Iodine-polyurethane matrices: antimicrobial activity vs method of preparation

Antimicrobial Activity and Biocompatibility of Polyurethane—Iodine Complexes

Polyurethane (PU), one of the most versatile biomedical materials, strongly binds iodine, one of the most effective antiseptics, through the formation of a charge-transfer complex. The PU—Iodine complexes were characterized with UV/Vis study and X-ray photoelectron spectroscopy (XPS) analysis. The new materials evoked potent antimicrobial activity against Gram-negative and Gram-positive bacteria (including methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecium, and bacterial spores), fungi, and viruses, as well as inhibited surface bacterial colonization and biofilm-formation. Based on the Kirby-Bauer test, the antimicrobial effects occurred through the slow release of iodine. The iodine release rate can be controlled by the preparation conditions of the PU—Iodine complex. Trypan blue exclusion analysis indicated that PU—Iodine has excellent mammalian cell viability. The PU—Iodine complexes have the potential for a wide range of medical, dental, and other related applications.

Antimicrobial behavior of polyelectrolyte-surfactant thin film assemblies

Layer-by-layer (LbL) assembly, a technique that alternately deposites cationic and anionic materials, has proven to be a powerful technique for assembling thin films with a variety of properties and applications. The present work incorporates the antimicrobial agent cetyltrimethylammonium bromide (CTAB) in the cationic layer and uses poly(acrylic acid) (PAA) as the anionic layer. When the films are exposed to a humid environment, these agents diffuse out of the film, inhibiting bacterial growth in neighboring regions. Film growth, microstructure, and antimicrobial efficacy are studied here, with 10-bilayer films yielding thicknesses on the order of 2 microm. Various factors are shown to influence the antimicrobial efficacy including time, temperature, secondary ingredients, and number of bilayers. As more layers are deposited, antimicrobial efficacy is increased because more CTAB is able to diffuse throughout the film, and higher amounts of antimicrobials are released. Additionally, inclusion of the cationic poly(diallyldimethylammonium chloride) (PDDA) in the cationic layer in conjunction with CTAB increases film uniformity, and as a result, antimicrobial effectiveness is enhanced. These thin films provide the ability to render a surface antimicrobial and may be useful for bandages or sterilization of disposable objects (e.g., surgical marker).

Effects of sugar ester and hydroxypropyl methylcellulose on the physicochemical stability of amorphous cefditoren pivoxil in aqueous suspension

The improvement in physicochemical stability of amorphous cefditoren pivoxil (CDTR-PI) in aqueous suspensions by addition of sugar ester (SE) and hydroxypropyl methylcellulose (HPMC) was explained by prolonging the induction period prior to crystallization and the reduction in crystal peak intensity. Furthermore, the stabilizing effect of these additives in a multiple additive system was greater than in a single additive system. To determine the mechanism, by which these additives stabilized the amorphous CDTR-PI, we evaluated the surface states of CDTR-PI in suspension by measuring Raman spectra and zeta potential. The change in Raman spectra demonstrated that SE and HPMC interacted with CDTR-PI at the same interaction sites on CDTR-PI. The zeta potential reflected the adsorption phenomena of the additives and indicated that both SE and HPMC adsorbed onto particles of CDTR-PI with no apparent competitive interaction and the response was complementary. It was considered, based on this study, that HPMC and SE would stabilize amorphous CDTR-PI by different mechanisms; HPMC would mainly inhibit crystal growth by small amount of adsorption and SE would inhibit both crystal growth and nucleation by large amount of adsorption. This was considered to result in the hybrid effect in the multiple additive system.