ATTACHMENT OF AN AMINOGLYCOSIDE, AMIKACIN, TO IMPLANTABLE COLLAGEN FOR LOCAL-DELIVERY IN WOUNDS

Cultured skin substitutes consisting of implantable collagen (COL) and cultured human skin cells often fail clinically from destruction by m icrobial contamination. Hypothetically, addition of selected antimicro bial drugs to the implant may control microbial contamination and incr ease healing of skin wounds with these materials. As a model for drug delivery, bovine skin COL (1 mg/ml) and amikacin (AM; 46 mug/ml) were modified by covalent addition of biotin (B-COL and B-AM, respectively) from B-N-hydroxysuccinimide and bound together noncovalently with avi din (A). B-COL was incubated with A and then with B-peroxidase (B-P) o r by serial incubation with B-AM and B-P, before P-dependent chromogen formation. Colorimetric data (n = 12 per condition) from spot tests o n nitrocellulose paper were collected by transmission spectrophotometr y. Specificity of drug binding in spot tests was determined by (i) ser ial dilution of B-COL; (ii) reactions with COL, AM, or P that had no B ; (iii) removal of A; or (iv) preincubation of B-COL-A with B before i ncubation with B-P. Binding of B-AM was (i) dependent on the concentra tion of B-COL; (ii) specific to B-COL, A, and B-P (P < 0.05); and (iii ) not eluted by incubation in 0.15 or 1.0 M NaCl. B-AM was found to bl ock binding of B-P to the B-COL-A complex and to retain bacteriocidal activity against 10 clinical isolates of wound bacteria in the wet dis c assay. Antimicrobial activity of B-AM was removed from solution by t reatment with magnetic A and a permanent magnet. These results suggest that selected antimicrobial drugs can be biotinylated for attachment to COL-cultured cell implants without loss of pharmacologic activity. Because this chemistry utilizes a common ligand, any molar ratio of ag ents may be administered simultaneously and localized to the site of i mplantation.