EFFECT OF POLYANILINE NANOTUBES ON ACETYLCHOLINESTERASE ACTIVITY

Resumo

Introduction: With the rapid growth of nanotechnology and its applications, environmental exposure to nanoparticles is increasing, and there is growing concern about their toxicity. However, their impact on human health and the environment is still poorly studied. Danio rerio (zebrafish) is a widely used vertebrate model to assess the toxicity of nanomaterials. Objective: This report presents a preliminary study about the effect of polyaniline nanotubes (PANI-NTs) on Danio rerio (zebrafish) and their spectroscopic and structural features. Materials and Methods: Adult Zebrafish were exposed for one hour to different PANI-NTs concentrations of 1.0, 2.5, 5, and 10 mg L-1. The nanotubes comprised 100 nm and 160 nm inner and outer diameter, respectively, length > 500 nm, and 9797 molecular weight value. A control group was maintained only in water. After exposure, acetylcholinesterase (AChE) activities were evaluated. Results and Discussion: The PANI-NTs samples have benzenoid units, polarons, and delocalized free charge carriers. The infrared spectra showed active modes at 1496 cm-1 of ν C-C in N=B=N rings, where B is a benzenoid unit, and 1540 cm-1 of ν C-C in N=Q=N rings, where Q is the quinoid unit. After one hour of exposure to PANI-NTs at a concentration of 10 mg L-1, the activity was up to 30 % higher than the control of the AChE brain activity of zebrafish. A derivative UV-VIs ex-situ spectra of PANI-NTs sample after the treatment and the control sample showed a slight shift wavelength at 258 nm and 283 nm bands, which are associated with benzene ring distortions. This means that uptake, elimination, and compartmental distribution dynamics could be affected by the weak basicity of aniline, nitrogen charge moieties, and nanotube lipophilicity. Considering this finding, further analysis will be required to clarify the structural implications. Finally, this report will allow us to create spectroscopic guidelines for studying aspects involved in Zebrafish neurotoxicity.