Scaffold Design for Bone Tissue Engineering: From Micrometric to Nanometric Level - Biologically Responsive Biomaterials for Tissue Engineering - page 11

fibrous material to be efficaciously used as scaffold for the ECM. Electrospinning
is a simple and versatile technique for producing nonwoven, interconnected
nanofiber mats that have potential applications in the field of engineering and
medicine. Traditionally, electrospinning has been used to generate platforms on
submicron or nanometric scale in order to overcome the limitation connected to
traditional fiber drawing processes. Today, the current surge in nanotechnology
has adopted electrospinning as an elegant technique to produce nanofibrous struc-
tures for biomedical applications such as wound healing, tissue engineering, and
drug delivery. In comparison with conventional techniques, electrospinning has
demonstrated its ability to fabricate nanofiber scaffolds that closely mimic the
native ECM structure [ 26 ]. This technique exhibits a large versatility to produce
scaffolds with a range of mechanical properties (either in plastic and elastic field),
optimized porosity, and pore volume for tissue engineering applications [ 34, 41 ] .
Here, different polymer and composite electrospun membranes with various
micro- or nano-metric architecture were investigated in order to analyze the con-
tribution of fiber patterning and biochemical signals to the biological response of
mesenchymal stem cells (MSCs).

1.5.1 Micro or Nanotexture?

In the biomedical field, micro- or nanoscale textured surfaces have gained important
attention, because the majority of tissues present in ECM commonly composed of
collagen fibers hierarchically assembled into dense bundles. The mimicking of the
structural organization firstly is due to the spatial distribution of collagen fibers into
the extracellular matrix. The need of regenerating these structurally complex tissues
imposes to develop novel technologies which can impart multi-scale organization of
fibers from the micron and nanometric level. Electrospinning is a versatile tech-
nique which promises to produce fibers on the micro or nano-length scale with tai-
loring physical, chemical, and biological properties, largely adaptable to various
cellular environments for specific biomedical applications.
The ability of modulating the fiber size to reach the desired morphology depends
upon a large number of variables including materials (i.e., polymer concentration,
solvent chemistry) and process parameters (i.e., voltage, flow rate). In particular, the
creation of a microstructured fibers network based on synthetic polymers (i.e., PCL)
provides to support mechanical properties while nanotexture firstly contributes to
cell-material interaction by offering a higher surface for binding sites to cell mem-
brane receptors promoting cellular attachment, proliferation, and growth.
From a biological point of view, it is generally recognized the relevance of micro-
and nano-patterning and texture size scale on the cell-materials interaction mecha-
nisms may be crucial to improve the cell adhesion and spreading [ 11 ] . Several
studies also demonstrated that the variation of the characteristic size scale of fiber
meshes obtained by an accurate control of fiber diameter significantly influences the
cytocompatibility [ 28 ]. In particular, it has been proven that nanotopography