Study Of Supporting Drugs Graphene Oxide And Mesoporous Silica Enhancing Against Resistant Bacterial Activity And Mechanism

The threaten of pathogens has always existed, especially in the more complex environment today, the bacteria problem more prominent. In recent years, in order to suppress and kill pathogens, many researchers have proposed different proposals:(1) developing new antibacterial agents, such as antibacterial peptides;(2) combined with using a variety of antibacterial agents;(3) development of new antibacterial carrier. There are studies have found that the efficacy of antibiotics against resistant bacteria were low because the antibiotics distribution is disperses. so that develop a new drug carrier, centralized administration of antibiotics can effectively kill the resistant bacteria. For the development of new drugs and combination therapy in the last decades researching dedicate that new medicine is low output, and the combination of antibiotic has been in debating. Therefore, using nanotechnology to develop new antibiotics and antibacterial drugs is a good strategy. This thesis consists of three chapters:In chapter 1, Introduction, we introduces the biology and structure of bacteria,bacterial hazards and application of bacteria, then we introduces the current classification and antibacterial principle mechanism of antibacterial agents. Finally, we introduces the development and antibacterial application of nanotechnology, highlight several methods of antibacterial.In chapter 2, In this study, we developed an approach of polyoxyethylene bis(amine)(PEG) directed AgNPs grown on GO, then we combined the two materials to prepare a series of functionalized GO bearing different size AgNPs, and studied the size effects of Ag NPs on growth inhibition of Escherichia coli(E.coli) and Staphylococcus aureus(S.aureus). We evaluated the antibacterial effect of GO@PEG@AgNPs on E.coli and S.aureus by various methods such as Minimum Inhibitory Concentration(MIC) experiment, cell wall/membrane integrity assay and Scanning Electron Microscope(SEM) characterisation of bacterial morphology. The GO@PEG@AgNPs composites exhibited markedly higher antibacterial efficacy than AgNPs alone because of synergistic effect between GO@PEG and AgNPs. The smallest GO@PEG@AgNPs(10 nm) particularly demonstrated higher antibacterial activity than other sizes(30, 50, and 80 nm). We believe these findings contribute to great potential application as a regulated graphene-based antibacterial solution.In chapter 3, Bacterial resistant which induce inefficiency of antibiotics is a huge threat to people’s health. There is a new strategy to change this situation that through synthesis a drug delivery loading antibiotic. Here, we synthesis a antibiotic nanocarriers(MSN@FA@CaP@FA) which can targeted to bacterial DNA, and then the ampicillin(Amp) is releasing because of phosphoric acid monocalcium(CaP) layer dissociated under the acidic conditions made the ampicillin diffused into cytoplasm. With the ampicillin released, its antibacterial behavior from inside to out in bacterial cell. Ampicillin disrupted the cytoplasm solution and destroy the protein of cell, then the cell membrane was disrupted lead bacterial rupture that make bacteria died. From the results of antibacterial experiments show that the loading ampicillin nanocomposites not only better than the individual ampicillin, and have no resistance. In addition there is a synergies that enhances the antibacterial effect between nanocarriers with ampicillin in antibacterial process. The experiments of mice found that the Amp-MSN@FA@CaP@FA can greatly improve the survival rate and the survival time of infected mice with Escherichia coli(E.coli). In wound experiments, Amp-MSN@FA@CaP@FA made into a Band-Aid not only effectively killed bacteria and accelerate wound healing of infected mice with Staphylococcus aureus(S.aureus). these results thus open new opportunities for biomineralization guided nanostructure assemblies with great potential for biomedical applications.