Abstract
PurposeTo evaluate titanium (Ti) sputtering of the poly(methyl methacrylate) (PMMA) stem of the Boston Keratoprosthesis (BK) as a method to enhance interfacial adhesion between the PMMA and the recipient corneal tissue.MethodsPMMA specimens were plasma treated with Ar/O2 and coated with Ti using a DC magnetron sputtering instrument. The topography and hydrophilicity of the surfaces were characterized using atomic force microscopy and a water contact angle instrument, respectively. Scratch hardness and adhesion of the Ti film were measured using a mechanical tester. Biocompatibility assessments were performed using cultured human corneal fibroblasts and whole blood ex vivo. The optical quality of the Ti sputtered BK was evaluated using a custom-made optical bench.ResultsBy contact angle studies, the Ti coating improved PMMA hydrophilicity to match that of medical-grade Ti (Ti-6Al-4V-ELI). Ti sputtering of contact surfaces resulted in a plate-like morphology with increased surface roughness, without impacting the transparency of the BK optical component. Scratch testing indicated that the mechanical behavior of the Ti coating was similar to that of casted Ti, and the coating was stable in pull-off adhesion testing. Sputtered Ti film was highly biocompatible based on tests of cell viability, adhesion, proliferation, differentiation, collagen deposition, and keratocan expression, the properties of which exceeded those of uncoated PMMA and did not induce increased complement activation.ConclusionsTitanium coating of the BK stem generated a mechanically and biologically favorable interface, which may help to enhance corneal stromal adhesion and biocompatibility.Translational RelevanceImproving the biocompatibility of the BK PMMA stem may improve long-term outcomes of implantation.
Highlights
The Boston Keratoprosthesis (BK) is composed of a front plate/stem made of poly(methyl methacrylate) (PMMA) and a back plate made of PMMA or titanium (Ti), assembled in bolt (PMMA front plate/stem) and nut (Ti back plate) fashion within a donor cornea that serves as a carrier; the donor cornea is sutured to the eye as in standard corneal transplantation.[13,14,15]
Our findings suggest that Ti sputtering on the BK stem may help corneal tissue adhesion and have the potential to improve clinical outcomes in patients with an implanted BK device
Our studies demonstrate that plasma treatment and Ti sputtering of the PMMA stem can be accomplished without negatively impacting the optical properties of the device
Summary
The Boston Keratoprosthesis (BK) is a medical device indicated for patients with corneal blindness not amendable to standard corneal transplantation.[1,2,3,4,5,6,7,8,9,10,11,12] The BK is composed of a front plate/stem (optical portion) made of poly(methyl methacrylate) (PMMA) and a back plate made of PMMA or titanium (Ti), assembled in bolt (PMMA front plate/stem) and nut (Ti back plate) fashion within a donor cornea that serves as a carrier; the donor cornea is sutured to the eye as in standard corneal transplantation.[13,14,15] The BK is globally the most commonly implanted artificial. TVST | December 2020 | Vol 9 | No 13 | Article 41 | 2. To improve the interfacial adhesion, numerous surface modification approaches have been proposed, including biomineralization of hydroxyapatite (HAp) onto the PMMA surface,[17] calcium phosphate coating (dCaP),[18] TiO2 nanoparticle dip coating,[19] TiO2 coating over a layer of polydopamine,[20] covalent functionalization with l-3,4-dihydroxyphenylalanine (l-DOPA),[21] and nanopatterning with cell adhesive peptides.[22]
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