2.1. Electrospinning

The commercially available PVA with low viscosity and high viscosity (Aladdin reagent, Shanghai) were respectively dissolved in acetic acid (70 wt.% in water) and magnetically stirred for 2 h at 80 °C to form two solutions with the concentration of 30 wt.%. The viscosity of high viscosity PVA is 50.0–65.0 mPa∙s and the viscosity of low viscosity PVA is 5.0–7.0 mPa∙s. The two solutions were mixed at a volume ratio of 43:7 (low viscosity: high viscosity) for electrospinning. After that, MoS₂ nanosheets that were prepared according to our previous research [18] and DOX (Beijing Huafeng Pharmaceutical Co., Ltd., Beijing, China) were mixed with the PVA solution for electrospinning under ambient conditions to prepare PVA/MoS₂ and PVA/MoS₂/DOX microspheres. DOX and MoS₂ nanosheets concentrations were set as 10 and 6 mg/mL, respectively. PVA/MoS₂/DOX PVA/MoS₂ and PVA microspheres were prepared via a home-made electrospinning machine. The feeding rate of the solution was 0.5 mL/h, the collecting distance was 15 cm, and the applied voltage was set at 20 kV. After the electrospinning, the microsphere mats were removed from the collector and put in a vacuum oven for drying. All water used in this study with the resistivity >18.2 MΩ·cm was distilled with a Millipore water purification system (Milli-Q Plus 185).