Abstract
Nowadays, several pathogenic strains of bacteria and fungi have become resistant against many therapeutic drugs. Therefore, using novel biologically synthesized nanomaterials as antimicrobial drugs against the human pathogens is of great concern. Consequently, here, the study was aimed to assess the antimicrobial activity of titanium dioxide nanoparticles (TiO2NPs) phycosynthesized from Spirulina platensis and some conventional antifungal (clotrimazole, itraconazole, ketoconazole, micconazole, and nystatin) and antibacte-rial (amoxicillin and gentamicin) drugs against both Candida parapsilosis and Prototheca ciferrii. The TiO2NPs-and clotrimazole-induced ultrastructure changes on the microbes using transmission electron microscope were also investigated. The TiO2NPs significantly inhibited the growth of C. parapsilosis. The clo-trimazole and ketoconazole showed the highest inhibitory effect against both tested microorganisms. The ultrastructure changes affected by TiO2NPs or clotrimazole were represented by damage in the cell wall, invagination in the cell membrane, and discrimination of peroxisomes. Furthermore, accumulation of TiO2NPs inside C. parapsilosis cells led to abnormality in nuclear division, irregular shape of the nucleus (crescent shape). We conclude that the studied TiO2NPs offer promising potential for the development of novel technologies that control contaminations and infections caused by Candida parapsilosis and Prototheca ciferrii. The findings of the present study create a novel antimicrobial drug exploited to prevent candidiasis and protothecosis. However, further studies are needed to understand clearly the mechanism of action of these nanoparticles.(c) 2022 SAAB. Published by Elsevier B.V. All rights reserved.