GOx@ZIF-90@CuCo-MOF paper-based nanozyme sensor for rapid and noninvasive glucose detection in saliva.

Glucose biosensors are pivotal to diabetes management; however, traditional fingerstick blood collection methods are often challenging due to their invasiveness, pain, high cost, and inability to provide continuous monitoring. Here, we constructed a paper-based colorimetric sensing platform using a multifunctional metal-organic framework (MOF) composite system to enable rapid, noninvasive detection of glucose in saliva. This platform utilized a CuCo-MOF framework, loaded with glucose oxidase (GOx) and ZIF-90 via a synergistic self-assembly mechanism, to catalyze the colorimetric reaction of H2O2 and tetramethylbenzidine (TMB). The synergistic effect of the composite significantly enhanced the overall catalytic efficiency, enabling a sensitive response to glucose levels in saliva. Using ImageJ, color images captured with a smartphone were analyzed using RGB color channels to quantitatively determine glucose levels in saliva. The detection time was 20 minutes, with a detection limit (LOD) of 13.5 μM and a linear range of 50-2000 μM. This platform offered advantages with the absence of blood sample collection, ease of operation, and visual response. It provided new material strategies and design ideas for developing portable, non-invasive blood glucose monitoring technology.