EVALUATION OF GROWTH ENHANCEMENT AND TOXICITY OF ASTAXANTHIN-LOADED SOLID LIPID NANOPARTICLES IN Artemia sp.

Introduction

Astaxanthin (ASTX) is a carotenoid extensively used in aquaculture because of its antioxidant activity and pigmentation properties. However, its application is limited by poor water solubility and susceptibility to degradation under environmental conditions. Solid lipid nanoparticles (SLNs) have emerged as promising carriers capable of improving the stability and delivery of lipophilic compounds. This study aimed to develop ASTX-loaded SLNs and evaluate their physicochemical characteristics, toxicity, and biological effects in Artemia sp.

Materials and Methods

SLNs composed of stearic acid and Tween 20 were synthesized and loaded with ASTX. Nanoparticles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential analysis, and Fourier-transform infrared spectroscopy (FTIR). Toxicity was assessed through acute exposure assays to determine median lethal concentrations (LC50). Growth performance was evaluated by measuring body length and width, while oxidative status and metabolic activity were determined through reactive oxygen species (ROS) production and electron transport system (ETS) activity, respectively.

Results

The developed formulation achieved an ASTX concentration of 0.47 mg mL^-1 and an encapsulation efficiency of 87.3%. TEM analysis revealed nanoparticles with an average diameter of 45.0 ± 1.4 nm, whereas DLS and zeta potential measurements indicated satisfactory colloidal stability. FTIR spectra confirmed the successful incorporation of ASTX into the lipid matrix. Acute toxicity assays resulted in LC50 values of 0.21 mg mL^-1 for unloaded SLNs and 0.13 mg mL^-1 for ASTX-loaded SLNs. Despite the increased toxicity associated with the encapsulated formulation, exposure to a sublethal concentration of 0.06 mg ASTX mL^-1 significantly enhanced both body length and width in Artemia compared with the control group. No significant differences were observed in ETS activity among treatments. In contrast, ROS production was influenced by nanoparticle composition, with unloaded SLNs inducing a pro-oxidant response and ASTX-loaded SLNs reducing oxidative stress at intermediate concentrations.

Figure 1. Carotenoid content of Artemia sp. nauplii after 24 h exposure to increasing concentrations of astaxanthin-loaded solid lipid nanoparticles (ASTX-SLNs).

Conclusion

ASTX-loaded SLNs improved growth performance and contributed to oxidative balance in Artemia sp. when applied at concentrations below 0.12 mg ASTX mL^-1. These findings demonstrate the potential of lipid-based nanoformulations as innovative delivery systems for bioactive compounds in aquaculture, supporting their future application in nutritional and functional feeding strategies.

Acknowledgment

This study was funded by Foundation for Research Support of the State of Rio Grande do Sul – FAPERGS (process number: 24/2551-0002352-6).

References

Gulcin, I. Antioxidants: a comprehensive review. Archives of Toxicology, v. 99, n. 5, p. 1893-1997, 2025.

Kamalakannan, M., Rajendran, D., Thomas, J., & Chandrasekaran, N. Synergistic impact of nanoplastics and nanopesticides on Artemia salina and toxicity analysis. Nanoscale Advances, v. 6, n. 12, p. 3119-3134, 2024.