Open Access Conference Proceedings

Metallic nanoparticles, particularly zinc oxide nanoparticles (ZnONPs), are innovative tools for modulating the metabolic activity of photosynthetic microorganisms and are increasingly used in bionanotechnology, as controlled stress inducers that can redirect biosynthetic pathways toward the accumulation of high-value compounds. The morphology of nanoparticles significantly influences their interaction with biological systems and the resulting effects, making the study of their properties essential for the development of biotechnological applications. In this study, the effects of lab-synthesized ZnONPs with multipod morphology, were compared with those of commercially available spherical ZnONPs (Sigma-Aldrich) on the cyanobacterium Arthrospira platensis (spirulina). Nanoparticles were added to the spirulina culture at the beginning of the exponential growth phase (day 3), in two concentration ranges: 0.01–1.0 mg/L and 10–30 mg/L. To evaluate the cyanobacterial response to nanoparticle interaction, two parameters were assessed at the end of the cultivation cycle (day 7): accumulated biomass and C-phycocyanin content, a photosynthetic pigment with high biotechnological value. The results demonstrated that both ZnO multipods and spherical ZnONPs stimulated biomass production by 12–14% at higher concentrations. However, a marked difference in pigment response was observed. Spherical nanoparticles caused a substantial reduction in C-phycocyanin content by 57.5–87.9%, whereas multipod ZnONPs stimulated pigment synthesis at low concentrations and exerted a weaker inhibitory effect at high concentrations (50.3–59.7%). ZnONP morphology significantly modulates pigment biosynthesis and cytotoxicity in Arthrospira platensis, with multipod structures showing a more favorable interaction profile. These data support the morphological optimization of metal oxide nanoparticles for use in controlled cyanobacterial cultivation systems.

Keywords: Arthrospira platensis, ZnO multipods, Spherical ZnONPs, biomass, C-phycocyanin

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