This paper reports a systematic study of spatially extended atmospheric plasma (SEAP) arrays employing many parallel plasma jets packed densely and arranged in an honeycomb configuration. The work is motivated by the challenge of using inherently small atmospheric plasmas to address many large-scale processing applications including plasma medicine. The first part of the study considers a capillary-ring electrode configuration as the elemental jet with which to construct a 2D SEAP array. It is shown that its plasma dynamics is characterized by strong interaction between two plasmas initially generated near the two electrodes. Its plume length increases considerably when the plasma evolves into a high-current continuous mode from the usual bullet mode. Its electron density is estimated to be at the order of 3.7 × 10 12 cm −3 . The second part of the study considers 2D SEAP arrays constructed from parallelization of identical capillary-ring plasma jets with very high jet density of 0.47-0.6. Strong jet-jet interactions of a 7-jet 2D array are found to depend on the excitation frequency, and are effectively mitigated with the jet-array structure that acts as an effective ballast. The impact range of the reaction chemistry of the array exceeds considerably the cross-sectional dimension of the array itself, and the physical reach of reactive species generated by any single jet exceeds significantly the jet-jet distance. As a result, the jet array can treat a large sample surface without relative sample-array movement. A 37-channel SEAP array is used to indicate the scalability with an impact range of up to 48.6 mm in diameter, a step change in capability from previously reported SEAP arrays. 2D SEAP arrays represent one of few current options as large-scale low-temperature atmospheric plasma technologies with distinct capability of directed delivery of reactive species and effective control of the jet-jet and jet-sample interactions.

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Three types of atmospheric dielectric-barrier discharges are presented to illustrate their potential for uniform surface treatment with a length scale spanning from 1 mm to 1 m. As these atmospheric discharges are scaled up in size, it is increasingly difficult to sustain their plasma stability. By using nanosecond images, it is shown that the use of high excitation frequencies is beneficial in achieving excellent uniformity and robust plasma stability, which are both desirable for uniform and reproducible surface treatment.Index Terms-Atmospheric pressure glow discharges, pulsed plasmas, radio-frequency discharges.

BackgroundVEGF is a well-validated target for antiangiogenic intervention in cancer. To date, RNAi technology has been proven to be a promising approach for targeted therapy. DDP is frequently used as a first-line drug in chemotherapy for lung cancer but usually causes severe toxicity. In this study, we investigated a novel strategy of administering and combining RNAi mediated VEGF-targeted therapy with DDP for treatment of lung cancer, with the aim of increasing efficacy and decreasing toxicity.MethodsIn this study, a plasmid encoding VEGF shRNA was constructed to knockdown VEGF both in vitro and in vivo. In vitro, specificity and potency of the targeting sequence were validated in A549 lung adenocarcinoma cells by RT-PCR and ELISA assays. In vivo, therapy experiments were conducted on nude mice bearing A549 xenograft tumors. The VEGF shRNA expressing plasmids were administered systemically in combination with low-dose DDP on a frequent basis. The tumor volume and weight were measured. MVD, the number of apoptotic cells and proliferation index in tumor tissues were assessed by CD31, TUNEL and PCNA immunostaining.ResultsThe VEGF shRNA was highly effective in attenuating VEGF expression both in vitro and in vivo. The treatment with the VEGF shRNA alone reduced the mean tumor weight by 49.40% compared with the blank control (P < 0.05). The treatment with the VEGF shRNA plus DDP yielded maximal benefits by reducing the mean tumor weight by 83.13% compared with the blank control (P < 0.01). The enhanced antitumor efficacy was associated with decreased angiogenesis and increased induction of apoptosis.ConclusionsOur study demonstrated synergistic antitumor activity of combined VEGF shRNA expressing plasmids and low-dose DDP with no overt toxicity, suggesting potential applications of the combined approach in the treatment of lung cancer.

This study investigated whether radiation-induced overexpression of superoxide dismutase 2 (SOD2) exerts radio-sensitizing effects on tumor cells while having radio-protective effects on normal cells during radio-activated gene therapy for human colorectal cancer. A chimeric promoter, C9BC, was generated by directly linking nine tandem CArG boxes to a CMV basic promoter, after which lentiviral vectors containing GFP and SOD2 gene driven by the C9BC promoter were constructed. Stably transfected HT-29 colorectal cancer cells and CCD 841 CoN normal colorectal cells were irradiated to a dose of 6-Gy, and cell proliferation and apoptosis were observed. Tumor xenografts and peritumoral skin tissue in BALB/c mice were infected with the therapeutic lentivirus and subsequently irradiated with a total dose of 6 Gy. In vitro experiments revealed that radiation-induced SOD2 overexpression inhibited tumor cell proliferation (61.89% vs. 40.17%, P < 0.01) and decreased apoptosis among normal cells (14.8% vs. 9.6%, P = 0.02) as compared to untransfected cells. Similar effects were observed in vivo. Thus radiation-induced SOD2 overexpression via the chimeric C9BC promoter increased the radiosensitivity of HT-29 human colorectal cancer cells and concurrently protected normal CCD 841 CoN colorectal cells from radiation damage.