Biomedical Engineering Reference
In-Depth Information
Syringe
(a)
Nozzle
ring
Sample collector
Grounded needle
Air supply
Flow meter
(c)
(b)
FIGURE 11.18
A diagram of electrospraying (a) and images of multiple-cone spraying (b) and single-cone
spraying (c). (Reprinted from Xie, J.W., Marijnissen, J.C.M., and Wang, C.H.,
Biomaterials
, 27, 3321, 2006. ©
Elsevier Science. With permission.)
shapes, and corrugated shapes were successfully generated by using different processing parameters
and precursors. The particle sizes can be controlled in a range of several tens of micrometers to hun-
dreds of nanometers, which is advantageous for manufacturing targeted delivery carriers through
different administration based on the particle sizes. Figure 11.19 shows SEM images of micro-
particles generated with different organic solvents. The experiments demonstrated that the drug
encapsulation effi ciency was around 80% and more than a 30-day
in vitro
release was achieved. The
cell-cycling results suggested that paclitaxel after encapsulation through electrospraying can keep
its biological function and inhibit most of C6 glioma cells in the G
2
/M phase.
11.2.8.2
Deposition of Bioactive Coatings and Films
Electrospraying is considered as a simple method to prepare dense or porous biomedical fi lms or
coatings at a low cost and high effi ciency in which a solution is atomized to aerosol droplets by an
electric fi eld and then is directed onto a substrate. The precursor can be atomized in many different
spraying patterns, depending on the processing parameters and the physical properties of the solu-
tion. To prepare bioactive fi lms or coatings, a cone-jet spraying mode is preferred because of the
uniform electrosprayed droplets in a micrometer to nanometer range [62,63]. The other important
characteristics of electrospraying technique for producing fi lms or coatings are the evaporation of
solvents and the spreading of droplets on the substrates. The spreading behaviors of electrosprayed
droplets on the substrate play an important role in the microstructured development for the fi lms
and coatings [64,65]. In general, dense fi lms or coatings could be produced while using a high
boiling point solvent, whereas a porous microstructure could be formed using a low boiling point
solvent. This feature is attributed to the different evaporation and spreading rates. The composi-
tion of the biomedical fi lms or coatings can easily be controlled by mixing precursor materials and
solvents. Therefore, the advantages of electrospraying deposition of bioactive coatings and fi lms are
that they are cost-effective, simple, and provide a wide choice of precursors.
