Design,Preparation And Application Study Of Biomimetic Artificial Periosteum And Flexible Electronic Devices Based On Electrospinning

Bone defect is a kind of common disease in orthopedics.The cooperation with periosteum is highly desirable for bone grafts to enhance its osteogenetic ability due to the significant role of periosteum in bone regeneration.Autograft or allograft periosteal transplantation has disadvantages of limited donated sources,donor morbidity and immune reaction.Thus,the in vitro design and construction of the artificial periosteum mimicking the fibrous microstructure and osteogenesis function of natural periosteum would therefore be a novel approach to get large bone defects better treated.Electrospinning has gained widespread interests to the design and integration of high-performance and flexible membranes for healthcare due to the structural similarity of the electrospun configuration to the extracellular cell matrix,the preparation simplicity,tunable surface morphologies,conformability to complex three dimensional(3D)profile,low cost and can be used as effective drug carrier.This study aims to design and fabricate electrospun fibers-based biomimetic artificial periosteum with flexibility,permeability and bone osteoinductivity to cover the complex surface of bone grafts for the facilitation of bone regeneration.Since conventional growth factors such as bone morphogenetic proteins(BMPs),insulin-like growth factor(IGF)and fibroblast growth factor(FGF)have disadvantages of rapid degradation,high cost,easy deactivation and associated side effects,the clinical use of these growth factors has been limited.Herein,the traditional Chinese medicine ingredient icariin(ICA)was introduced into poly(s-caprolactone)(PCL)/gelatin nanofibers to fribricate osteoiductive artificial periosteum.The effects of ICA content(0,0.005,0.01,0.05,0.1,0.5 wt.%of the polymer)on morphology,physical properties,drug release profile,in vitro degradability,biocompatibility and osteogenesis differentiation properties were investigated.The ICA-loaded electrospun membranes showed significantly improved hydrophilicity,high mechanical strength,appropriate degradation rate and excellent biocompatibility.Furthermore,the obviously enhanced alkaline phosphatase(ALP)activity,osteocalcin(OCN)and type collagen I(COL I)expression,and calcium deposition content of MC3T3-E1 cells cultured on ICA-loaded fibrous matrix were detected.The membrane loaded with 0.05 wt.%ICA possessed the outstanding comprehensive properties contributing to cells attachment,proliferation and differentiation.These results indicated the great potential of this ICA-loaded PCL/gelatin electrospun membrane as biomimetic artificial periosteum to accelerate bone regeneration.In addition,infection is a major cause of implant failure.Herein,we present a rational and effective strategy for eonstructing a dual drug loaded fibrous membrane which could integrate multiple cues including flexibility,antibacterial property,osteogenic property,and barrier functions by coaxial electrospinning.Briefly,traditional Chinese medicine ICA and broad spectrum antibacterial drug moxifioxacin hydrochloride(MOX)were introduced into the PCL core and gelatin shell respectively.The physical properties,drug release,degradation,antibacterial property,in vitro and in vivo osteogenesis performance were investigated.Our research demonstrated that the core-sheath configuration was an effective carrier for two drugs with different functions.The MOX in gelatin shell was released rapidly during the first month which could reduce the incidence of infection effectively while the ICA in PCL core was released in a slow and sustained manner and correspondingly could provide favorable osteoinductive cue for the long-term bone regeneration process.Core-sheath configuration and disparate degradation rate of PCL and gelatin both contributed to the hierarchical and sustained release of the two drugs.Moreover,clear in vitro antibacterial effect and enhancement in osteogenic marker expressions including osteocalcin,type-1 collagen expression,and calcium deposition were observed.Also notably,the dual drug-loaded membrane displayed fascinating properties contributing to in vivo bone formation in a rabbit radius defect model.These results indicate that the electrospun dual drug-loaded core-sheath fiber membrane is promising as multifunctional artificial periosteum to facilitate bone regeneration.Considering the difficulty of structure control over electrospun core-sheath configuration,we fabricated a novel twin-fiber membrane with antibacterial and osteo-inductive properties as an artificial periosteum by a double spinneret electrospinning method in the fourth part of our study.The antibacterial drug MOX and Chinese medicine ICA were introduced into PCL/gelatin nanofibers and PCL micro/nano fibers respectively to endow the membrane with antibacterial and osteoinduction properties.The twin-fiber structure membrane not only acted as carriers for two different drugs with drastically different solubility in the same fiber membrane,but also achieved stepwise and controlled drug release profiles based on different degradation rates of the two fibers matrix and diffusion rates of the two drugs.Most importantly,only 35%ICA was released out from this dual drug loaded membrane after 1 month and such slow release rate would match with the bone regeneration rate which can hardly be achieved by other drug delivery system.Besides,this dual drug loaded twin-fiber membrane exhibited clear antibacterial effect and excellent in vitro biocompatibility for cells to adhere to and proliferate on.Furthermore,an obvious up-regulation of OCN,COL I expression and calcium deposition of MC3T3-E1 cells demonstrated the improved osteogenic differentiation capability.Also,the dual drug loaded twin-fiber membrane displayed fascinating properties contributing to new bone formation in rabbit radius defect model.These results indicate the huge potential of this dual drug loaded twin-fiber membrane as an effective drug release controller and biomimetic multifunctional artificial periosteum to accelerate bone regeneration.In addition to bone defects,the management of chronic wounds on the skin is also a conceemed issue in clinical.Real-time monitoring of the wound state and timely anti-infective treatments at the early stage of infections would be very helpful in reducing patient suffering and economic burden on our health care system as well as providing diagnostic information to medical workers.Flexible wearable electronic devices are drawing tremendous interests for various applications in wearable healthcare biomonitoring,on-demand therapy,and human-machine interaction.However,conventional plastic substrates with uncomfortableness,mechanical mismatch and impermeability have limited the application of flexible on-skin electronic devices for healthcare biomonitoring and on-demand therapy.Herein,flexible breathable electronic devices with the capabilities of real-time temperature sensing and timely on-demand anti-infection therapy at wound sites are presented,which are assembled from the crosslinked electrospun MOX-loaded thermo-responsive polymer nanomesh film with the conductive pattern.The conductive polymer nanomesh film demonstrates excellent flexibility,reliable breathability,and robust environmental stability.Furthermore,the assembled temperature sensor displays a linear relationship between the electrical resistance and temperature for potentially real-time biomonitoring of tissue temperature at wound site.The smart artificial electronic skins(E-skins)are assembled from the thermo-responsive polymer nanomesh film for spatial touching sensing mapping of temperature changes.Meanwhile,the flexible temperature sensor is coupled with a wireless transmitter for real-time wireless temperature monitoring.Also notably,the thermo-responsive polymer nanomesh film can be assembled as highly efficient flexible heater to trigger the on-demand release of antibiotics in the fibers to eleminate bacterial colonization in the wound site once the infection happened.The purpose of this thesis is to design,prepare and investigate the application of biomimetic artificial periosteum and flexible electronic devices based on electrospinning to achieve better bone regeneration and wound management and finally reduce the economic burden of patients and the pressure of our medical healthcare system as well as to promote the development of our country's economic development.