Topic4-Differentially Charged Hollow Core/Shell Lipid–Polymer–Lipid Hybrid Nanoparticles for Small Interfering RNA Delivery
siRNA, double emulsion nanoparticles, lipids, vesicles
Small Interfering RNA (SiRNA)
These nanoparticles were formulated using a double emulsion technique. This technique involves the use of a sonicator probe that sends out high frequency sound waves instigating the self assembly of the independant elements of the system such as the PLGA polymer and two different types of lipid. The directionality of the lipid formation (hydrophobic centre vs. hydrophilic centre) is dependant on the ratio of organic solvent to aqueous solution used. Double emulsion particles are formed with two sonications. The first sonication is performed using a high ratio of organic phase to aqueous phase. The organic phase contains the hydrophobic PLGA polymer and lipid. The aqueous phase contains siRNA. A high ratio of an organic solvent to aqueous phase ensures that the first sonication forms particles with a hydrophilic core and the hydrophobic tails facing outward into the polymer. The second sonication involves the addition of an aqueous phase containing a different lipid (the lipid is below the critical micelle concentration in the water) in which the ratio of the organic solvent to the aqueous phase is low. This ensures that the hydrophilic heads of the lipid are facing outward and the particles are suspended in water. Figure 1 illustrates the final particle.