A silicon nanoparticle-based nanoprobe for ratiometric fluorescence and visual detection of glucose

Diabetes mellitus is a chronic disease that affects human health worldwide. Monitoring of glucose levels in the blood is still vital for the early clinical diagnosis and management of diabetes. Since single-wavelength fluorescence probes are prone to being influenced by instrument fluctuations, the design of simple and cheap ratiometric fluorescence probes is urgently needed for glucose determination. Silicon nanoparticles (SiNPs) possess excellent properties, such as biocompatibility, low toxicity and good water solubility, which makes them suitable for nanosensors. Herein, we synthesized SiNPs by a one-step method that simplifies the preparation procedure, and for the first time established a novel SiNP-based nanoprobe (denoted as SiNPs/OPD/HRP/GOx) for ratiometric fluorescence and visual detection of glucose. Glucose oxidase (GOx) catalyzes glucose to produce gluconic acid and hydrogen peroxide (H2O2) under appropriate conditions. The H2O2 can oxidize o-phenylenediamine (OPD) to generate 2,3-diaminophenazine (oxOPD) in the presence of horseradish peroxidase (HRP). The oxOPD has strong fluorescence and can quench the fluorescence of SiNPs by means of the inner filter effect. With elevated glucose concentration, the fluorescence of SiNPs decreases gradually, while the fluorescence of oxOPD increases, thus achieving ratiometric fluorescence detection of glucose. Likewise, the color change with increasing amounts of glucose realizes the visual detection of glucose. This SiNP-based nanoprobe has good selectivity toward glucose and a simple preparation approach, which provides a new method for establishing glucose sensors.