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DPPC-Water Interface - water insertion mechanism

Lipids are amphiphilic molecules with hydrophilic head groups and hydrophobic tails. Lipids, self assembled as bilayers form the basic structure of cell membranes. DPPC is a phospholipid. Phospholipids are the most abundant class of lipids in the biological system. We study the interactions between DPPC bilayer and water using classical molecular dynamics simulations. We have proposed that water molecules get inserted deep into the DPPC bilayer- water interface, which is aided by NMe3 group present at the head group of DPPC. We also study the structuring and hydrogen bonding dynamics of the interfacial water molecules.

SOPC gold nanoparticle 

Current research on bio-membrane-nanoparticle interaction revealed many important facets of the nano-biotechnology experimentally and theoretically. We study the interaction of gold nanoparticle on SOPC lipid bilayer to investigate the perturbation effect of bilayer on nanoparticle invasion. Focusing on the fact that local interacting molecules get mostly deformed, we tried to explore nanoparticle invasion effect at the bulk lipid (long range) molecules. Also contribution of the nanoparticle size on the  perturbation effect.
PEI - DOPC interaction  

Polyethylenimine (PEI) is a pH sensitive polymer, possessing stretched and coiled conforma
tion at low and high pH, respectively. It is an efficient gene delivery agent. Thus, the interaction of PEI with the biomembrane is very crucial to understand the gene delivery mechanism. We have investigated the structural properties of PEI and bilayer due to the interaction of PEI with lipid molecules. We observe that the neutral PEI chain predominately settles itself at the bilayer water interface. We do not find any disruption or pore formation on the bilayer due to interaction of neutral PEI chain. PEI at low pH gets elongated due to electrostatic interaction between charges of the protonated sites. This protonated PEI chain interacts with bilayer membrane which leads to formation of water/ion channel through the membrane. We have also studied the structure of the channel and water dynamics along the channel.

For further details please refer :

Chandan Kumar Choudhury* , Abhinaw Kumar and Sudip Roy, Characterization of Conformation and Interaction of Gene Delivery Vector Polyethylenimine with Phospholipid Bilayer at Different Protonation State

Biomacromolecules2013, 14 (10), 3759 - 3768