Formulation and Evaluation of PD-Incorporated Hydrogel

Methicillin-resistant Staphylococcus aureus MRSA (ATCC 43300) was taken from the Guangdong Microbial Culture Collection Centre (Guangzhou, Guangdong, China). PD was synthesized by ourselves and the structural formula and mass spectra are provided in the Supplementary Material (Figure S1). Further, in Figure S2, we found that the inhibition circle diameter was larger than that of vancomycin in vitro for the guidelines [40 (link)]. Sliver Sulphadiazine (SSD) and the commercialized 1% cream SSD were obtained from Guangdong, China. SSD is a topical antibacterial cream with combined silver and sulfonamide as active ingredients at 1% of the composition. Carbomer 940 (CBM940) is a complex polymer designed as a gelling agent for lipid vesicles in transdermal applications and does not cause skin irritation. Phosphate-buffered saline (PBS, pH = 7.0) was purchased from Gibco-BRL, Los Angeles, CA, USA. Gel carbomer 940 was used as a carrier for PD gel applications. Afterwards, we mixed in two different concentrations of PD, stirred for 5 min, and then adjusted the pH to 7 with triethanolamine. Subsequently, the mixture was filled with ultrapure water (q.s.p 10 mL) to give a 1% Carbopol gel containing 1% (w/v) and 2.5% (w/v) PD and stirred periodically at 25 °C for 20 min until a homogeneous mixture was formed, formed as a transparent and well-gelled hydrogel for in vivo wound healing. The vancomycin hydrogel was also produced in the same way. The dose of protective and antimicrobial agents was determined according to the standard dose, and the appropriate pH is around 7.0. SSD cream (1%) and Van hydrogel (1%) were used as drug-positive controls.