Strategies for controlled delivery of therapeutic siRNA into living cells are in high demand as endosomal escape remains the most prominent bottleneck at the intracellular level. Photothermal properties of gold nanoparticles (AuNP) can be used to overcome the endosomal membrane barrier upon laser irradiation by two mechanisms: endosomal rupture by mechanical energy from water vapor nanobubbles (VNBs), or permeabilization of the endosomal membrane by heat diffusion. Here we evaluated how both mechanisms influence cargo release, transfection efficiency, acute cytotoxicity and cell homeostasis. Using a siRNA/AuNP drug delivery system we found that the in vitro release of siRNA from the AuNP carrier occurs equally efficiently by VNB formation or heat generation. Heat-mediated endosomal escape happened more efficiently in cells that had more particles per endosome, resulting in variable siRNA-induced downregulation (20-50%). VNB-mediated endosomal escape did not dependent on the number of AuNP per endosome, yielding high downregulations (50-60%) independent of the cell type. Effects on cell homeostasis by whole transcriptome analysis, showed a quick recover after 24 h or 48 h for either of both photothermal mechanisms. We conclude that VNBs are more consistent to induce efficient endosomal escape and gene silencing independent of the cell type without long lasting effects on cell homeostasis.

中文翻译：

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蒸气纳米气泡是诱导siRNA内体逸出而不干扰细胞稳态的更可靠的光热机制。

由于内体逃逸仍然是细胞内水平上最突出的瓶颈，因此迫切需要将治疗性siRNA控释到活细胞中的策略。金纳米颗粒（AuNP）的光热特性可用于通过两种机制克服激光辐照后的内体膜屏障：水蒸气纳米气泡（VNBs）产生的机械能引起内体破裂，或通过热扩散使内体膜透化。在这里，我们评估了这两种机制如何影响货物释放，转染效率，急性细胞毒性和细胞稳态。使用siRNA / AuNP药物递送系统，我们发现，通过VNB形成或发热，从AuNP载体中体外释放siRNA的效率相同。热介导的内体逃逸在每个内体具有更多颗粒的细胞中更有效地发生，从而导致可变的siRNA诱导的下调（20-50％）。VNB介导的内体逃逸不取决于每个内体的AuNP数量，产生高下调（50-60％），与细胞类型无关。通过全转录组分析对细胞稳态的影响表明，两种光热机制中的任何一种在24 h或48 h后都可以快速恢复。我们得出的结论是，VNB更一致，可以诱导有效的内体逃逸和基因沉默，而与细胞类型无关，而对细胞稳态没有长久的影响。产生高下调（50-60％），与细胞类型无关。通过全转录组分析对细胞稳态的影响表明，两种光热机制中的任何一种在24 h或48 h后都可以快速恢复。我们得出的结论是，VNB更一致，可以诱导有效的内体逃逸和基因沉默，而与细胞类型无关，而对细胞稳态没有长久的影响。产生高下调（50-60％），与细胞类型无关。通过全转录组分析对细胞稳态的影响表明，两种光热机制中的任何一种在24 h或48 h后都可以快速恢复。我们得出的结论是，VNB更一致，可诱导有效的内体逃逸和基因沉默，而与细胞类型无关，而对细胞稳态无长久影响。