Toxicity in vitro and in Zebrafish Embryonic Development of Gold Nanoparticles Biosynthesized Using Cystoseira Macroalgae Extracts

Abstract

Introduction: Research on gold nanoparticles (AuNPs) occupies a prominent place in the field of biomedicine nowadays, being their putative toxicity and bioactivity areas of major concern. The green synthesis of metallic nanoparticles using extracts from marine organisms allows the avoidance of hazardous production steps while maintaining features of interest, thus enabling the exploitation of their promising bioactivity. Objective: To synthesize and characterize AuNPs using, for the first time, macroalga Cystoseira tamariscifolia aqueous extract ( [email protected] ). Methods: Algal aqueous extracts were used for the synthesis of AuNPs, which were characterized using a wide panel of physicochemical techniques and biological assays. Results: The characterization by UV-Vis spectroscopy, transmission electron microscopy, Z-potential and infrared spectroscopy confirmed that [email protected] were stable, spherical and polycrystalline, with a mean diameter of 7.6 ± 2.2 nm. The antioxidant capacity of the extract, prior to and after synthesis, was analyzed in vitro, showing that the high antioxidant potential was not lost during the synthesis. Subsequently, in vitro and in vivo toxicity was screened, by comparing two species of the genus Cystoseira ( C. tamariscifolia and C. baccata ) and the corresponding biosynthesized gold nanoparticles ( [email protected] and [email protected] ). Cytotoxicity was tested in mouse (L929) and human (BJ5ta) fibroblast cell lines. In both cases, only the highest (nominal) test concentration of both extracts (31.25 mg/mL) or [email protected] (12.5 mM) significantly affected cell viability, as measured by the MTT assay. These results were corroborated by a Fish Embryo Acute Toxicity (FET) test. Briefly, it was shown that, at the highest (nominal) tested concentration (31.25 mg/mL), CT extract induced significantly higher cytotoxicity and embryotoxicity than CB extract. However, it was demonstrated that [email protected] , but not [email protected] , were generally non-toxic. At sub-lethal (nominal) test concentrations (1.25 and 2.5 mM), [email protected] affected zebrafish embryonic development to a much lesser extent than [email protected] In vitro wound healing assays also revealed that, while other experimental conditions did not impact cell migration, CT and [email protected] displayed a moderate positive effect. Conclusion: [email protected] and [email protected] display promising features, desirable for biomedical applications, as wound healing. Keywords: gold nanoparticles, green synthesis, Cystoseira sp., zebrafish embryotoxicity test, bioactivity, toxicity

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