76
UV-Vis spectroscopy is used for the confirmation of the successful
encapsulation of the drugs into the polymeric micelles. Since it is
known that the copolymers do not absorb in the UV-Vis region, the
wavelength of each peak observed from the drug/copolymer solutions is referred to as the drug characteristic UV-Vis absorption.
UV-Vis measurements were performed using a Perkin Elmer
(Lambda 19) UV-Vis-NIR spectrophotometer (Waltham, MA,
USA). The wavelength of the measurements ranged from 200 to
800 nm. It should be noted that absorption observed in all cases
comes from the encapsulated drugs and not from the copolymers.
1. Select the desired measurement settings.
2. Perform a reference measurement without sample.
3. In a quartz cuvette (H × D × W: 48 mm × 12.5 mm × 12.5 mm,
from Sigma-Aldrich) add 3 mL of the solution and place it in
the instrument.
4. Perform the measurement.
5. We used 200 μL of the initial solution diluted with 2.8 mL
H 2 O (see Note 6).
6. The Pluronic F-127 solution does not show absorption in the
UV spectrum. On the contrary, the Pluronic F-127/curcumin
solutions show the characteristic peaks of curcumin at approximately 420 nm. This observation, together with the absence
of any precipitation, proves the successful encapsulation of
curcumin in the polymeric micelles (Fig. 3a).
7. Again, there are no peaks observed for the PEO-b-PCL micellar
solution in the UV-Vis region before the encapsulation of indomethacin. On the contrary, after the encapsulation of indomethacin with both protocols, the characteristic peak of
indomethacin can be observed at approximately 260 nm, implying the existence of the hydrophobic drug in polymeric micelles
(Fig. 3b). Solutions containing the micelle-encapsulated drugs
show no hint of precipitation.
Attenuated total reflection-Fourier transform infrared (ATRFTIR) spectroscopy is used for the identification of the block
copolymers/drug chemical structure, as well as for the confirmation of the successful drug loading into the hydrophobic cores of
the micelles (appearance of new absorption peaks that correspond
to the characteristic functional groups of the drug).
Fourier transform infrared spectroscopy (FTIR) measurements
are performed in order to examine drug encapsulation into the
polymeric micelles core, using a Fourier transform instrument
(Bruker Equinox 55), equipped with a single-bounce attenuated
total reflectance (ATR) diamond accessory (Dura-Samp1IR II by
SensIR Technologies).
3.5 UV-Vis
Spectroscopy
3.6 Fourier
Transform Infrared
Spectroscopy
(ATR-FTIR)
Angeliki Chroni et al.
UV-Vis spectroscopy is used for the confirmation of the successful
encapsulation of the drugs into the polymeric micelles. Since it is
known that the copolymers do not absorb in the UV-Vis region, the
wavelength of each peak observed from the drug/copolymer solutions is referred to as the drug characteristic UV-Vis absorption.
UV-Vis measurements were performed using a Perkin Elmer
(Lambda 19) UV-Vis-NIR spectrophotometer (Waltham, MA,
USA). The wavelength of the measurements ranged from 200 to
800 nm. It should be noted that absorption observed in all cases
comes from the encapsulated drugs and not from the copolymers.
1. Select the desired measurement settings.
2. Perform a reference measurement without sample.
3. In a quartz cuvette (H × D × W: 48 mm × 12.5 mm × 12.5 mm,
from Sigma-Aldrich) add 3 mL of the solution and place it in
the instrument.
4. Perform the measurement.
5. We used 200 μL of the initial solution diluted with 2.8 mL
H 2 O (see Note 6).
6. The Pluronic F-127 solution does not show absorption in the
UV spectrum. On the contrary, the Pluronic F-127/curcumin
solutions show the characteristic peaks of curcumin at approximately 420 nm. This observation, together with the absence
of any precipitation, proves the successful encapsulation of
curcumin in the polymeric micelles (Fig. 3a).
7. Again, there are no peaks observed for the PEO-b-PCL micellar
solution in the UV-Vis region before the encapsulation of indomethacin. On the contrary, after the encapsulation of indomethacin with both protocols, the characteristic peak of
indomethacin can be observed at approximately 260 nm, implying the existence of the hydrophobic drug in polymeric micelles
(Fig. 3b). Solutions containing the micelle-encapsulated drugs
show no hint of precipitation.
Attenuated total reflection-Fourier transform infrared (ATRFTIR) spectroscopy is used for the identification of the block
copolymers/drug chemical structure, as well as for the confirmation of the successful drug loading into the hydrophobic cores of
the micelles (appearance of new absorption peaks that correspond
to the characteristic functional groups of the drug).
Fourier transform infrared spectroscopy (FTIR) measurements
are performed in order to examine drug encapsulation into the
polymeric micelles core, using a Fourier transform instrument
(Bruker Equinox 55), equipped with a single-bounce attenuated
total reflectance (ATR) diamond accessory (Dura-Samp1IR II by
SensIR Technologies).
3.5 UV-Vis
Spectroscopy
3.6 Fourier
Transform Infrared
Spectroscopy
(ATR-FTIR)
Angeliki Chroni et al.