Recent Advances in Novel Materials and Techniques for Developing Transparent Wound Dressings

Optically transparent wound dressings offer a range of potential applications in the biomedical field, as they allow for the monitoring of wound healing progress without having to replace the dressing. These dressings must be impermeable to water and bacteria, yet permeable to moisture vapor and atmospheric gases in order to maintain a moist environment at the wound site. This review article provides a comprehensive overview of the types of wound dressings, novel wound dressing materials, advanced fabrication techniques for transparent wound dressing materials, and the key features and applications of transparent dressings for the healing process, as well as how it can improve healing outcomes. This review mainly focuses on representing specifications of transparent polymeric wound dressing materials, such as transparent electrospun nanofibers, transparent crosslinked hydrogels, and transparent composite films/membranes. Due to the advance properties of electrospun nanofiber such as large surface area, enable efficient incorporation of antibacterial molecules, a structure similar to the extracellular matrix, and high mechanical stability, is often used in wound dressing applications. We also highlight the hydrogels or films for wound healing applications, it's promote the healing process, provide a moisture environment, and offer pain relief with their cool, high-water content, excellent biocompatibility, and bio-biodegradability.Comment: N

Investigation of nanofiber nonwoven meshes produced by electrospinning of cellulose nanocrystal suspensions in cellulose acetate solutions

The development of nonwoven meshes based on cellulose acetate (CA) reinforced by cellulose nanocrystals (CNC) is reported. The meshes were electrospun from 15 wt% CA (M<inf>n</inf> = 30,000) in dimethylacetamide/acetone (1:2, w/w) solutions with various concentrations of CNC dispersions. The investigated six levels of CNC dispersions in CA solutions were: 0, 0.075, 0.147, 0.225, 0.300 and 0.382 wt%, which corresponded to 0, 0.50, 1.00, 1.50, 1.99 and 2.55 wt% of CNC in solid fibers. The basis of the impact of CNC nano-particles on fiber diameter and morphology was explored by assessing their contributions to the viscosity, conductivity and homogeneity of CA/CNC solutions. CA/CNC nonwoven meshes spun from suspensions with 0.075 wt% CNC had best results in morphology and fiber uniformity. Additionally, mechanical properties of CA nonwoven meshes with five levels of CNC loading (0, 0.50, 1.00, 1.50 and 1.99 wt%) were examined. The CA nonwoven mesh with 0.50 wt% CNC showed best mechanical properties, and its elastic modulus (E) was improved to an average value of 1.68 GPa from 1.17 GPa of neat CA nanofiber nonwoven mesh. These improved meshes would have applications such as separation membranes, supports for catalysts and sensors, engineered tissues and other smart materials.Peer reviewed: YesNRC publication: Ye

OSM-Classic: An optical imaging technique for accurately determining strain

OSM-Classic is a program designed in Matlab ® to provide a method of accurately determining strain in a test sample using an optical imaging technique. Measuring strain for the mechanical characterization of materials is most commonly performed with extensometers, LVDT (linear variable differential transistors), and strain gauges; however, these strain measurement methods suffer from their fragile nature and it is not particularly easy to attach these devices to the material for testing. To alleviate these potential problems, an optical approach that does not require contact with the specimen can be implemented to measure the strain. OSM-Classic is a software that interrogates a series of images to determine elongation in a test sample and hence, strain of the specimen. It was designed to provide a graphical user interface that includes image processing with a dynamic region of interest. Additionally, the stain is calculated directly while providing active feedback during the processing. Keywords: Strain measurement, Optical strain measurement, OSM, Optical extensometry, Matla

Effect of Moisture on Shape Memory Polyurethane Polymers for Extrusion-Based Additive Manufacturing

Extrusion-based additive manufacturing (EBAM) or 3D printing is used to produce customized prototyped parts. The majority of the polymers used with EBAM show moisture sensitivity. However, moisture effects become more pronounced in polymers used for critical applications, such as biomedical stents, sensors, and actuators. The effects of moisture on the manufacturing process and the long-term performance of Shape Memory Polyurethane (SMPU) have not been fully investigated in the literature. This study focuses primarily on block-copolymer SMPUs that have two different hard/soft (h/s) segment ratios. It investigates the effect of moisture on the various properties via studying: (i) the effect of moisture trapping within these polymers and the consequences when manufacturing; (ii) and the effect on end product performance of plasticization by moisture. Results indicate that higher h/s SMPU shows higher microphase separation, which leads to an increase of moisture trapping within the polymer. Understanding moisture trapping is critical for EBAM parts due to an increase in void content and a decrease in printing quality. The results also indicate a stronger plasticizing effect on polymers with lower h/s ratio but with a more forgiving printing behavior compared to the higher h/s ratio

Characterizing short-fiber-reinforced composites produced using additive manufacturing

Material extrusion additive manufacturing (MEAM), a sub-branch of three-dimensional (3D) printing is growing in popularity. Test specimens were 3D-printed using commercial polylactic acid (PLA) filament, and PLA filament reinforced with short-carbon fibers (PLA/CF). As-printed specimens and specimens that were annealed at three different temperatures, then subjected to tensile testing. The internal microstructures of the samples were also examined. The effects of the short-carbon fiber fillers on the mechanical properties of 3D-printed PLA were investigated, and the effects of the annealing process on polymer crystallinity and mechanical properties. The annealing process was shown to increase the crystallinity of both sample groups, though no statistically significant effect of annealing on mechanical properties was observed. The tensile properties of the PLA and PLA/CF filaments showed that the addition of carbon fibers to the PLA filament led to a significant increase in elastic modulus of the MEAM samples

Cleaning carbohydrate impurities from lignin using Pseudomonas fluorescens

A novel method of cleaning waste lignin biomass by means of selective biodegradation of cellulose and hemicellulose is investigated. This method uses Pseudomonas fluorescens (P. fluorescens), a non-pathogenic bacterium capable of producing cellulolytic enzymes, cleaving polymeric carbohydrates into free sugars and utilizing them as their carbon source. The growth of P. fluorescens on lignin biomass was confirmed by increasing cell count with time and visualized by scanning electron microscopy (SEM). Depletion of free sugars in the growth medium was measured by Technical Association of the Pulp and Paper Industry (TAPPI) methods and by time-of-flight secondary ion mass spectrometry (ToF SIMS), which showed a significant decrease in the carbohydrate content and an increase in the lignin fraction after P. fluorescens biodegradation. The molar mass distribution of lignin before and after the biodegradation of carbohydrate impurities showed no indication of lignin depolymerization. Our results strongly support the biodegradation of carbohydrate impurities from waste lignin by P. fluorescens as an effective, green and eco-friendly process