Dual-functional hydrogel optical fiber for monitoring glucose and pH

This research presents a dual-functional hydrogel optical fiber sensing probe capable of simultaneously detecting glucose and pH. The core and cladding of the hydrogel optical fiber were prepared using 2-hydroxy-2-methylpropiophenone as a photoinitiator, along with different concentrations of polyethylene glycol diacrylate (PEGDA). The core was doped with the fluorescent indicator o-phenanthroline ruthenium and glucose oxidase (GOD) for glucose detection, and with the fluorescent indicator 5(6)-carboxyfluorescein (5(6)-FMA) for pH measurement. For glucose detection, the probe demonstrated a linear response range of 0.6–2.2 mg/mL, with a correlation coefficient (R²) of 0.99616 and a response time of 12 min. The limit of detection (LOD) was 0.1 mg/mL. For pH detection, the probe exhibited a detection range of 4.5–8.0. Within the pH range of 5.5–7.5, the correlation coefficient (R²) was 0.99071, and the response time was 24 min. The LOD was 0.23 pH units. The probe exhibited excellent repeatability and reversibility. Its ion-permeable and biocompatible properties make it clinically significant for the simultaneous monitoring of glucose and pH in the blood of diabetic patients.