title: Protective coatings for intraocular wirelessly controlled microrobots for implantation: Corrosion, cell culture, and in vivo animal tests.
abstract: Diseases in the ocular posterior segment are a leading cause of blindness. The surgical skills required to treat them are at the limits of human manipulation ability, and involve the risk of permanent retinal damage. Instrument tethering and design limit accessibility within the eye. Wireless microrobots suturelessly injected into the posterior segment, steered using magnetic manipulation are proposed for procedures involving implantation. Biocompatibility is a prerequisite for these procedures. This article investigates the use of polypyrrole- and gold-coated cobalt-nickel microrobots. While gold has been used in ocular implants, no ocular implantation involving polypyrrole is reported, despite its well-established biocompatibility properties. Coated and uncoated microrobots were investigated for their corrosion properties, and solutions that had contained coated and uncoated microrobots for one week were tested for cytotoxicity by monitoring NIH3T3 cell viability. None of the microrobots showed significant corrosion currents and corrosion potentials were as expected in relation to the intrinsic nobility of the materials. NIH3T3 cell viability was not affected by the release medium, in which coated/uncoated microrobots were stored. In vivo tests inside rabbit eyes were performed using coated microrobots. There were no significant inflammatory responses during the first week after injection. An inflammatory response detected after 2 weeks was likely due to a lack of longer-duration biocompatibility. The results provide valuable information for those who work on implant technology and biocompatibility. Coated microrobots have the potential to facilitate a new generation of surgical treatments, diagnostics and drug-delivery techniques, when implantation in the ocular posterior segment will be possible. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 836-845, 2017.
authors.affiliation: Institute of Robotics and Intelligent Systems, ETH Zurich, CH-8092, Zurich, DE-97074 Switzerland.
authors.forename: Juho
authors.initials: J
authors.lastname: Pokki
authors.affiliation: Institute of Robotics and Intelligent Systems, ETH Zurich, CH-8092, Zurich, DE-97074 Switzerland.
authors.forename: Olgaç
authors.initials: O
authors.lastname: Ergeneman
authors.affiliation: Institute of Robotics and Intelligent Systems, ETH Zurich, CH-8092, Zurich, DE-97074 Switzerland.
authors.forename: George
authors.initials: G
authors.lastname: Chatzipirpiridis
authors.affiliation: Institute for Pharmacy and Food Chemistry, University of Würzburg, DE-97070, Würzburg, Germany.
authors.forename: Tessa
authors.initials: T
authors.lastname: Lühmann
authors.affiliation: Institució Catalana de Recerca i Estudis Avançats (ICREA) and Departament de Física, Universitat Autònoma de Barcelona, E-08193, Bellaterra, Spain.|Departament de Física, Universitat Autònoma de Barcelona, E-08193, Bellaterra, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Sort
authors.affiliation: Departament de Física, Universitat Autònoma de Barcelona, E-08193, Bellaterra, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Pellicer
authors.affiliation: Equine Department, Vetsuisse Faculty, University of Zurich, CH-8057, Zurich, Switzerland.
authors.forename: Simon A
authors.initials: SA
authors.lastname: Pot
authors.affiliation: Equine Department, Vetsuisse Faculty, University of Zurich, CH-8057, Zurich, Switzerland.
authors.forename: Bernhard M
authors.initials: BM
authors.lastname: Spiess
authors.affiliation: Institute of Robotics and Intelligent Systems, ETH Zurich, CH-8092, Zurich, DE-97074 Switzerland.
authors.forename: Salvador
authors.initials: S
authors.lastname: Pané
authors.affiliation: Institute of Robotics and Intelligent Systems, ETH Zurich, CH-8092, Zurich, DE-97074 Switzerland.
authors.forename: Bradley J
authors.initials: BJ
authors.lastname: Nelson
mesh_terms: D000818:Animals; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry; D005260:Female; D006046:Gold / Q000737:chemistry; D020007:Implants, Experimental; D056965:Injections, Intraocular; D008422:Materials Testing; D051379:Mice; D041681:NIH 3T3 Cells; D009532:Nickel / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011758:Pyrroles / Q000737:chemistry; D011817:Rabbits; D012371:Robotics; D059015:Wireless Technology
chemical_list: D020099:Coated Materials, Biocompatible; D011108:Polymers; D011758:Pyrroles; C067635:polypyrrole; D003035:Cobalt; D006046:Gold; D009532:Nickel
keywords: biocompatibility; cell culture; corrosion; ophthalmic microrobots; rabbit model