| Background:How to treat all kinds of acute and chronic wounds with high quality and rapid speed is still a serious problem facing contemporary medicine.Wound healing is a complicated and orderly physiological process that is coordinated by many components including a large number of cells,cytokines,and various extracellular matrix components.As an important participant in the wound healing process,cytokines often exert very significant effects at very small doses.Therefore,cytokines are undoubtedly an ideal bioactive drug for treating wounds and promoting wound healing.However,in regard to the application of cytokines as therapeutic agents,the extremely short halflife(mostly only a few minutes)in the microenvironment of the body leads to the need to increase the dosage and the number of administrations to maintain its effect,thereby greatly increasing the cost of treatment.In recent years,a variety of controlled release systems of drugs have been studied and applied in the treatment of various diseases.Polymer microspheres are one of the most popular drug delivery systems.Their low cost,good plasticity,and good biocompatibility and biodegradability make them ideal biological and tissue engineering materials.Many drug-loaded microspheres have been successfully prepared using macromolecular polymers as matrix.These microspheres have been proved to have good biocompatibility and be capable of protecting and realizing slowly controlled release of the drug contained in the encapsulated microspheres.Basic fibroblast growth factor(bFGF)is an important mitogen in the wound repair process.It regulates a variety of cells and events in the wound repair process.The main functions in the body are: 1)Promote wound healing and tissue repair;2)Promote neovascularization as an angiogenic factor;3)Promote tissue regeneration.However,as a cytokine,it has the typical disadvantage that cytokines generally have,namely,that the half-life is very short in vivo.Therefore,it is encapsulated in sustained-release microspheres as a controlled-release drug system for controlled release and prolonged action.The most common complication of wound healing is chronic wounds,and one of the most common causes of chronic wounds is infection.Therefore,as a biomaterial that promotes wound repair,if it simultaneously promotes tissue repair and antiinfection,it can play a role in preventing and treating infection while promoting tissue repair,which will enable the material to have a wider range of applications.And get better quality promotion of tissue repair.As a broad-spectrum antibacterial agent,Silver Nanoparticle(AgNP)was encapsulated in polymer microspheres together with bFGF in the present study and played a role in the wound repair process.Objectives:In this study,PLGA/PCL core-shell drug controlled-release microspheres encapsulating AgNP and bFGF were successfully prepared by coaxial electrospray technique,and their physicochemical properties and drug release profiles were characterized to determine their use in preparation to promote wound healing.The optimal parameters of the microspheres and the in vivo and in vitro evaluation of the bioavailability of the drug-loaded microspheres.Methods:1、 Coaxial electrospraying was used to prepare bFGF-loaded core-shell microspheres with different parameters.Their structure was determined by scanning electron microscope(SEM)and transmission electron microscope(TEM),etc.The drug encapsulation efficiency and release patterns were also characterized.2、 On the basis of the previous experiments,the preparation parameters of the microspheres were improved.PLGA/PCL core-shell microspheres encapsulating AgNP and bFGF were prepared,and various properties were characterized.3、 Co-culture of PLGA/PCL core-shell microspheres encapsulating AgNP and bFGF and human fibroblasts was performed.The scratch essay,immunofluorescence and western blot were used to evaluate the microspheres in vitro.4、 Establish a full-thickness skin defect model of rat’s back and apply AgNP and bFGF loaded PLGA/PCL core-shell microspheres on the wound surface.Through gross observation,immunohistochemical staining,HE staining,Masson staining and western blot experiment.In vivo evaluation of microspheres were performed.Results:1、 Through SEM observation,it can be concluded that within a certain range,increasing the voltage and decreasing the concentration of the shell polymer solution can help to reduce the size of the microspheres and can make the microspheres have a more uniform particle size distribution.Through the observation and analysis of TEM,the core-shell structure of the microspheres was determined.In addition,the relationship between drug release and particle size was also discussed with the encapsulation efficiency and drug release curve.2、 Based on the previous experiments,AgNP and bFGF loaded PLGA/PCL coreshell microspheres were successfully prepared by coaxial electrospray technique.At the same time,a preliminary in vitro evaluation of the microspheres was conducted.On the one hand,the antibacterial activity of AgNP and bFGF loaded PLGA/PCL coreshell microspheres was verified by the Staphylococcus aureus antibacterial experiment,and the The effects of different components of the microspheres on cell proliferation were examined by CCK-8,and it was determined that the microspheres were noncytotoxic and had good biocompatibility.At the same time,the bFGF-loaded microspheres had a good role in promoting cell proliferation.3、 First,the scratch essay demonstrated that the microspheres containing bFGF alone and the AgNP and bFGF loaded microspheres had a significant role in promoting the migration of fibroblasts in vitro;on the other hand,immunofluorescence and Western blotting experiments demonstrated that both microspheres loaded with bFGF alone and AgNP/bFGF loaded microspheres significantly promoted the proliferation of fibroblasts cultured in vitro.4、 By applying the microspheres to the full-thickness skin defect model of the rat’s back,the AgNP and bFGF loaded PLGA/PCL core-shell microspheres have been proved to be beneficial for wound healing by various experiments,such as gross observation,histological evaluation and western blot.Conclusion:AgNP and bFGF loaded PLGA/PCL core-shell microspheres can be successfully prepared through co-axial electrospray technology.The microspheres have good drug release characteristics,biocompatibility,and antibacterial properties and can promote wound healing in many ways. |
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