Bioprinting is the most convenient microfabrication method to create biomimetic
three-dimensional (3D) cardiac tissue constructs, that can be used to regenerate
damaged tissue and provide platforms for drug screening. However, existing
bioinks, which are usually composed of polymeric biomaterials, are poorly conductive
and delay efficient electrical coupling between adjacent cardiac cells. To solve
this problem, a gold nanorod (GNR)-incorporated gelatin methacryloyl (GelMA)-
based bioink is developed for printing 3D functional cardiac tissue constructs.
The GNR concentration is adjusted to create a proper microenvironment for the
spreading and organization of cardiac cells. At optimized concentrations of GNR,
the nanocomposite bioink has a low viscosity, similar to pristine inks, which allows
for the easy integration of cells at high densities. As a result, rapid deposition of
cell-laden fibers at a high resolution is possible, while reducing shear stress on the
encapsulated cells. In the printed GNR constructs, cardiac cells show improved
cell adhesion and organization when compared to the constructs without GNRs.
Furthermore, the incorporated GNRs bridge the electrically resistant pore walls of
polymers, improve the cell-to-cell coupling, and promote synchronized contraction
of the bioprinted constructs. Given its advantageous properties, this gold nanocomposite
bioink may find wide application in cardiac tissue engineering.