In this study, the potential of melatonin hormone loaded in nanostructured lipid carriers (Mel-NLCs) in the in vitro fertilization (IVF) environment is investigated by measuring the oocyte maturation, the two-prenucleus embryo development, the two-cell stage embryo development, and blastocyst production on the oocytes of mice. Mel-NLCs are prepared using the hot homogenization-ultrasonication method. A response surface method is utilized to determine the best independent variables to obtain nanoparticles with a small particle size and high hormone entrapment efficiency. The optimized nanoparticles have a particle size of 119 nm with a polydispersity index of 0.09 and hormone entrapment efficiency of 94%. Characterization results such as TEM and AFM analysis confirm the spherical and relatively uniform structure of the optimal sample. FTIR and XRD analyses indicate that the hormone is properly loaded within the amorphous nanostructure. Drug release from NLC under the in vitro environment exhibits a biphasic domain including burst release in the first 2 hours and the controlled release in 48 h 92% of the drug is released from nanoparticles in 48 hours, but the same amount of hormone is released from the marketed drug suspension during 2 hours. Results of IVF experiments reveal that the nanostructured form has a positive effect on all IVF parameters compared to the free form of the hormone. In addition, using the hormone nanostructured form can reduce the dosage of the melatonin free form with the same efficacy in the IVF environment. Finally, the nanostructured form of melatonin based on NLC nanostructure can be a good candidate for application in IVF media.

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