The Preparation And Cytotoxicity Of A Hydrogel Wound Dressing With Temperature-Sensitive & Antibacterial Properties

Objective:As WHO recommended,first aid treatment of burn injuries should consist of regional surface cooling and the prevention of infection.The challenge of antibiotic resistance,which was mainly induced by long-term and high-dose use of antibacterial agent,has become increasingly rigorous globally.In the current study,we formulated a temperature-regulated releasing silver nanoparticles hydrogel.Since silver nanoparticles possess broad-spectrum antibacterial activity without inducing drug resistance,this kind of temperature-sensitive silver nanoparticle-releasing hydrogel could be used as an ideal first-aid wound dressing with antibacterial property.Contents and Methods:1.The synthesis of smart silver nanoparticles antimicrobial agents:1)Three kinds of AgNPs were synthesized with silver nitrate as raw materials.The diameter of small size AgNPs is 5 to 10 nm,the diameter of sphere AgNPs is 20 to 30nm and the side length of triangle AgNPs is about 500nm;2)PNIPAM were synthesized with NIPAM as raw materials,the diameter of PNIPAM varies from 600 to 800 nm;3)PNIPAM loaded three kinds of AgNPs respectively to prepare corresponding AgNPs@PNIPAM.2.Physical properties:1)The representations of the AgNPs and corresponding AgNPs@PNIPAM were determined by Transmission electron microscope.2)The morphology and size of PNIPAM hydrogel were observed by scanning electron microscope.3)UV-Vis absorption spectroscopy showed silver nanoparticles successful loaded in PNIPAM.4)X-ray diffraction measured the crystallization states of silver nanoparticles.3.In vitro antibacterial study1)Antibacterial study of three kinds of silver nanoparticles;2)Antibacterial study of three kinds of AgNPs@PNIPAM in the 26? and 37?.4.In vitro cytotoxicity testThe cytotoxicity of the AgNPs and the corresponding AgNPs@PNIPAM were evaluated by HFF(Human foreskin fibroblasts)and CCK8 method.Results:1.The size and morphology of the as-prepared AgNPs and AgNPs@PNIPAM were examined by transmission electron microscopy(TEM).The average diameter of small size AgNPs is about 9.6nm with an uniform size distribution.The sphere AgNPs presented an average diameter of about 28 nm and we also prepared triangle AgNPs of regular shape with about 200 nm of average side length.The PNIPAM were examined by scanning electron microscopic(SEM),which was close to spherical and was about 600 nm of average diameter.There are four main diffraction peaks of sphere AgNPs snd triangle AgNPs in the XRD date respectively,corresponding to(111),(200),(220)and(311),reflecting both of them with metallic silver structures.These AgNPs and AgNPs@PNIPAM were also characterized by UV-Vis absorption spectroscopy.The high intensity absorbance band of small size AgNPs was observed at 430 nm,sphere AgNPs was at 400 nm.However,triangle AgNPs had two high intensity absorbance band,330 nm and 390 nm.2.Result of in vitro antibacterial study showed: Under the 37?,with the adding of PNIPAM,the antibacterial rates of the sphere and the triangle AgNPs declined.However,under the 26?,the antibacterial rates of the sphere and triangle AgNPs significantly increased by combined with PNIPAM.Which confirmed the sphere and the triangle AgNPs can be intelligent released by combined with PNIPAM3.Cell counting kit(CCK-8)assay showed the RGR of the small size AgNPs and corresponding AgNPs@PNIPAM were both below 30%,their toxicity gradeswere between grade 3 to grade 4.Toxicity grades of sphere AgNPs and corresponding AgNPs@PNIPAM were grade 2.And Toxicity grades of triangle AgNPs and corresponding AgNPs@PNIPAM were both grade 1.There were no statistical difference between AgNPs based groups and their corresponding AgNPs@PNIPAM.Conclusion:This work successful synthesize three kinds of AgNPs and the corresponding AgNPs@PNIPAM hydrogel.The triangle AgNPs@PNIPAM possess superior antibacterial regulation and low toxicity properties.