title: Self-assembled monolayer films of phosphonates for bonding RGD to titanium.
abstract: Modification of the implant surface with the Arg-Gly-Asp tripeptide (RGD) putatively facilitates osteoblast attachment for improved implant fixation in the laboratory. We compared the histomorphometric and mechanical performance of titanium implants coated with RGD using a novel interface of self-assembled monolayers of phosphonates (RGD/SAMP) and implants coated with RGD using the more conventional thiolate-gold interface (RGD/thiolate-gold). We hypothesized RGD/SAMP-coated implants would show greater bone ongrowth and implant fixation than RGD/thiolate-gold-coated ones. We implanted an RGD/SAMP-coated implant in one femur and an RGD/thiolate-gold-coated in the contralateral femur of 60 rats. At 2, 4, and 8 weeks after implantation, 10 rats were sacrificed for histologic evaluation and another 10 for biomechanical testing. Bone-implant ongrowth and implant force-to-failure of the two implants were similar at all times. Although RGD/SAMP-coated implants did not show superior bone ongrowth and implant fixation, RGD/SAMP-coated implants have at least equally good histomorphometric and mechanical in vivo performance as RGD/thiolate-gold-coated ones. Additional in vivo characterization of self-assembled monolayer films of phosphonates as interface to bond RGD to titanium is needed to explore its full potential and seems justified based on the results of this study.
authors.affiliation: Biomechanics Laboratory, Division of Orthopedic Research, Mayo Clinic, Rochester, MN, 55905, USA. heijink.andras@mayo.edu
authors.forename: Andras
authors.initials: A
authors.lastname: Heijink
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Schwartz
authors.forename: Mark E
authors.initials: ME
authors.lastname: Zobitz
authors.forename: K
authors.initials: K
authors.lastname: Nicole Crowder
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Lutz
authors.forename: Jean D
authors.initials: JD
authors.lastname: Sibonga
mesh_terms: D000497:Alloys; D000818:Animals; D020099:Coated Materials, Biocompatible; D005269:Femur / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D006046:Gold / Q000737:chemistry; D020007:Implants, Experimental; D008297:Male; D008422:Materials Testing; D009842:Oligopeptides / Q000737:chemistry*; D063065:Organophosphonates / Q000737:chemistry*; D016348:Osseointegration; D011474:Prosthesis Design; D011475:Prosthesis Failure; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*
chemical_list: D000497:Alloys; D020099:Coated Materials, Biocompatible; D009842:Oligopeptides; D063065:Organophosphonates; D013438:Sulfhydryl Compounds; C031462:titanium alloy (TiAl6V4); D006046:Gold; C047981:arginyl-glycyl-aspartic acid; D014025:Titanium