High modulus hydrogels for ophthalmic and related biomedical applications

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Ophthalmic Materials

Background:

• Semi-interpenetrating polymer network (SIPN) hydrogels offer tunable properties for biomedical applications.
• Ester-based polyurethane (EBPU) is a versatile polymer base for hydrogel development.
• Ophthalmic devices like keratoprostheses and specialized contact lenses require advanced hydrogel materials.

Purpose of the Study:

• To synthesize and characterize novel SIPN hydrogels for potential use in keratoprosthesis, orthokeratology, and mini-scleral lenses.
• To investigate the influence of EBPU content on the water content, mechanical properties, and surface energy of the synthesized hydrogels.
• To evaluate the suitability of these EBPU-based SIPN hydrogels for specific ophthalmic applications based on their material properties.

Main Methods:

• Free-radical polymerization was employed to synthesize three families of SIPN hydrogels.
• Hydrogel sheets were characterized for equilibrium water content, mechanical properties (stiffness), and surface free energy.
• The composition was varied with EBPU content ranging from below 10% to above 15%.

Main Results:

• Optically clear SIPN hydrogels were successfully synthesized with EBPU content exceeding 10% and water content ranging from 30% to 70%.
• Hydrogels with ≤15% EBPU showed minimal changes in mechanical properties and surface energy, while >15% EBPU significantly increased stiffness and decreased the polar component of surface free energy.
• The synthesized EBPU SIPN hydrogels exhibit a range of complementary material properties suitable for various ophthalmic applications.

Conclusions:

• EBPU-based SIPN hydrogels can be tailored for specific ophthalmic applications by controlling EBPU concentration.
• The developed hydrogels demonstrate promising characteristics for use as keratoprostheses, orthokeratology lenses, and mini-scleral lenses.
• These findings contribute to the development of advanced biomaterials for ocular surface reconstruction and vision correction.