Investigation On Structures And Properties Of Silver Ions/Small Biomolecules Coordination Self-Assembly And Nanogold Doped Assembly

Self-assembly refers to the process that the building blocks spontaneously assemble through the non-covalent interaction to form an ordered aggregate without external interference.Self-assembly at the nanoscale scale has always been one of the major research focuses in the fields of chemistry and materials science.It is an effective method for assembling nanostructured components and provides more options for exploring and preparing the functional materials.The self-assembled building blocks mainly include molecules or polymer molecules,metal-coordination complexes,colloidal particles,etc.The structures of the resulting assemblies are also different depending on the characteristics of different types of building blocks.In this paper,we use different self-assembly building blocks to construct the metal-coordination complex self-assembly system and gold nanoparticles modification assembly system.In this paper,starting from different self-assembly building elements,the self-assembly system of metal-coordination complex and the modified gold nanoparticles are constructed.And the self-assembled hydrogel are combined with metal nanoparticles to explore the structure,formation mechanism and application of the complex materials.The paper mainly includes the following five parts.Chapter ? is the introduction.The basic concepts,properties and features of colloid chemistry,surfactants and self-assembly,as well as the structural properties and applications of the constructed materials are briefly described.The related researches on the self-assembly of different building blocks and their properties are described in detail.Finally,the basis for the selection of the topic and the research content of this paper are pointed out.In Chapter ?,Silver ions induce the self-assembly of small biomolecules via coordination.In the first section,a supramolecular hydrogel was formed by the self-assembly of silver ions and adenosine monophosphate,and its gelation capability was influenced signally by the concentration of silver ions and the pH of the system.The gels are very sensitive to light,which endows them with potential applications as visible-light photosensitive materials.Coordination between the nucleobase of AMP and Ag+,as well as ?-? stacking of nucleobases,are considered to be the main driving forces for self-assembly.The hydrogels successfully achieved the encapsulation and enrichment of biomolecules.Hydrogen bonding between the amino groups of guest molecules is considered to be a crucial interaction during the enrichment.In the second section,the peptide similar to glutathione was designed and silver ions could induce the self-assembly.Besides,small-sized silver nanoparticles were generated in situ during the self-assembly process.The driving forces of self-assembly were summarized according to series characterization which is coordination and ?-?stacking interactions.The self-assembled complexes have good antibacterial and catalytic activity.In Chapter ?,gold nanoparticles(AuNPs)were modified with a negatively charged peptide for use as nanocarriers of a positively charged anti-tumor drug,doxorubicin hydrochloride(DOX).The Fmoc-GCE-modified AuNPs were further used to load DOX through electrostatic interaction.A temperature-sensitive gel,chitosan gel,was chosen to act as an appropriate platform to incorporate the modified AuNPs as a drug carrier.The incorporation of AuNPs makes the complex gel exhibit SERS characteristic and good biocompatibility.It also can significantly extend the release time of the incorporated drugs and possesses pH responsiveness,exhibiting the advantages of controlled release and reduced side effects.In Chapter ?,the influence of a series of cationic surfactants composed of cetyltrimethylammonium with different counterions on the ageing process of gold nanoclusters(AuNCs)was studied in detail.The finely different points of AuNCs treated by different surfactants were demonstrated by UV-Vis and fluorescence spectra,TEM images,etc.Due to the difference in counterions,these surfactants have diverse physicochemical properties in surface activity,specific conductivity,pH,and viscosity,which may account for the differences of AuNCs in the ageing process.In addition,the affinity of the counterions in surfactants to the surface of Au has also been demonstrated completely which further induces the differences of the synthesized Au nanomaterials.The understanding of the effect of surfactants on the preparation of gold nanomaterials can provide a theoretical basis for regulating the synthesis of nanomaterials.In Chapter ?,the gold nanostars(AuNSs)are assembled and modified on the surface of magnetic Fe3O4 nanoparticles.A suitable surfactant is selected as a template to ensure that the structure of the gold nanostars is not affected during the process of fabrication.The magnetic porous complex nanoparticles exhibit attractive characteristics including high magnetization,mesoporous nanostructure,photothermal properties and low in vitro toxicity,showing fascinating potential for drug delivery applications.