Nonendocytic delivery of lipoplex nanoparticles into living cells using nanochannel electroporation

The delivery of biomolecules, including siRNAs (≈21 bp) and large plasmids (≈10 kbp), into living cells holds a great promise for therapeutic and research applications. Lipoplex nanoparticles are popular nanocarriers for gene delivery. In conventional transfection methods, the cellular uptake of lipoplex nanoparticels occurs through the endocytosis process. The entrapment of lipoplex nanoparticles into endocytic vesicle is a major barrier in achieving efficient gene silencing and expression. Here, a novel nanochannel electroporation (NEP) method is employed to facilitate the cellular uptake and release of siRNAs/DNAs from lipoplexes. First, it is demonstrated that in a NEP device, lipoplex nanoparticles can be injected directly into the cell cytoplasm within several seconds. Specifically, it is found that lipoplexes containing MCL-1 siRNA delivered by NEP can more efficiently down-regulate the expression of MCL-1 mRNA in A549 cancer cells than conventional transfection. Quantum dot-mediated Förster resonance energy transfer (QD-FRET) reveals that lipoplexes delivered via NEP can directly release siRNA in the cytoplasm without going through the endocytosis route, which unravels the responsible mechanism for efficient gene delivery. Furthermore, the advantage of combining NEP with lipoplex nanoparticles by the successful delivery of large plasmids (pCAG2LMKOSimO, 13 kbp) into CHO cells is demonstrated.