Reversibly Interfacing Biomaterials With the Retina

Abstract

Purpose: : To determine the in vitro effectiveness of polymers coated with peptides Contortrostatin (CN), Vicrostatin (VN) and temperature responsive plasma polymerized N-isopropyl acrylamide (pNIPAM), for reversible adhesion to retinal tissue.

Methods: : Silicone (100 µm) coated with Contortrostatin (CN) and Vicrostatin (VN), and Parylene C [poly(monochloro-p-xylylene)] (30 µm) coated with pNIPAM were used as implant materials to test reversible retinal adhesion in enucleated porcine eyes. Following preparation of the 2 x 2 mm implant materials (n = 30 for each group) and retinal tissue, the implants were placed on the inner limiting membrane (ILM) surface of the retina in a saline bath at 37°C. To attempt detachment, plasmin was added to the saline for CN and VN, and the temperature was lowered for pNIPAM. The adhesive force for each bioadhesive was measured by a traction test using a Bose ELF3100 mechanical analysis equipment.

Results: : The adhesion of each biomaterial developed strongly within 10 seconds. This adhesion was persistent until reversed by either plasmin for CN and VN, or reducing the temperature of the saline bath to 28 ± 1°C for pNIPAM. The strength of adhesion for each bioadhesive was greater than the strength of the retina, resulting in tearing of the retina on each occasion.

Conclusions: : CN, VN and pNIPAM provide effective in vitro retinal adhesion at 37°C and this adhesion is reversible by adding plasmin for CN and VN or lowering the temperature of the saline environment for pNIPAM.

Keywords: retina • retinal adhesion • vitreoretinal surgery