PBA nanocube using ammonia, and then a biphasic heterostructure (H-NiCoP/PBA) with intimate interfacial contact was successfully constructed via lowtemperature partial phosphidation. XRD, FTIR, and Raman spectroscopy confirmed the coexistence of metal phosphide phases and PBA frames in the composites, and XPS analysis revealed that phosphorus incorporation effectively regulated the electronic environment around the active sites. Based on this, a Glu electrochemical sensor was fabricated based on a flexible laser-induced graphene (LIG) electrode, which owns high electroconductivity and porous framework. Thanks to the synergistic effect between the high electroconductivity of LIG, excellent electrocatalytic activity of H-NiCoP/PBA heterostructure, and the acceleration of charge transport at the heterogeneous interface, the H-NiCoP/PBA/LIG sensor has a linear response range of 1-1988 & micro;M, high sensitivity (4.19 & micro;A center dot & micro;M- 1 center dot cm- 2), and a detection limit as low as 0.54 & micro;M for Glu detection, as well as excellent anti-interference, repeatability, and mechanical stability. Integrated with the smartphone, the sensor successfully realizes dynamic non-invasive tracking of human saliva Glu levels throughout the day, with a spiked recovery rate of 98.8%-108.6%, and the postprandial Glu response trend is highly consistent with physiological expectations. This work provides an effective new approach for the development of high-performance non-enzymatic electrochemical sensors and shows good application prospects in the field of non-invasive health monitoring.