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

Abstract

Modern technology's development is also towards using microorganisms as micro-factories of biomaterials with unique properties and combining the original properties of biosilica extracted from diatoms (microalgae) together with immobilised silver and cerium in nanoparticle forms allowed to obtain a modern composite material with antibacterial activity. The synthesised composites containing heteroepitaxially growing Ag/AgCl/CeO2 complex nanoparticles were studied using different types of instrumental analysis. SEM-EDX and XRD analysis allowed the qualitative and quantitative determination of the elements present and their forms in the composites. TEM permitted analysis of information about the created nanoparticles shape, size and structure specificity. The possible mechanism of nanoparticle formation was suggested. Antibacterial properties of synthesised composites were characterised using a minimum inhibitory concentration test on six selected bacterial strains. Diatomaceous biosilica containing heteroepitaxially growing silver chloride, metallic silver, and cerium (IV) oxide nanoparticles have been prepared for the first time. The proposed method for synthesising composites did not use toxic reagents, making it environmentally friendly. Graphical Abstract

Diatom Biosilica Functionalised with Metabolically Deposited Cerium Oxide Nanoparticles

“…Figure 4G presents a single, well-defined, quasicubic ceria nanoparticle with a size of 20 nm. In our previous work, using the chemical reduction of cerium ion precursor, we obtained CeO 2 nanoparticles with sizes ranging from 3-5 nm [28].…”