Penetration of silicate nanoparticles into the corneal stroma and intraocular fluids.

PURPOSE: The aim of this study was to investigate transmission of topical silicate nanoparticles (SiNPs) through the corneal stroma, anterior chamber, and vitreous fluids by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and inductively coupled plasma atomic emission spectrometry (ICP-AES), respectively.

METHODS: SiNPs with a mean diameter of 40.6 ± 5.6 nm determined by dynamic light scattering were used in this study. The permeability of SiNPs was examined across isolated corneal buttons over a 30-minute period. To visualize the transport and diffusion of nanoparticles through the corneal tissue, SiNPs were applied over the corneal surface and evaluated at 5 and 30 minutes after SiNPs loading for SEM and 15 minutes for TEM. Sections of 10-μm thickness were cut and visualized using SEM. TEM study was performed on 70- to 90-nm-thick sections. ICP-AES was used to determine the concentration of SiNPs.

RESULTS: The determined range of synthesized SiNPs by dynamic light scattering was 40 nm (41.9 ± 5.6 nm). Transmission of SiNPs through the corneal stroma was shown successfully with electron microscopic (SEM and TEM) images. The ICP-AES results revealed SiNPs in the anterior chamber and vitreous fluid.

CONCLUSIONS: Topical administration of SiNPs, as a noninvasive, and available modality with acceptable penetration through the corneal stroma and deep into the intraocular fluids including the anterior chamber and vitreous cavity, may be considered as a suitable alternative to invasive intravitreal injection of other expensive antineovascularization agents.