Riau Andri K, Venkatraman Subbu S, Dohlman Claes H, Mehta Jodhbir S
*Tissue Engineering and Stem Cell Group, Singapore Eye Research Institute, Singapore;†School of Materials Science and Engineering, Nanyang Technological University, Singapore;‡Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA;§Singapore National Eye Centre, Singapore; and‖Department of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore.
Cornea. 2017 Nov;36 Suppl 1:S15-S25. doi: 10.1097/ICO.0000000000001352.
Biointegration of a keratoprosthesis (KPro) is critical for the mitigation of various long-term postoperative complications. Biointegration of a KPro occurs between the haptic skirt (corneal graft) and the central optic [poly(methyl methacrylate) (PMMA)]. Various studies have highlighted common problems associated with poor bonding and biointegration between these 2 incompatible biomaterials. Resolution of these issues could be achieved by surface modification of the inert material (PMMA). A calcium phosphate (CaP) coating deposited on dopamine-activated PMMA sheets by simulated body fluid incubation (d-CaP coating) was shown to improve adhesion to collagen type I (main component of corneal stroma) compared with untreated PMMA and PMMA with other surface modifications. However, the d-CaP coating could easily undergo delamination, thereby reducing its potential for modification of KPro optical cylinders. In addition, the coating did not resemble the Ca and P composition of hydroxyapatite (HAp). A novel dip-coating method that involves the creation of cavities to trap and immobilize HAp nanoparticles on the PMMA surface was introduced to address the problems associated with the d-CaP coating. The newly obtained coating offered high hydrophilicity, resistance to delamination, and preservation of the Ca and P composition of HAp. These advantages resulted in improved adhesion strength by more than 1 order of magnitude compared with untreated PMMA. With respect to biointegration, human corneal stromal fibroblasts were able to adhere strongly and proliferate on HAp-coated PMMA. Furthermore, the new coating technique could be extended to immobilization of HAp nanoparticles on 3-mm-diameter PMMA cylinders, bringing it closer to clinical application.
角膜假体（KPro）的生物整合对于减轻各种长期术后并发症至关重要。KPro的生物整合发生在触觉裙边（角膜移植片）和中央光学部件[聚甲基丙烯酸甲酯（PMMA）]之间。各种研究都强调了这两种不相容生物材料之间结合不良和生物整合相关的常见问题。这些问题可以通过对惰性材料（PMMA）进行表面改性来解决。通过模拟体液孵育在多巴胺活化的PMMA片材上沉积的磷酸钙（CaP）涂层（d-CaP涂层），与未处理的PMMA和其他表面改性的PMMA相比，显示出对I型胶原（角膜基质的主要成分）的粘附性有所提高。然而，d-CaP涂层很容易发生分层，从而降低了其对KPro光学圆柱体进行改性的潜力。此外，该涂层与羟基磷灰石（HAp）的钙磷组成不同。引入了一种新颖的浸涂方法，该方法涉及在PMMA表面创建空腔以捕获和固定HAp纳米颗粒，以解决与d-CaP涂层相关的问题。新获得的涂层具有高亲水性、抗分层性以及HAp钙磷组成的保留。与未处理的PMMA相比，这些优点使粘附强度提高了1个多数量级。在生物整合方面，人角膜基质成纤维细胞能够在HAp涂层的PMMA上牢固粘附并增殖。此外，新的涂层技术可以扩展到将HAp纳米颗粒固定在直径3毫米的PMMA圆柱体上，使其更接近临床应用。
