A novel strategy for the preparation of multifunctional and robust polyhydroxyalkanoates/GQDs nanocomposites with UV-resistance, pH-responsive and antibacterial properties

Biosynthesized polyhydroxyalkanoates (PHAs) offer several compelling advantages, including biodegradability, biocompatibility, and suitability for use in environmentally friendly packaging materials. However, poor crystallization ability and lack of functionality (e.g., UV-resistance and antibacterial properties) significantly restrict the practical applications of PHAs. In this study, graphene quantum dots (GQDs) containing with rich amino groups, carboxy groups and conjugate structure were tailor-made as multifunctional nanofillers to prepare PHAs/GQDs composites. The GQDs not only exhibited excellent dispersion within the PHAs matrix at the nanoscale but also act as nucleating agents to dramatically increase the nucleation density of PHAs. Remarkably, the incorporation of just 0.5 wt% GQDs led to outstanding antibacterial performance (99.99%), UV resistance (90.50%), transparency (>80%) and mechanical properties in the PHAs composite. ​Moreover, these PHAs composites displayed strong fluorescence stability and demonstrated sensitivity to pH variations. Building upon these findings, we propose a novel concept for a wearable device capable of intelligently detecting changes in sweat pH during human exercise. This work presents a straightforward and effective method for preparing multifunctional GQDs, thereby expanding the potential applications of PHAs in the realm of green packaging and intelligent sensing.