Hybrid hydrogels containing vertically aligned carbon nanotubes with anisotropic electrical conductivity for muscle myofiber fabrication

Abstract

Biological scaffolds with tunable electrical and mechanical properties are of great interest in many different fields, such as regenerative medicine, biorobotics, and biosensing. In this study, dielectrophoresis (DEP) was used to vertically align carbon nanotubes (CNTs) within methacrylated gelatin (GelMA) hydrogels in a robust, simple, and rapid manner. GelMA-aligned CNT hydrogels showed anisotropic electrical conductivity and superior mechanical properties compared with pristine GelMA hydrogels and GelMA hydrogels containing randomly distributed CNTs. Skeletal muscle cells grown on vertically aligned CNTs in GelMA hydrogels yielded a higher number of functional myofibers than cells that were cultured on hydrogels with randomly distributed CNTs and horizontally aligned CNTs, as confirmed by the expression of myogenic genes and proteins. In addition, the myogenic gene and protein expression increased more profoundly after applying electrical stimulation along the direction of the aligned CNTs due to the anisotropic conductivity of the hybrid GelMA-vertically aligned CNT hydrogels. We believe that platform could attract great attention in other biomedical applications, such as biosensing, bioelectronics, and creating functional biomedical devices.

Bioinspired Nanocomposite Hydrogels with Highly Ordered Structures

“…[71][72][73][74][75][76] For example, CNTs were connected and aligned as a bundle that was oriented parallel to their axis. [72,75] By adjusting voltages and frequencies, the CNTs were connected and then aligned as the bundle in their axial direction within gelatin methacrylate (GelMA) hydrogels (Figure 4b). Due to their high levels of nanostructure order, these aligned GelMA-CNT hydrogels showed tunable mechanical properties and higher conductivity than that of randomly distributed CNTs in the GelMA hydrogel and pristine GelMA hydrogels.…”

Conductive gelatin methacrylate-poly(aniline) hydrogel for cell encapsulation

“…[4,5] However, the electrically nonconductive nature of hydrogels impedes its use for excitable cells such as neural, skeletal and cardiac muscle, and bone cells. [6,7] To extend the utility of hydrogels, conducting 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 3 elements like metallic nanoparticles [8][9][10][11][12][13][14] and inherently conductive polymers (IHPs) [6,[15][16][17][18][19] have been incorporated within hydrogel matrices in order to add conductive properties to the 3D microenvironments.…”

Composite Hydrogels with Tunable Anisotropic Morphologies and Mechanical Properties

“…Alternately, dielectrophoresis has been utilized to align carbon nanotubes in an isotropic hydrogel matrix. 17 Micropatterning approaches 7 and 3D printing 31 have been applied to create anisotropic hydrogels with pores of well-defined sizes and geometries.…”

“…Since many tissues, e.g., striated muscle, 6 cartilage, 7 or cornea 8 , to name just a few examples, have anisotropic hierarchical morphologies, there is a growing interest in developing approaches for the fabrication of anisotropic hydrogels that exhibit direction-dependent pore shape, microstructure, stiffness, and conductivity. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] In tissue engineering, aside from biomimicry, anisotropic pore shape and hydrogel structure, in general, are important for cell guidance 22 and differentiation, 23 as well as mass transport of biofactors and nutrients throughout the scaffold. 19,24,25 In bioseparation, control over the shape anisotropy of hydrogel pores may enhance the selectivity of the filtration of biological species and/or minimize the pressure drop across the matrix.…”