Abstract
A novel nanofiber insert was prepared with a modified electrospinning method to enhance the ocular residence time of ofloxacin (OFX) and to provide a sustained release pattern by covering hydrophilic polymers, chitosan/polyvinyl alcohol (CS/PVA) nanofibers, with a hydrophobic polymer, Eudragit RL100 in layers, and by glutaraldehyde (GA) cross-linking of CS-PVA nanofibers for the treatment of infectious conjunctivitis. The morphology of the prepared nanofibers was studied using scanning electron microscopy (SEM). The average fiber diameter was found to be 123 ± 23 nm for the single electrospun nanofiber with no cross-linking (OFX-O). The single nanofibers, cross-linked for 10 h with GA (OFX-OG), had an average fiber diameter of 159 ± 30 nm. The amount of OFX released from the nanofibers was measured in vitro and in vivo using UV spectroscopy and microbial assay methods against Staphylococcus aureus, respectively. The antimicrobial efficiency of OFX formulated in cross-linked and non-cross-linked nanofibers was affirmed by observing the inhibition zones of Staphylococcus aureus and Escherichia coli. In vivo studies using the OFX nanofibrous inserts on a rabbit eye confirmed a sustained release pattern for up to 96 h. It was found that the cross-linking of the nanofibers by GA vapor could reduce the burst release of OFX from OFX-loaded CS/PVA in one layer and multi-layered nanofibers. In vivo results showed that the AUC0–96 for the nanofibers was 9–20-folds higher compared to the OFX solution. This study thus demonstrates the potential of the nanofiber technology is being utilized to sustained drug release in ocular drug delivery systems.
Highlights
Bacterial conjunctivitis is a common infection, which occurs in patients of all ages and requires emergency treatment
chitosan/polyvinyl alcohol (CS/Polyvinyl alcohol (PVA)) nanofibers dissolve immediately when exposed to water making a substance similar to that of a gelatinous material, which provides an immediate release for the drug used
The high entrapment efficiency is attributed to the technique used which involves the incorporation of OFX into the CS/PVA nanofibers
Summary
Bacterial conjunctivitis is a common infection, which occurs in patients of all ages and requires emergency treatment. Nanofibers have been studied for ocular drug delivery due to their large surface-to-volume ratio. These systems can be introduced into the conjunctival sac with effective contact with the ocular tissue. Chitosan (CS) is a broadly used polymer to design ocular drug delivery systems because of its unique biological properties including antimicrobial activity, biodegradability, and biocompatibility [5]. Polyvinyl alcohol (PVA) is a synthetic polymer which is biodegradable, harmless, and has good biocompatible properties [6]. Electrospinning of CS and its derivatives is feasible by the addition of a flexible polymer such as PVA which can offer advantageous effects on the biological properties of blend fibers [7, 8]. Preparing the water-insoluble nanofibrous mat is desirable and is possible by cross-linking the PVA hydroxyl groups with the CS amino groups using chemical agents such as glutaraldehyde, which is a much more suitable cross-linking agent than other aldehydes [9,10,11]
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