The present invention is concerned with a system and method for introducing a substance into cells. The system has an assembly including a plurality of elongate non-hollow nanoneedles forming a nanoneedle array or patch for delivering the substance into the cells, at least some of the nanoneedles have a non-uniform diameter with a wider upper end, a narrower lower end for penetration into the cells and a length from substantially 200 nm to 100 um. The lower end has a diameter from substantially 20-436 nm. Adjacent nanoneedles are spaced apart by substantially 5-50 um. The nanoneedles are made from a material selected from the group consisting of diamond, cubic boron nitride, carbon nitride, boron nitride, boron carbon nitride, metal borides and essentially boron materials, allowing the nanoneedles to maintain sufficient thinness and yet adequate rigidity during penetration. The nanoneedles are applied onto the cells grown on substrates at a preferred rate from 1 to 5 m/s. Alternatively, the nanoneedles are applied onto the cells grown on substrates by centrifugation force from 0.5 to 10 nN. Yet alternatively, the cells suspended in a fluid are applied to the nanoneedle array at a rate of 1 to 10 m/s.
