Fabrication of a Micellar Supramolecular Hydrogel for Ocular Drug Delivery.

In this paper, we describe a simple method for constructing a micellar supramolecular hydrogel, composed of a low-molecular-weight methoxy poly(ethylene glycol) (Mn = 2000 Da) block polymer and α-cyclodextrin (α-CD), for topical ocular drug delivery. Adding aqueous block polymer micelles into an α-CD aqueous solution resulted in the formation of a micellar supramolecular hydrogel through host-guest inclusion. The effects of the drug payload, block polymer, and α-CD concentrations as well as the block polymer structure on gelation time were investigated. The resultant micellar supramolecular hydrogels were thoroughly characterized by X-ray diffraction, rheological studies, and scanning electron microscopy. The hydrogels exhibited thixotropic properties, which are beneficial to ocular drug delivery. In vitro release studies indicated that the α-CD concentration strongly influenced the release rate of diclofenac (DIC) from supramolecular hydrogel. The hydrogels showed relatively low cytotoxicity toward L-929 and HCEC cells and did not significantly affect the migration of the latter after 24 h incubation. The hydrogel was nonirritant toward the rabbit eye, as indicated by the Draize test, fluorescein staining, and histological observation. Nile Red-labeled micellar supramolecular hydrogel showed that it could significantly extend the retention time on the corneal surface in rabbits, compared with a plain micellar formulation. In vivo pharmacokinetics indicated that the hydrogel could greatly improve ocular drug bioavailability, compared with that of micellar formulation. Our results suggest that the micellar supramolecular hydrogel is a promising system for ocular drug delivery.

Pose-Aware 3D Talking Face Synthesis using Geometry-guided Audio-Vertices Attention.

Most of the existing 3D talking face synthesis methods suffer from the lack of detailed facial expressions and realistic head poses, resulting in unsatisfactory experiences for users. In this paper, we propose a novel pose-aware 3D talking face synthesis method with a novel geometry-guided audio-vertices attention. To capture more detailed expression, such as the subtle nuances of mouth shape and eye movement, we propose to build hierarchical audio features including a global attribute feature and a series of vertex-wise local latent movement features. Then, in order to fully exploit the topology of facial models, we further propose a novel geometry-guided audio-vertices attention module to predict the displacement of each vertex by using vertex connectivity relations to take full advantage of the corresponding hierarchical audio features. Finally, to accomplish pose-aware animation, we expand the existing database with an additional pose attribute, and a novel pose estimation module is proposed by paying attention to the whole head model. Numerical experiments demonstrate the effectiveness of the proposed method on realistic expression and head movements against state-of-the-art methods.

Combination of dexamethasone and Avastin® by supramolecular hydrogel attenuates the inflammatory corneal neovascularization in rat alkali burn model.

Corneal neovascularization (CNV) is one of the leading causes of vision loss and a high-risk factor for transplant rejection. The present study proposed a supramolecular hydrogel comprised of MPEG-PCL micelles and α-cyclodextrin (α-CD) for co-delivery of dexamethasone sodium phosphate (Dexp) and Avastin® (Ava), and further evaluated its therapeutic efficacy in rat alkali burn model. A physical mixing of Dexp/Ava, MPEG-PCL micelles, and α-CD aqueous solution leads to a spontaneous formation of the supramolecular hydrogel via a "host-guest" recognition between MPEG and α-CD. The supramolecular hydrogel provides a relatively quick release of Dexp over Ava during the study of the 5-day in vitro release. The results of in vitro cytotoxicity test and wound healing assay illustrated that the proposed supramolecular hydrogel was non-toxic against L-929 and HCEC cells and did not significantly affect the migration of HCEC cells after 24h incubation. The corneal distribution test suggested that the precorneal duration of Ava was significantly extended by the supramolecular hydrogel with respect to its solution formulation. Moreover, the supramolecular hydrogel showed high ocular biocompatibility and was a non-irritant after topical instillation. Furthermore, the Dexp-Ava hydrogel medication, but not by Ava solution and Ava hydrogel medication, could greatly attenuate the alkali burn-induced corneal inflammation and remarkably suppress the corneal neovascularization via the downregulation of VEGF, CD31, and α-SMA expression in the rat alkali burn model. As a result, the combined Dexp and Ava by supramolecular hydrogel exhibited an advantage over Ava monotherapy approach, which might be a promising alternative therapy for inflammatory CNV.

Intravitreal injection of rapamycin-loaded polymeric micelles for inhibition of ocular inflammation in rat model.

The therapeutic efficacy of rapamycin conjugated monomethoxy poly(ethylene glycol)-poly(ε-caprolactone) (MPEG-PCL) micelles (rapamycin micelles) was evaluated in a rat experimental autoimmune uveitis (EAU) model. Rapamycin micelles exhibited spherical morphology and had a mean particle size of 40nm and a zeta-potential of -0.89mv. The water solubility of rapamycin improved by more than 1000-fold in a micellar formulation. Intravitreal injection of MPEG-PCL micelles did not result in vitreous hemorrhage or retinal detachment. Fluorescence microscopy demonstrated that labeled micelles localized to the retinal pigment epithelium for at least 14 days following injection and the drug concentration of rapamycin micelles in the retinal tissue was significantly higher than unconjugated rapamycin over this period. At the optimal concentration of rapamycin micelles (9µg/eye), clinical signs of EAU were abolished via the downregulation of the Th1 and Th17 response. There were no significant difference in T cell proliferation and delayed-type hypersensitivity between the treatment and control groups, suggesting that the therapeutic effect of rapamycin manifested locally in the eye and not systemically. These results indicate that intravitreal injection of rapamycin micelles is a promising therapy for controlling sterile intraocular inflammation.