| The partial or whole body damages caused by burn wound areassociated with the lacking of skin barrier. The immediate goal of treatment iseffective wound closure in early time. The appropriate wound dressings areparticularly important for the early wound closure and later restoration inmassive burns. The ideal dressings should be recognized as:1.Betterbiocompatibility.2.Better protective and mechanical function.3. Higher watervapor transmission rate and gas transmission rate.4.Better antibacterial effect.Polylactic acid has better biocompatibility and bioabsorbability as a kind of bio-polymer material.Nontoxic, nonirritant,high mechanical strength,highlyplasticity. The catabolites are wanter and carbon dioxside,so there are greaterapplication potentials in the field of clinical medicine.Ofloxacin is the third generation of fluoroquinolone antibiotics that has Thebroad spectrum antibacterial action,with strong antibiosis on most ofgram-negative Enterobacteriaceae such as Escherichia coli, Klebsiellapneumoniae, Bacillus proteus.The Ofloxacin also has antibiosis on grampositive bacteria such as Streptococcus pneumoniae, Staphylococcus aureus,buthas poor effect on Anaerobic bacteria and enterococci.The mechanism of actionthat leading to bacteria death is to prevent the synthesis and replication ofbacterial DNA by inhibiting the activity of bacterial DNA gyrase.Mupirocin isthe topical antibiotics that are directed against gram positive bacteria,particularly high sensititive to the Staphylococcus aureus and Streptococcus(alsohave effect on the resistanced Staphylococcus aureus.At a certain extent,it alsohave antibiosis on some gram-negative bacteria. And the Mupirocin has no crossresistance with other antibiotics. It can stop the synthesis of the bacteria protein by selectively making the bacterial isoleucyl-tRNA synthetase inactivated,sothat preventing the growth of bacteria.Electrospinning is a simple and effective method for preparing nanometerfiber. It can pull the high molecular polymer into fine fibers vie electric fields.The diameters of this method can reach nanometer level, with high porosity,large specific surface area, and with the advantage of small aperture, conduciveto the migration and proliferation and drug release of load cell. So use ofpolylactic acid composite antibiotic prepared by electrospinning, is a goodchoice for antimicrobial dressings.Firstly, we ascertain the parametre of electorysink:High voltageelectrostatic is1500Volts, the receiving distance is15cm, the ratio of polylactic acid quality is1:500.They successfully construct the fibre which iscomposite of nanocrystalline Scaffold structure that is composed ofPLA,Ofloxacin and Mupirocin. The result of scanning electron microscopedisplays the less smooth fiber surface, the average fiber diameter that is evenlydistributing is400nm,the higher porosity and specific surface area. Whether thismaterial system is in accordance with the requirements of medical antimicrobialdressing is still unknown.Contents:1. To prapare the PLA/Ofl, PLA/Mu, and PLA/Oflo/Mucomposite nano-fiber dressing via electrostatic spinning technology.2.Toobserve the microstructure characteristics via scanning electron microscopy(SEM); using infrared analysis to check whether containing ofloxacin and Momupirocin effective components or not.3.To carry out the antibacterialexperiment of PLA/Ofloxacin, PLA/Mupirocin, and PLA/Ofloxacin/Mupirocincomposite nano-fiber dressing with the method of Kirby-Baucer in vitro. Andcontinues for a week.4.To study the degradation behavior in vitro of PLA/Ofloxacin, PLA/Mupirocin, and PLA/Ofloxacin/Mupirocin composite nano-fiber dressing. With standard PBS (pH7.4) solution,37℃water bath incubation, in after incubation for3days,7days and14days, analysing under the conditionof vacuum drying samples after spraying with the scanning electron microscope.Results:1、To prepare the PLA/Ofloxacin/Mupirocin composite nano-fiberdressing via electrostatic spinning technology.2、Morphological characterizationof electrospun PLA/Ofloxacin/Mupirocin composite nano fiber structure: theaverage diameter of the composite nanofibers is400nm,and is relatively straight,fiber separation is better, but the surface is not smooth.3、The experimentconfirmed by K-B disk diffusion method:①PLA/Ofloxacin has goodantibacterial effects on Escherichia coli strains, but for the standard strains ofStaphylococcus aureus shows no inhibitory effect. The PLA/Mupirocin hasgood antibacterial effects on Staphylococcus aureus, but on Pseudomonasaeruginosa and E. coli basically shows no inhibitory effect.③PLA/Ofloxacin/Mupirocin composite nano fibers shows effective inhibitory on thestandard strains of Staphylococcus aureus, Pseudomonas aeruginosa and E. coli,and the inhibitory effect of PLA/and PLA/were better than that of OfloxacinMo mupirocin. By K-B disk diffusion method, for a week of continuousobservation, composite dressing on Staphylococcus aureus and Escherichia colipresent obvious antibacterial effect.4、The in vitro degradation showed that twogroups of scaffold morphology changes are obvious, from the fiber swelling tofiber dissolution and adhesion, and finally to the fiber surface fracturedisappearance.Conclusion: the preparation of polylactic acid composite antibioticnanofiber dressing via electrospinning, posssessinf good antibacterial anddegradation rate, it is a good choice for making antimicrobial dressing. |
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