Biomedical Engineering Reference
In-Depth Information
polymer solution, as shown in Figures 11.10e through 11.10g. PCL particles collected from the areas
close to the spraying zone sometimes stuck to each other. Figure 11.10c shows the ultrasonic treat-
ment of these particles. The scanning electron microscopy (SEM) image revealed that the particles
were shaped as thick disks with visible pores and that the diameters of such thick disks were larger
than those of the microspheres collected from other locations.
The release profi le revealed that the drug released within 45 days amounted to less than 40% of
the total drugs encapsulated in the particles for all samples. It was attributed to the semicrystalline
structure of PCL and the hydrophobic characteristics of Taxol. From SEM image in Figure 11.10d, it
can be seen that the outer shell of the PCL particle has no sign of signifi cant erosion after a 45-day
release. This feature may be attributed to the highly crystalline structure of PCL, which resulted in
the slow degradation of polymer. Cell uptake features of electrosprayed PCL particles were investi-
gated to determine how the particles could be localized within the tumor cell and how well the anti-
cancer drug Taxol could be absorbed and affected the viability of the tumor cell. The results showed
the uptake effi ciencies of the three samples to be around 60% after a 2 h experiment. This result dem-
onstrates that particles generated using the electrospraying technique can have an effi cient uptake. By
modifying the processing parameter and collection method, the yields of the drug encapsulation can
reach about 80%, demonstrating a practical technique for fabricating fi ne drug carrier particles.
Xu and Hanna prepared bovine serum albumin (BSA)-loaded poly(lactide) acid (PLA) particles
using the electrospraying technique [54]. PLA has been used as a biomaterial because of its biode-
gradability and biocompatibility as well as because of its approved regulatory status. The PLA solu-
tion was prepared by dissolving 300 mg of PLA in 10 mL of 1,2-dichloroethane (DCE) and stirring
for 8 h at room temperature. Specifi ed amounts of BSA previously dissolved in distilled water were
mixed with PLA solutions and emulsifi ed by a sonication for 10 min. A schematic illustration of
the electrospraying setup is shown in Figure 11.11. A positive electrode from a high-voltage power
supply was connected to the needle, and a negative electrode was placed in the collection solution
10 cm away from the needle. The precursor was electrosprayed at an applied voltage of 12.5 kV and
at a fl ow rate of 1.0 mL/h to a receiving beaker containing distilled water (the collection solution).
The PLA particles were separated from the collecting solution by fi ltering and drying at room tem-
perature. The size of the PLA particles ranged from 0.84
±
0.18 to 3.95
±
0.51 μm, and increased
b
a
c
g
d
f
e
FIGURE 11.11
A schematic diagram of the electrospraying setup (a) pump, (b) feeding line, (c) needle,
(d) collecting solution, (e) magnetic stirrer, (f) copper collector ring, and (g) high-voltage power supply.
(Reprinted from Xu, Y.X. and Hanna, M.A.,
Int. J. Pharm.
, 320, 30, 2006. © Elsevier Science. With
permission.)
