Avaliação da biocompatibilidade do polímero polipirrol utilizando Zebrafish (Danio Rerio) como organismo modelo

Abstract

The polymer polypyrrole (PPy) has been of great interest in nanomedicine as a smart nanobiomaterial due to stimulus-response characteristics that are useful for tissue regeneration, neural implants and drug delivery systems. Although PPy has become a suitable tool for health sciences, nanoparticles might exert toxic effects in organisms and environment and, consequently, nanotoxicological approaches and toxicological screenings are needed to ensure their safety. Under this scenario, zebrafish emerges as a useful model organism to refine and deepen understanding of potential toxicological effects of nanomaterials. The current work aimed to synthesize and characterize PPy nanoparticles (doped with p-toluenesulfonic acid; PPy/p-TSA) and to evaluate the effects of 3- and 6-day exposure to different concentrations (25, 100, 250 e 500 μg/mL of PPy/p-TSA) on morphological, functional, behavioral, biochemical and molecular parameters in vivo, using zebrafish embryo and larva as model organism. Data show that both synthesis lot were able to produce PPy/p-TSA particles with nanoscale size and suspensions, performed in 1% PF68, were able to reach stability with 12-18h. Exposure to PPy/p-TSA suspension did not alter animals’ survival, however, it promoted early hatching, in a dose-dependent manner. Electronic microscopy analysis showed PPy/p-TSA particles affinity to biological tissue, with significant dose-dependent envelopment of embryo chorion. Morphological data showed significant changes in body length and ocular distance, especially in higher doses, which also presented changes in behavioral parameters compatible with animals hypoactivity. Therefore, results emphasize adverse effects of PPy/p-TSA exposures on development and behavior. To understand the potential underlying mechanisms contributing to the scenario, markers of inflammation, oxidative stress and cellular death were also evaluated. Myeloperoxidase activity, as an inflammatory marker, showed no alterations, except for reduction in the group with highest dose of PPy/p-TSA. Acridine orange staining indicated consistent cellular death in neuromasts and tail region exclusively in animals exposed to PPy/p-TSA. Oxidative stress markers were also found to be altered in terms of gene expression and/or protein activity. Activity of catalase and glutathione reductase content, for example, were, respectively, increased and reduced among exposed groups. Taken together, data indicate that PPy/p-TSA exposure induces oxidative stress responses that might led to cellular death. Additional markers of oxidative stress and cellular death will be investigated to broaden the analysis and robustly address these preliminary findings; aiming, more importantly, to highlight and refine previously unknown adverse effects that PPy exposure might exert in vivo.