Pyrolized Diatomaceous Biomass Doped with Epitaxially Growing Hybrid Ag/TiO2 Nanoparticles: Synthesis, Characterisation and Antibacterial Application

Abstract

In the pursuit of innovative solutions for modern technologies, particularly in the design and production of new micro/nanostructured materials, microorganisms acting as “natural microtechnologists” can serve as a valuable source of inspiration. This research focuses on harnessing the capabilities of unicellular algae (diatoms) to synthesize hybrid composites composed of AgNPs/TiO2NPs/pyrolyzed diatomaceous biomass (AgNPs/TiO2NPs/DBP). The composites were consistently fabricated through metabolic (biosynthesis) doping of diatom cells with titanium, pyrolysis of the doped diatomaceous biomass, and chemical doping of the pyrolyzed biomass with silver. To characterize the synthesized composites, their elemental and mineral composition, structure, morphology, and photoluminescent properties were analysed using techniques such as X-ray diffraction, scanning and transmission electron microscopy, and fluorescence spectroscopy. The study revealed the epitaxial growth of Ag/TiO2 nanoparticles on the surface of pyrolyzed diatom cells. The antimicrobial potential of the synthesized composites was evaluated using the minimum inhibitory concentration (MIC) method against prevalent drug-resistant microorganisms, including Staphylococcus aureus, Klebsiella pneumonia, and Escherichia coli, both from laboratory cultures and clinical isolates.

Diatomaceous Biosilica Doped with Heteroepitaxially Growing Ag/AgCl/CeO2 Composite Nanoparticles: Synthesis, Characterisation and Antibacterial Application

“…On the other hand, the support used for the nanocomposites preparation can also influence the antimicrobial activity once the formulations obtained in the present research display a lower MIC value (1.25 mg/mL) compared to the based AgNPs/kaolinite [47], whereas AgNPs/TiO 2 /DBP [43] nanocomposite where the MIC value was found to be ranged between 2.5 and 10 mg/mL against the same bacterial strains. Furthermore, noteworthy the fact that DBioSiO 2 (unmodified matrix) used in the present study as support exhibits antimicrobial activity compared to the TiO 2 /DBP and kaolinite support that have not displayed any move against the same bacterial strains.…”

“…Many research studies demonstrated the antimicrobial activity, synergistic effect of silver formulations against clinical isolates and its application in pharmacology and cosmetology [44][45][46]. In another trend of thoughts, our previous studies [43,47] show dissimilarity in the antimicrobial activity of AgNPs/kaolinite and AgNPs/TiO 2 /DBP nanocomposites that used additional support for the synthesis. Additionally, the support influences the antimicrobial effect, the metal (element) used, and the synthesis method; the TiO 2 /DBP nanocomposites display higher antimicrobial potential against the same bacterial strains than AgNPs/ kaolinite.…”

“…The unique structural and physicochemical properties and biocompatibility undoubtedly point to the prospect of using this material for, among other things, the synthesis of antibacterial agents. Additionally, due to its adsorption properties, diatomaceous biosilica can be an excellent support for the synthesis of nanoparticles, reducing their toxic effects on living cells [43].…”