简介:Polyvinylalcoholcoatedmagneticparticles(PVAferrofluids)havebeensynthesizedbychemicalco-precipitationofFe(Ⅱ)/Fe(Ⅲ)saltsin1.5mol/LNH4OHsolutionat70℃inthepresenceofPVA.Theresultantcolloidalparticleshavecore-shellstructures,inwhichtheironoxidecrystallitesformthecoresandPVAchainsformtheshells.Thehydrodynamicdiameterofthecolloidalparticlesisintherangeof108to155nm,whichincreaseswithincreasingPVAconcentrationfrom5wt%to20wt%.Thesizeofthemagneticcoresisca.5~10nm,whichisrelativelyindependentofPVAconcentration.Undertransmissionelectronmicroscopic(TEM)examination,themagneticcoresexhibitsomewhatirregularshapesvaryingfromspherical,oval,tocubic.MagnetometrymeasurementrevealedthatthePVAcoatedmagneticparticlesaresuperparamagnetic.Thesaturationmagnetizationof5wt%and20wt%PVAferrofluidsat300Kis54and49emu/g.respectively.AllthePVAferrofluidsexhibitedexcellentcolloidalstabilityinpurewaterandphosphatebuffersaline(PBS,pH=7.4).Theferrofluidscanremainstableinabovesolutionsformorethanthreemonthsat4℃.
简介:目的通过反复冻融法制备胶原-聚乙烯醇(PVA)复合水凝胶材料。方法制备组分比例(胶原固含量为0%、5%、10%、15%、20%)不同的5组胶原-PVA复合水凝胶试样,对其进行一些物理和化学性能的表征.选出性能最优的胶原/PVA配比。将最优配比制备出的胶原-PVA复合水凝胶进行细胞毒性实验的生物学评价。结果实验制备所得胶原一PVA复合水凝胶的红外图谱可见明显的酰胺谱带;差动扫描式热量法(DSC)图出现2个热吸收峰,峰值温度分别为65℃~72℃、222℃C~225℃;扫描电子显微镜显示材料为多孔结构;X射线衍射(XRD)峰值为20°;溶胀值最高为24g怃透水气性最高的达1400g/(m^2·24h);降解性能良好,15d内大部分降解率达80%:细胞毒性为0~1级。结论胶原-PVA复合水凝胶作为体表创伤敷料具有良好的应用前景.但尚需对其进行体表创伤修复效果及其他生物相容性的评价。
简介:Usingpolyvinylalcohol(PVA)asrawmaterialandvacuumpumpoilasoilphasemedium,PVA-basedmicrocarrierswerepreparedbysuspensionmethodThediametersofthebeadswere100-180μm.LO2cellswereculturedonPVA-basedmicrocarriersandcytodexⅢmicrocarriers.Morphology,attachmentandgrowthrateofLO2cellswerestudied.
简介:Poly(vinylalcohol)(PVA)/hydroxyapatite(HA)compositehydrogelspecimenswerepreparedwith15%PVAand1%,2%,3%,4%and5%HAbyrepeatedfreezing-thawing.ThetestsofstaticanddynamicmechanicalpropertieswerecarriedouttodiscusstheinfluenceofdifferentcontentsofHAandfreezing-thawingcyclesonthemechanicalpropertiesofPVA/HAcompositehydrogel.TheresultsofstaticmechanicaltestsshowedthatthePVA/HAcompositehydrogelwith3%HAandninefreezing-thawingcycleshadexcellentstressrelaxationproperties,higherrelaxationratio,lowerstressequilibriumvalueandpresentedbetterpropertiesofcreepandrecovery.TheresultsofdynamicmechanicaltestshowedthatthePVA/HAcompositehydrogelwithninefreezing-thawingcycleshadhigherstoragemodulusandlossmodulus,sowasthePVA/HAcompositehydrogelwith3%HA.
简介:Theapplicationof5'-nitrosalicylfluorone(5'-NSF)-molybdenum(Ⅵ)complexasaspectroscopicprobewasstudied.InthebuffermediumofHOAc-NaOAcat3.45andinthepresenceofPVA124microemulsion,5'-NSF-Mo(Ⅵ)complexcombinesproteinrapidlytoformastablecompound,leadingtoanabsorbancedecreaseat525nmof5'-NSF-Mo(Ⅵ)complex.Accordingtothischange,microdeterminationofproteinhasbeendescribed.Bovineserumalbumin(BSA)couldbedeterminedinthelinearrangeof0—16μg·mL^-1withthedetectionlimitof11ng·mL^-1.Manyaminoacidandmetalionsstudieddonotinterferewiththeassay.Themethodpossesseshighsensitivityaswellashighselectivity.Itcanbeusedtodetermineproteininhumanurineandmilkpowdersuccessfully.Therelativestandarddeviationsareinallinstanceslessthan4.7%,andtherecoveriesarebetween97.6%and106.0%.Moreover,thebindingnumberofBSAwiththecomplex,whichisdeterminedbyusingmolarratio,Rosenthanlgraphicandsloperatiomethods,isingoodagreementwitheachother.
简介:将微晶纤维素溶解于N-甲基吗啉-N-氧化物(NMMO)溶剂体系,并与聚乙烯醇(PVA)NMMO溶液混合,采用溶胶-凝胶工艺制备纤维素-PVA复合凝胶,探究不同凝固浴对复合凝胶性能的影响,并利用X射线衍射(XRD)、热重分析(TGA)、扫描电子显微镜(SEM)等表征手段考察了复合凝胶的晶体结构、热稳定性、微观结构等性能,讨论基于NMMO溶剂体系纤维素与PVA复合的成胶机理。结果表明,与分别以水及无水乙醇为凝固浴制得的复合凝胶相比,以20%NMMO/1%硼砂为凝固浴制得的复合凝胶无裂纹,且具有良好的韧性,机械性能最佳;经NMMO溶解后制得的纤维素凝胶由纤维素Ι型转变为纤维素Ⅱ型,而经1%硼砂交联后制得的纤维素-PVA复合凝胶在2θ=13.18°和19.46°处出现新的结晶峰,其为PVA的衍射峰,说明纤维素与PVA交联复合;热重分析显示,与纤维素凝胶相比,纤维素-PVA复合凝胶的热稳定性显著提高,热降解初始温度从270℃升高至280℃左右;利用SEM可观察到经硼砂交联后的纤维素-PVA复合凝胶的孔隙约500nm,相对于纤维素凝胶,其孔隙结构更均匀紧凑。