title: Prevention of microbial colonization by advanced biochemical and biophysical methods
Creators: name: Meng, Xiangjun
Publisher: name: Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)
Year: 2024
Subjects: subject: DDC Classification::5 Naturwissenschaften und Mathematik :: 57 Biowissenschaften; Biologie :: 579 Mikroorganismen, Pilze, Algen

description: Bacterial-induced chronic infections remain a major clinical challenge, and especially biofilm-related diseases are still hard to be treated by existing means. As the workhorse against microorganism infections, antibiotics are hard to penetrate into biofilms, and the abuse of antibiotics caused the emergence of antimicrobial resistance (AMR) strains. Some infections are becoming challenging while the speed of identifying new antibiotics could not catch up with the speed of AMR bacterial strains generation. Thus, new materials with good activities of antibacterial and inhibit the formation of biofilm are necessary. Up to now, numerous methods have been used in applications against pathogens, while antibiotic treatment is the main mean. Meanwhile, scientists are still focusing on searching for other modes to replace the antibiotic treatment, such as biophysical decorations (changing the characteristics of the surface, such as the nature of the substrate, free energy of the surface, roughness, wettability, surface charge, and so on), electrochemical methods, photo-thermal therapies, and biomedical methods (antibiotic, metal elements, non-metal elements, organic compounds and so on). In this thesis, the antibacterial activities of different antimicrobial agents were tested, and various methods were jointly used to gain materials with satisfactory antibacterial properties. The thesis included analysis of eight antibacterial-related projects: 1) Mg discs (WE43), which had been reported to own antibacterial activity, were treated with DMEM and decorated with chitosan. Then, the silver-, copper-, and silicon-loaded bioglasses (Ag@BG, Cu@BG, and Si@BG) were coated onto the surface of the materials by the electrophoretic deposition (EPD) method. 2) Ti and Mg were mixed to form Ti-Mg metal composite (Ti-Mg MMC) alloys by spark plasma sintering (SPS) method. Furthermore, tannic acid (TA) was added to enhance the biocompatibility of Ti-Mg MMCs. 3) Chitosan (CS) was chelated with copper (II) as a complex material of Cu (II)-CS with antibacterial activity and metallic substrates were decorated with Cu (II)-CS nanoparticles by the electrophoretic deposition (EPD) method. 4) Mesoporous bioactive glass nanoparticles (MBGN) were synthesized and loaded with copper as an antibacterial element. As polyvinyl alcohols (PVA) are characterized by excellent physical properties, chemical resistance, biodegradability, biocompatibility, and non-toxicity, the formed Cu@MBGN were trapped in PVA to form a material with good antibacterial activity as a wound healing dressing. 5) Silver (Ag) nanoparticles were synthesized and loaded into mesoporous bioactive glass nanoparticles (MBGN). As reported, the strong antibacterial activity of Ag accompanies high cytotoxicity. The antibacterial property of Ag was proven in the experiment. Furthermore, bovine serum albumin (BSA), a serum albumin protein derived from cows, was added to the system to decrease the toxicity of Ag for further application. 6) Bacteriophages, bacteria-specific virues that can attach to bacterial host strains with high specificity, were conjugated onto synthesized mesoporous bioactive glass nanoparticles (MBGN) and aminopropyltriethoxysilane (APTES) modified MBGN (MBGN-APTES). The bound rates of phages with materials were measured and infective activities were tested. 7) Boron-doped diamond (BDD) electrodes were fabricated from niobium wires and assembled as a single instrument for implant cleaning against different microorganisms.