Synthesis and characterization of soft contact lens based on the combination of silicone nanoparticles with hydrophobic and hydrophilic monomers

Antifouling hydrogel with different mechanisms:Antifouling mechanisms, materials, preparations and applications

Biofouling is a long-standing problem for biomedical devices, membranes and marine equipment. Eco-friendly hydrogels show great potential for antifouling applications due to their unique antifouling characteristics. However, a single antifouling mechanism cannot meet a wider practical application of antifouling hydrogels, combined with multiple antifouling mechanisms, the various antifouling advantages can be played, as well as the antifouling performance and service life of antifouling hydrogel can be improved. For the construction of the antifouling hydrogel with multiple antifouling mechanisms, the antifouling mechanisms that have been used in antifouling hydrogels should be analyzed. Hence, this review focus on five major antifouling mechanisms used in antifouling hydrogel: hydration layer, elastic modulus, antifoulant modification, micro/nanostructure and self-renewal surface construction. The methods of exerting the above antifouling mechanisms in hydrogels and the materials of preparing antifouling hydrogel are introduced. Finally, the development of antifouling hydrogel in biomedical materials, membrane and marine related field is summarized, and the existing problems as well as the future trend of antifouling hydrogel are discussed. This review provides reasonable guidance for the future and application of the construction of antifouling hydrogels with multiple antifouling mechanisms.

Mechanically Enhanced Soft Contact Lenses from Photodimerization Cross-Linking

In this study, we synthesized three novel acrylic monomers with a cinnamate group. We then mixed each monomer with 2-hydroxyethyl methacrylate (HEMA) to prepare soft contact lenses through bulk polymerization. Fourier transform infrared (FT-IR) and UV spectral analyses confirmed that the cinnamate group in the polymer undergoes a photodimerization reaction via UV irradiation. After UV curing, the present lenses stably maintained their shapes even in a water-swollen state and showed significantly improved mechanical properties compared to conventional lenses manufactured using a cross-linking agent. These lenses showed slightly lower water contact angles than the conventional lenses, although the water content was slightly reduced. The present photodimerization cross-linking method was found to be useful in reducing the tearability of soft lenses.

Inorganic-Organic Interpenetrating Network Hydrogels as Tissue-Integrating Luminescent Implants: Physicochemical Characterization and Preclinical Evaluation

Sensors capable of accurate, continuous monitoring of biochemistry are crucial to the realization of personalized medicine on a large scale. Great strides have been made to enhance tissue compatibility of long-term in vivo biosensors using biomaterials strategies such as tissue-integrating hydrogels. However, the low level of oxygen in tissue presents a challenge for implanted devices, especially when the biosensing function relies on oxygen as a measure-either as a primary analyte or as an indirect marker to transduce levels of other biomolecules. This work presents a method of fabricating inorganic-organic interpenetrating network (IPN) hydrogels to optimize the oxygen transport through injectable biosensors. Capitalizing on the synergy between the two networks, various physicochemical properties (e.g., swelling, glass transition temperature, and mechanical properties) are shown to be independently adjustable while maintaining a 250% increase in oxygen permeability relative to poly(2-hydroxyethyl methacrylate) controls. Finally, these gels, when functionalized with a Pd(II) benzoporphyrin phosphor, track tissue oxygen in real time for 76 days as subcutaneous implants in a porcine model while promoting tissue ingrowth and minimizing fibrosis around the implant. These findings support IPN networks for fine-tuned design of implantable biomaterials in personalized medicine and other biomedical applications.

Evaluation of silicone hydrogel contact lenses based on poly(dimethylsiloxane) dialkanol and hydrophilic polymers

Silicone hydrogel lenses were prepared by copolymerizing PDMS-PEGMA macromer (PGP) with various combinations of DMA, NVP, and PEGMA through UV initiated polymerization process. The resultant PGP macromer were characterized by gel permeation chromatography (GPC), and scanning electron microscope (SEM-EDS). Characterization of all the resultant co-polymers included Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), equilibrium water content (EWC), oxygen permeability (Dk), optical transparency, contact angle, mechanical properties, zeta potential, protein deposition, and cytotoxicity. The results show that higher content of hydrophilic polymers increased water uptake ability as well as improved hydrophilicity and modulus of silicone hydrogel lenses; however, oxygen permeability decreased with the decrease of PDMS content (145 barrers of PGP to 37 barrers of DP0). In addition, these silicone hydrogel lenses exhibited relatively optical transparency, anti-protein deposition, and non-cytotoxic according to an in vitro L929 fibroblast assay. Therefore, these silicone hydrogel polymers would be applicable for making contact lens.

Recent Advances in New Copolymer Hydrogel‐Formed Contact Lenses for Ophthalmic Drug Delivery

Pharmaceuticals delivery to the eye sites of interest via the means of contact lenses (CLs) has attracted significant research attention in recent years. Compared with the conventional formulation in eye treatment such as eye drops, CLs administration has shown remarkable advantages in overcoming the challenges involved in ocular drug delivery such as higher bioavailability, longer drug residence and better medication compliance. This review will first detail each of the material components which have been used in the context of CLs, including HEMA, MAA, DMA, NVP, EGDMA, TRIS and PDMS. The pros and cons of each material in tailoring drug release rates of different encapsulated payloads will be discussed, with special focus on their impact on the therapeutic efficiency. In addition, the advancement of recent emerging copolymer CLs hydrogels, originated from these sophisticated monomers with distinct functions, are further summarized into several synthetic strategies in the means of copolymer architecture design and function‐performance relationship in ophthalmic applications. Finally, the possible considerations for future design of multifunctional CLs hydrogels by combing material selection rationales with biological interface science are proposed.

A Novel Approach to Increase the Oxygen Permeability of Soft Contact Lenses by Incorporating Silica Sol

This study presents a novel approach to increase the oxygen permeability of hydrogel by the addition of silica sol. Herein, 2-hydroxyethyl methacrylate (HEMA) was copolymerized with N-vinyl-2-pyrrolidone (NVP) after mixing with silica sol. The resultant hydrogel was subject to characterizations including Fourier-transform infrared (FTIR), equilibrium water content (EWC), contact angle, optical transmittance, oxygen permeability (Dk), tensile test, anti-deposition of proteins, and cytotoxicity. The results showed that with the increase of silica content, the Dk values and Young’s moduli increased, the optical transmittance decreased slightly, whereas the EWC and contact angle, and protein deposition were not much affected. Moreover, the cytotoxicity of the resultant poly(HEMA-co-NVP)-SNPs indicated that the presence of silica sol was non-toxic and caused no effect to the growth of L929 cells. Thus, this approach increased the Dk of soft contact lenses without affecting their hydrophilicity.

The Ophthalmic Performance of Hydrogel Contact Lenses Loaded with Silicone Nanoparticles

In this study, silicone nanoparticles (SiNPs) were prepared from polydimethylsiloxane (PDMS) and tetraethyl orthosilicate (TEOS) via the sol-gel process. The resultant SiNPs were characterized by dynamic light scattering (DLS), transmission electron microscope (TEM), and scanning electron microscope (SEM). These SiNPs were then blended with 2-hydroxyethylmethacrylate (HEMA) and 1-vinyl-2-pyrrolidinone (NVP) before polymerizing into hydrogel contact lenses. All hydrogels were subject to characterization, including equilibrium water content (EWC), contact angle, and oxygen permeability (Dk). The average diameter of SiNPs was 330 nm. The results indicated that, with the increase of SiNPs content, the oxygen permeability increased, while the EWC was affected insignificantly. The maximum oxygen permeability attained was 71 barrer for HEMA-NVP lens containing 1.2 wt% of SiNPs with an EWC of 73%. These results demonstrate that by loading a small amount of SiNPs, the Dk of conventional hydrogel lenses can be improved greatly. This approach would be a new method to produce oxygen-permeable contact lenses.