Vancomycin release from OPF/SMA hydrogels.

(A) Diagram representing release of vancomycin from charged hydrogels. OPF/SMA hydrogels loaded with vancomycin were placed in DPBS solutions and incubated at 37°C for 96 hours. Solutions were collected and fresh DPBS was replaced at the indicated time points. The concentration of eluted vancomycin was measured by HPLC. Cumulative release is represented as a percentage of the total amount of measured drug released. (B) Best fit of data as calculated by phenomenological mathematical model described in text. (C) Experimentally measured data points obtained, plotted for comparison to mathematical model. (D) Comparison of fitted model to obtained data points for 0%SMA and 50%SMA hydrogels. (E) Efficacy of released drug was determined by treating a strain of MRSA (MIC₅₀ for vancomycin = 1.0 μg/mL) with solutions of released drug from the 12 hour sample group. Stock concentrations of vancomycin hydrochloride were compared to released drug at equivalent concentrations of 5.0, 2.5, or 1.0 μg/mL. Efficacy tested in a quantitative colony forming assay and compared to PBS treated control. (F) Zone of clearing assay comparing vancomycin loaded and unloaded hydrogels (0%SMA or 50%SMA). Values normalized to vancomycin unloaded hydrogels (zone of clearing = 1). (G) Representative images of hydrogels ability to clear bacteria from a dish. Error bars represent +/- one standard deviation, N = 3 in all groups. Statistical representation: (*) indicates p<0.05.