Research On The Construction Of PH Nanosensor And The In-situ Measurement Method Of Paper Surface Acidity

Acidity(pH) is one of the most important factors for the stability of paper,which can damage the paper during production and upon prolonged by the atmospheric pollutants.In fact,paper with low acidity is highly desirable to assure permanence of valuable paper materials.The deacidification of value books,archives,calligraphy and painting is a worldwide problem.In the face of acidification,there is a lot of deacidification methods emerged in endlessly.The result of acidification is directly characterized by the changes of paper treated with deacidification before and after.Therefore,in the deacidification,protection and repairing work of paper relics,it is important for determination of surface pH of paper relics.The size of nanosensor is in nanometer,and the distance between the detected.substances and nanosensor is also in nanosize.The data at the atomic scale is obtained by nanosensor,and the data can be used in the macro world.Based on the small size of nanosensor,it can be distributed to the cellulose fiber of paper and supply more precise information of cellulose fiber to the protection of cultural relics.This paper is divided into five chapters.In chapter 1,the common on fluorescent nanomaterials is introduced and the application of five kinds of fluorescent nano materials in cells and in vivo are reviewed.At the same time,the comment on the application of nanomaterials in the paper conservation of cultural relics has made.Last,the purpose of this research work was presented.In chapter 2,a new fluorescent nanosensor was developed for measurement surface pH of paper.The nanosensor is based on the chitosan-modified silica nanoparticles,where Ru(bpy)32+(bpy=2l 2'-bipyridyl)was doped in the nanoparticles as reference dye and pH sensitive fluorescein isothiocyanate(FITC)were used as pH indicator.The nanocomposite was prepared by the modified reverse microemulsion method and charterized by TEM.The dynamic performances of the nanosensor on the paper fiber showed the nanosensor was suitable for sensing in-situ surface pH of paper fiber because it could actively infiltrate into the surface of paper fiber.We demonstrated one practical application of the nanosensor for detection of surface pH in the precious art sample by integrating our nanosensor into the paper fiber.Simply washing by water,the nanosensor could be easily removed from the measured precious art sample without any damage after measurement.Taken together,this work established a modular approach to pH nansensor design for detection of surface pH in precious art sample.In chapter 3,a visual fluorescence method was developed for non-destructive detection of surface pH of paper using deoxyribonucleic acid(DNA)nanoprobe.The nanometer scale of the nanoprobe showed it was suitable for sensing in-situ surface pH of paper because it could actively infiltrate into the surface of paper fiber.We demonstrated one practical application of the nanoprobe for detection of surface pH in the precious art sample by visual colorimetry.The pH nanoprobe could be easily removed from the measured precious art sample by water without any damage after measurement.Taken together,a new approach to pH nanoprobe design for in-situ detection of surface pH in precious art sample was established in this work.In chapter 4,a fluorescent nanoprobe was constructed using DNA tetrahedron structure to sensing surface pH of paper.Carboxyfluorescein(FAM)was modified on the single stranded DNA.After the formation of DNA tetrahedron structure,FAM is located on the vertex of tetrahedral structure.Thus,a fluorescent nanoprobe based on DNA tetrahedron structure was fabricated.When this fluorescent nanoprobe was dropped on paper surface with different pH,under the irradiation of UV lamp it can be seen fluorescent spots with different intensity.According to the fluorescence intensity,a visual detecting of surface pH of paper was developed.After the determination of sample,the fluorescent nanoprobe was removed by simple washing from the surface of paper and the removed ration was about 90%.Thus,a new method for in-situ detecting of surface pH of paper was developed based on the DNA tetrahedron structure.The fifth chapter is the overall summary of the research work of this thesis,and further research work is put forward.In this thesis,fluorescent nanomaterials were introduced into the design of pH nanosensor for detecting surface pH of paper.The application of fluorescent nanomaterials was expanded in the area of cultural heritage.And also a new idea for the determination of surface acidity of paper and cultural relics was provided.