307
As long as the DSC results (Fig. 3), the incorporation of
the first form of polymer (called PNIPAM 1) (20  kDa) in
DPPC liposomes affected only the specific enthalpy ΔH m of
the main transition, reflecting an alteration at the mobility
of the lipid polar head groups. The main transition temperature  T m was slightly reduced, while the system
cooperativity was reduced (increase of ΔΤ 1/2 ) at a
Temperature / ºC
Temperature / ºC
Heat
flow/mW,
endothermic Heat
flow/mW,
endothermic
a
b
a.
a.
b.
b.
c.
c.
d.
d.
e.
e.
f.
f.
24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56
22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56
Fig. 3 (A) DSC heating scans of DPPC:PNIPAM 1: (a) 9:0, (b) 9:0.1, (c) 9:0.5, (d) 9:1, (e) 9:2, and (f) 9:3 molar
ratio chimeric liposomes. (B) DSC heating scans of DPPC:PNIPAM 2: (a) 9:0, (b) 9:0.1, (c) 9:0.5, (d) 9:1, (e)
9:2, and (f) 9:3 molar ratio chimeric liposomes. The limits for the calculation of thermotropic parameters are
from 25 °C to 45 °C. Adapted from Ref. [12]
DSC on Liposomes and Bilayers Incorporating Drugs and Biomaterials