Electrostatic Accumulation and Release of DNA Using a Micromachined Lance

This paper investigates the accumulation and release of deoxyribonucleic acid (DNA) relative to a surface micromachined silicon lance. The lance is a critical element of nanoinjection, a proposed approach for injecting foreign DNA into living cells. The quantity of DNA accumulated on the nanoinjector lance and the speed at which it can be moved on and off the lance are essential to the proposed system´s function. Prototype nanoinjector lances were fabricated using a multilayer surface micromachining process. DNA stained with the fluorescent dye 4´, 6-diamidino-2-phenylidole dihydrochloride was visualized using fluorescent illumination as the DNA was accumulated on and released from the tips of microelectromechanical systems (MEMS) microlances using a 1.5-V dc source. In 5 min 46 s, the lance accumulated over 32 000 DNA molecules from a dilute DNA solution. The lance then released over 6200 DNA molecules within 6 s. Finally, the nanoinjector lance was used to inject a reporter gene encoding a red fluorescent protein into a mouse embryo, resulting in expression of the gene. The nanoinjector lance represents an important and significant step in the development of a self-contained MEMS-based DNA injection system.