Bhushan S. Pattni,† Vladimir V. Chupin,‡ and Vladimir P. Torchilin*,†,§,∥ †Department of Pharmaceutical Sciences, Center for Pharmaceutical Biotechnology and Nanomedicine, Northeastern University, Boston, Massachusetts 02115, United States ‡Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russia Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia

New Developments in Liposomal Drug Delivery.

Phospholipid bilayer Nanodiscs are novel model membranes derived from high-density lipoprotein particles and have proven to be useful in studies of membrane proteins. Membrane protein enzymology has been hampered by the inherent insolubility of membrane proteins in aqueous environments and has necessitated the use of model membranes such as liposomes and detergent-stabilized micelles. Current model membranes display a polydisperse particle size distribution and can suffer from problems of inconsistency and instability. It is also unclear how well they mimic biological lipid bilayers. In contrast, Nanodiscs, the particle size of which is constrained by a coat of scaffold proteins, are relatively monodisperse, stable model membranes with a "nativelike" lipid bilayer. Nanodiscs have already been used to study a variety of membrane proteins, including cytochrome P450s, seven-transmembrane proteins, and bacterial chemoreceptors. These proteins are simultaneously monomerized, solubilized, and incorporated into the well-defined membrane environment provided by Nanodiscs. Nanodiscs may also provide useful insights into the thermodynamics and biophysics of biological membranes and binding of small molecules to membranes.

http://depts.washington.edu/wmatkins/PDF/ApplicationsOf.pdf

Applications of phospholipid bilayer nanodiscs in the study of membranes and membrane proteins.

Isothermal titration calorimetry (ITC) can provide a full thermodynamic characterization of an interaction. Its usage does not suffer from constraints of molecular size, shape or chemical constitution. Neither is there any need for chemical modification or attachment to solid support. This ease of use has made it an invaluable instrumental resource and led to its appearance in many laboratories. Despite this, the value of the thermodynamic parameterization has, only quite recently, become widely appreciated. Although our understanding of the correlation between thermodynamic data and structural details continues to be somewhat naive, a large number of publications have begun to improve the situation. In this overview of the literature for 2005, we have attempted to highlight works of interest and novelty. Furthermore, we draw attention to those works which we feel have provided a route to better analysis and increased our ability to understand the meaning of thermodynamic change on binding.

Survey of the year 2005: literature on applications of isothermal titration calorimetry.

We present a general survey of the preparation, the behaviour and the characterization of liposomes, and their versatility as analytical tools. Advances on the design of artificial liposomes have allowed manipulation of their features (size, lamellarity, resistance, fusion capability and encapsulation efficiency), which have given rise to a wide range of procedures to encapsulate or internalise a variety of reagents. These approaches have been used to study solute-membrane interactions and to improve sensitivity and/or selectivity in different analytical methods. We discuss the advantages and the limitations of the most recent applications of liposomes in chromatography, capillary electrophoresis, immunoassays, sensors and microfluidic systems.

The role of liposomes in analytical processes

Peptides in general hold much promise as a major ingredient in novel supramolecular assemblies. They may become essential in vaccine design, antimicrobial chemotherapy, cancer immunotherapy, food preservation, organs transplants, design of novel materials for dentistry, formulations against diabetes and other important strategical applications. This review discusses how novel formulations may improve the therapeutic index of antimicrobial peptides by protecting their activity and improving their bioavailability. The diversity of novel formulations using lipids, liposomes, nanoparticles, polymers, micelles, etc., within the limits of nanotechnology may also provide novel applications going beyond antimicrobial chemotherapy.

/pdf/novel-formulations-for-antimicrobial-peptides-4fdctuku3y.pdf

Novel formulations for antimicrobial peptides.

Development and initial evaluation of PEG-stabilized bilayer disks as novel model membranes.

Effects of ions and detergents in drug partition chromatography on liposomes.

We studied the effect of charged lipids or detergent on the retention of drugs and an oligonucleotide by immobilized liposome chromatography to characterize solute-membrane interactions This is a novel approach in analysis of oligonucleotide-liposome interactions The charged lipids (phosphatidylserine or distearoyltrimethylammoniumpropane) or detergent (sodium dodecylsulfate) interacted electrostatically in a concentration-dependent matter with the solutes The oligonucleotide ions presumably bound to the liposomes by multipoint interactions, which was saturable Sodium dodecylsulfate seemed to affect the drug-membrane interactions more strongly than phosphatidylserine did, probably due to different positioning in the bilayer

http://www.boc.uu.se/boc14www/publications/362.pdf

Caroline Engvall

Papers

Development and initial evaluation of PEG-stabilized bilayer disks as novel model membranes.

Effects of ions and detergents in drug partition chromatography on liposomes.

Interactions of drugs and an oligonucleotide with charged membranes analyzed by immobilized liposome chromatography.

Drug partition chromatography on immobilized porcine intestinal brush border membranes.