Collagen–carbon nanotube composite materials as scaffolds in tissue engineering

Abstract

Carbon nanotubes (CNT) are attractive for use in fiber-reinforced composite materials due to their very high aspect ratio, combined with outstanding mechanical and electrical properties. Composite materials comprising a collagen matrix with embedded CNT were prepared by mixing solubilized Type I collagen with solutions of carboxylated single-walled carbon nanotubes (SWNT) at concentrations of 0, 0.2, 0.4, 0.8, and 2.0 weight percent. Living smooth muscle cells were incorporated at the time of collagen gelation to produce cell-seeded collagen-CNT composite matrices. Constructs containing 2.0 wt % CNT exhibited delayed gel compaction, relative to lower concentrations that compacted at the same rate as pure collagen controls. Cell viability in all constructs was consistently above 85% at both Day 3 and Day 7, whereas cell number in CNT-containing constructs was lower than in control constructs at Day 3, though statistically unchanged by Day 7. Scanning electron microscopy showed physical interactions between CNT and collagen matrix. Raman spectroscopy confirmed the presence of CNT at the expected diameter (0.85-1.30 nm), but did not indicate strong molecular interactions between the collagen and CNT components. Such collagen-CNT composite matrices may have utility as scaffolds in tissue engineering, or as components of biosensors or other medical devices.

Nanostructured 3-D collagen/nanotube biocomposites for future bone regeneration scaffolds

“…For instance, MacDonald et al [43], using aortic smooth muscle cells, showed that constructs containing 2 wt% CNTs in a 2 mg/mL collagen gel exhibited delayed gel compaction compared to that observed with lower concentrations of CNTs and to the control (absence of CNTs). Importantly, they also determined that the cell viability was consistently above 85% in all the constructs.…”

“…When collagen fibrillogenesis is initiated, CNTs may become incorporated into the triple-helical collagen molecule, or may remain as a separate phase linking the collagen fi bers. It is likely that the carboxyl and hydroxyl groups present on the surface of CNTs can form covalent and hydrogen bonds with amino groups extending from the collagen chains [41,43]. However, further theoretical and experimental work still needs to be performed to clarify these assumptions.…”

“…MacDonald et al showed that the presence of carboxylated CNTs in collagen/SWCNT composites did not alter the initial formation of gels containing live smooth muscle cells, nor affect the cell viability or proliferation of these cells. However, they noted that matrices containing 2 wt% SWCNTs showed a delay in gel compaction during the first three days of the experiment, indicating that CNTs improve the mechanical strength of the biocomposite gel [43]. In recent work, MacDonald et al used collagen/CNT biocomposites to show that this product can be used as a substrate to study electrical stimulation of cells and can act as a transducer for future biosensors [44,45].…”

Collagen gel formation in the presence of a carbon nanobrush

“…Isolated collagen monomers can re-assemble in vitro to form fibrils that resemble those in living tissue, with a characteristic 67 nm periodic structure called a D-period. [3,4] There is much interest in carbon nanotubes as a reinforcement additive for tissue engineering materials such as collagen gels, and cartilagenous simulants, [5][6][7][8][9]. In the present work, results are presented showing the in-vitro fibril formation of pepsin treated collagen in the presence of carbon nanotubes coated with polystyrene/polyanaline side chains, which resemble, somewhat, proteoglycan macromolecules, [10].…”

Carbon Nanotubes Engineering Assisted by Natural Biopolymers

“…In vitro work has shown that several different cells types have been successfully grown on CNT/biopolymer composites. MacDonald found t h a t b l e n d s o f S W N T w i t h c o l l a g e n support smooth muscle cell growth (MacDonald, et al 2005). L929 mouse fibroblasts have been successfully grown on CNT scaffolds (Correa-Duarte, et al 2004) Abarrategi et al demonstrates the use of scaffolds composed of a major fraction of MWCNT (up to 89wt%) and a minor one of chitosan, and with a well-defined microchannel porous structure as biocompatible and biodegradable supports for culture growth.…”