Controlled Delivery of Methotrexate from Channel-Protein Containing Liposomes

The goal of this study is to develop a controlled methotrexate delivery system that releases its content by a target specific stimulus. To accomplish this, both methotrexate and an engineered channel protein (MscL) were incorporated into DOPC/CH/DSPE-PEG liposomes, providing a controlled drug delivery system. Reconstitution and encapsulation methods were optimized in order to ensure optimal channel gating activity and high drug:lipid ratio. At the optimal conditions, a 95% release of MTX could be reached.

Channel Protein-Containing Liposomes as Delivery Vehicles for the Controlled Release of Drugs-Optimization of the Lipid Composition

In the design of liposomal drug formulations containing a controllable channel protein (MscL), the lipid composition is dictated in part by this membrane protein. This work addresses the question whether therapeutically optimal lipid compositions (phospholipid with high Tm/cholesterol/PEG) are compatible with channel activity. As a result of optimization, MscL-proteoliposomes have been prepared that rapidly release encapsulated model drug (calcein), as well as the chosen cytostatic drug, cisplatin.

Novel Biodegradable Pyridinium Amphiphiles for Gene Delivery

Biodegradable synthetic cationic pyridinium-based amphiphiles (SAINTs) prove to be promising non-viral carrier systems for delivery of DNA into eukaryotic cells. Six novel SAINTs were synthesised from 3,5-pyridinedicarboxylic acid as starting material, with two ester groups as linkers between the cationic headgroup and the hydrophobic tails. The vesicle-forming properties of the amphiphiles were studied by differential scanning calorimetry and transmission electron microscopy, whereas the hydrolysis of the diesters in water was investigated by NMR spectroscopy. Finally, the transfection potential and cytotoxicity were determined on COS-7 and HepG-2 cells in culture.

In-Vivo Delivery of DNA and Protein Using Conceptually New Cationic, Sunfish', Amphiphiles

Sunfish' are suitable cationic amphiphiles for the in vivo delivery of genes and proteins. With PEGylated Sunfish included, the circulation time of the protein complex is prolonged making the complex applicable for extra-hepatic targeting delivery. In principle, further improvement can be obtained by optimising the Sunfish structure.

Sunfish cationic amphiphiles:Toward an adaptative lipoplex morphology

A detailed physicochemical study is presented on a new class of cationic amphiphiles, Sunfish amphiphiles, recently designed, synthesized, and tested for gene delivery. These materials have two hydrophobic tails, connected to the cationic pyridinium headgroup at the 1- and 4-positions. Two extreme morphologies can be visualized, i.e. one by back-folding involving association of both tails at one side of the pyridinium ring and one by independent unfolding of the tails, the two molecular geometries leading to considerable differences in the aggregate morphology. The behavior of six members of the Sunfish family in mixtures with DOPE, applying different conditions relevant for transfection, has been studied by a combination of techniques (DLS, DSC, NMR, SAXS, Cryo-TEM, fluorescence, etc.). The effects of structural parameters such as the presence of unsaturation in the tails and length of the alkyl chains on the properties of the aggregates have been assessed. A correlation of these structural data with cellular transfection efficiencies reveals that the highest transfection efficiency is obtained with those amphiphiles that are easily hydrated, form fluid aggregates, and undergo a transition to the inverted hexagonal phase in the presence of plasmid DNA (p-DNA) at physiological ionic strength

Sunfish Amphiphiles: Conceptually New Carriers for DNA Delivery

A conceptually new class of cationic amphiphiles, Sunfish amphiphiles, designed for the delivery of genes into cells is introduced. Sunfish amphiphiles have two hydrophobic tails, connected at the 4- and the N-position to the cationic pyridinium headgroup. Two extreme morphologies visualised by backfolding and combining of both tails at one site (matching situation) or unfolding of the tails at distinct interaction sites at biological membranes will lead to considerable differences in morphological behaviour. The underlying rationale allows controlled release by using this morphological alteration of the Sunfish/helper-lipid/DNA complex (lipoplex). The often-excellent transfection efficiencies are probably related to these morphological changes. In addition, the Sunfish amphiphiles possess low toxicities, resulting in high cell survival after internalisation. The underlying rationale, design, synthesis and in vitro transfection potential are discussed in detail. Moreover, some physico-chemical characteristics of the Sunfish amphiphiles have been studied.