Biomedical Engineering Reference
In-Depth Information
Table 2
Stability study design for assessing the stability of PLA/PLGA nanoparticles
Study
Storage condition
Duration
Time points for analysis
5
3
C
Long term
12 months
At the end of 0.5, 1, 2, 3, 6
and 12 months
25
2
C/60
5 % RH
Accelerated
6 months
At the end of 0.5, 1, 2, 3,
and 6 months
4. Samples are withdrawn at time points as depicted in Table
2
.
5. 1 mg sample is used for measurement of particle size and zeta
potential as described in Sections
3.2.1
and
3.2.3
. 2 mg sample
is used for determining the drug loading by the method
described in Section
3.2.4
.
For reconstituted nanoparticles
:
1. 10 mg of nanoparticles are weighed and reconstituted with
10 ml PBS pH 7.4 and are stored at 37
C.
2. Samples are withdrawn at 0, 24, and 48 h and analyzed for
particle size and zeta potential as described in Sections
3.2.1
and
3.2.3
, respectively.
4 Notes
1.
L
-PLA (Lactel
®
) should be stored at
10
C and
DL
-PLGA
(50:50) (Resomer
®
RG 503H) should be stored at 2-8
C.
2. Negative stain solution should be stored at 4
C. Each time
before using the solution, it should be centrifuged to remove
the undissolved uranyl acetate or ammonium molybdate that
may have precipitated during storage.
3. For the disposable folded capillary cell (Malvern
®
Instruments,
Westborough, MA, USA) to measure zeta potential, the man-
ufacturer recommends single use and proper wetting of the
container with ethanol or methanol followed by flushing of
the container five times with de-ionized water or the vehicle.
The cell is not compatible with organic solvents.
4. Spectra/Por
®
regenerated cellulose (RC) dialysis membranes
(Spectrum Laboratories, Inc.) are superior to cellulose ester
membranes in terms of tolerated pH and temperature range
and the tolerance of exposure to acids, basis, and organic sol-
vents. Therefore, RCmembranes are recommended for dialysis.
Supplier recommends that the RC dialysis membranes should
be stored at 4
C. The supplier provides the RC membranes
