Biotechnology: Nanoparticles and Delibery of siRNA Into The Cell
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Liposomes are the most commonly used method of delivery for siRNA . The most effective type of lipids used in transfection liposomes have tertiary amines or cations in the head group, allowing for spontaneous conjugation and tight packaging of siRNA, with polyunsaturated tails. They provide protection from nucleases, fuse with the plasma membrane quite readily, and prevent siRNA clearance by RES . Additionally, lipid micelles conjugate with siRNA spontaneously, so they are relatively easy to prepare for siRNA delivery [2-4]. Another important aspect of liposome delivery is that they can be conjugated with a number of small molecules and ligands for increased cell targeting, cellular penetration and liposome fusion. Such small molecules and ligands include monoclonal antibodies, hormones, poly(ethylene glycol) (PEP) , vitamin E, cholesterol, polyethylenimine (PEI), and cell penetration proteins (CPPs) [2-4]. However, cationic liposomes recently have been observed to induce cytotoxicity in cells and uptake differently depending on cell differentiation, and further efforts are being made to make neutral liposomes to decrease toxicity .
Nanoparticles offer another major avenue for delivery of siRNA into the cell. With sizes ranging from 5 nm-200 nm, nanoparticles are small enough to access cell receptors yet large enough to be retained by the body and evade RES elimination, allowing for a prolonged residence time . Like liposomes, nanoparticles can be conjugated with small molecules for cellular uptake via endocytosis, including hormones, cell recognition peptides, monoclonal antibodies, and other ligands . The controllable morphology of nanoparticles varies significantly, being either hollow or solid, where the hollo...