(122e) Sprayable, Thermoreversible Hydrogels for Improved Treatment of Burn Wound Infections

Due to the high rate of infection in hospitalized burn wounds and the painful treatment of applying antimicrobial creams and ointments, the goal of this project is to develop a sprayable, antimicrobial hydrogel to use as a treatment for burn wound infections. Sprayable hydrogels are expected to be less painful to apply than current topical, antimicrobial products, will sustain drug release over longer periods of time, and will keep the wound bed under optimal conditions (moist, absorbing wound exudate, etc.). Pluronic F127, a commercially available thermoreversible hydrogel, and hyaluronic acid, an active healing agent and hydrogel, were combined in various percentages to test which formulations have desirable spray patterns, gelation temperatures, drug diffusion, and gel dissolution. Methylene blue was incorporated into the gel for visualization and to act as a model drug in diffusion studies. Ciprofloxacin, an antimicrobial agent, was added after preliminary studies using methylene blue. To determine spray characteristics of the formulations, cold hydrogels were loaded into Aptar Pharma sprayers and sprayed four, five, and six inches away from a target. The targets were photographed and analyzed to determine the spray spread, and the sprays were characterized via high-speed imaging to examine the plume differences from different nozzles. The gelation temperature and viscosity of each gel composition was determined using a rheometer, with a desirable gelation temperature between 21 and 32°C to avoid gelation while spraying but allowing gelation on skin. Diffusion and dissolution experiments were conducted in vitro to determine how quickly the gel compositions release drug and dissolve in saline solution. Our results show that changes in the spray pattern are largely controlled by the choice of nozzle and the gel viscosity. These results will be important for application purposes because we want to cover large, irregularly shaped wounds quickly and completely. Drug and other gel additives were shown to alter the gelation temperature, and several gel formulations with drug additives have been made that transition to a gel within the desired range for application. Preliminary diffusion and dissolution experiments showed that increasing the gel percentage prolonged drug release and dissolution in saline solution. These results will influence the amount of drug that will need to be loaded into the gel to maintain effective dosing and the number of dressing changes required for the system. Future studies will include antimicrobial testing against three common burn wound pathogens and transport studies across skin.