| As a milestone in soft and hard tissue engineering, a precise
control over the micropatterns of scaffolds has lightened new opportunities
for the recapitulation of native body organs through three dimentional
(3D) bioprinting approaches. Well-printable bioinks are prerequisites for the
bioprinting of tissues/organs where hydrogels play a critical role. Despite the
outstanding developments in 3D engineered microstructures, current printer
devices suffer from the risk of exposing loaded living agents to mechanical
(nozzle-based) and thermal (nozzle-free) stresses. Thus, tuning the rheological,
physical, and mechanical properties of hydrogels is a promising solution to
address these issues. The relationship between the mechanical characteristics
of hydrogels and their printability is important to control printing quality and
fidelity. Recent developments in defining this relationship have highlighted
the decisive role of main additive manufacturing strategies. These strategies
are applied to enhance the printing quality of scaffolds and determine the
nurture of cellular morphology. In this regard, it is beneficial to use external
and internal stabilization, photocurable biopolymers, and cooling substrates
containing the printed scaffolds. The objective of this study is to review
cutting-edge developments in hydrogel-type bioinks and discuss the optimum
simulation of the zonal stratification in osteochondral and cartilage units |