Graphene Derivatives Coatings for the Prevention of Opacification Due to Calcification of Hydrophilic Intraocular Lenses

The widespread use of hydrophilic intraocular lenses (IOL) in eye surgery, fabricated by poly-2- (hydroxyethylmethacrylic acid) (PHEMA), has highlighted their calcification as a serious problem, which implies their surgical explantation a rather risky process. The field of biomaterials has been developing rapidly in recent years with research interest turning to the development of novel ma-terials which involve either copolymers of PHEMA or protective functional coatings. Graphene coatings are particularly attractive because of the respective unique properties. In the present work we present the results of the investigation of the development of graphene coatings on hydrophilic IOLs and their subsequent performance with respect to calcification opacification. Hydrophilic IOL with water content of 18% by weight, were coated with graphene oxide (GO) by equilibration with GO suspensions in water. The concentrations of the suspensions ranged 1x10-4 to 20x10-4 % w/v. The GO suspensions were equilibrated with the IOLs for 5 days at constant temperature, 37°C, rotated in 30 mL tubes end over end. This treatment, resulted in the formation of a uniform coating of GO on the IOLs verified by scanning electron microscopy (SEM) and other physicochemical methods. The contact angle of the GO coated IOLs decreased significantly in comparison with the uncoated. The GO-coated IOLs exhibited higher tendency to calcify in supersaturated solutions simulating aqueous humor (SAH). The growth rate of hydroxyapatite (Ca5(PO4)3OH, HAP) on GO-coated IOLs was higher, in comparison with the respective untreated IOLs. The conversion of the GO coating by reduction with phenyl hydrazine resulted in the formation of reduced graphene (rGO) surface film, identified by Raman and XPS spectroscopy. of the rGO film was hydrophobic (contact angle 100 o) and did not calcify in supersaturated calcium phosphate solutions.