Preparation And Properties Of Quercetin Nanofibers By Electrospinning

Geranium wilfordii Maxim.is a kind of traditional Chinese medicine.Quercetin is a flavonoid component.It has been proved to have significant anti-inflammatory and antibacterial activities in recent years.It also has the potential to be used in wound dressings.Multilayer composite wound dressings not only have certain mechanical properties to protect the wound from the external environment,but also maintain a suitable environment for wound healing.It can be used as a drug delivery system to promote wound healing.Based on the optimization of the extraction process and drying process of quercetin from Geranium wilfordii Maxim.,we chose quercetin as a model drug to prepare different functional layers of multilayer wound dressings by electrospinning on PVP,PVA and Eudragit L-100.The structure of each layer was characterized and the biocompatibility was evaluated.The main research contents and conclusions were as follows:(1)The extraction process of quercetin from Geranium wilfordii Maxim.was optimized to evaluate the difference of quercetin extraction rate processed by several typical drying methods.The suitable drying method in processing Geranium wilfordii Maxim.was illustrated.The ultrasonic-assisted ethanol reflux method was used to explore the effects of the medicinal material particle size,reflux temperature,ethanol concentration and material-to-liquid ratio on the extraction rate of quercetin.Based on the single factor experiments,the optimal extraction process of quercetin was obtained by response surface methodology.The relative content of quercetin was used as the evaluation index.The results showed that the optimum extraction technology of quercetin was as follows:The 120-mesh fine powder of Geranium wilfordii Maxim.were extracted by 80%ethanol with a solid-liquid ratio of 1:15(g/mL).The experiment was done at room temperature under 60 kHz ultrasound for 30 min.The reflux extraction was evaluated at 85℃ for 1 h.The relative content of quercetin was 77.02%under this parameter.In addition,the smaller the crystallinity of Geranium wilfordii Maxim.powder processed under different drying methods,the higher the extraction rate of quercetin.Hot air drying at 60℃ could maintain the content of quercetin from Geranium wilfordii Maxim.maximally.In these cases,the bulk density of 120 mesh Geranium wilfordii Maxim.powder was 0.26 g/ml,and the crystallinity was 8.7%.(2)The suitable carrier matrix was screened to load quercetin.We prepared electrospun fibers with PVA,PVP and Eudragit L-100.Utilizing the characteristics that the evaporation rate of the solvent used to dissolve the polymer had effects on the formation of fiber from the polymer jet,we analyzed the effects of DMF as the inducer of fiber differentiation.In addition,Ag+was used as a hydrophilic drug model to explore the inhibitory effect of the fiber membrane on Staphylococcus aureus and Escherichia coli.The cytotoxicity of fiber membrane on L-929 was investigated by loading Ag+.The results confirmed that DMF induced the diameter of the fiber to be as low as 50 nm.It affected the change of hydrophilic groups on the fiber surface,enhancing the water absorption performance of the fiber.DMF provided more binding sites for hydrophilic drugs to enhance the antibacterial properties of the fiber membranes.The prepared fiber membranes had no obvious cytotoxicity to L-929 cells.It had the potential to be used as an antibacterial layer for multilayer wound dressings.(3)Based on the screening of carrier materials,Eudragit L-100 fibers loaded with different concentrations of quercetin were prepared by electrospinning.PEG-4000 was added to improve the ductility of the mat.The drug release properties and biocompatibility of the drug loaded fiber membrane in vitro were evaluated.PEG-4000 was added to improve the ductility of the mat.We evaluated the in vitro drug release performance and biocompatibility of the drug-loaded mat.The results confirmed that PEG-4000 effectively improved the ductility of the fibers.It enhanced the mechanical properties of the fibers and increased the in vitro release of the drug-loaded fiber membranes.The drug-loaded fibers had no obvious cytotoxicity to L-929 cells.The in vitro release curve of drug-loaded fibers could be approximately described by Korsmeyer-Peppas model.It had the potential as an antibacterial layer and protective layer of multilayer wound dressing.In conclusion,the extraction process of quercetin from Geranium wilfordii Maxim.was optimized to evaluate the difference of quercetin extraction rate processed by several typical drying methods.The different functional layers of multilayer composite wound dressings were prepared by electrospinning based on PVP,PVA and Eudragit L-100 which quercetin was used as a model drug.In addition,we evaluated the cytotoxicity.It provided data and theoretical basis for the preparation of multilayer composite wound dressings and clinical skin injury repair.