Preparation Of Functional Natural Biological Materials And The Applications In SERS Analysis And PH Sensing

Along with the development of functional natural biological materials and nanometal materials,it has given rise to the combination of natural biological material and noble metal nanoparticles which was equipped with unique photo electromagnetic features compound structure of nanoparticles and natural biological materials.Due to the unique properties such as high reactivity resulted by multifunctional groups,porous structure caused by specific biological materials,this kind of functional biomaterials can be used as nano reactor.Multifunctional groups such as hydroxyl,aldehyde can make it possible to reduce metal ions to be nanoparticles with different shape,size.The unique LSPR characteristic brought by the noble metal nanoparticles not only endow those natural biological materials vivid color,but also expand the applications in those research fields such as photonics,sensing and bioscience.In addition,with the improvement of living standards and enhancement of the awareness towards environmental protection,the natural pigments have drawn more and more extensive attention.We combine the natural biological materials with the special natural pigments which is sensitive to environmental acidity and alkalinity.It's no doubt that the combinanation will greatly expand the applications of natural biological materials.In this thesis,to aim developing functions,the silk fabric and tremella used as carriers,we designed and fabricated the composites with multifunctions including SERS sensing and pH sensing.The concrete contents include:(1)Preparation of gold nanoparticles and silk fabric composites and their application inSERS analysisFlexible SERS active substrates were prepared by modification of silk fabrics with gold nanoparticles.Gold nanoparticles were in-situ synthesized after heating the silk fabrics immersed in gold ion solution.Localized surface plasmon resonance(LSPR)properties of the treated silk fabrics varied as the concentration of gold ions changed,in relation to the morphologies of gold nanoparticles on silk.In addition,X-ray diffraction(XRD)was used to observe the structure of the gold nanoparticle treated silk fabrics.The SERS enhancement effect of the silk fabrics treated with gold nanoparticles was evaluated by collecting Raman signals of different concentrations of p-aminothiophenol(PATP),4-mercaptopyridine(4-MPy)and crystal violet(CV)solutions.The results demonstrate that the silk fabrics corresponding to 0.3 and 0.4 mM of gold ions possess high SERS activity compared to the other treated fabrics.It is suggested that both the gold content and morphologies of gold nanoparticles dominate the SERS effect of the treated silk fabrics.(2)Preparation of gold nanoparticles and tremella composites and their application in the adsorption,enrichment and the detection of dye molecules.Taking advantage of the active functional group-aldehyde group contained in the main composition of tremella,the gold nanoparticles can be in situ synthesis on the tremella through heating.In addition,testing method such as SEM,XRD,XPS was characterized to prove that gold nanoparticle has been synthesized on the tremella.The porous structure of tremella makes it possible to quickly absorb two kinds of cationic dye molecules: methylene blue,crystal violet.We can monitor the adsorption process by means of the UV extinction spectrum.At the same time,natural drying process of tremella may result in the the enrichment of dye molecules,which can be confirmed by the Raman spectra of dye molecules from wet to dye.Experimental results show that SERS spectra of dye molecules on dry tremella is much higher than that of wet.We may draw the conclusion: gold nanoparticles/tremella composite material is a comprehensive platform of adsorption,enrichment,and analysis of the detection.(3)Preparation of purple potato pigment and silk fabric composites and their applicationin pH sensing.In this paper,the effective ingredient of purple potato is extracted by means of mixed solution of hydrochloric acid and ethanol.The paper probed into the color and absorbance changes of purple potato pigment resulted by the surrounding pH value.The extracted pigment was fixed on silk fabric.When extracted pigment of purple potato and dyed silk fabric contacted with solutions of different pH value,obvious changes are taken place and can be observed by naked eye.Experimental results show that the purple potato pigment and dyed silk fabrics is sensitivity to pH value changes,The dyed acid-base indication silk fabric has significant color changes in a wide range of pH from 2 to 10,from red to yellow green gradually,which is a sensitivity and reversible process.