Study On Preparation And Properties Of BFGF Controlled-release Nano Dressings For Wound Healing

Basic fibroblast growth factor(bFGF)plays an important role in active wound repair,and the existing dosage forms in clinical application are mainly sprays and freeze-dried powders,which are prone to inactivation and cannot achieve controlled release.Nanofibers prepared by electrospinning technology have the appearance of non-woven membranes and distinct features including high porosity,good bactericidal resistance and breathability,as well as the structure and biological function of the extracellular matrix,which all endow the nanofibrous membrane ideal material for the preparation of bioactive dressings.However,there are still some challenges demanding prompt solutions yet,such as complicated preparation process,low activity recovery after loading protein,the uncontrollable release of drugs,and so on.In view of the above problems,this work designed a bFGF-adenosine triphosphate(ATP)-Zn ternary combination system to improve the stability and biological activity of bFGF,with polycaprolactone(PCL)having good biocompatibility as a polymer substrate,a novel bFGF controlled-release nano-dressing was fabricated through emulsion electrospinning technology and its active repair function was fully evaluated.The main research contents are as follows:(1)Due to the similarity of lysozyme(14.38 kD,pI=10.7)and bFGF(17.2 kD,pI=9.6)in molecular weight and isoelectric point,lysozyme was used as the model protein to optimize the emulsion preparation conditions.Under optimal emulsion preparation conditions(10%(w/v)PCL for oil phase,5%(v/v)water-to-oil ratio,1.5%(v/v)Span 80,ultrasonic emulsification for 5 min),lysozyme-loading nanofiber membrane(Lyso/PCL NM)with uniform diameter and shell-core structure was successfully prepared by emulsion electrospinning.The lysozyme activity recovery in Lyso/PCL reached 91.96%,and the Lyso/PCL retained more than 65.62%of its original activity after 30 days stored at 4?,while the residual activity of the free enzyme was only 36.92%.(2)Lyso/PCL NM exhibited good cytocompatibility,biodegradability,controlled release property,and anti-bacterial capability.The in vitro release test indicated that about 82.68%was gradually released over 30 days.The density and alignment of human dermal fibroblasts(HDF)cultured on Lyso/PCL NM were significantly increased after 6-day culture,accompanied by type-I collagen secretion.The Lyso/PCL NM showed high antibacterial activity against gram-positive bacteria such as Staphylococcus aureus,and the higher lysozyme concentration in the water phase,the higher activity anti-bacterial activity was detected.(3)Based on the coordination and electrostatic interactions among bFGF,ATP and Zn2+,as well as the synergistic effect of Zn2+to bFGF to promote cell proliferation,a bFGF-ATP-Zn ternary system was proposed.In presence of this bFGF-ATP-Zn combination,the HDF cells activity was increased by 46.67%,and the activity was maintained at 97.63%after heating at 60?,confirming that the joint action of ATP and Zn2+ can promote the cell proliferation activity and stability of bFGF.With this bFGF-ATP-Zn ternary system as the internal water phase,bFGF-ATP-Zn/PCL nano dressing was prepared by emulsion electrospinning.The prepared nano dressing exhibited good controlled release property,the cumulative release rate of bFGF in 14 days was 22.76%.Compared with the bFGF/PCL nano dressing containing bFGF only,the activity of the bFGF-ATP-Zn/PCL nano dressing to promote the proliferation of HDF cells increased by 1.39 times,the volume of type ? collagen secretion increased by 3.45 times,and the hemolysis rate decreased from 14.72%to 3.13%.Finally,the bFGF-ATP-Zn/PCL nano dressing was applied to the skin defect model in mice,results demonstrated that bFGF-ATP-Zn/PCL nano dressing was better able to accelerate wound healing and reduce the peri-wound scar compared with the bFGF/PCL group.In summary,based on the emulsion electrospinning system and using lysozyme as the model protein,the preparation conditions of the emulsion electrospinning system of protein drugs were optimized,Lyso/PCL NM with high activity and good stability was prepared.Based on the stability of bFGF-ATP-Zn ternary complex,a novel nano-dressing with good biocompatibility,sustained release of bFGF and active wound healing function was prepared,which provided a basis for the development and application of bioactive wound dressing products.