Role of molecular weight of atactic poly(vinyl alcohol) (PVA) in the polarizing efficiency of PVA/azo dye complex film with high durability

Preparation and Evaluation of Nanofibrous and Film-Structured Ciprofloxacin Hydrochloride Inserts for Sustained Ocular Delivery: Pharmacokinetic Study in Rabbit’s Eye

Conventional anti-infective eye drops are the most common forms of drugs prescribed for the management of topical ocular infections. Despite their convenience, topical eye drops face multiple challenges, including limited bioavailability and repetitive administration. The present study aimed to prepare, evaluate, and compare film-structured and nanofibrous ocular inserts using biocompatible polymers of polyvinyl alcohol (PVA) and polycaprolactone (PCL) to achieve sustained ciprofloxacin Hydrochloride (CIP) delivery. The nanofibrous formulations were prepared by electrospinning and glutaraldehyde crosslinking while the film formulation was prepared by solvent casting. Nanofibrous inserts had mean diameters in the range 330–450 nm. Both film and nanofibrous inserts were strong, although the nanofibers had higher flexibility. In vitro antibacterial efficacy against Staphylococcus aureus and Escherichia coli was observed for all formulations and cell viability of more than 70% confirmed their non-toxicity. In vitro release studies showed prolonged release of 2 days for the film and 5 days for the nanofibers compared with a 10-h release of CIP from the eye drop. Pharmacokinetic studies of rabbits’ eyes showed 4.5–5-folds higher AUC for the nanofiber formulations compared with the eye drop. Thus, prolonged-release film-structured and nanofibrous inserts are suitable carriers for ocular delivery of CIP.

An active carbon-nanotube polarizer-embedded electrode and liquid-crystal alignment

We report a method for constructing an active optical polarizer using an aligned carbon nanotube (CNT) sheet that is flexible, bendable, transparent, conductive, and also serves to anchor liquid-crystal (LC) molecules. A horizontally aligned CNT sheet was obtained by mechanical stretching from a vertically grown CNT forest, which was then transferred onto a substrate. A liquid polymer was infiltrated into the CNT sheet followed by UV curing, while a part of the CNT sheet was still exposed on the film surface without polymer coating. The polymer-embedded CNT sheet (P-ECS) film with 10 layers of CNT sheets exhibited a good polarization efficiency of 87%, a sheet resistance of 340 Ω□^-1, and excellent ability to align LC molecules. The high stability of the P-ECS film was confirmed from the very low variation of sheet resistance (2%) and transmittance (10%) observed during a bending test of 1000 cycles. In addition, a twisted nematic LC device constructed using the P-ECS films shows a good bright-dark switching performance. The P-ECS film functions simultaneously as a transparent electrode, a film-type polarizer, and a LC alignment layer, demonstrating the multi-functionality of the active CNT film. This study thus highlights a wide range of possible applications for active polarizers and flexible displays.