The impact of first-aid dressing design on healing of porcine partial thickness wounds.

Literature describes that a well-maintained moist wound healing environment leads to faster healing by preventing scabbing and drying of the wound. A moist wound speeds healing by allowing for unimpeded movement of newly dividing epidermal cells in the wound. Contrary to what is described in literature and practiced by clinicians, first-aid dressings used at home by consumers advertise breathability and absorptivity as benefits. This manuscript examines the effects of dressing breathability and highly absorptive pads on healing and wound appearance in a porcine dermatome wound model, designed to mimic an abrasion injury. Partial thickness wounds were covered with an experimental silicone-polymer film dressing and various over-the-counter bandages for time frames ranging from 4 to 11 days. The progression of healing was quantified by histology and wound-size reduction measurements. The thickness and persistence of a scab or serocellular crust (SCC) over the injury was measured using both pixel density and optical coherence tomography to supplement visual observations, demonstrating new tools for quantification of SCC over wounds. The results of the experiments illustrate the impact of dressing features on the rate of wound reepithelialization and the formation of SCC. Both a low moisture vapor transmission rate (MVTR) and the absence of an absorptive layer were important in speeding wound healing. Surprisingly, use of a dressing with a low MVTR and a highly absorptive pad healed significantly more slowly than a comparative dressing with a low MVTR and no absorptive pad, even though both dressings had very little scab formation over the wound. This study shows that breathability and absorbency of dressings play independent roles in providing an optimal healing environment, and that these properties can vary widely among commercially available dressings.

Crosslinked, Glassy Styrenic Surfactants Stabilize Quantum Dots Against Environmental Extremes.

Semiconductor, quantum dot (QD) nanoparticles (including CdSe/ZnS, CdTe/ZnS, and CdSe) were encapsulated within cross-linked shells of amphiphilic polystyrene-block-poly(acrylic acid) block copolymer. Transmission electron microscopy revealed that each particle was surrounded by a uniform, layer of copolymer, and that the average diameter of the resulting QD-core micelles was between 25 and 50 nm, depending on the conditions of particle assembly. Overall, we found that aqueous suspensions of these QDs were substantially more stable to heat and pH than particles with other surface preparations; we argue that the enhanced stability is due to the uniform, hydrophobic coating of polystyrene around each particle and the reinforcement of this layer by shell-cross-linking. The biocompatibility of these particles was investigated by microinjection of particle suspension into live zebrafish embryos. The particles permanently stained the fish vasculature, but did not interfere with the normal development of the fish. We propose that QDs encapsulated in cross-linked block-copolymer shells allow QDs to be used in biological or biotechnological protocols requiring harsh reaction conditions.