  The study of the structural behaviour of pure and multi-component lipids at
various temperatures and the interaction of these multi-component lipids with
pharmaceutically important drugs carry huge importance. Here, we investigated
the phase behaviour of the pure PSPC
(1-palmitoyl-2-stearoyl-sn-glycero-3-phosphocholine), and multicomponent PSPC
and
DSPE-PEG2000(1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N[amino(polyethylene
glycol)-2000]) membranes at seven different temperatures ranging from 280 K to
360 K, and calculated their structural properties. We observe a transition from
the gel phase to the liquid crystalline phase between 320 K and 330 K in
agreement with experimental reports for pure PSPC. PSPC remained in the tilted
gel phase L\b{eta}$'$ at 320 K and 310 K, entered the 'mixed ordered' domain
with a partially interdigitated region at 300 K, and finally formed the sub gel
phase at 280 K. We studied the self-assembly for the multicomponent PSPC and
DSPE-PEG2000 membranes and found the coexistence of ordered and disordered
phases at 320 K. In comparison to the pure PSPC, for multicomponent system,
this transition was gradual, and a complete liquid crystalline to gel phase
transformation occurred between 320 K and 310 K. We further studied the
interaction of Paclitaxel with pure PSPC and PEGylated multicomponent lipid
bilayers using umbrella sampling technique and observed PEG promotes the
interaction of Paclitaxel with the later one in comparison to the former. Above
the bilayer transition temperature, Paclitaxel interacts more with the bilayer
and enters inside the bilayer easily for both systems. Understanding of
structural and interaction behaviour of the PEGylated multicomponent lipid
bilayers with Paclitaxel will help explore Paclitaxel based drug applications
in the future.
