Preparation And Performance Study Of Medical Antibacterial Dressings Based On Inorganic Porous Materials

This paper focuses on the preparation of three antimicrobial agents using diatomaceous earth as a carrier,which were compounded with polyacrylic acid/polyvinyl alcohol(PAA/PVA)hydrogels to prepare antimicrobial hydrogels and their properties were investigated,including silver-loaded diatomaceous earth/silver-loaded hydroxyapatite(Ag-DE/Ag-HA)antimicrobial powders,p-thymol-loaded diatomaceous earth,and sulfadiazine loaded diatomaceous earth.Firstly,the optimum synthesis process for silver-loaded diatomite was explored in the preparation of silver-loaded diatomite,with the following results.The silver-loaded diatomaceous earth prepared when UV irradiated silver nitrate solution for 20 min,silver ammonia solution concentration of 0.3 mol/L,reaction temperature of 45℃ and reaction time of 60 min contained the highest amount of silver,up to 12.0%.The factors influencing the water absorption of PAA/PVA hydrogels were explored.The results showed that the maximum water absorption was reached when the polymerisation temperature was 50℃,the reaction time was 28 h,the mass ratio of acrylic acid to polyvinyl alcohol was 7:3 and the amount of cross-linking agent N-N’methylene bisacrylamide was 0.15 g,with a water absorption rate of 145 times.The Ag-DE/Ag-HA antimicrobial powders were prepared by co-precipitation and ion exchange methods.Compared to the silver-loaded diatomaceous earth,the Ag-DE/Ag-HA antimicrobial powders had a higher silver content,able to reach 23.9% and 27.3%,respectively,with a sterilisation rate of 99%.Both silver-loaded diatomaceous earth and Ag-DE/Ag-HA showed significant bacterial inhibition against E.coli and S.aureus,with a minimum inhibitory concentration(MIC)of 250 μg/mL for silver-loaded diatomaceous earth and a lower MIC of 62.5 μg/mL for Ag-DE/Ag-HA antimicrobial powder,achieving a bacterial inhibition rate of 90%.The MIC of the PAA/PVA hydrogel containing Ag-DE/Ag-HA antimicrobial powder was 1.0%,which is a good antimicrobial effect.The next step was to prepare a diatomaceous earth loaded with p-thymol and to compound it with PAA/PVA to produce an antibacterial hydrogel,which was characterised and studied.The inorganically modified diatomaceous earth loaded with pthymol showed a better loading effect than the unmodified diatomaceous earth.The pthymol loaded diatomaceous earth showed a slow release effect in different pH buffers,with a basic release in 0.1 mol/L hydrochloric acid buffer,0.01 mol/L sodium hydroxide buffer and phosphate buffer at pH 7.2 for 24 hours.The MICs of both the diatomaceous earth-loaded p-thymol and the unmodified diatomaceous earth-loaded p-thymol were 250μg/mL by inorganic modification.the products were bactericidal up to 99% with a minimum bacterial inhibition content of 1.5%,which had a good antibacterial effect.The water uptake of the hydrogels of the added products was 163 times.Finally,sulfadiazine-loaded diatomaceous earth was prepared and compounded with PAA/PVA hydrogels to produce PAA/PVA antibacterial hydrogels containing sulfadiazine-loaded diatomaceous earth,which were characterised and studied for their properties.The minimum bactericidal content of the antimicrobial hydrogel containing sulfadiazine-loaded diatomaceous earth was 1.5%,with a width of 16 mm and a bactericidal rate of 99% and an MIC of 250 μg/mL.Moderate addition of diatomaceous earth improved the water absorption multiplicity of the hydrogel,which could reach 184 times when 2% diatomaceous earth was added.