title: Silsesquioxane nanocomposites as tissue implants.
abstract: BACKGROUND
  Silicone implants are being used increasingly worldwide, especially in breast augmentation procedures. The most common morbidity observed is capsular contracture, which occurs in 15 percent of cases. To overcome this problem, the authors have developed a novel nanocomposite based on polyhedral oligomeric silsesquioxane-poly(carbonate-urea)urethane (POSS-PCU) for use as tissue implants.
  
  
  METHODS
  These polymers were implanted in six healthy sheep (n = 6) for 36 months and a siloxane served as the positive control. After explantation, these polymers were extracted, as was the surrounding capsule, if any. Attenuated total reflectance Fourier transform infrared spectroscopy analysis was performed to look for signs of surface degradation on the polymers and histopathologic and electron microscopic examinations were performed to study the interaction between the biomaterial and the host environment in greater detail.
  
  
  RESULTS
  After implantation, the authors observed minimal inflammation of the nanocomposite within the sheep model as compared with the siloxane control. Contact angle measurements and fibrinogen enzyme-linked immunosorbent assay tests were then conducted on the POSS-PCU nanocomposite to determine the reason for this behavior. The increased fibrinogen adsorption on POSS-PCU, its amphilicity, and large contact-angle hysteresis indicated that POSS-PCU inhibits inflammation by adsorbing and inactivating fibrinogen on its surface. In complete contrast, the control siloxane in the same setting demonstrated very significant inflammation and degradation, resulting in capsular formation. Naturally, there was no evidence of degradation of the nanocomposite compared with the siloxane control.
  
  
  CONCLUSIONS
  POSS-PCU nanocomposites have enhanced interfacial biocompatibility and better biological stability as compared with conventional silicone biomaterials, thus making them safer as tissue implants.
authors: London, United Kingdom; and Tehran, Iran From the Biomaterials and Tissue Engineering Center, Academic Division of Surgery and Interventional Sciences, University College London; Departments of Plastic and Reconstructive Surgery and Histopathology, Royal Free Hampstead NHS Trust; Nanomedicine Research Center, Shaheed Beheshti University of Medical Sciences; and Department of Materials Chemistry, Birkbeck College, University of London.
authors: Ruben Y
authors: RY
authors: Kannan
authors: Henryk J
authors: HJ
authors: Salacinski
authors: Jalal-Edin
authors: JE
authors: Ghanavi
authors: Ashish
authors: A
authors: Narula
authors: Marianne
authors: M
authors: Odlyha
authors: Habiballah
authors: H
authors: Peirovi
authors: Peter E
authors: PE
authors: Butler
authors: Alexander M
authors: AM
authors: Seifalian
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D020878:Device Removal; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D008422:Materials Testing; D023421:Models, Animal; D053761:Nanocomposites / Q000009:adverse effects / Q000737:chemistry*; D019736:Prostheses and Implants; D011475:Prosthesis Failure; D011897:Random Allocation; D012680:Sensitivity and Specificity; D012756:Sheep; D012833:Siloxanes / Q000009:adverse effects / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013314:Stress, Mechanical; D013499:Surface Properties; D023822:Tissue Engineering
chemical_list: D012833:Siloxanes