Synthesis And Application Of Polyethyleneimine Modified Silver Nanomaterials

Silver nano-material is a new type of noble metal nano-materials. In scientificactivities, it has been widely applied in several fields including chemical sensing,bio-medicine, bio-imaging and microelectronic materials. Because of its unique blockstructure it has appeared an excellent optical property and a well biocompatibility.However, those special properties are strongly depending on size, surface morphologyand ligand differences. In recent research, scholars are interested in accelerating thespeed of synthesis and seeking a faster and simpler method to produce this newfunctional material, for the ultimate purpose of exploiting its potential applicationvalue.According to previous reports, we found that silver nano-material has a greatpotential. In this paper, we are focusing on finding a faster and simpler way tosynthesize the silver nano-material and apply it to photochemical sensing. Initially, weconduct following studies base on polyethyleneimine (PEI):(1) In chapter2, we synthesized the silver nano-particles with polyethyleneimineand sodium borohydride under the ambient conditions by using chemical reductionmethod. This method was easy, convenient and repeatable. We conducted a series oftests to testing the characteristics of our new synthesized sliver nano-particle. Thosetests were included using UV-visible spectrum, dynamic light scattering andtransmission electron microscope methods. At meanwhile, we established acolormetric sensor for heparin detection and limited the detection at1g/mL. Thistesting method has high selectivity and sensitivity, and less time costing and alsoprovide an easy observing condition for researchers. As the results, these particlesgave a positive feedback.(2)In chapter3, under room temperature and the value of pH5conditions, weaccelerated and simplified the synthese process by directly reducing the silver ions andproduced the yellow green silver nanoclusters with PEI template. After examining acatena of characterization, the size of silver nanoclusters has been determined as1.8nm.Because of highly stability, it has a well foundation for further application. Sincecopper ions can quench the fluorescence of silver nanoclusters, we constructed aturn-off copper ions sensor with the silver nanoclusters, the limit of detection was aslow as10nmol/L. And the same time, we put clusters and gel together to synthesize fluorescent silver nanoclusters gel, then applied to the detection of water samples ofcopper ions.(3)In order to explore other potential features of those stable silver nanoclusterswe had synthesized, in chaper4, on the basis of yellow green silver nanoclusters, weset up a turn-off ions sensor for ClO—detection, the limit of detection was2mol/L.It was also a quenching fluorescence sensor, but through our experimental study, wefound that the detection mechanism was very different from copper (II) ion sensorwhich we had introduced in the previous chapter.