Ionic liquids-based processing of electrically conducting chitin nanocomposite scaffolds for stem cell growth

Abstract

In the present study, we have successfully combined the biocompatible properties of chitin with the high electrical conductivity of carbon nanotubes (CNTs) by mixing them using an imidazolium-based ionic liquid as a common solvent/dispersion medium. The resulting nanocomposites demonstrated uniform distribution of CNTs, as shown by scanning electron microscopy (SEM) and optical microscopy. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction confirmed the α-crystal structure of chitin in the regenerated chitin nanocomposite scaffolds. Increased CNT concentration in the chitin matrix resulted in higher conductivity of the scaffolds. Human mesenchymal stem cells adhered to, and proliferated on, chitin-CNT nanocomposites with different ratios. Cell growth in the first 3 days was similar on all composites at a range of (0.01 to 0.07) weight fraction of CNT. However, composites at a 0.1 weight fraction of CNTs showed reduced cell attachment. There was a significant increase in cell proliferation using 0.07 weight fraction CNT composites, suggesting a stem cell enhancing function for CNTs at this concentration. In conclusion, the ionic liquid allowed the uniform dispersion of CNTs and dissolution of chitin to create a biocompatible, electrically conducting scaffold permissive for mesenchymal stem cell function. This method will enable the fabrication of chitin-based advanced multifunctional biocompatible scaffolds where electrical conduction is critical for tissue function. † A portion of this work was carried out by the National Institute of Standards and Technology (NIST), an agency of the U. S. government, and by statute is not subject to copyright in the United States. Certain commercial equipment, instruments, materials, cell culture, services, or companies are identified in this paper in order to specify adequately the experimental procedure. This in no way implies endorsement or recommendation by NIST.

Macroscale Biomolecular Electronics and Ionics

“…As such, cellulose is a good candidate due to its natural abundance. Indeed, several studies have investigated blends of cellulose with electron conductive molecules/polymers, such as carbon nanotubes, graphene, polyaniline, and polypyrrole motivated by the development of conductive paper for “green electronics.” Chitosan and chitin have also been used as templates for the formation of electron conducting polymers upon blending with polyaniline, carbon nanotubes, or graphene . The strategy of using carbon nanotubes and graphene for enhanced conductance across the biopolymer can be considered as an intermediate between strategies (2) and (3) in Figure , since they are not organic polymers, but have considerably larger molecular weights than molecular dopants.…”

Chitin and carbon nanotube composites as biocompatible scaffolds for neuron growth

“…All the tissue culture chemicals were purchased from Sigma, unless otherwise stated. Two-dimensional chitin membranes were produced using the procedure described elsewhere 39 . Briefly, 1.5 % (mass fraction) of chitin was dissolved in 5 g of EMI Ac in a glass vial accompanied by constant heating and stirring for 2 h at 130 °C.…”

Effect of fibre spinning conditions on the electrical properties of cellulose and carbon nanotube composite fibres spun using ionic liquid as a benign solvent

“…To overcome the first challenge, room temperature ionic liquids such as EMIMAc can be employed as environmentally benign solvent, which is safer and easier to handle than traditionally used solvents such as carbon disulphide [9], sulphuric acid [10] and N-methylmorpholine-N-oxide (NMMO) [11]. A number of researchers have used ionic liquids for fibre stretching/spinning of cellulose [12][13][14][15][16][17][18], wool [19,20], chitin [21][22][23][24] and other natural polymers [25][26][27][28], as well as composite fibres of cellulose [8,29]. Despite this progress, the remaining two challenges, uniform dispersion of carbon nanotube in cellulose solution dope and avoidance of high degree of alignment of carbon nanotubes during fibre spinning, still remain largely unaddressed.…”