title: Biosafety of non-surface modified carbon nanocapsules as a potential alternative to carbon nanotubes for drug delivery purposes.
abstract: BACKGROUND
  Carbon nanotubes (CNTs) have found wide success in circuitry, photovoltaics, and other applications. In contrast, several hurdles exist in using CNTs towards applications in drug delivery. Raw, non-modified CNTs are widely known for their toxicity. As such, many have attempted to reduce CNT toxicity for intravenous drug delivery purposes by post-process surface modification. Alternatively, a novel sphere-like carbon nanocapsule (CNC) developed by the arc-discharge method holds similar electric and thermal conductivities, as well as high strength. This study investigated the systemic toxicity and biocompatibility of different non-surface modified carbon nanomaterials in mice, including multi-walled carbon nanotubes (MWCNTs), single-walled carbon nanotubes (SWCNTs), carbon nanocapsules (CNCs), and C ₆₀ fullerene (C ₆₀). The retention of the nanomaterials and systemic effects after intravenous injections were studied.
  
  
  RESULTS
  MWCNTs, SWCNTs, CNCs, and C ₆₀ were injected intravenously into FVB mice and then sacrificed for tissue section examination. Inflammatory cytokine levels were evaluated with ELISA. Mice receiving injection of MWCNTs or SWCNTs at 50 µg/g b.w. died while C ₆₀ injected group survived at a 50% rate. Surprisingly, mortality rate of mice injected with CNCs was only at 10%. Tissue sections revealed that most carbon nanomaterials retained in the lung. Furthermore, serum and lung-tissue cytokine levels did not reveal any inflammatory response compared to those in mice receiving normal saline injection.
  
  
  CONCLUSIONS
  Carbon nanocapsules are more biocompatible than other carbon nanomaterials and are more suitable for intravenous drug delivery. These results indicate potential biomedical use of non-surface modified carbon allotrope. Additionally, functionalization of the carbon nanocapsules could further enhance dispersion and biocompatibility for intravenous injection.
authors.affiliation: Institute of Clinical Medicine, National Cheng Kung University & Hospital, Tainan, Taiwan.
authors.forename: Alan C L
authors.initials: AC
authors.lastname: Tang
authors.forename: Gan-Lin
authors.initials: GL
authors.lastname: Hwang
authors.forename: Shih-Jung
authors.initials: SJ
authors.lastname: Tsai
authors.forename: Min-Yao
authors.initials: MY
authors.lastname: Chang
authors.forename: Zack C W
authors.initials: ZC
authors.lastname: Tang
authors.forename: Meng-Da
authors.initials: MD
authors.lastname: Tsai
authors.forename: Chwan-Yao
authors.initials: CY
authors.lastname: Luo
authors.forename: Allan S
authors.initials: AS
authors.lastname: Hoffman
authors.forename: Patrick C H
authors.initials: PC
authors.lastname: Hsieh
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D002244:Carbon / Q000737:chemistry*; D016207:Cytokines / Q000097:blood; D016503:Drug Delivery Systems; D018836:Inflammation Mediators / Q000097:blood; D051379:Mice; D053769:Nanocapsules / Q000009:adverse effects*; D037742:Nanotubes, Carbon / Q000009:adverse effects*; D013499:Surface Properties
chemical_list: D001672:Biocompatible Materials; D016207:Cytokines; D018836:Inflammation Mediators; D053769:Nanocapsules; D037742:Nanotubes, Carbon; D002244:Carbon