To achieve efficient drug delivery to the posterior segment of the eye via topical instillation, novel multifunctional nanocomposites were prepared by hybridizing dexamethasone disodium phosphate (DEXP)-loaded liposome (LP) glycylsarcosine (GS)-anchored layered double hydroxides (named DEXP-HSPC@LDH-GS) and then fully characterized. The nanocomposites exhibited sustained-release performance as well as prolonged precorneal retention ability. MTT assays showed that the nanocomposites were not cytotoxic to both human corneal epithelial cells (HCEpiC) and human conjunctival epithelial cells (HConEpiC) at an LDH concentration of 100 μg/mL. The DEXP-HSPC@LDH-GS nanocomposites showed superior in vitro permeability on the HConEpiC-cell-based model. In the case of HConEpiC cells, both clathrin-mediated endocytosis and active transport by the peptide transporter-1 (PepT-1) were involved in the internalization of the nanocomposites. Fluorescent images of frozen sections of ocular tissues suggested that the possible route for the delivery of doxorubicin hydrochloride (DOX)-labeled nanocomposites from the ocular surface to the back of the eye was a non-corneal pathway. Furthermore, in rabbit eyes, the hybrid nanocomposites displayed markedly higher drug concentration in choroid-retina tissue than other single nanocarriers, such as LPs and LDH. Besides, the results of the eye irritancy test showed that nanocomposite eye drops can be classified as nonirritant, which are suitable to be used as eye drops. In a word, multifunctional nanocomposites based on LPs and LDH could be used as promising vehicles for efficient noninvasive drug delivery to the posterior segment of the eye.
Keywords: efficient ocular drug delivery; layered double hydroxides (LDH); liposomes; posterior segment of the eye; topical instillation.