Construction And Performance Study Of A Novel Unidirectional Self-pumping Multilayer Gradient Wound Dressing

As the largest organ in the human body,the skin serves as a biological barrier between the internal environment and the outside world,and also serves as the most important defense line for the human body to resist the invasion of external microorganisms and pathogens.However,chronic wounds of skin tissue caused by pressure injuries,venous ulcers of lower limbs,foot ulcers of diabetes,radiation ulcers and postoperative wounds are increasing,and the demand for care and treatment of chronic wounds closely related to them is also increasing.Chronic wounds have become a common health problem in today’s society.Starting from the management of chronic wound exudation and effective antibacterial activity,this article selects chitosan(CS)with certain broad-spectrum antibacterial properties,hydrophilic polyvinyl alcohol(PVA),biocompatible polycaprolactone(PCL),and high hygroscopic gelatin(Gel)as carriers,loaded with the antibiotic Amoxicillin sodium(AOMX),and successfully prepared antibacterial unidirectional self-pumping multilayer gradient medical dressings through electrospinning technology,And its structure and performance were characterized to explore its potential as a multifunctional medical dressing.The main conclusions obtained are as follows:(1)PVA/CS fiber membranes with varying mass ratios were created using electrospinning technology.As the mass fraction of PVA increased as a spinning aid,the spinnability,moisture absorption,and mechanical properties of fiber membranes also increased progressively.Particularly,PVA/CS fiber membranes with a mass ratio of 70/30 possessed a moisture absorption rate of 487.4%,a moisture retention rate of328.1%,a mass loss rate of 29.5%,and a tensile strength of 3.55 MPa.Optimization of spinning process parameters entailed single factor experiments and orthogonal experiments.With an increased voltage,injection speed,and receiving distance,the diameter of the fiber showed a decreasing and subsequently increasing trend.The optimal spinning parameters for drug-loaded fiber membranes were ultimately identified as follows:spinning voltage of 18 k V,spinning rate of 0.35 m L/h,and receiving distance of 20 cm.The PVA/CS/AMOX fibers’average diameter was424.55 nm,with a coefficient of variation(CV)value of 16.11%.The fiber morphology was uniform,with a smooth microstructure surface and low fiber diameter dispersion.(2)PCL-PVA/CS fiber membrane was fabricated through the process of electrospinning,with a PCL:PVA/CS flow rate ratio of 1.05:0.35 m L/h.When combined with PVA/CS/AMOX fiber membrane,the respective static contact angle of PCL-PVA/CS fiber membrane was 93°,and the static contact angle of PVA/CS/AMOX fiber membrane was 38°.The result yielded a multi-layer fiber membrane with varying hydrophilicity along its thickness.The droplet spreads evenly on the surface diffusion of PCL-PVA/CS fiber membrane and can gradually penetrate the less hydrophilic fiber membrane surface and transfer to the more hydrophilic fiber membrane as time elapses.The process completes in an increasing amount of time required for complete penetration from the PCL-PVA/CS surface with the increase of interlayer spacing.When the interlayer spacing between fiber membranes is 1:3,it takes 24 seconds.The drug release efficiency from the surface of PCL-PVA/CS fiber membrane within 24 hours is 61%(3)PCL/Gel composite fiber membranes were prepared using electrospinning technology with varying mass fractions of each component.Ordered fiber membranes with specific orientations were obtained by utilizing high-speed rollers as receiving devices.Increasing the mass fraction of PCL resulted in improved spinnability of the composite membrane,leading to smoother and more uniform fiber morphology.Conversely,increasing the Gel mass fraction enhanced moisture absorption and moisturizing performance of the fiber membrane.By altering the receiving method,the mechanical properties of the fiber membrane were also fortified.The ordered fiber membrane composed of 12%PCL and 4%Gel exhibited remarkable moisture absorption properties,with a rate of 632%and the ability to absorb 5.32 times its weight in water,while also boasting a moisture-retention rate of 529%and a tensile strength of 9.1 MPa.(4)Multi-layer gradient medical dressings with unidirectional self-pumping performance were obtained through layer-by-layer electrospinning of composite fibers,including PCL-PVA/CS,PVA/CS/AMOX,and PCL/Gel,on non-woven fabric.A theoretical model of the composite fiber membrane structure was built to analyze the force distribution of droplets between various fibers and confirm the existence of a theoretical basis for unidirectional self-pumping.By applying different infiltration methods,the multi-layer gradient dressing’s droplet infiltration on both sides adhered to the theoretical model.The dressing’s moisture vapor transmission rate(MVTR)was measured at 1080-920 g/m~2 24h within 24 hours,compared to the common Kefu dressing on the market,it has increased by 220%-230%.The survival rates of 3T3cells on the multi-layer gradient dressing were 153.99%after 24 hours and 174.85%after 48 hours.Within the first 24 hours of contact,the AMOX loaded multilayer gradient dressing exhibited excellent antibacterial activity,with respective antibacterial circle widths of 7.3±0.1 mm and 6.5±0.1 mm against Staphylococcus aureus and Escherichia coli.Compared to the control group,it increased by 82.5%and 62.5%,Its antibacterial effect also increased with contact time.