Feasibility study of astaxanthin-loaded nanoparticles targeting neurons

Abstract

Objective In order to improve the problems about poor water solubility of astaxanthin (ATX), Fe3O4 nanoparticles (NPs) were used to encapsulate ATX and evaluate its targeted aggregation by cortical cultured neurons in vitro. Methods The Fe3O4 nanoparticles were synthesized by a thermal decomposition method. For the formulation of astaxanthin nanoparticles (ATX-NPs), ATX was directly absorbed on the particle surfaces and encapsulated with polyethylene glycol (PEG) by hydrophobic interaction. In order to target neurons, transferrin was effectively conjugated with ATX-NPs by Carbodiimide method. Then, we used transmission electron microscopy (TEM) for observation and dynamic light scattering (DLS) for particle size and zeta-potential. In vitro experiment, primary neurons were cultured from the embryonic cortex of C57BL/6 mice aged 16-18 d of gestation. Lactate dehydrogenase (LDH) kit was used to study the toxic effect of ATX-NPs on neurons. Next, TEM, laser confocal fluorescence microscopy (LSCM) and flow cytometry were used to investigate the effect of ATX-NPs targeting neurons. The data was calculated by SPSS 25.0 software. Results According to the TEM, the ATX-NPs were observed to be near-spherical. The constructed ATX-NPs were about 21 nm with Fe3O4 core and zeta potential of -28.8 mV, analyzed by DLS. After incubation with ATX-NPs for 24 h, LSCM showed that ATX-NPs gathered in the cytoplasm of neurons. TEM exhibited that the endosome formed by endocytosis of neurons through transferrin and flow cytometry also confirmed that ATX-NPs distributed in neurons. The LDH assay demonstrated that LDH in medium was not significantly changed by ATX-NPs at different concentrations (F=0.610, P>0.05). Conclusion The constructed ATX-NPs containing transferrin presented both favourable stability and biocompatibility. They were able to target neurons and aggregate as well. Key words: Astaxanthin; Nanoparticles; Transferrin; Primary neurons; Targeting