155
Drug encapsulation or drug loading is the process of incorporating
the pharmaceutical compound into a polymeric network or capsule. The release of the drug in a controlled manner is the inverse
process by which the drug molecules leave the solid phase of the
polymeric network. Loading and drug release are closely related
processes that depend on the physicochemical properties of the
polymeric network, the physicochemical properties of the drug,
and the environmental impact [16].
The drug can be trapped in the system by intermolecular interactions with the polymeric network, such as hydrogen bonds, ionic
interactions, and intramolecular dipole-dipole interactions. It can
also be trapped on the surface by adsorption. In most drug delivery
systems, encapsulation occurs through different mechanisms at the
same time [16].
In the present study, the anticancer drug daunorubicin was
used as a standard pharmaceutical compound (Fig. 1).
1. In a beaker disperse 10.0 mg of synthesized nanospheres in
10 mL of isotonic solution (0.9 wt% NaCl).
2. Add 4 mg of daunorubicin hydrochloride, DNR.
3. Leave the mixture to stir gently for 48 h at 25 °C.
4. Centrifuge (see Note 11) and keep the isolated supernatant to
determine the amount of daunorubicin not entrapped in the
spheres through standard curve method (Scheme 1, see Note
12). UV–vis absorption spectra in the wavelength range of
200–800 nm were obtained on a Jasco V-650 spectrometer,
with UV–vis at 480 nm spectrometer. An ultrasonic bath was
used for sonication.
Using the reference curve (Fig. 2), the amount of drug trapped
can be calculated. The absorbance of isolated supernatant (1 mL)
was A = 2.38, so we can calculate the concentration of daunorubicin from the equation y = 0.0157x + 0.0619 (y = A and x = c (μg/
mL)). The concentration of the non-loaded drug was 147.65 μg/
mL, and as we know the total volume of the supernatant solution,
we can easily calculate the mass of the non-loaded
(10 mL × 147.65 μg = 1.4765 mg) and loaded drug (4 mg –
1.4765 mg = 2.5235 mg). Also, the encapsulation efficiency and
the ability to capture it from the microspheres (loading capacity)
are calculated according to the following equations (see Table 1):
Encapsulation capacity
Weight of the loaded drug in vehicles
To
%
( ) =
t tal weight of the vehicles
×100
Encapsulation efficiency
Weight of the loaded drug in vehicles
%
( ) = W Weight of the starting amount of drug
×100
3.2 Drug
Encapsulation
Design of Drug Delivery Systems Based on Polysaccharides
Drug encapsulation or drug loading is the process of incorporating
the pharmaceutical compound into a polymeric network or capsule. The release of the drug in a controlled manner is the inverse
process by which the drug molecules leave the solid phase of the
polymeric network. Loading and drug release are closely related
processes that depend on the physicochemical properties of the
polymeric network, the physicochemical properties of the drug,
and the environmental impact [16].
The drug can be trapped in the system by intermolecular interactions with the polymeric network, such as hydrogen bonds, ionic
interactions, and intramolecular dipole-dipole interactions. It can
also be trapped on the surface by adsorption. In most drug delivery
systems, encapsulation occurs through different mechanisms at the
same time [16].
In the present study, the anticancer drug daunorubicin was
used as a standard pharmaceutical compound (Fig. 1).
1. In a beaker disperse 10.0 mg of synthesized nanospheres in
10 mL of isotonic solution (0.9 wt% NaCl).
2. Add 4 mg of daunorubicin hydrochloride, DNR.
3. Leave the mixture to stir gently for 48 h at 25 °C.
4. Centrifuge (see Note 11) and keep the isolated supernatant to
determine the amount of daunorubicin not entrapped in the
spheres through standard curve method (Scheme 1, see Note
12). UV–vis absorption spectra in the wavelength range of
200–800 nm were obtained on a Jasco V-650 spectrometer,
with UV–vis at 480 nm spectrometer. An ultrasonic bath was
used for sonication.
Using the reference curve (Fig. 2), the amount of drug trapped
can be calculated. The absorbance of isolated supernatant (1 mL)
was A = 2.38, so we can calculate the concentration of daunorubicin from the equation y = 0.0157x + 0.0619 (y = A and x = c (μg/
mL)). The concentration of the non-loaded drug was 147.65 μg/
mL, and as we know the total volume of the supernatant solution,
we can easily calculate the mass of the non-loaded
(10 mL × 147.65 μg = 1.4765 mg) and loaded drug (4 mg –
1.4765 mg = 2.5235 mg). Also, the encapsulation efficiency and
the ability to capture it from the microspheres (loading capacity)
are calculated according to the following equations (see Table 1):
Encapsulation capacity
Weight of the loaded drug in vehicles
To
%
( ) =
t tal weight of the vehicles
×100
Encapsulation efficiency
Weight of the loaded drug in vehicles
%
( ) = W Weight of the starting amount of drug
×100
3.2 Drug
Encapsulation
Design of Drug Delivery Systems Based on Polysaccharides