Key Features

A fusion reagent for rapid and efficient gene silencing in living cells—the improvement of siRNA transfection

  • Exceptionally efficient siRNA transfection, especially in primary and non-dividing cells, such as keratinocytes
  • Extremely low cytotoxicity
  • Fastest siRNA delivery—no endocytosis or lysosomal degradation

in cooperation with


Special Requirements?



  • Gene silencing / Protein knockdown

Technical Features:

  • Lipofection-independent transfer of siRNA into living cells
  • Fast siRNA transfection into the cytoplasm: no endocytosis, no lysosomal degradation, and no gene transfer to the nucleus
  • siRNA transfer completed within 5-20 minutes
  • Small amount of siRNA is sufficient for effective knockdown
  • Excellent biocompatibility because of low cytotoxicity
  • siRNA transfer into cells without generating genetically modified organisms (GMO), in contrast to viral or plasmid-based approaches


Form Solution
Concentration 6 mM
Storage -20 °C
ExMax/EmMax 750/780 nm (infrared)

Kit Components:

Fusogenic solution (FS) 2 vials
Neutralization Buffer (NB) 2 vials

Highly Efficient Gene Silencing, While Retaining Cell Viability

High knockdown levels of target genes can be achieved—almost 100% gene silencing at very low siRNA concentrations.

Fuse-It liposomal lipids do not contain any chemical compounds used for endosomal release. This results in maximal siRNA transfer and high knockdown efficiency, even in sensitive primary cells, such as neurons and keratinocytes.

Fuse-It-siRNA maximizes knockdown efficiency and completely retains viability, even after multiple transfections in sensitive primary cells. Murine keratinocytes were fused with Fuse-It-siRNA vesicles containing α-Catenin siRNA (Qiagen), which led to highly efficient α-Catenin knockdown measured by qPCR. Viability was retained even after multiple transfers, in contrast to classical siRNA lipofection reagents (competitor A, B, and C).

Note: All cells were treated twice with the siRNA transfection reagent to achieve high knockdown efficiency (24 hours in between). As competitors B and C resulted in nearly complete cell death, α-Catenin expression could not be determined (marked with *).

Fuse-It-siRNA results in efficient GFP knockdown in adherent cells. Transiently GFP-expressing CHO-K1 cells were fused with Fuse-It-siRNA vesicles containing Silencer® GFP (eGFP) siRNA (Thermo Fisher Scientific). Fuse-It-siRNA provided more efficient knockdown than classical lipoplex-based siRNA reagents (competitor A and B).

Membrane Fusion – The Direct Path to Gene Silencing

Immediate siRNA Delivery

Fuse-It-siRNA uses a completely new technology, because—unlike classical lipoplex-based methods—cells do not internalize the siRNA by endocytosis. The Fuse-It liposomal carrier, which includes the siRNA, simply fuses with the cell membrane and then releases the siRNA directly into the cytoplasm.

Fuse-It-siRNA is especially useful in non-proliferating cell lines and primary cells such as keratinocytes and neurons. This is because the transferred siRNA is immediately incorporated into the RISC complex without the interfering processes of endocytosis, lysosomal degradation, or mitosis.

Since the Fuse-It liposomal carrier contains a fusion control dye, the membrane fusion process can easily be imaged by infrared fluorescence.

NOTE: Use high quality siRNAs to achieve the best results.

Extremely Low Cytotoxicity

In contrast to classical lipoplex-based siRNA delivery methods, Fuse-It-siRNA requires only brief incubation times (5-20 minutes) for maximal siRNA transfer rates. Furthermore, low amounts of liposomal lipids result in the highest siRNA transfer, without the need of chemical compounds for endosomal release. This feature excludes the potential toxic effects of carrier reagents on sensitive cells.

High cell viability even after multiple transfections with Fuse-It-siRNA. For enhanced gene knockdown, primary murine keratinocytes were fused twice (24 hours in between) with Fuse-It-siRNA vesicles containing α-Catenin siRNA (Qiagen). The very gentle fusion process retained cell viability, even after multiple Fuse-It-siRNA treatments.

Fuse-It-siRNA Results in Extremely Fast siRNA Transfer and Highly Efficient Knockdown of GFP

Transiently GFP-expressing CHO-K1 cells were fused with Fuse-It-siRNA vesicles containing Silencer® GFP (eGFP) siRNA (Thermo Fisher Scientific) for 8 minutes. In contrast to the control cells, GFP was almost completely diminished in Fuse-It-siRNA-treated cells 18 hours after the transfer.

Additional information


2 x 150 µl, 2 x 300 µl