Biomedical evaluation of a novel nitrogen oxides releasing wound dressing.

Chronic wounds are a major cause for both suffering and economical losses. Management of chronic non-healing wounds requires multipronged approach. They are polymicrobial and agonizing for the patient due to associated pain. Moist dressing providing antimicrobial action is a highly desirable chronic wound management option. Here we report a hydrogel based dressing that possesses the antimicrobial properties of acidified sodium nitrite and the homeostatic property of a hydrogel. The dressing was developed by combining citric acid cross-linked cotton gauze and sodium nitrite loaded gelatin. The cotton gauze was cross-linked with citric acid by pad-dry-curing in presence of nano-titania catalyst. The cotton gauze-gelatin hydrogel combination was gamma-irradiated and freeze-dried. At the time of application, the freeze-dried dressing is wetted by sodium nitrite solution. The dressing has a fluid uptake ability of 90 % (w/v) and the water vapour evaporation rate was estimated to be 2,809 ± 20 g/m(2)/day. The dressing showed significant antimicrobial activity against both planktonic and biofilm forms and was effective during consecutive re-uses. Cytotoxicity study showed inhibition of fibroblasts, but to a lesser extent than clinically administered concentrations of antiseptic like povidone iodine. Storage at 37 °C over a 3 month period resulted in no significant loss of its antimicrobial activity.

Novel biocatalytic polymer-based antimicrobial coatings as potential ureteral biomaterial: preparation and in vitro performance evaluation.

Catheters and other indwelling devices placed inside human body are prone to bacterial infection, causing serious risk to patients. Infections associated with implants are difficult to resolve, and hence the prevention of bacterial colonization of such surfaces is quite appropriate. In this context, the development of novel antimicrobial biomaterials is currently gaining momentum. We describe here the preparation and antibacterial properties of an enzyme-embedded polycaprolactone (PCL)-based coating, coimpregnated with the antibiotic gentamicin sulfate (GS). The enzyme uses PCL itself as substrate; as a result, the antibiotic gets released at a rate controlled by the degradation of the PCL base. In vitro drug release studies demonstrated sustained release of GS from the PCL film throughout its lifetime. By modulating the enzyme concentration in the PCL film, we were able to vary the lifetime of the coating from 33 h to 16 days. In the end, the polymer is completely degraded, delivering the entire load of the antibiotic. The polymer exhibited antibacterial properties against three test isolates: Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Foley urinary catheters coated with the modified polymer exhibited sustained in vitro release of GS over a 60-h period. The results suggest that the antibiotic-plus-enzyme-loaded polymer can be used as tunable self-degrading antimicrobial biomaterial coating on catheters.