Fabrication And Performance Of Graphene-based Flexible Composites For Functional Wound Dressing

Functional Wound Dressing(FWD)is a new type of dressing which could adheres to the wound surface,promotes wound healing,reduces wound infections,and accelerate wound healing.The ideal FWD has excellent biocompatibility,can maintain the humidity and temperature of the wound,accelerate the formation of epithelial tissue,effectively absorb the wound exudate,has good permeability and effectively block the pathogenic microorganisms,accumulate antibacterial,anti-inflammatory,stable storage,and easy to use.However,FWD are currently in the initial stage of development.There are many key issues that need to be further studied.For example,the clinical effect of the existing dressings remains to be tested,and the mechanism for promoting wound healing needs to be improved.FWD represented by sustained-release dressings are still difficult to control,and the sustained-release mechanism of drugs is still difficult to control.The mechanism of sustained-release is lacking in depth and systemic research.The appraisal system of the dressings is not yet perfect;in functional applications FWD still faces huge challenges.Therefore,this dissertation focuses on the main problems of functional dressings: performance evaluation of novel antibacterial materials,dressing material and structure design with sensing function,and the relationship between the design and application of controlled release dressings.The surface modification of graphene oxide(GO)prepared by oxidation-reduction process by polydopamine(PDA)weakens the strong interaction between GO flakes and promotes the dispersion of the system.Bacteria concentration MIC was tested for the antibacterial properties of GO and pDA-rGO composites.The experimental results showed that the MIC value of GO for E.coli and S.aureus was 64 ?m/m L,and the MIC value of pDA-rGO for E.coli and S.aureus was 32 ?m/m L,the modified pDA-rGO composite has improved antibacterial properties compared to GO.The long-term antibacterial activity of 50 ?m/m L GO and different proportions of pDA-rGO composites was tested and compared.The results showed that pDA-rGO-1.5 had the best antibacterial properties against E.coli and S.aureus,and the antibacterial effect of E.coli was better than that of S.aureus.The results of the inhibition zone test showed that the diameters of GO for E.coli and S.aureus were 0.9 cm and 0.7 cm,respectively,smaller than that of pDA-rGO-1.5 for E.coli and The diameter of S.aureus is 1.4 cm and 1.2 cm.The antibacterial kinetics of 50 ?m/mL GO and different proportions of pDA-r GO composites were tested.The results showed that when the pDA-rGO-1.5 reacted with bacteria for 140 min,the survival rate of bacterial colonies basically reached a low level.In steady state,140 min can be selected as the effective antibacterial time for pDA-rGO-1.5 to contact with bacteria.The AgNWs and pDA-rGO conductive network structures were prepared on the surface of the bio-based sponge by a simple “dip-coating” process to prepare a flexible functional dressing with force-sensitive sensing response.The bio-based sponge has excellent mechanical stability and flexibility.After 5000 cycles of 50% deformation,the mechanical strength decreased from 59.3 kPa to 55.2 kPa,and the overall mechanical strength loss was 6.91%.The AgNWs and pDA-rGO conductive network structures were prepared using the PDA excellent adhesion to the interface.The volume resistance decreased to 8.1±0.3 ?.cm after four dip-coating treatments.The prepared DGA-S force-sensitive functional dressing has a stable sensitivity(GF=1.5)and is stable in the 0-60 kPa pressure range.It has a stress response time of 54 ms and excellent stability(>7000 times)DGA-S force-sensitive functional dressings can be used to carry out stress-sensitive testing of human body parts that carry relatively large stress,such as chronic diabetic foot wounds,which can meet the stability of use and instantly respond to the stress and movement state of the foot.A flexible temperature control film was prepared by a "dip-coating" process,and a poloxamer P407/188 temperature-sensitive sustained release layer loaded with a tannic acid drug was prepared on the basis of a thin film.Encapsulated to prepare a flexible,temperature-sensitive,sustained-release dressing that can be controlled and sustained release at low pressure.A flexible temperature control film was prepared by a “dip-coating” process.By adjusting the preparation process,the temperature range of near body temperature(30.3-56.4°C)can be achieved under low pressure(1.0-3.0V),in the cotton fiber matrix.After dipping five times with AgNWs and pDA-rGO,respectively,the voltage of 2.0 V can reach 38.2°C within 80 s.The temperature-sensitive hydrogel hydrogels Poloxam P407/188 were used to control the phase transition temperature of the thermo-sensitive hydrogels by adjusting the mass fraction of the thermo-sensitive hydrogels to obtain the temperature-sensitive hydrogel phase transitions with the mass fractions of 22% and 10% for P407 and P188,respectively.The temperature is 35°C.Using tannic acid as a sustained-release drug,the experimental results of the controlled release of the flexible temperature-sensitive sustained-release dressing were tested.The experimental results show that the functional dressing prepared in this chapter can control the dressing-loaded drug under the drive of 2.0 V voltage.Sustained release is expected to be used for the clinical application of functional slow-release dressings.