Template-synthesized gold microneedle arrays for gene delivery to the Chlamydomonas reinhardtii chloroplast

In this paper, an array of conically shaped gold microneedles protruding from a substrate was prepared. We show for the first time, that such microneedles can penetrate through the intact cell wall of Chlamydomonas reinhardtii (C. reinhardtii), a unicellular plant organism. We demonstrate that this approach can be used to deliver a recombinant gene into the chloroplast of the C. reinhardtii. The microneedle array were coated with an orange fluorescence protein (OFP)—conferring gene, and the C. reinhardtii cells were deposited onto this array using centrifugal force. We show that the microneedle and the cells withstand the impact, and the gene is successfully delivered and expressed by the C. reinhardtii cells. The gene delivery method described here offers significant advantages relative to more conventional methods, which includes the ability to use microalgal cells with intact cell walls, and the ability to rapidly perform multiple transformations simultaneously through a simple centrifugal approach.