Biomimetic Materials for Engineering Stem Cells and Tissues - Biomimetics: Advancing Nanobiomaterials and Tissue Engineering - page 327

applied between the tip and grounded collector. As voltage is applied,
the charges get accumulated on the droplet, which elongates into conical
shape called Taylor cone. When the electric fi eld strength overcomes the
surface tension of the droplet, a polymeric jet is initiated from the Taylor
cone and is accelerated towards the grounded collector. As the jet travels
through the air, the solvent evaporates and the polymer jet simultaneously
elongates, leading to the deposition of fi bers on the collector.
Zhang et al. fabricated a method for biomimetic fabrication of HA/chi-
tosan nanocomposites in which the nanocomposite, containing uniformly
dispersed HA in chitosan, was electrospun using ultra-high molecular
weight poly(ethylene oxide) (UHMWPEO) as an additive. By this method,
they obtained biomimetic nanofi bers of about 200 nm [3]. Choi et al. have
fabricated electrospun gelatin nanofi bers that were subject to biomimetic
mineralization to develop a gelatin/CaP composite nanofi brous scaffold
[12]. Gelatin nanofi bers containing Ca 2+ ions showed better adsorption of
HA layer than gelatin nanofi bers containing PO 4 3− ions. The hydroxyapa-
tite layer formed consisted of nanosheets self-assembled to form three-
dimensional structures after immersion for 48 hrs in simulated body fl uid.
The authors concluded that the type of ion included in the gelatin nanofi -
ber strongly infl uenced the biomimetic mineralization process.
14.2.2 Electrospraying
Electrospraying is a process similar in concept to electrospinning, but the
morphology of the polymer scaffold, i.e., droplets or fi bers, depends on
the parameters during electrospraying such as concentration of the poly-
mer, fl ow rate of the polymer, the applied voltage and tip to target dis-
tance [13]. Hong et al. have developed an electrosprayed three-dimensional
nanofi ber scaffold and tested the same for the culture of human foreskin
fi broblast (HFF-1) cells [14]. They demonstrated successful cell attachment
and spreading on the scaffold because of the increased pore size of the
electrosprayed nanofi ber scaffold. Gupta et al. have fabricated a nano-
structured scaffold by electrospraying of HA nanoparticles on electros-
pun poly(L-lactic acid)-co-poly(3-capro-lactone)/gelatin nanofi bers [15].
Electrospraying of HA imparted surface roughness to the scaffold that
enabled the successful adhesion and proliferation of human fetal osteo-
blast cells (hFOB). As a biomimetic approach to ECM, electrosprayed
nano HA on electrospun gelatin scaffolds has also been developed [16].
The scaffold showed better adhesion and proliferation of hFOB and better
mineralization. Some works also describe the electrospraying of cells onto
electrospun polymer scaffolds to aid in better cellular infi ltration of the
scaffold [17, 18]. For example, Paletta et al. demonstrated the successful
proliferation of electrosprayed MG63 cells on electrospun PLLA or PLLA/
Col blend scaffolds [18]. Thus electrospraying could be used to fabricate