Arrested Phase Separation Enables High‐Performance Keratoprostheses

Abstract

but donor cornea is scarce, [2] leading to delayed intervention and an increased probability of visual loss. [3] Furthermore, many patients cannot tolerate the donor cornea owing to repeated graft failure, autoimmune diseases, and ethical reservations. [4] To address these issues, effort has been devoted to exploring potential artificial corneas (keratoprostheses). [2] The prevailing keratoprosthesis approaches are either a pre-made synthetic prosthesis for restoring vision or a tissue-engineering scaffold for generating new tissue in situ. [5] Although tissue-engineered keratoprostheses can effectively regenerate the damaged cornea tissues, it is not free of ethical conundrums, and the immune rejection of the matrix's natural or artificial and donated cells can occur. [4b,6] In contrast, the completely synthetic cornea substitutes are merely constructed by synthetic materials, and thus overcome both sociocultural and policy difficulties in addition to avoiding viral invasion and immune rejection, [5,7,8] From the perspective of materials science, an optimal substrate for a synthetic cornea should combine vital features (Figure 1a) such as transparency for vision, processability for personalized geometry and size, [9] permeability for oxygen and nutrient transportation, and robustness to withstand the mechanical and environmental Corneal transplantation is impeded by donor shortages, immune rejection, and ethical reservations. Pre-made cornea prostheses (keratoprostheses) offer a proven option to alleviate these issues. Ideal keratoprostheses must possess optical clarity and mechanical robustness, but also high permeability, processability, and recyclability. Here, it is shown that rationally controlling the extent of arrested phase separation can lead to optimized multiscale structure that reconciles permeability and transparency, a previously conflicting goal by common pore-forming strategies. The process is simply accomplished by hydrothermally treating a dense and transparent hydrophobic association hydrogel. The examination of multiscale structure evolution during hydrothermal treatment reveals that the phase separation with upper miscibility gap evolves to confer time-dependent pore growth due to slow dynamics of polymer-rich phase which is close to vitrification. Such a process can render a combination of multiple desired properties that equal or surpass those of the state-of-the-art keratoprostheses. In vivo tests confirm that the keratoprosthesis can effectively repair corneal perforation and restore a transparent cornea with treatment outcomes akin to that of allo-keratoplasty. The keratoprosthesis is easy to access and convenient to carry, and thus would be an effective temporary substitute for a corneal allograft in emergency conditions.

Strain-Stiffening Transparent Hydrogel: Integrating Mechanical Adaptability and Solar Polarization Positioning

“…It was found that both samples exhibited high transmittance in the visible light range (Figure a) with a low haze (∼0.15, Figure S8). This high transmittance is attributed to the absence of pores caused by solvent evaporation under low-humidity conditions , (Figure b), which prevents light scattering-induced transmittance loss. The prestretching and cross-linking step, however, influences the orientation of the hydrogel, imparting unique birefringent properties to the APO-6–10 hydrogel.…”

“…Figure shows a brief description of the preparation process. First, C8–0.1 was dissolved in DMF and then exposed to low humidity (RH ∼ 17%) to approach gelation. , Then, the resultant hydrogel was stretched n times and soaked in glutaraldehyde for t minutes for cross-linking.…”

Engineering a polyvinyl butyral hydrogel as a thermochromic interlayer for energy-saving windows

“…The formation of a biphasic structure arises from the collapse of the thermoresponsive segments. 47 Additionally, the arrangement and (topological or cohesive) entanglement of the alkyl side chains function as sticky groups to associate polymers, predominantly governing the viscoelasticity of networks, as per the established model of associating polymers. 50 Below the LCST, scanning electron microscopy (SEM) analysis revealed that the FIRST hydrogel appears compact at a scale of approximately 100 nm to micrometers.…”

“…38 In previous works, we have explored the synthesis and application of a series of PVB analogues. 46,47 In the network-forming process, the alkyl side chains in these polymers coalesce following a This journal is © The Royal Society of Chemistry 2024 nucleation-growth mechanism, giving rise to hydrophobic nano-nodules. 48 The nucleation occurs in random order, resulting in hydrophobic nano-nodules with dispersed sizes.…”

“…S1, ESI †). 47 Moreover, the polymer-rich phase can form agglomerates resembling glass-like domains, which often retards the required phase transition (Supplementary Note 3 and Fig. S2, ESI †).…”