Thread size and polymer composition are critical properties to
consider for achieving a positive healing outcome with a wound dressing.
Three-dimensional (3D) printed scaffolds and electrospun mats both
offer distinct advantages as replaceable wound dressings. This research
aims to determine if the thread size and polymer compositions of the
scaffolds affect skin wound healing outcomes, an aspect that has not
been adequately explored. Using a modular polymer platform, four polyester
direct-write 3D printed scaffolds and electrospun mats were fabricated
into wound dressings. The dressings were applied to splinted, full
thickness skin wounds in an excisional wound rat model and evaluated
against control wounds to which no dressing was applied. Wound closure
rates and reduction of the wound bed width were not affected by the
thread size or polymer composition. However, epidermal thickness was
larger in wounds treated with electrospun dressings and was slightly
affected by the polymer composition. Two of the four tested polymer
compositions lead to delayed reorganization of granulation tissues.
Moreover, enhanced angiogenesis was seen in wounds treated with 3D
printed dressings compared to those treated with electrospun dressings.
The results from this study can be used to inform the choice of dressing
architecture and polymer compositions to achieve positive wound healing
outcomes.
Pressure-sensitive
adhesives (PSAs) such as sticky notes and labels
are a ubiquitous part of modern society. PSAs with a wide range of
peel adhesion strength are designed by tailoring the bulk and surface
properties of the adhesive. However, designing an adhesive with strong
initial adhesion but showing an on-demand decrease in adhesion has
been an enduring challenge in the design of PSAs. To address this
challenge, we designed alkoxyphenacyl-based polyurethane (APPU) PSAs
that show a photoactivated increase and decrease in peel strength.
With increasing time of light exposure, the failure mode of our PSAs
shifted from cohesive to adhesive failure, providing residue-free
removal with up to 83% decrease in peel strength. The APPU-PSAs also
adhere to substrates submerged underwater and show a similar photoinduced
decrease in adhesion strength.
The effect of polymer side chain on extrusion-based direct-write 3D printing and rheology is examined. Longer side chain length improves printability at ambient temperatures.
We report a novel pathway for the reductive activation of CO2 by the [NiIII(OMe)(P(C6H3-3-SiMe3-2-S)3)]– complex, yielding the [NiIII(κ1-OCO˙–)(P(C6H3-3-SiMe3-2-S)3)]– complex.
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