  Micro-sized cold atmospheric plasma (uCAP) has been developed to expand the
applications of CAP in cancer therapy. In this paper, uCAP devices with
different nozzle lengths were applied to investigate effects on both brain
(glioblastoma U87) and breast (MDA-MB-231) cancer cells. Various diagnostic
techniques were employed to evaluate the parameters of uCAP devices with
different lengths such as potential distribution, electron density, and optical
emission spectroscopy. The generation of short- and long-lived species (such as
hydroxyl radical (.OH), superoxide (O2-), hydrogen peroxide (H2O2), nitrite
(NO2-), et al) were studied. These data revealed that uCAP treatment with a 20
mm length tube has a stronger effect than that of the 60 mm tube due to the
synergetic effects of reactive species and free radicals. Reactive species
generated by uCAP enhanced tumor cell death in a dose-dependent fashion and was
not specific with regards to tumor cell type.
