Dielectric microsphere mediated transfection using a femtosecond laser

We demonstrate the permeabilization of cell membranes by an enhanced optical field generated under polystyrene microspheres of 1000 nm diameter excited by a femtosecond laser pulse. Fluorescent molecules and short interfering RNA (siRNA) have been successfully delivered to many cells in the irradiated area by a single 80 fs laser pulse at 800 nm wavelength in the presence of antibody-conjugated polystyrene spheres. The ratios of the cells showing permeabilization were 38% and 21% for Fluorescein isothiocyanate-dextran and siRNA, respectively, at the laser fluence of 1.06 J/cm(2). The present method has advantages both in high throughput of many cell treatments and precise processing of minute areas on cell membranes.