Effect of multiwall carbon nanotube reinforcement on coaxially extruded cellular vascular conduits

Abstract

Due to its abundant source, good biocompatibility, low price and mild crosslinking process, alginate is an ideal selection for tissue engineering applications. In this work, alginate vascular conduits were fabricated through a coaxial extrusion-based system. However, due to the inherent weak mechanical properties of alginate, the vascular conduits are not capable of biomimicking natural vascular system. In this paper, multiwall carbon nanotubes (MWCNT) were used to reinforce vascular conduits. Mechanical, dehydration, swelling and degradation tests were performed to understand influences of MWCNT reinforcement. The unique mechanical properties together with perfusion and diffusional capability are two important factors to mimic the nature. Thus, perfusion experiments were also conducted to explore the MWCNT reinforcement effect. In addition, cell viability and tissue histology were conducted to evaluate the biological performance of conduits both in short and long term for MWCNT reinforcement.

Keywords: Artificial vascular constructs; Biofabrication; Carbon nanotubes; Tissue engineering.

Figure 1

Experimental setup: (A) extrusion-based system, and, (B) coaxial nozzle unit.

Figure 2

Experimental setup for perfusion test: (A) perfusion system consists of three parts, a cell media reservoir, a peristaltic pump and a perfusion chamber, and (B) a conduit under perfusion.

Figure 3

Fabrication of vascular conduits: (A) vascular conduit made of 4% (w/v) alginate with 1% WMCNT reinforcement, (B) dehydrated vascular conduit, (C) SEM image of dehydrated vascular conduit inner wall surface, (D) SEM image of dehydrated vascular conduit outer wall surface, and (E) dimensional characterization of vascular conduits.

Figure 4

Influence of MWCNT reinforcement on vascular conduit dehydration process:(A)vascular conduit diameter after dehydration, (B) SRD, and (C) SRW and VSR.

Figure 5

Influence of MWCNT reinforcement on vascular conduit swelling process: (A) swelling ratio curve, (B) maximum swelling ratio and (C) vascular conduit liquid reabsorption capacity.

Figure 6

Mechanical Tests: (A) tensile strength, and (B) estimated burst pressure.

Figure 7

Perfusion capability of vascular conduits.

Figure 8

Cell viability study: (A) cell viability over time, (B) fluorescence microscopy image of a three days cultured plain alginate conduit, and (C) fluorescence microscopy image of a three days cultured 1% (w/v) MWCNT reinforced vascular conduit.

Figure 9

Immunohistochemistry: (A) damaged cells with disintegrated nucleus presented in the longitudinal section of MWCNT-reinforced conduits (shown by arrow head); (B) most of the cells in control group were undamaged showing regular morphology (shown by asterisks); (C) no visible matrix deposition was present in MWCNT-reinforced conduits; (D) substantial amount of extra cellular matrix was deposited along the peripheral part of the wall of the control group (shown by dashed boxes).