Free-standing conductive ultra-thin films based on poly(3,4-ethylenedioxythiophene)/poly (styrenesulfonate) (PEDOT/PSS) are realized. A fabrication process based on a modified Supporting Layer technique is proposed that provides for the easy production of conductive nanofilms having a very large surface area with typical thickness of tens of nanometres. The proposed free-standing nanofilms can be manipulated, folded and unfolded in water many times without suffering from cracks, disaggregation or from loss of conductive properties. After collecting them onto rigid or soft substrates, they retain their functionality. Structural and functional properties of the nanofilms are described by means of their thickness, topography, conductivity and Young's modulus. Strong dependences of these properties on residual water, post-deposition treatments and environmental moisture are clearly evidenced. Possible applications are foreseen in the field of sensing and actuation, as well as in the biomedical field, e.g. as smart substrates for cell culturing and stimulation.

Most polymers solidify below a glass transition temperature (T g), which is important for the fabrication of polymeric materials. The glass transition dynamics (GTD) of polymers alters their physical properties and therefore the range of applications suitable for the particular materials. In this regard, most GTD studies were oriented to the thermodynamics of amorphous polymer systems, while little studies were known for semicrystalline polymers. Here, we focus on the glassy and crystalline properties of semicrystalline polymers such as poly(l-lactic acid) (PLLA) and envisage to control the nanostructure of free-standing PLLA ultrathin films (referred as “PLLA nanosheets”), via thermodynamic rearrangement of polymer chains entangled in a quasi-two-dimensional interface during the GTD process. The annealing process on the PLLA nanosheets (<100 nm thick) resulted in the formation of semicrystalline domains and microscopic apertures with polymer chains (∼100 nm in size). Such nanostructure surprisingly induced selective molecular permeability, which was controlled as a function of film thickness and inherent crystallinity. The present methodology demonstrates the direct conversion of thermodynamic properties of semicrystalline polymers into the functional nanostructured polymeric materials.

Age‐related macular degeneration (AMD) is the leading cause of severe vision impairment in patients over the age of 60 years. Choroidal neovascularization (CNV) is the hallmark of neovascular AMD and vascular endothelial growth factor (VEGF) plays a causal role in the formation of CNV. Although regorafenib and pazopanib, small molecule VEGF receptor (VEGFR) inhibitors, were developed as eye‐drops, their efficacies were insufficient in clinical. In this study, we evaluated ocular pharmacokinetics and pharmacological activities of regorafenib and pazopanib after ocular instillation in multiple animal species. In rats, both regorafenib and pazopanib showed high enough concentrations in the posterior eye tissues to inhibit VEGFR. In laser‐induced rat CNV model, regorafenib showed clear reduction in CNV area. On the other hand, the concentrations of regorafenib and pazopanib in the posterior eye tissues were much lower after ocular instillation in rabbits and monkeys compared to those in rats. Pazopanib did not show any improvement in monkey model. Regorafenib was nano‐crystalized to improve its drug delivery to the posterior eye tissues. The nano‐crystalized formulation of regorafenib showed higher concentrations in the posterior segments in rabbits compared to its microcrystal suspension. From these studies, large interspecies differences were found in ocular delivery to the posterior segments after ocular instillation. Such large interspecies difference could be the reason for the insufficient efficacies of regorafenib and pazopanib in clinical studies. Nano‐crystallization was suggested to be one of the effective ways to overcome this issue.

Citation: Kashiwagi K, Ito K, Haniuda H, Ohtsubo S, Takeoka S. Development of latanoprost-loaded biodegradable nanosheet as a new drug delivery system for glaucoma. Invest Ophthalmol Vis Sci. 2013;54:5629-5637. DOI:10.1167/iovs.12-9513 PURPOSE. We investigated the IOP reduction and safety of latanoprost-loaded biodegradable nanosheet (LBNS) as a new antiglaucoma drug delivery system (DDS).METHODS. We fabricated a 40 nm thick multilayered biodegradable nanosheet that is composed of chitosan and sodium alginate by means of the layer-by-layer method. Latanoprost isopropyl ester was loaded on the nanosheet to prepare 25, 2.5, and 0.25 lg/ cm 2 LBNSs. A nanosheet without latanoprost isopropyl ester (NS) and 0.005% latanoprost ophthalmic solution were prepared as controls. LBNSs or NS was applied to rat cornea, and IOP was monitored for 9 days. Local adverse effects and eye scratching movement also were investigated. The amount of latanoprost acid in aqueous humor and was measured in rabbits.RESULTS. The 0.25 lg/cm 2 LBNS and 0.005% latanoprost ophthalmic solution showed significant IOP reduction only for 1 day after application, whereas the IOP reduction rates of 2.5 lg/cm 2 LBNS at 1, 2, 4, 7, and 9 days after application were À27.0% 6 14.8%, À22.0% 6 16.7%, À25.8% 6 18.0%, À22.7% 6 20.9%, and À6.6% 6 17.0%, respectively. The 25 lg/cm 2 LBNS reduced IOP in a similar manner. The 25 lg/cm 2 LBNS induced transient hyperemia, whereas the 0.25 and 2.5 lg/cm 2 LBNSs did not exert any local adverse effects. The eye scratching movement test showed that application of 25 lg/cm 2 LBNS did not cause any irritation of the eye. Latanoprost acid was detected in aqueous humor up to 6 days after application of 2.5 lg/cm 2 LBNS.CONCLUSIONS. LBNS may be used as a novel antiglaucoma DDS.

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