Event Abstract Back to Event Comparison of enzymatic and accelerated oxidative degradation methods to evaluate chitosan Carlos Wells1, Michael Harris1, Marmadou B. Diallo1, Warren Haggard1 and Jessica A. Jennings1 1 The University of Memphis, Biomedical Engineering, United States Introduction: Biodegradable local drug delivery devices for antibiotics are preferable over non-degradable polymethlymethacrylate beads because they minimize the need for surgical removal. Modifications of the biopolymer chitosan (CS) have been developed to control degradation timing of devices such as lyophilized sponges to match healing rates and needed elution profiles [1],[2]. Although enzymatic degradation is reported to be the primary mechanism by which chitosan degrades in vivo, oxidative and hydrolytic mechanisms may also play a role in macrophage-facilitated biodegradation. To compare between chitosan formulations, accelerated testing with oxidative solutions may provide reliable means to quickly assess degradation propoerties. This investigational study compared different formulations of chitosan sponges using enzymatic and oxidative testing, evaluated timing, and clinical relevance of results. Methods: CS sponges 9 cm2 in size from 3 groups, 2% CS, 1.5% CS blended with 0.5% polyethylene glycol (PEG), and a commercially available sponge were hydrated. For enzymatic degradation, samples were immersed in 30 mL1 mg/ml lysozyme and incubated with shaking [1],[2]. Samples (n=4/group) were taken every 2 days for 10 days with complete solution refreshment. For accelerated oxidative degradation sponges were immersed in 30 mL of 0.1 M CoCl2 in 3% H2O2. Samples were taken every 3.6h for 18h and dried in an oven. Degradation percentage was calculated as change in mass divided by original mass. ANOVA with Holm-Sidak post-tests were used to detect differences in means of at least 9% at α=0.05 with 80% power, assuming standard deviation of 3.2%. Results: Sponges in each group from the lysozyme degradation test showed little to no degradation over 10 days. While undergoing enzymatic degradation 35% of the samples showed mass increase after day 2 (Fig1). In the oxidative degradation test, commercial and 2% CS sponges showed approximately linear degradation trends over time (Fig 2). Differences between different sponge types were more evident during the accelerated degradation testing. Discussion: The lysozyme degradation test showed no discernable degradation pattern over a 10 day period at concentrations well above physiological levels. This test is limited by the rate of enzymatic reaction, enzyme activity, and surface area of implant. The accelerated oxidative degradation method provided evidence of differences between CS formulations within a shorter time frame. Shorter intervals or lower H2O2 concentrations may be required to model degradation of the PEG/CS blends. This acclerated approach can be used to more effectively model CS degradation in vitro for comparison to performance in vivo [1],[2]. Conclusion: Accelerated degradation studies of CS can be quickly performed in vitro using oxidative solutions to determine the degradation performance of CS, providing comparative results within a shorter time frame than enzymatic models of degradation. Jonathan Tapp; Parwinder Singh