Chitosan Sponge Microbead Delivery Composite for External Stimuli Responsive Local Drug Delivery

Orthopedic wound infections from complex trauma are a prevalent problem. Systemic delivery of antibiotics may result in sub-inhibitory concentrations of antibiotic in the wound site due to avascular nature of these injuries and can lead to development of antibiotic resistant infections. Local antibiotic delivery can overcome this shortcoming of systemic therapy. A customizable bio-polymer that can be loaded with antibiotics and be stimulated to release a drug on demand may provide an improved adjunct clinical therapy for preventing/treating infections in complex trauma injuries. The aim of this study is to incorporate iron oxide laden chitosan microbeads into the chitosan sponge to create a local delivery composite that is responsive to externally applied electromagnetic stimulation. Composites were evaluated for degradation, antibiotic and representative protein elution, antibiotic activity, and biocompatibility. When excited with ultrasound, the composite has a higher burst release of a loaded drug followed by less of a sustained release. Magnetic pulse stimulation increases the release of loaded vancomycin at 3 and 6 hours of elution but seems to decrease the release of loaded amikacin through 48 hours of elution. Vancomycin and amikacin eluted from the composites was active against Staphylococcus aureus and Pseudomonas aeruginosa respectively through 48 hours of elution. These results indicate that the addition of iron oxide containing chitosan microbeads to the chitosan sponge has potential as a tailorable adjunctive therapy for infection control