ABSTRACT
Skeletal muscle is one of the most abundant tissues in the body. Although it has a relatively good regeneration capacity, it cannot heal in the case of disease or severe damage. Many current tissue engineering strategies fall short due to the complex structure of skeletal muscle. Biofabrication techniques have emerged as a popular set of methods for increasing the complexity of tissue-like constructs. In this paper, 4D biofabrication technique is introduced for fabrication of the skeletal muscle microtissues. To this end, a bilayer scaffold consisting of a layer of anisotropic methacrylated alginate fibers (AA-MA) and aligned polycaprolactone (PCL) fibers were fabricated using electrospinning and later induced to self-fold to encapsulate myoblasts. Bilayer mats undergo shape-transformation in an aqueous buffer, a process that depends on their overall thickness, the thickness of each layer and the geometry of the mat. Proper selection of these parameters allowed fabrication of scroll-like tubes encapsulating myoblasts. The myoblasts were shown to align along the axis of the anisotropic PCL fibers and further differentiated into aligned myotubes that contracted under electrical stimulation. Overall the significance of this approach is in the fabrication of hollow tubular constructs that can be further developed for the formation of a vascularized and functional muscle.
Subject(s)
Muscle, Skeletal/cytology , Myoblasts/cytology , Tissue Engineering/methods , Tissue Scaffolds/chemistry , Animals , Cell Differentiation , Cell Proliferation , Mice , Muscle Fibers, Skeletal/cytology , Muscle, Skeletal/chemistry , Myoblasts/chemistry , Polyesters/chemistry , Tissue Engineering/instrumentationABSTRACT
In the title ternary co-crystalline adduct, C7H14N4·2C6H5NO3, mol-ecules are linked by two inter-molecular O-Hâ¯N hydrogen bonds, forming a tricomponent aggregates in the asymmetric unit. The hydrogen-bond formation to one of the N atoms is enough to induce structural stereoelectronic effects in the normal donorâacceptor direction. In the title adduct, the two independent nitro-phenol mol-ecules are essentially planar, with maximum deviations of 0.0157â (13) and 0.0039â (13)â Å. The dihedral angles between the planes of the nitro group and the attached benzene rings are 4.04â (17) and 5.79â (17)°. In the crystal, aggregates are connected by C-Hâ¯O hydrogen bonds, forming a supra-molecular dimer enclosing an R 6 (6)(32) ring motif. Additional C-Hâ¯O inter-molecular hydrogen-bonding inter-actions form a second supra-molecular inversion dimer with an R 2 (2)(10) motif. These units are linked via C-Hâ¯O and C-Hâ¯N hydrogen bonds, forming a three-dimensional network.
ABSTRACT
The structure of the 1:2 co-crystalline adduct C8H16N4·2C6H5BrO, (I), from the solid-state reaction of 1,3,6,8-tetra-aza-tri-cyclo-[4.4.1.1(3,8)]dodecane (TATD) and 4-bromo-phenol, has been determined. The asymmetric unit of the title co-crystalline adduct comprises a half mol-ecule of aminal cage polyamine plus a 4-bromo-phenol mol-ecule. A twofold rotation axis generates the other half of the adduct. The primary inter-species association in the title compound is through two inter-molecular O-Hâ¯N hydrogen bonds. In the crystal, the adducts are linked by weak non-conventional C-Hâ¯O and C-Hâ¯Br hydrogen bonds, giving a two-dimensional supra-molecular structure parallel to the bc plane.
ABSTRACT
The title molecular salt, C11H21N4(+)·C6H4NO3(-)·C6H5NO3, (II), crystallizes with two independent three-component aggregates in the asymmetric unit. In the cations, the cyclohexane rings fused to the cage azaadamantane systems both adopt a chair conformation. In the crystal structure, the aggregates are connected by C-H···O hydrogen bonds, forming a supramolecular unit enclosing an R4(4)(24) ring motif. These units are linked via C-H···O and C-H···N hydrogen bonds, forming a three-dimensional network. Even hydrogen-bond formation to one of the N atoms is enough to induce structural stereoelectronic effects in the normal donorâacceptor direction. The C-N bond distances provide structural evidence for a strong anomeric effect. The structure also displays O-H···O and N-H···O hydrogen bonding. Geometric optimization and natural bond orbital (NBO) analysis of (II) were undertaken by utilizing DFT/B3LYP with the 6-31+G(d,p) basis set. NBO second-order perturbation theory calculations indicate donor-acceptor interactions between nitrogen lone pairs and the antibonding orbital of the C-C and C-N bonds for the protonated polyamine, in agreement with the occurrence of bond-length and bond-angle changes within the aminal cage structure.
