Single-cell-level cancer therapy using a hollow optical fiber-based microplasma.

Atmospheric-pressure plasmas have been used in cancer therapies, but the size of the delivery systems precludes single-cell treatments. Plasmas are gaseous collections of ionized particles that include free electrons and radicals that are short-lived but strongly reactive species. Cancer therapies based on plasmas that operate at atmospheric pressure have been developed, which expose these free radicals to tumor cells causing their subsequent apoptosis at a rapid pace. To define the mechanism of plasma-induced tumor cell apoptosis, it would be preferred to have a plasma device that can treat tumor cells at the single-cell level. Thus, the challenge is to generate and deliver plasmas to a single cell. A microplasma jet device consisting of a tube with electrodes has been demonstrated as a source for creating nonthermal atmospheric-pressure plasmas with dimensions on the order of several hundred micrometers. There are two principal methods for reducing the size of the plasma. The first method utilizes a glass capillary tube with a small inner diameter. The second approach employs a thin metal wire as an electrode. Because microplasma jets were originally developed for superficial work (i.e., treating only the surface of objects),