2019년 02월 Nanoinjection system for precise direct delivery of biomolecules into single cells (Featured Cover Article)

Intracellular delivery of functional molecules such as proteins, transcription factors and DNA is effective and promising in cell-biology. However, existing transfection methods are often unsuitable to deliver big molecules into cells or require carriers such as virus and peptides specific to the target molecules. In addition, the nature of bulk processing does not generally provide accurate dose control of the individual cells. The concept of single-cell-based material injection based on the electrokinetic pumping through nanocapillaries could overcome these problems, yet the fabrication and operation of the nanoscale 3-dimensional structure have remained unsolved. In this research, hybrid (PDMS/glass) microfluidic chip with the true 3-dimensional nanoinjection structure is presented (called "Nanoinjection system"). The nanoinjection structure was fabricated by the femtosecond-laser (fs-laser) ablation in a single solid glass, which showed very successful delivery of red fluorescent protein (RFP) and expression of plasmid DNA into several different types of cells. This system is promising in that the amount of molecules to be delivered is controllable and the processed cells are systematically separated into the harvesting chamber, which can radically improve the purity of the processed cells. In addition, it was confirmed that the cells were healthy even after the molecules injection for a few seconds period, indicating that the injection time can be significantly elongated, further improving the delivery efficiency of biomolecules without affecting the cell viabilities. We envision that the nanoinjection system having the major features of carrier-free, dose-controllable, unlimited-injection period, and ease of harvest will greatly contribute to the next-generation researches in the fields of cell biology and cell therapeutics.