Graphene oxide reinforced nanocomposite oleogels improves corneal permeation of drugs

Abstract

The research on ocular drug delivery (ODD) has attracted a continual interest of researchers in the last decade. Herein, we propose to develop oleogel-based formulations for ODD applications. A series of novel nanocomposite oleogels of groundnut oil (GNO) and stearic acid (SA) were prepared, which contained graphene oxide (GO) in the concentration range of 0.00 wt% and 0.05 wt%. The pristine oleogel appeared yellowish-white. However, an increment in the GO content correspondingly imparted a black color hue to the oleogels. Confocal microscopy suggested a considerable branching of the fibrillar network of the fat crystals at lower concentrations of GO. FTIR spectroscopy revealed that GO did not tailor the interactions among the functional groups that are present within the different components of the oleogels. The X-ray diffraction study suggested that the oleogel with the highest GO content was the most crystalline in nature and had a low lattice strain. The mechanical stability of the oleogels was significantly increased when the GO concentration was >0.015 wt%. Thermal analysis of the oleogels confirmed the crystallization of SA in different polymorphic forms. Furthermore, the thermal stability of the fat network structure was higher in the nanocomposite oleogels. The rate of crystallization of SA was higher in the GO-containing oleogels. In general, the in vitro release and ex vivo corneal permeation of the model antibacterial drug (Ciprofloxacin HCl) from the prepared oleogels was Fickian diffusion mediated. Oleogel that contained 0.015% of GO exhibited a ~2.00 fold increase in the cumulative percentage of drug release. The cumulative percentage of drug permeation through caprine cornea was increased by ~2.00 folds in the oleogel that contained 0.05% of GO. The prepared oleogels were cytocompatible with human mesenchymal stem cells. The drug-loaded oleogels showed good bactericidal activity against E. coli. In conclusion, GNO/SA/GO-based nanocomposite oleogels were found to have the potential to be explored for ODD applications.