title: Comparative study of bioactivity of collagen scaffolds coated with graphene oxide and reduced graphene oxide.
abstract: BACKGROUND
  Graphene oxide (GO) is a single layer carbon sheet with a thickness of less than 1 nm. GO has good dispersibility due to surface modifications with numerous functional groups. Reduced graphene oxide (RGO) is produced via the reduction of GO, and has lower dispersibility. We examined the bioactivity of GO and RGO films, and collagen scaffolds coated with GO and RGO.
  
  
  METHODS
  GO and RGO films were fabricated on a culture dish. Some GO films were chemically reduced using either ascorbic acid or sodium hydrosulfite solution, resulting in preparation of RGO films. The biological properties of each film were evaluated by scanning electron microscopy (SEM), atomic force microscopy, calcium adsorption tests, and MC3T3-E1 cell seeding. Subsequently, GO- and RGO-coated collagen scaffolds were prepared and characterized by SEM and compression tests. Each scaffold was implanted into subcutaneous tissue on the backs of rats. Measurements of DNA content and cell ingrowth areas of implanted scaffolds were performed 10 days post-surgery.
  
  
  RESULTS
  The results show that GO and RGO possess different biological properties. Calcium adsorption and alkaline phosphatase activity were strongly enhanced by RGO, suggesting that RGO is effective for osteogenic differentiation. SEM showed that RGO-modified collagen scaffolds have rough, irregular surfaces. The compressive strengths of GO- and RGO-coated scaffolds were approximately 1.7-fold and 2.7-fold greater, respectively, when compared with the non-coated scaffold. Tissue ingrowth rate was 39% in RGO-coated scaffolds, as compared to 20% in the GO-coated scaffold and 16% in the non-coated scaffold.
  
  
  CONCLUSIONS
  In summary, these results suggest that GO and RGO coatings provide different biological properties to collagen scaffolds, and that RGO-coated scaffolds are more bioactive than GO-coated scaffolds.
authors: Department of Periodontology and Endodontology, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors: Izumi
authors: I
authors: Kanayama
authors: Department of Periodontology and Endodontology, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors: Hirofumi
authors: H
authors: Miyaji
authors: Support Section for Education and Research, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors: Hiroko
authors: H
authors: Takita
authors: Department of Periodontology and Endodontology, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors: Erika
authors: E
authors: Nishida
authors: Mitsubishi Gas Chemical Company, Inc., Tokyo, Japan.
authors: Maiko
authors: M
authors: Tsuji
authors: Division of Frontier Research, Research Department, Creative Research Institution Sousei, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan ; Graduate School of Environmental Science, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors: Bunshi
authors: B
authors: Fugetsu
authors: Division of Frontier Research, Research Department, Creative Research Institution Sousei, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan ; Graduate School of Environmental Science, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors: Ling
authors: L
authors: Sun
authors: Department of Periodontology and Endodontology, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors: Kana
authors: K
authors: Inoue
authors: Department of Periodontology and Endodontology, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors: Asako
authors: A
authors: Ibara
authors: Department of Biomedical, Dental Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors: Tsukasa
authors: T
authors: Akasaka
authors: Department of Periodontology and Endodontology, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors: Tsutomu
authors: T
authors: Sugaya
authors: Department of Periodontology and Endodontology, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan.
authors: Masamitsu
authors: M
authors: Kawanami
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001415:Back / Q000601:surgery; D001672:Biocompatible Materials / Q000737:chemistry* / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D003094:Collagen / Q000737:chemistry* / Q000494:pharmacology; D004247:DNA; D006108:Graphite / Q000737:chemistry* / Q000494:pharmacology; D008297:Male; D051379:Mice; D019736:Prostheses and Implants; D051381:Rats; D017208:Rats, Wistar; D023822:Tissue Engineering; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D001672:Biocompatible Materials; D006108:Graphite; D003094:Collagen; D004247:DNA; D000469:Alkaline Phosphatase; D002118:Calcium
keywords: GO; RGO; biomaterials; cell ingrowth; regenerative scaffold; tissue engineering