Surface Modification of PMMA to Improve Adhesion to Corneal Substitutes in a Synthetic Core–Skirt Keratoprosthesis

Abstract

Patients with advanced corneal disease do poorly with conventional corneal transplantation and require a keratoprosthesis (KPro) for visual rehabilitation. The most widely used KPro is constructed using poly(methyl methacrylate) (PMMA) in the central optical core and a donor cornea as skirt material. In many cases, poor adherence between the PMMA and the soft corneal tissue is responsible for device "extrusion" and bacterial infiltration. The interfacial adhesion between the tissue and the PMMA was therefore critical to successful implantation and device longevity. In our approach, we modified the PMMA surface using oxygen plasma (plasma group); plasma followed by calcium phosphate (CaP) coating (p-CaP); dopamine followed by CaP coating (d-CaP); or plasma followed by coating with (3-aminopropyl)triethoxysilane (3-APTES). To create a synthetic KPro model, we constructed and attached 500 μm thick collagen type I hydrogel on the modified PMMA surfaces. Surface modifications produced significantly improved interfacial adhesion strength compared to untreated PMMA (p < 0.001). The p-CaP group yielded the best interfacial adhesion with the hydrogel (177 ± 27 mN/cm(2)) followed by d-CaP (168 ± 31 mN/cm(2)), 3-APTES (145 ± 12 mN/cm(2)), and plasma (119 ± 10 mN/cm(2)). Longer-term stability of the adhesion was achieved by d-CaP, which, after 14 and 28 days of incubation in phosphate buffered saline, yielded 164 ± 25 mN/cm(2) (p = 0.906 compared to adhesion at day 1) and 131 ± 20 mN/cm(2) (p = 0.053), respectively. In contrast, significant reduction of adhesion strength was observed in p-CaP group over time (p < 0.001). All surface coatings were biocompatible to human corneal stromal fibroblasts, except for the 3-APTES group, which showed no live cells at 72 h of culture. In contrast, cells on d-CaP surface showed good anchorage, evidenced by the expression of focal adhesion complex (paxillin and vinculin), and prominent filopodia protrusions. In conclusion, d-CaP can not only enhance and provide stability to the adhesion of collagen hydrogel on the PMMA surface but also promote biointegration.

Fabrication of Polymerase Chain Reaction Plastic Lab-on-a-Chip Device for Rapid Molecular Diagnoses

“…Pristine PMMA ( Fig. 3A ) exhibited spectral regions around 1,080–1,202, 1,232–1,274, and 1,725/cm, which corresponded to the presence of C–O–C, C–O, and C=O stretching vibrations of the ester group, respectively [ 29 - 31 ]. Absorption bands corresponding to the –CH 2 twisting modes of PMMA appeared around 760–960/cm.…”

Fabrication and investigation of high-quality glass-ceramic (GC)–polymethyl methacrylate (PMMA) composite for regenerative medicine

“…The results clearly point out that with increase of PMMA content the intensity of vibrational modes of PMMA (bands located at 1656, 1595, 1228 and 1192 cm À1 ) also increases. Furthermore, the intense PMMA band cantered at 1722 cm À1 assigned to the C]O stretching vibrations 17,35 disappears in the spectra of GC-PMMA composites. Moreover, to see if spectral features of the composite surface vary from the bulk material the FTIR spectra from the powdered composites (pellets were grinded in an agate mortar) were additionally recorded.…”

“…For instance, it is not biodegradable, the surface properties of PMMA are unfavourable for tissue adhesion and the tissues damage around cement surface due to thermal necrosis caused by PMMA polymerization and residual liquid monomer may also occur. [15][16][17] Several PMMA-bioceramic composites have been studied as alternatives to PMMA with objective to improve bioactivity and accelerate bone restoration. For instance, to improve the ller/ cement interface the b-tricalcium phosphate (b-TCP) has been encapsulated with poly(ethylene glycol) (PEG) and later incorporated to a poly(methyl methacrylate) bone cement.…”

PMMA Surface Functionalization Using Atmospheric Pressure Plasma for Development of Plasmonically Active Polymer Optical Fiber Probes

“…Plasma treatment has several advantages: (a) modification of the top nanometer layer of the polymer without changing the bulk properties, (b) surface activation without generation of chemical wastes unlike wet-chemical methods, and (c) ability to obtain a variety of surface functional groups with different densities by varying the process parameters and working gases. A number of studies based on plasma treatment on PMMA has already been conducted, mainly to increase the surface free energy and hence improve the adhesive properties of the polymer [12][13][14]. Further studies on optimum process parameters, electrode configurations [15], process gas selection [16], and ageing [17] of plasma treatment for PMMA have been carried out.…”