• Railean, Viorica
• Buszewski, Bogusław
• Gloc, Michał
• Pomastowski, Paweł
• Król-Górniak, Anna
• Dobrucka, Renata
• Plocinski, Tomasz
• Kurzydlowski, Krzysztof

Abstract

In this study, for the first time, the comparison of commercially available chemical ZnO NCs andbio-ZnO NCs produced extracellularly by two different probiotic isolates (Latilactobacillus curvatusMEVP1 [OM736187] and Limosilactobacillus fermentum MEVP2 [OM736188]) were performed. Alltypes of ZnO formulations were characterized by comprehensive interdisciplinary approach includingvarious instrumental techniques in order to obtain nanocomposites with suitable properties for furtherapplications, i.e. biomedical. Based on the X- ray diffraction analysis results, all tested nanoparticlesexhibited the wurtzite structure with an average crystalline size distribution of 21.1 nm (CHEM_ZnONCs), 13.2 nm (1C_ZnO NCs) and 12.9 nm (4a_ZnO NCs). The microscopy approach with use of broadrange of detectors (SE, BF, HAADF) revealed the core–shell structure of bio-ZnO NCs, compared tothe chemical one. The nanoparticles core of 1C and 4a_ZnO NCs are coated by the specific organicdeposit coming from the metabolites produced by two probiotic strains, L. fermentum and L. curvatus.Vibrational infrared spectroscopy, photoluminescence (PL) and mass spectrometry (LDI-TOF-MS) havebeen used to monitor the ZnO NCs surface chemistry and allowed for better description of bio-NCsorganic coating composition (amino acids residues). The characterized ZnO formulations were thenassessed for their photocatalytic properties against methylene blue (MB). Both types of bio-ZnO NCsexhibited good photocatalytic activity, however, the effect of CHEM_ZnO NCs was more potent thanbio-ZnO NCs. Finally, the colloidal stability of the tested nanoparticles were investigated based on thezeta potential (ZP) and hydrodynamic diameter measurements in dependence of the nanocompositesconcentration and investigation time. During the biosynthesis of nano-ZnO, the increment of pH from5.7 to around 8 were observed which suggested possible contribution of zinc aquacomplexes andcarboxyl-rich compounds resulted in conversion of zinc tetrahydroxy ion complex to ZnO NCs. Overallresults in present study suggest that used accessible source such us probiotic strains, L. fermentumand L. curvatus, for extracellular bio-ZnO NCs synthesis are of high interest. What is important, nosignificant differences between organic deposit (e.g. metabolites) produced by tested strains werenoticed—both of them allowed to form the nanoparticles with natural origin coating. In comparisonto chemical ZnO NCs, those synthetized via microbiological route are promising material with furtherbiological potential once have shown high stability during 7 days.

Topics

• nanoparticle
• nanocomposite
• impedance spectroscopy
• surface
• compound
• photoluminescence
• zinc
• spectrometry
• infrared spectroscopy
• microscopy
• time-of-flight mass spectrometry
• laser desorption ionisation