A review on wound dressings with an emphasis on electrospun nanofibrous polymeric bandages

Collagen-based membranous materials of various shapes (gel, film, sponge) are known to be the most promising materials in terms of facilitating the regeneration of dermal defects. In this study, dense and porous collagen membranes were fabricated using air-drying and freeze-drying processes, respectively, and the effect of ultraviolet (UV) radiation on the degree of membrane crosslinking was evaluated by in vitro biodegradation and mechanical testing. A non-irradiated membrane group was used as the negative control and a glutaraldehyde (GA) treated group as the positive control. Scanning electron microscopy showed that, as the freezing temperature decreased to -196 degrees C, the resultant mean pore sizes also decreased; optimal pore size was obtained at a freezing temperature of -70 degrees C. In vitro biodegradation and mechanical testing demonstrated that GA treatment or 4 hours of exposure to UV radiation significantly increased both resistance to collagenase and mechanical strength versus the untreated controls, regardless of the collagen membrane type (dense or porous). Our results suggest that UV treatment is a useful tool for the fabrication of collagen membranes designed to be used as dermal dressings.

To evaluate the clinical impact of using a silver-releasing hydroalginate dressing to minimise the risk of local infection in colonised chronic wounds. This was a randomised (stratification according to wound type) open-label multicentre comparative two-arm parallel-group study. Thirteen centres recruited 99 patients with either a venous leg ulcer or a pressure ulcer. None of the wounds required systemic antibiotics or were associated with lymphangitis and/or fever, but at least two of the following criteria had to be present: continuous pain; erythema; oedema; heat; and moderate to high levels of serous exudate. Patients were allocated to receive either a silver-releasing hydroalginate dressing (Silvercel, the test group) or a pure calcium alginate dressing (Algosteril, the control group). Wounds were assessed daily over 14 days to complete a modified ASEPSIS index to evaluate risk of infection, and then weekly for two additional weeks. A global wound severity score and area tracings were recorded weekly. Fifty-one and 48 patients were randomised in the test and control groups respectively: 28 pressure ulcers and 71 venous leg ulcers. The total mASEPSIS score over 14 days did not differ significantly between groups: 95.4 +/- 62.2 and 104.2 +/- 72.8 in control and test groups respectively (p = 0.791). Of the patients who completed the total four-week study duration, four out of 38 (10.5%) in the control group and none of the 40 in the test group were treated with systemic antibiotics at the final visit (p = 0.053). According to the investigators, fewer wounds developed a clinical infection over the four-week follow-up in the test group (33% versus 46%; p = 0.223). Overall, the four-week closure rate was statistically greater in the test group (0.32 +/- 0.57cm2/day versus 0.16 +/- 0.40cm2/day; p = 0.024). Compared with baseline, the absolute decrease in wound severity score at week four was higher in the test group (-5.6 +/- 3.2 versus -4.1 +/- 4.3; p = 0.063); this was also true of the percentage reduction (-32 +/- 17% versus -23 +/- 25%; p = 0.034). Poor dressing acceptability and/or tolerability was noted in five out of 48 patients (10.4%) in the control group and in five out of 51 (9.8%) in the test group. This study suggests that the use of silver-releasing dressings in the management of wounds at high risk of infection may have a clinically favourable influence on wound prognosis; the dressings also appeared to be well tolerated. However, the evaluation of these advantages in controlled clinical trials is complex and requires potent studies and the development of more specific endpoints than those currently used.