Integrating water-exfoliated phosphorene into poly(lactic-co-glycolic) acid: Stability and photoactivity potential

In this study, we report the development and comprehensive characterization of novel poly(lactic-co-glycolic acid) (PLGA)-based nanocomposites incorporating phosphorene nanoflakes. Phosphorene was produced by ultrasound-assisted exfoliation of black phosphorus in the presence of sodium dodecyl sulfate (SDS) as a surfactant, and was then subsequently embedded into a PLGA matrix to fabricate phosphorene–PLGA nanocomposite films, prepared here for the first time, and emulsions. The structural, thermal, and photophysical properties of these hybrid materials were systematically investigated, with a focus on the interfacial interactions between the polymer matrix and the 2D nanofillers. The integration of phosphorene nanosheets significantly enhances the thermal stability of PLGA at elevated temperatures (with a notable shift of ~40 ◦C), while slightly accelerating its hydrolytic degradation at lower temperatures, resulting in a ~20 % reduction in molecular weight. More interestingly, the PLGA matrix plays a protective role, mitigating the degradation of phosphorene during the polymer hydrolytic degradation. Importantly, we study for the first time the photophysical behaviour of phosphorene nanoflakes embedded in PLGA emulsions, highlighting their potential for photodynamic therapy (PDT) applications. While free phosphorene nanoflakes exhibit outstanding photocatalytic activity in generating singlet oxygen, their embedding within PLGA micelles causes a marked suppression (~90 %) of this activity, likely due to restricted oxygen diffusion in the polymeric environment. This previously unreported limitation is crucial for evaluating the applicability of phosphorene–PLGA systems in biomedical contexts, particularly in PDT.