Study On The Preparation And Antimicrobial Properties Of Novel Regenerated Bacterial Cellulose Dressing S

The purpose of this paper is to prepare bacterial cellulose based composite dressings with good absorption of wound exudates and good antimicrobial activity.Regenerated bacterial cellulose(RBC),which was regenerated by dissolving native bacterial cellulose(BC),was used as matrix material.Drug sustained-release dressings,surface contact antimicrobial dressings and nano-sized synergistic antimicrobial dressings were prepared,and their composition,structure and antimicrobial properties were characterized and analyzed.And the main results in this work are listed as follows:BC was produced by Acetobacter xylinum,and BC solution and gel with different concentrations were prepared by dissolving BC with ionic liquid([Bmim]Cl).According to rheological properties and mechanical properties,the optimum concentration is 1.5 wt%.The morphologies and structures of BC and 1.5 wt% RBC were characterized by Infrared Spectroscopy(FTIR),Scanning Electron Microscopy(SEM),X-ray Diffraction(XRD),Thermogravimetry(TG),and Ultraviolet-visible Absorption Spectroscopy(UV-vis).The performance differences between BC and RBC were also observed.RBC and gelatin were chemically crosslinked by glutaraldehyde to obtain composite materials.Then ampicillin(AP)was loaded into the matrix material by physical blending,and a kind of drug sustained-release dressing(BG)was constructed.SEM images showed that BG aerogels not only show micron-sized macropores,but also exhibit nanometer three-dimensional network structure.The results of FTIR showed that RBC and gelatin were successfully crosslinked by glutaraldehyde.The results of TG analysis showed that the thermal stability of BG aerogels was lower than that of RBC.The results of porosity and swelling behavio r showed that,compared with RBC,the porosity,swelling ratio and water absorption of BG aerogels increased.The results of drug release showed that BG aerogels possessed the ability of slow release of drugs.The results of antibacterial test showed that BG aerogels had good antibacterial activity against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus),while the antibacterial activity against Candida albicans(C.albicans)was limited.With the modification of RBC by 3-aminopropyltriethoxysilane(APTES)and the subsequent grafting of amoxicillin(AM),a kind of surface contact antimicrobial dressing(AM-g-RBC)was constructed.The results of SEM images showed that the AM-g-RBC aerogel fibers were more rounded than RBC and the drug molecules were successfully grafted.The results of FTIR showed that RBC was successfully modified by APTES and AM was successfully grafted.The results of TG analysis showed that the thermal stability of AM-g-RBC aerogel decreased.The results of porosity and swelling behavior showed that,compared with RBC,the porosity and swelling ratio of AM-g-RBC aerogels decreased.The results of antibacterial test showed that AM-g-RBC aerogels had good antibacterial activity against E.coli and S.aureus,while the antibacterial activity against C.albicans was limited.The gold nanoparticles(AuNPs)were functionalized with gentamicin sulfate(GS)to obtain a kind of antimicrobial nanocomposite agent(GS-AuNPs).Then,GS-AuNPs was loaded into polydopamine(PDA)modified RBC matrix material to construct a novel antimicrobial dressing(PBC-GS-AuNPs)with multiple antimicrobial mechanisms.At the same time,RBC aerogels,PDA modified RBC aerogels(PBC)and GS-AuNPs loaded RBC aerogels(RBC-GS-AuNPs)were also constructed.The results of TEM,DLS of GS-AuNPs sol indicated that a layer of GS was adsorbed on the surface of AuNPs.The results of MIC showed that there was synergistic antimicrobial effect between GS and AuNPs.The results of antibacterial test showed that GS-AuNPs sol could cause the death of E.coli,C.albicans and S.aureus.The SEM images of PBC-GS-AuNPs aerogels showed that PDA successfully modifies RBC fibers,while the GS-AuNPs size is too small to be observed in the images.The results of FTIR showed that the binding of GS and AuNPs was caused by GS partial displacement of polyvinylpyrrolidone(PVP),and then a layer of GS was adsorbed on the surface of AuNPs.It also showed that repeated washing of RBC-GS-AuNPs and PBC-GS-AuNPs gel resulted in a loss of GS-AuNPs.The results of TG analysis showed that the thermal stability of PBC aerogel increased,the residual percentage of PBC aerogel decreased,the thermal stability and the residual percentage of PBC-GS-AuNPs aerogel increased,the thermal stability of RBC-GS-AuNPs aerogel did not decrease significantly,while the residual percentage of RBC-GS-AuNPs aerogel increased slightly.The results of porosity and swelling behavior showed that compared with RBC,the porosity of PBC had little change,the swelling rate of PBC increased,the porosity and the swelling rate of RBC-GS-AuNPs and PBC-GS-AuNPs decreased.The results of bacterial inhibition zone showed that PDA could anchor nanoparticles,and PBC-GS-AuNPs had limited antibacterial activity against E.coli,and good antibacterial activity against C.albicans and S.aureus.