Novel biocompatible chitosan decorated single-walled carbon nanotubes (SWNTs) for biomedical applications: theoretical and experimental investigations

Abstract

Molecular mechanics and molecular dynamics simulations have been employed to characterise the interactions between SWNTs and biocompatible amphililic derivatives of chitosan, namely N-butyl-O-sulfate chitosan (NBSC), N-octyl-O-sulfate chitosan (NOSC) and N-palmitoyl-O-sulfate chitosan (NPSC). The computational simulations have shown that the affinity of the polymer for the hydrophobic surface of the nanotubes depends on the length of the chitosan hydrophobic pendant chain. Longer chains have a higher flexibility and therefore a better ability to wrap around the nanotubes. To underpin the theoretical calculations, experimental studies revealed that NPSC exhibits highest affinity for SWNTs with up to 66.9 ± 19.7% SWNTs stably suspended in an aqueous environment; this affinity was confirmed by the calculated binding energy of five polymer chains with a SWNT that was found to be -300.93 kcal mol(-1), the highest amongst the three polymers studied. Furthermore, the high value of cell viability after incubation with NPSC indicates that this is a good candidate for the preparation of biocompatible SWNTs dipersions that could be used in biomedical and pharmaceutical applications.

Synthesis of carbon nanotubes loaded hydroxyapatite: Potential for controlled drug release from bone implants

“…The same was not true for composites containing MWNTs that gave a higher overall release (109.9%±8.6% and 88.3%±4.0%, with chitosan and NOSC respectively); this may be due to a poorer dispersion in the reaction mixture with more tubes interacting with each other and not available for interaction with the drug. The good dispersion ability of NOSC was previously demonstrated in our lab [16,27,28]. In general, composites containing NOSC presented a lower amount of ibuprofen released in comparison with the composites containing chitosan; this might be due to hydrophobic interaction between the C8 chain on the polymer and the drug.…”

“…Carboxylated single-wall (outer diameter 1-4 nm, length 3-30 µm, -COOH content 7±1.5 wt%) and multi-wall (outer diameter 8-15 nm, length 10-50 µm, -COOH content 2.56 wt%) carbon nanotubes were obtained from Cheaptubes Ltd., USA. N-octyl-O-sulphate chitosan (NOSC) was prepared as described previously [15,16].…”

“…Figure 2 shows the morphology of CNTs as received. These are present as bundles of entangled tubes; therefore, before inclusion, CNTs were suspended in a solution of NOSC or chitosan by sonication, process known to stabilise and separate the CNTs into single entities [16,27,28]. Figure 3(a) shows the presence of some crystalline impurities in the HA control prepared in water; this is consistent with the earlier observation of the high conductivity measured in the washing medium, further confirmed by the high water absorption observed in the DVS study (see below).…”

Transactivator of transcription (TAT) peptide–chitosan functionalized multiwalled carbon nanotubes as a potential drug delivery vehicle for cancer therapy

“…[22][23][24][25] Previous reports showed that the functionalization of CNTs with CS through surface adsorption could increase their dispersibility in the solution. [26][27] A novel immunologically modified nanotube system invented by Zhou et al 28 using glycated CS-modified single-walled CNTs resulted in highly effective tumor suppression in animal tumor models, with complete tumor regression and long-term survival in many cases.…”

Protein expression profiles of intestinal epithelial co-cultures: effect of functionalised carbon nanotube exposure

“…Despite this potential for GI exposure, only a few previous studies have investigated the effect of CNTs on Caco-2 cell monolayers (Kulamarva et al, 2008; Jos et al, 2009; Piovesan et al, 2010; Ponti et al, 2010; Coyuco et al, 2011) and HT29 monolayers (Pelka et al, 2011), and only two in vivo studies examined the toxicity of SWCNT in the intestine after oral gavage (Folkmann et al, 2009; Kolosnjaj-Tabi et al, 2010). A recent review does not even address GI effects (Johnston et al, 2010), since little is known about the biological effects of CNTs or f-CNTs in that regard.…”