Biomedical Applications Of Montmorillonite Doped Electrospun Polyurethane Nanofibers

Electrospinning has been considered as a potential method to generate nanofibers on a large scale. Electrospun nanofibers has large surface area to volume ratio, high porosity and three-dimensional network structure that can imitate human extracellular matrix, which has aroused the interest of scientific research workers. Polyurethane(PU) has been widely applied in the biomedical field due to its physical, chemical, biological properties, and excellent biodegradability and cell compatibility in particular.Montmorillonite(MMT) is a kind of non-toxic and layered silicate material possessing excellent dispersive performance and biocompatibility, which is a potential drug carrier. Aspirin(ASP) is a kind of anti-inflammatory, antipyretic and analgesic drugs. In this study, we used polyurethane loaded of montmorillonite aspirin sustained-release preparations as based materials to explore nanocomposites by means of electrospinning technology, which formed an anti-inflammatory, antibacterial and controlled-release material after carrying on the antibacterial finishing.We studied the effect of electrospinning parameters such as polymer concentration,flow rate and applied voltage on the formation of PU nanofibers by using home-made electrostatic spinning device. Smooth and uniform PU nanofibers were produced under 15% polyurethane concentration, 20 kv applied voltage and 0.5 ml/h flow rate conditions. To optimize effects of morphology, mechanical properties and porosity, we added different montolivo soil to polyurethane nanofiber adding different montmorillonites to polyurethanes under the optimized experimental conditions. After adding 0%, 2%, 4%, 6%,montmorillonite to polyurethane solution, we can still produce uniform, continuous, smooth nanofiber, and there is no observed nodes on fiber surface. With the increase of the content of montmorillonite, the nanometer fiber diameter is decreasing, when montmorillonite content is 6%, the fiber diameter reduced to 513 ? 83 nm. Under adding a little montmorillonite to polyurethane solution, the mechanical properties of materials can be improved. When montmorillonite content is 2%, the fracture strength is largest, and is 1.6 times longer than pure polyurethane. Mat porosity of polyurethane fiber coated montmorillonite is larger than pure polyurethane fiber. However porosity change is not obvious under the content of soil increasing. In order to solve a problem that the aspirin release suddenly from polyurethane nanofibers, sustained-release preparations(ASP/MMT)was prepared by coating aspirin onto montmorillonite. On the basis of the previous studies, the ASP/MMT was dispersed in polyurethane solution, ASP/MMT/PU composite nanofibers was prepared by using electrospinning. ASP/MMT/PU nanofibers were LBL-assembled with multilayers of polyacrylic acid(PAA) and poly(ethylene imine)(PEI) through electrostatic interaction.The silver(Ag) nanoparticles was loaded onto the ASP/MMT/PU composite nanofiber felt by chemical reduction method. We studied kinetics of the ASP/MMT/PU nanofibers release ASP, evaluated antimicrobial properties, cell compatibility of the Ag/ASP/MMT/PU nanofibers. Results show that the ASP release from ASP/MMT/PU nanofibers with the phenomenon of sudden release, and there is quick release before the stage of sustained release. Ag/ASP/MMT/PU nanofiber mat can inhibit effectively the growth of staphylococcus aureus. Colorimetric method and SEM prove that Ag/ASP/MMT/PU nanofiber mat has excellent cell compatibility.