Storage | Should always be stored at in the dark at 4 °C, except when brought to room temperature for brief periods prior to animal dosing. DO NOT FREEZE. If the suspension is frozen, the encapsulated drug can be released from the liposomes thus limiting its effectiveness. In addition, the size of the liposomes will also change upon freezing and thawing. |
Appearance | White translucent liquid made of nano size unilamellar liposomes. Usually due to the small size of liposomes no settling will occur in the bottom of the vial. The liposomes are packaged in an amber vial. |
Description | Cationic liposomes are traditionally used for the delivery of genetic materials such as various types of DNA (pDNA, cDNA, CpG DNA, oligonucleotide, antisense oligonucleotide, etc.), various types of RNA such as (siRNA, mRNA, etc.) and nucleic acid mimics (NAMs).The encapsulation of DNA into the conventional neutral charged PC based liposomes can be a technical problem mainly due to the plasmid size. Due to this problem in late 80s, the liposomes composed of cationic lipids and PE have been developed. The idea was to neutralize the negative charge of pDNA with positive charge of cationic lipids in order to capture more plasmid efficiently mainly due to electrostatic interaction and deliver them into the cells. Generally, the procedure is simply based on mixing the cationic liposomes with DNA or RNA and adding them to the cells. This results in the formulations of aggregates. In order to design a proper cationic lipid for gene delivery, two approaches have been used for the cationic lipid synthesis: 1) cholesterol-based design such as DC-Cholesterol and GL-67 lipids, and 2) non-cholesterol-based designs such as DOTAB, DDAB and DOTMA.To successfully transfer the gene in vitro using liposomes, some consideration should be taken into account:i) the ability of binding and packing DNA/RNA in liposomes;ii) the interaction of the packaged DNA/RNA to the cell surface;iii) the efficiency of the internalization of DNA/RNA;iv) the intracellular DNA-release from endosomes in case of endocytosis involvement;v) the transgenic expression level in cell nuclei.pH-sensitive liposomes have been designed based on their tendency to release their content in the acidic condition. The primary concept was based on viruses that fuse with the endosomal membrane by means of a protein at pH 5-6, delivering their genetic material to the cytosol before reaching the lysosomes.Typically, a pH-sensitive liposome consists of dioleoylphosphatidylethanolamine (DOPE). Since phosphatidylethanolamine (PE) changes in acidic conditions, it is believed to act as a membrane fusion promoter.The effectiveness of the interaction between liposomes and cells is highly dependent on the liposome compositions. Liposomes are captured by various endocytosic processes, and the efficiency depends on the cell type and liposome size. Liposomes of various sizes and charges can attach to the macrophages and neutrophils through active phagocytosis. After attachment of the liposome to the cell surface, the internalization into the endosomes occurs due to a more acidic pH (6.50) at early endosomes. The liposomes are transferred to the last endosome with more acidic pH (5.5-6.0) by maturation or vesicular fusion, which takes 10-15 min. Twenty minutes (or more) after uptake, the contents are delivered to the lysosome with pH 5.0 or less. Lysosomes are the main degrading and last endocytotic section in the endocytotic pathway, in where pH-insensitive liposomes are accumulated and degraded. However, after penetration of pH-sensitive liposomes into cells, the accumulation and degradation do not occur. |
Lipid composition | GL-67/DOPE (1/2 molar ratio) |
Liposome Size | 100 nm |
Buffer | Deionized RNAse-free Water, pH 7.0 |
Shelf-life | 4 months. |
Technical Notes | Liposomes for DNA/RNA Delivery products are formulated using deionized RNAse-free water. N/P ratio means nitrogen to phosphate ratio. N stands for nitrogen and NOT negative. As a matter of fact, nitrogen is positive. P also stands for phosphate and NOT positive. Phosphate carries negative charge. Therefore N/P ratio also stands for positive to negative ratio. Some cationic lipids contain more than one nitrogen, but not all nitrogen atoms carry a positive charge. For example, DC-Cholesterol has two nitrogen atoms and only one of them positive charged. The nitrogen next to the carboxyl group is not positively charged and should not be included in N/P calculation. Cytotoxicity can also be assessed using the CytoTox 96? Non-Radioactive Cytotoxicity Assay (Promega, Madison, WI) per manufacturer’s instructions. |
Surface Charge | Cationic |
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