High Refractive Index Inorganic–Organic Interpenetrating Polymer Network (IPN) Hydrogel Nanocomposite toward Artificial Cornea Implants

Abstract

The use of artificial cornea implants has received increasing attention for treating cornea-related diseases and vision errors due to the low side effects. To achieve long-term successful vision correction, stable and biocompatible materials of high refractive index (RI) need to be developed. Herein, we developed an interpenetrating polymer network (IPN) hydrogel containing well-dispersed ZnS nanoparticles (∼3 nm) covalently linked to the first polymer network, poly(2-hydroethyl methacrylate) (PHEMA). The second polymer network used was poly(acrylic acid) (PAA). The resultant ZnS/PHEMA/PAA IPN nanocomposite is clear and transparent at both dry and hydrated states with their RIs measured to be as high as 1.65 and 1.49, respectively. The equilibrium water content of the hydrogel nanocomposite reached 60.2% which is reasonably near to that of cornea. The material exerted minimal cytotoxicity toward primary epidermal keratinocyte cells. The high RI IPN hydrogel nanocomposite developed here might be an excellent candidate for artificial cornea implants.

Polymeric nanobiocomposites for biomedical applications

“…It becomes extremely difficult to treat the defect or diseases associated to the eyes, and to design an implant or drug, which has the biocompatibility and mechanical properties similar to that of the natural eye. [181][182][183] Artificial cornea implants can be made of polymeric nanocomposites of having higher refractive index, 156,184,185 flexibility, 184,185 hydrophilicity, 184,185 and biocompatibility 184,186,187 as similar as that of human cornea. To achieve the refractive index approximately similar to that of natural eye, numerous efforts have been made by employing combination of different types of hydrophilic and hydrophobic copolymers.…”

“…For example, combination of various copolymer of n-butyl methacrylate (BMA), hexa(ethylene glycol) methacrylate (HEGMA) and polyurethane oligomer or interpenetrating polymer network (IPN) complemented with nanoparticles were found to accomplish desired higher level of refractive index so that the nanocomposites to be qualified as ocular implants. 156,184,185,188 Yet another factor that plays crucial part in the development of successful implants is their ability to absorb water. Traditionally, although the polymers selected for ophthalmological implants were able to reach reasonable refractive index, but the implants lacked in water absorption ability and flexibility.…”

“…The primary factor that encourages the researchers to choose hydrogel is its competence in absorbing high percentage of water while upholding the polymeric network structure. 190,191 By exploiting this property, Zhang et al 184,185 designed IPN/hydrogel network on which Zinc nanoparticles are dispersed uniformly by free radical co-polymerization method. These nanocomposites could be promising ingredients in artificial corneal implants, because they not only exhibit excellent refractive index, high water absorptivity, and only minimum toxicity toward the cells, but also the final composites are transparent and clear.…”

Photocurable Polymer Nanocomposites for Magnetic, Optical, and Biological Applications

“…Zhang and coworkers fabricated artificial cornea implants with ZnS nanoparticles inside two biocompatible polymers, poly(2-hydroethyl methacrylate) and poly(acrylic acid) [70]. They showed that this nanocomposite has a RI as high as 1.65, and performed various in vitro cell viability and cytotoxicity tests.…”

One-pot blue-light triggered tough interpenetrating polymeric network (IPN) using CuAAC and methacrylate reactions

“…16, 30, 31, 41 The brittleness of the pure methacrylate network (i.e., 100% Methacrylate) is clearly evident in Figure 4A with a strain at break of 8.3 ± 1.2% in tension. In the IPN form, the brittle methacrylate network component is reinforced by the tough CuAAC component imparting the high toughness associated with it.…”