The invention of pronuclear microinjection initiated the field of transgenic research. Over 30 years later microinjection remains the most straight-forward and most commonly used transgene delivery option. In this work we address the current progress of microelectromechanical systems (MEMS) used as transgenic delivery mechanisms. The nanoinjector is a specially designed MEMS device which uses electrostatic charge to manipulate transgene molecules. The process of nanoinjection was designed as an alternative to microinjection which causes less damage to developing embryos, improves embryo survival, birth rates, and overall efficiency of injections. In vivo testing of nanoinjection demonstrates it is both safe and effective. Additionally nanoinjection has the potential to make transgenesis via yeast artificial chromosomes more practical as the nanoinjector may prevent shearing of the YAC molecules. A second nanoinjection protocol termed intracellular electroporetic nanoinjcetion (IEN) was designed to allow for cytoplasmic injections. Cytoplasmic injections are faster and easier than pronuclear injection and do not require the pronuclei to be visible; yet previous attempts to develop cytoplasmic injection have met with limited success. In IEN injections the nanoinjector is used to place transgenic molecules in the cytoplasm. The transgenes are then propelled through the cytoplasm and electroporated into the pronucleus using electrical pulses. Electroporation of whole embryos has not resulted in transgenic animals, but the MEMS device allows localized electroporation to occur within the cytoplasm, giving transgene access to the pronucleus before degradation can occur. In this report we describe the principles which allow for localized electroporation of the pronuclei including: the location of the pronuclei between 21-28 hours post-hCG treatment, modeling data predicting the voltages needed for localized electroporation of pronuclei, and data on the movement of transgenic DNA based on the voltages delivered by IEN. We further report results of an IEN versus microinjection comparative study in which IEN produced transgenic pups with viability, transgene integration, and expression rates statistically comparable to microinjection. The ability to perform injections without visualizing or puncturing the pronuclei will widely benefit transgenic research, and will be particularly advantageous for the production of transgenic animals with embryos exhibiting reduced pronuclear visibility.



College and Department

Life Sciences; Microbiology and Molecular Biology



Date Submitted


Document Type





nanoinjection, microinjection, transgenic, electroporation, DNA transfer



Included in

Microbiology Commons