Highly Sensitive Detection of Glucose in the Presence of Serum Based on Signal Amplification of Persistent Luminescence Nanoparticles Functionalized by Glucose Oxidase

A new method is presented for the in vitro detection of glucose using glucose oxidase (GOx) covalently linked to persistent luminescent nanoparticles (PLNPs). This method ensures both sensitive and specific glucose detection by exploiting the enhanced luminescence of PLNPs in the presence of H₂O₂, generated by an enzymatic reaction. To this end, three different PLNPs composed of ZnGa₂O₄:Cr³⁺ (ZGO) nanoparticles are prepared by hydrothermal synthesis at 120 °C for 6 h (ZGO1), 12 h (ZGO2), and 24 h (ZGO3), followed by a calcination at 500 °C, resulting in nanoparticles with an average hydrodynamic diameter of 100 nm ± 5 nm after grinding and centrifugation. These nanoparticles are efficiently covalently functionalized with GOx, via a PEG linker. Following the production of H₂O₂ by the enzymatic reaction between GOx bound to the ZGO surface and glucose present in 100-fold diluted serum, a significant increase in the persistent luminescent signal is observed. This phenomenon is most pronounced for ZGO2, for which a detection limit of 0.01 µm and a detection range from 0.05 to 1 µm is obtained. These results demonstrate the innovative potential of this new technique in glucose monitoring, opening up new avenues for real-time monitoring and effective management of diabetes.