Ecotoxicity Assessment of Fe3O4 Magnetic Nanoparticle Exposure in Adult Zebrafish at an Environmental Pertinent Concentration by Behavioral and Biochemical Testing.

Nemi Malhotra,Petrus Siregar,Tzong-Rong Ger,Geng-Ming Lin,Gilbert Audira,Chung-Der Hsiao,Sung-Tzu Liang,Sreeja Sarasamma,Jung-Ren Chen,Yu-Heng Lai

doi:10.3390/nano9060873

Abstract

Magnetic Nanoparticles (MNPs) are widely being investigated as novel promising multifunctional agents, specifically in the fields of development for theranostics, electronics, waste water treatment, cosmetics, and energy storage devices. Unique, superior, and indispensable properties of magnetization, heat transfer, and melting temperature make MNPs emerge in the field of therapeutics in future healthcare industries. However, MNPs ecotoxicity as well as behavioral toxicity is still unexplored. Ecotoxicity analysis may assist investigate MNPs uptake mechanism and its influence on bioavailability under a given set of environmental factors, which can be followed to investigate the biomagnification of MNPs in the environment and health risk possessed by them in an ecological food chain. In this study, we attempted to determine the behavioral changes in zebrafishes at low (1 ppm) or high (10 ppm) concentration levels of Fe3O4 MNPs. The synthesized Fe3O4 MNPs sized at 15 nm were characterized by the transmission electron microscope (TEM), the superconducting quantum interference device (SQUID) magnetometer, and the multiple behavior tests for novel tank, mirror biting, conspecific social interaction, shoaling, circadian rhythm, and short-term memory of zebrafish under MNPs chronic exposure were demonstrated. Low concentration MNP exposure did not trigger alteration for majority behavioral and biochemical tests in adult zebrafish. However, tight shoal groups were observed at a high concentration of MNPs exposure along with a modest reduction in fish exploratory behavior and a significant reduction in conspecific social interaction behavior. By using enzyme-linked immunosorbent assays (ELISA), we found a high dose of MNPs exposure significantly elevated cortisol, acetylcholine, and catalase levels while reducing serotonin, acetylcholine esterase, and dopamine levels in the brain. Our data demonstrates chronic MNPs exposure at an environmentally-relevant dose is relatively safe by supporting evidence from an array of behavioral and biochemical tests. This combinational approach using behavioral and biochemical tests would be helpful for understanding the MNPs association with anticipated colloids and particles effecting bioavailability and uptake into cells and organisms.

Highlights

Magnetic nanoparticles (MNPs) are approximately 1 to 100 nm in size with Fe, Co, Ni, and Al as the core with the crystal structure, physiochemical properties, and magnetic properties [1,2,3]
The toxicity of Fe3O4 Magnetic Nanoparticles (MNPs) is explained to be dependent on its surface coating and tissue examined, e.g., transcriptome sequence analysis to liver and gill transcriptomes of adult zebrafish on exposure to bare and starch-coated MNPs for seven days resulted in significant changes in a differentially expressed genes (DEGs) profile of both tissues [7]
With a superconducting quantum interference device (SQUID) magnetometer analysis, we obtained the hysteresis curve where applied magnetics field 30 Oe resulted in zero coercivity and remanence indicating no hysteresis in magnetization and good quality of the superparamagnetic MNPs (Figure 1C) [40]

Summary

Introduction

Magnetic nanoparticles (MNPs) are approximately 1 to 100 nm in size with Fe, Co, Ni, and Al as the core with the crystal structure, physiochemical properties, and magnetic properties [1,2,3]. Bare MNPs tend to form large aggregates in fluids, which impedes their utility [6]. To avoid the aggregation of MNPs, a polymer (e.g. starch, dextran etc.) coating is applied over MNPs. The diffusion of surface-coated MNPs in fluids have been reported [3,7]. The toxicity of Fe3O4 MNPs is explained to be dependent on its surface coating and tissue examined, e.g., transcriptome sequence analysis to liver and gill transcriptomes of adult zebrafish on exposure to bare and starch-coated MNPs for seven days resulted in significant changes in a differentially expressed genes (DEGs) profile of both tissues [7]. The regime of MNPs is gaining attention rapidly, but the ecotoxicity of MNPs is still under apprehension, including influence of environmental factors on bioavailability of MNPs and its uptake mechanism in the organism [9]

Results

Discussion

Conclusion