There are many techniques for introducing substances into cells, but the only method including extraction is the physical method using nanoneedles.The method using a single needle is difficult to handle because it cannot be used if the tube is clogged, but the method using multiple needles (nanotube arrangement) makes it easy to insert the needle into the cell and has high efficiency of introduction and extraction.Currently, the multiple needles that are being developed are mainly insulating and semiconductor nanotubes, and metal tubes have been realized with a high aspect ratio (ratio of long side to short side) of nanoscale diameter and microscale length. There is no example.

　The research group has developed a simple method for producing metal nano-processed puncture thin films by microfabrication technology that combines electroless plating and etching technology.First, an Au / PC thin film is prepared by electroless plating gold (Au) on a polycarbonate (PC) thin film (track-etched membrane) with pores dispersed on the surface.After that, the gold thin film was removed by wet / dry processing and the exposed PC thin film was etched to form a nano-processed puncture thin film.Various nanotubes were produced by this method, and calcein dye and oligo DNA were successfully introduced.Its introduction efficiency and cell viability were also high.

　Since this method can directly insert nanotubes into cells, intracellular access is realized without endocytosis (substance uptake action by cell membrane invagination).In addition, it achieves simplicity and high introduction efficiency that allows various substances to be introduced into many cells with a single imprint, and it is also possible to adjust the introduction timing.In the future, it is expected to expand from basic research on cells to applied research such as regenerative medicine, drug discovery, and culture promotion.

Paper information:[Scientific Reports] Nanostraw membrane stamping for direct delivery of molecules into adhesion cells