title: Hemocompatibility of silicon-based substrates for biomedical implant applications.
abstract: Silicon membranes with highly uniform nanopore sizes fabricated using microelectromechanical systems (MEMS) technology allow for the development of miniaturized implants such as those needed for renal replacement therapies. However, the blood compatibility of silicon has thus far been an unresolved issue in the use of these substrates in implantable biomedical devices. We report the results of hemocompatibility studies using bare silicon, polysilicon, and modified silicon substrates. The surface modifications tested have been shown to reduce protein and/or platelet adhesion, thus potentially improving biocompatibility of silicon. Hemocompatibility was evaluated under four categories-coagulation (thrombin-antithrombin complex, TAT generation), complement activation (complement protein, C3a production), platelet activation (P-selectin, CD62P expression), and platelet adhesion. Our tests revealed that all silicon substrates display low coagulation and complement activation, comparable to that of Teflon and stainless steel, two materials commonly used in medical implants, and significantly lower than that of diethylaminoethyl (DEAE) cellulose, a polymer used in dialysis membranes. Unmodified silicon and polysilicon showed significant platelet attachment; however, the surface modifications on silicon reduced platelet adhesion and activation to levels comparable to that on Teflon. These results suggest that surface-modified silicon substrates are viable for the development of miniaturized renal replacement systems.
authors.affiliation: Department of Bioengineering and Therapeutic Sciences, University of California-San Francisco, CA 94158-2330, USA.
authors.forename: Lalitha
authors.initials: L
authors.lastname: Muthusubramaniam
authors.forename: Rachel
authors.initials: R
authors.lastname: Lowe
authors.forename: William H
authors.initials: WH
authors.lastname: Fissell
authors.forename: Lingyan
authors.initials: L
authors.lastname: Li
authors.forename: Roger E
authors.initials: RE
authors.lastname: Marchant
authors.forename: Tejal A
authors.initials: TA
authors.lastname: Desai
authors.forename: Shuvo
authors.initials: S
authors.lastname: Roy
mesh_terms: D001672:Biocompatible Materials; D001698:Biomedical Engineering; D001777:Blood Coagulation; D003167:Complement Activation; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D008904:Miniaturization; D015539:Platelet Activation; D010973:Platelet Adhesiveness; D011138:Polytetrafluoroethylene; D019736:Prostheses and Implants; D017582:Renal Replacement Therapy / Q000295:instrumentation; D012825:Silicon; D013193:Stainless Steel; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D013193:Stainless Steel; D011138:Polytetrafluoroethylene; D012825:Silicon