基于生物矿化原理的纳米复合材料制备及其应用研究1

基于生物矿化原理的纳米复合材料制备及其应用研究Synthesisandapplicationofnanocompositematerialsinspiredbybiomineralization摘要纳米复合材料在纳米材料领域得到了越来越广泛的研究。因此，简便、高效的纳米复合材料合成方法成为研究热点和前沿。如何实现室温，近中性pH的温和条件下合成；如何保证不同组分间良好的界面相容性；如何获得纳米复合材料的多功能性一直是纳米复合材料研究中的共性关键问题。本文受自然界中生物矿化现象和原理启发，采用生物法和仿生法，利用细菌，蛋白质,氨基酸和人工合成多肽合成了多种纳米复合材料，探索了相关的合成机理，考察了所合成的纳米复合材料在抗菌、光催化中的应用。首先，基于生物矿化的原理，利用醋酸杆菌合成了细菌纤维素(BC)-Ag/AgCl纳米复合材料。醋酸杆菌可合成生物聚合物BC，并可作为诱导剂和还原剂生物矿化合成Ag/AgCl纳米粒子，从而形成BC-Ag/AgCl纳米复合材料。进一步考察了BC-Ag/AgCl纳米复合物材料对革兰氏阴性菌和革兰氏阳性菌的抗菌性能。实验结果表明，醋酸杆菌在细菌纤维素网状结构中合成了平均直径为17.4nm的银纳米粒子，且对大肠杆菌和金黄色葡萄球菌均有良好的抗性，该复合材料有望用于抗菌组织愈合材料。其次，基于仿生矿化的原理，利用生物大分子溶菌酶合成了TiO2-SiO2-Ag纳米复合材料，并研究了该材料在可见光下降解污染物的性能。溶菌酶作为诱导剂可合成TiO2,作为还原剂可还原Ag+。实验结果表明，合成了24.5nm左右的Ag纳米粒子负载在平均粒径为280nm的TiO2上，SiO2层是通过溶胶-凝胶法形成在TiO2的表面，且该材料在可见光下对罗丹明B为模型的污染物有良好的降解效果。最后，基于仿生矿化的原理，研究了生物小分子氨基酸合成了TiO2-Ag纳米复合材料。精氨酸可诱导钛前驱体在常温常压中性条件下生成TiO2纳米粒子；色氨酸、酪氨酸可还原Ag+生成Ag纳米粒子。在此基础上，又进一步设计合成了由精氨酸、酪氨酸组成的多肽RRRRYY，并利用其合成了TiO2-Ag纳米复合材料。实验结果表明，该多肽合成了100~400nm的TiO2，并且可还原生成10~50nm的Ag纳米粒子。从而提出了一种绿色、简便的合成复合材料的方法，同时在分子水平上解释了蛋白质能够诱导合成纳米材料的机理。关键词：生物矿化纳米复合材料生物合成仿生光催化抗菌ABSTRACTNanocompositeisattractingintenseattentionamongnanomaterialssynthesis.Therefore,howtofacilelyandefficientlysynthesizenanocompositebecomethehotspotandfrontiernowadays.Thereexistthreemajorchallenges:developmentofroomtemperature,neturalpH,greenandnontoxicmethods,achievementofgoodinterfacecompabtilitybetweendifferentcompostionsofnanocomposite,exploitationoffunctionalityofnanocomposite.Inthepresentstudy,inspiredbybiomineralizationusingbiosynthesisandbiomimeticmethods,bacteria,protein,smallmoleculesandartificialpeptideareexploitedtosynthesizenanocomposite.Furthermore,therelevantmechanismsaretentivelystudied.Thesynthesizednanomaterialscanbeappliedintodifferentfieldssuchasantibacterialmaterialsandphotocatalsyst.First,anon-pathogenicbacterium,Gluconacetobacterxylinum,wasutilizedasaversatilebiofactory,whichproducedbiopolymerbacterialcellulose(BC)andinducedtheformationofAg/AgClnanoparticles,yieldingBC–Ag/AgClnanocomposite.Thecharacterizationrevealedthatnanoparticleswithaveragesizeof17.4nmwererandomlyembeddedintotheBCnetwork.TheresultantnanocompositedisplayedthedesirableactivityininhibitingbacterialgrowthofbothGram-positiveStaphylococcusaureusandGram-negativeEscherichiacolimicroorganisms,indicatingthepotentialofthematerialasantimicrobialwounddressingmaterials.Secondly,ternaryTiO2-SiO2-Agnanocompositeswithenhancedvisible-lightphotocatalyticactivityhavebeensynthesizedthroughafacilebiomimeticapproachbyutilizinglysozymeasbothinducingagentofTiO2andreducingagentofAg+.TiO2nanoparticles(ca.280nm)areatfirstfabricatedbytheinducingoflysozyme.Afterwards,SiO2layersareformedas―pencakes‖stickedoutofTiO2nanoparticlesthroughasol-gelprocess.Finally,Agnanocrystals(ca.24.5nm)aredepositedontothesurfaceofTiO2-SiO2compositesviathereductionoflysozyme,formingTiO2-SiO2-Agnanocomposites.TheresultantnanocompositesdisplayahighphotocatalyticactivityforthedegradationofRhodamineBunderthevisible-lightirradiation,whichcanbeattributedtothesynergisticeffectofenhancedphotonabsorptionfromthesurfaceplasmaresonanceofAgnanocrystalsandtheelevatedadsorptioncapacityforRhodamineBfromthehighspecificsurfaceareaofSiO2.Finally,smallmoleculesaminoacidswereusedtoproduceTiO2-Agnanocomposite.ArginecaninduceTiprecursortoformTiO2nanoparticlesundermildconditions.TryptophanandtyrosineareabletoreduceAg+intoAg.Basedontheresearch,artificialpeptideRRRRYYisusedtosynthesizeTiO2-Agnanocomposite.TheresultsshowthatAgnanoparticleswith10~50nmaredepositedonto100~400nmTiO2.Theapproachisnotonlyafacileandgreenwaytosynthesizenanocompositebutalsocontributestounderstandthebiomineralizationmechanisminmoleculeslevel.KEYWORDS：Biomineralization,Nanocomposite,Biosynthesis,Biomimetic,Photocatalysis,Antibacterial目录第一章文献综述...............................................................................11.1纳米材料概述..................................................................................................11.2生物法制备纳米材料......................................................................................11.2.1细菌.........................................................................................................21.2.2真菌.........................................................................................................41.2.3病毒.........................................................................................................51.2.4高等植物.................................................................................................61.3仿生法制备纳米材料......................................................................................61.3.1生物大分子............................................................................................61.3.2生物小分子...........................................................................................131.4本文研究思路和主要内容...........................................................................14第二章利用醋酸杆菌合成具抗菌性能的BC-Ag/AgCl纳米复合材料..........................................................................................................162.1引言...........