Surfactant-free one-step synthesis of dual-functional polyurea microcapsules: Contact infection control and drug delivery

Abstract

Surface functionalized polyurea microcapsules (MCQ) are synthesized in one step. Dimethyl-dodecyl-(5-hydroxy-pentyl)-ammonium bromide (DAB), a hydroxyl-end-capped quaternary ammonium salt, is synthesized and adopted as a new surfmer for the synthesis of MCQ. It is confirmed by fluorescein adsorption that DAB is covalently bonded to MCQ. The so-formed MCQ possess dual-functionality: contact infection control and sustained drug delivery. Agar diffusion antimicrobial tests confirm successful inhibition of multi-drug-resistant E. coli by MCQ alone instead of by leaching of free quaternary ammonium salts. Furthermore, few E. coli colonies survive on an agar plate coated with 3-4 layers of MCQ. Dissolution tests show a typical first-order release profile of courmarin-1, a model dye, from MCQ. An inherently biocidal shell of polyurea microcapsules (PUMCs) is formed in an oil-in-oil (dimethylformamide/cyclohexane) system without the use of surfactants. A new hydroxyl-ended quaternary ammonium salt dimethyl-dodecyl-(5-hydroxy-pentyl)- ammonium bromide (DAB) is the key to the in situ synthesis of the functional PUMCs. It serves to decrease interfacial tension of the oil/oil interface, to covalently bond to PUMC shells, and to inactivate bacteria. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.