Poly(2-Hydroxyethyl Methacrylate) Hydrogels for Contact Lens Applications–A Review

Novel Trends in Hydrogel Development for Biomedical Applications: A Review

“…pHEMA is a thermoplastic material that is not enzymatically degraded or hydrolyzed by acidic or alkaline solutions. pHEMA hydrogels are inexpensive, have excellent biocompatibility, non-biodegradability, high water content capacity, low thrombogenicity, cytocompatibility, abundant copolymer possibilities, soft materials with excellent temperature stability, acid and alkaline hydrolysis resistance, tunable mechanical properties and an optically transparent hydrophilic polymer that is desirable for various biomedical applications [ 39 , 40 , 128 ]. However, single pHEMA-based hydrogels have little commercial application; thus, numerous studies have been conducted to modify pHEMA structure with the aim of improving its properties, for example, using cross-linking agents such as ethylene glycol dimethacrylate (EGDMA) [ 41 ] and tetra(ethylene glycol) diacrylate (TEGDA) [ 42 , 43 ] to enhance its mechanical properties, or β-cyclodextrin-hyaluronan (β-CDcrHA) to reduce tear protein absorption in a contact lens [ 129 ].…”

“…However, single pHEMA-based hydrogels have little commercial application; thus, numerous studies have been conducted to modify pHEMA structure with the aim of improving its properties, for example, using cross-linking agents such as ethylene glycol dimethacrylate (EGDMA) [ 41 ] and tetra(ethylene glycol) diacrylate (TEGDA) [ 42 , 43 ] to enhance its mechanical properties, or β-cyclodextrin-hyaluronan (β-CDcrHA) to reduce tear protein absorption in a contact lens [ 129 ]. Another approach is to copolymerize pHEMA with other polymers, commonly with polyacrylamide (PAA) [ 130 ] or ethylene glycol dimethacrylate (EGDMA) [ 40 ] to improve its mechanical properties, poly (ethylene glycole) diacrylate (PEGDA) to improve host biosensors or enhance its water absorption capacity [ 131 ], glycidyl methacrylate (GMA) [ 132 ] to facilitate cell attachment and proliferation, or 2-methacryloyloxyethyl phosphorylcholine (MPC) [ 133 ] to improve the water content retention and anti-biofouling properties. Moreover, other possibilities to improve pHEMA-based hydrogels’ performance for biomedical applications include the formation of composites, e.g., pHEMA with boric acid (BA), with interesting applications as soft contact lens material, as reported by Ulu et al (2018) [ 134 ], or the formation of IPNs with gelatin to enhance biological properties for in vitro and in vivo performance [ 135 ].…”

Nano-Titanium Oxide in Polymeric Contact Lenses: Short Communication

“…Finally, Figure 5g shows a more homogeneous distribution of TiO 2 NPs and more surface adhesion with PGMA than with PHEMA [36]. Most medical contact lenses depend in their installation on the use of PHEMA as a basic polymer in their manufacture [37], but the physical problems resulting from it make contact lenses made of them less desirable because of related complications, visual problems, and discomfort it causes when wearing [2].…”