227
∙ PNIPAM-b-PLA 1 is more efficient in rendering the DPPC
membranes thermoresponsive, due to its higher molecular
weight, but also due to its more hydrophilic composition. This
is evident from the alterations in the thermodynamic behavior
of DPPC from the first to the second heating scan, where the
newly formed phase leads to functional behavior and new phenomena; phases appear after its transition, especially at high
polymer concentrations (see Note 20).
1. Dissolve the desired amount of DPPC and each one of the chimeric nanosystem DPPC:PNIPAM-b-PLA 1 at 9:0.02, 9:0.05,
and 9:0.1 molar ratios in chloroform.
2. Transfer each solution into a round flask, connected to a rotary
evaporator.
3. Evaporate the solvent under vacuum and heat conditions
(−1 bar and 40 °C).
4. Maintain the formed dry lipid films under these conditions for
30 min.
5. Place the dry lipid films in a desiccator, for at least 24 h, in order
to remove possible traces of solvent.
6. Hydrate the dry lipid films with PBS (pH = 7.4), for a final total
biomaterial concentration of 5 mg mL
−1
, and slowly stir for 1 h
in a water bath, above the phase transition temperature of the
containing phospholipid (45 °C) (see Notes 21–23).
7. Subject the resultant suspensions to two 5-min sonication cycles
(amplitude 70%, cycle 0.5 s), interrupted by a 5-min resting
period, by using a probe sonicator (see Note 24).
8. Allow the formed chimeric systems to anneal for 30 min (see
Note 25).
1. Dilute aliquots of the prepared chimeric systems 30-fold in
HPLC-grade water (see Notes 26 and 27).
2. Measure the size (hydrodynamic diameter, D h ) and size distribution (polydispersity index, PDI) with a photon correlation
spectrometer, at a detection angle of 90° and at 25 °C.
3. Analyze the measurements by the CONTIN method (see Note
28).
1. Place samples DPPC and DPPC:PNIPAM-b-PLA 1 9:0.02,
9:0.05, and 9:0.1 at 45 °C for 30 min (see Note 29).
2. Remove them from high temperature and allow them to reach
room temperature (see Note 30).
3. Measure the size (hydrodynamic diameter, D h ) and size distribution (polydispersity index, PDI) with a photon correlation
3.6 Preparation
of Thermoresponsive
Chimeric Liposomes
Through the Thin-Film
Hydration Method
3.7 Dynamic Light
Scattering (DLS)
3.8 Heating of the
Thermoresponsive
Chimeric Liposomes
Thermodynamics and Functionality of Thermoresponsive Chimeric Nanosystems
∙ PNIPAM-b-PLA 1 is more efficient in rendering the DPPC
membranes thermoresponsive, due to its higher molecular
weight, but also due to its more hydrophilic composition. This
is evident from the alterations in the thermodynamic behavior
of DPPC from the first to the second heating scan, where the
newly formed phase leads to functional behavior and new phenomena; phases appear after its transition, especially at high
polymer concentrations (see Note 20).
1. Dissolve the desired amount of DPPC and each one of the chimeric nanosystem DPPC:PNIPAM-b-PLA 1 at 9:0.02, 9:0.05,
and 9:0.1 molar ratios in chloroform.
2. Transfer each solution into a round flask, connected to a rotary
evaporator.
3. Evaporate the solvent under vacuum and heat conditions
(−1 bar and 40 °C).
4. Maintain the formed dry lipid films under these conditions for
30 min.
5. Place the dry lipid films in a desiccator, for at least 24 h, in order
to remove possible traces of solvent.
6. Hydrate the dry lipid films with PBS (pH = 7.4), for a final total
biomaterial concentration of 5 mg mL
−1
, and slowly stir for 1 h
in a water bath, above the phase transition temperature of the
containing phospholipid (45 °C) (see Notes 21–23).
7. Subject the resultant suspensions to two 5-min sonication cycles
(amplitude 70%, cycle 0.5 s), interrupted by a 5-min resting
period, by using a probe sonicator (see Note 24).
8. Allow the formed chimeric systems to anneal for 30 min (see
Note 25).
1. Dilute aliquots of the prepared chimeric systems 30-fold in
HPLC-grade water (see Notes 26 and 27).
2. Measure the size (hydrodynamic diameter, D h ) and size distribution (polydispersity index, PDI) with a photon correlation
spectrometer, at a detection angle of 90° and at 25 °C.
3. Analyze the measurements by the CONTIN method (see Note
28).
1. Place samples DPPC and DPPC:PNIPAM-b-PLA 1 9:0.02,
9:0.05, and 9:0.1 at 45 °C for 30 min (see Note 29).
2. Remove them from high temperature and allow them to reach
room temperature (see Note 30).
3. Measure the size (hydrodynamic diameter, D h ) and size distribution (polydispersity index, PDI) with a photon correlation
3.6 Preparation
of Thermoresponsive
Chimeric Liposomes
Through the Thin-Film
Hydration Method
3.7 Dynamic Light
Scattering (DLS)
3.8 Heating of the
Thermoresponsive
Chimeric Liposomes
Thermodynamics and Functionality of Thermoresponsive Chimeric Nanosystems