Biomed. Opt. Express 4, 1533–1547 (2013)

Credit: © 2013 OSA

Transfection, the injection of genes into living cells, is an essential component of gene therapy. However, existing transfection techniques that operate at the single-cell level either are clumsy or can damage the cells. Now, Muhammad Waleed and co-workers from Gwangju Institute of Science and Technology in South Korea have demonstrated a way to insert precisely a gene into an individual cell without damaging neighbouring cells during the process. They used a tightly focused near-infrared femtosecond laser pulse to puncture the cellular membrane of a MCF-7 cancer cell at a single point. They then used optical tweezers to insert a plasmid-coated polystyrene microparticle into the cell. Laser irradiation with a power of 75 mW for 100 ms was sufficient to form a 3-μm-diameter hole in the cell membrane and to insert a 1-μm-diameter microparticle. The team observed that, after irradiation had finished, the cell membrane healed completely within 3.5 s and that it grew like an unirradiated cell. The transfected cell exhibited green fluorescent protein expression, demonstrating successful transfection. Because of its high selectivity and control over a single cell, this approach will aid the monitoring and study of genetic changes in specific cells.