Faculty Profiles - ISHIKAWA, Kenji

Papers - ISHIKAWA, Kenji

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Leukocyte Depletion and Size-Based Enrichment of Circulating Tumor Cells Using a Pressure-Sensing Microfiltration Device Reviewed Open Access

Onoshima, D; Hase, T; Kihara, N; Kuboyama, D; Tanaka, H; Ozawa, N; Yukawa, H; Sato, M; Ishikawa, K; Hasegawa, Y; Ishii, M; Hori, M; Baba, Y

ACS MEASUREMENT SCIENCE AU Vol. 3 ( 2 ) page： 113 - 119 2023.4

Language：English Publishing type：Research paper (scientific journal) Publisher：ACS Measurement Science Au

Considering the challenges in isolating circulating tumor cells (CTCs) pertaining to cellular stress and purity, we report the application of a blood microfiltration device as an optimal approach for noninvasive liquid biopsy to target CTCs. We experimentally analyzed the filtration behavior of the microfilter using pressure sensing to separate tumor cells from leukocytes in whole blood. This approach achieved an average recovery of >96% of the spiked tumor cells and depletion of >99% of total leukocytes. Furthermore, we carried out genomic profiling of the CTCs using the blood microfiltration device. The method was also applied in a clinical setting; DNA amplification was performed using a small number of microfiltered CTCs and epidermal growth factor receptor mutations were successfully detected to characterize the efficacy of molecularly targeted drugs against lung cancer. Overall, the proposed method can provide a tool for evaluating efficient filtration pressure to concentrate CTCs from whole blood.

DOI： 10.1021/acsmeasuresciau.2c00057

Manipulation of etch selectivity of silicon nitride over silicon dioxide to a-carbon by controlling substate temperature with a CF4/H2 plasma Reviewed

Hsiao, SN; Britun, N; Nguyen, TTN; Tsutsumi, T; Ishikawa, K; Sekine, M; Hori, M

VACUUM Vol. 210 page： 111863 - 111863 2023.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Vacuum

The effects of substrate temperature (T<inf>s</inf>) on the etch rate (ER) of the PECVD-prepared SiN, SiO<inf>2</inf> and amorphous carbon (a-C) films, and their selectivity were investigated with a CF<inf>4</inf>/H<inf>2</inf> plasma. The ERs for the SiN at all T<inf>s</inf> were higher than that for the SiO<inf>2</inf> films. As T<inf>s</inf> was decreased from 50 to −20 °C, the ER for the SiN decreased. Contrarily, the ER of the SiO<inf>2</inf> films increased. The etching selectivity of SiN over SiO<inf>2</inf> reached to near unity when the T<inf>s</inf> was −20 °C. At the same time, the ER of for the a-C films was found to be around 0.1 nm/s and irrespective of T<inf>s</inf>. The fluorocarbon (FC) thickness was greater for the SiO<inf>2</inf> films than that of the SiN. The lower ER for the SiO<inf>2</inf> was therefore attributed to the thicker FC layer and resultant etching mechanism. As the T<inf>s</inf> was decreased, the FC thickness on the SiO<inf>2</inf> films decreased, which led to the ER decrease. The decrease of ER for the SiN etching at the low temperature was likely due to the higher stability of the surface N–H modification layer, compared with that processed at 20 °C, which was confirmed by the in situ FTIR.

DOI： 10.1016/j.vacuum.2023.111863

High-performance glass filters for capturing and culturing circulating tumor cells and cancer-associated fibroblasts Reviewed Open Access

Tanaka, H; Iwata, D; Shibata, Y; Hase, T; Onoshima, D; Yogo, N; Shibata, H; Sato, M; Ishikawa, K; Nagasawa, I; Hasegawa, Y; Ishii, M; Baba, Y; Hori, M

SCIENTIFIC REPORTS Vol. 13 ( 1 ) page： 4130 2023.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Scientific Reports

Various liquid biopsy methods have been developed for the non-invasive and early detection of diseases. In particular, the detection of circulating tumor cells (CTCs) and cancer-associated fibroblasts (CAFs) in blood has been receiving a great deal of attention. We have been developing systems and materials to facilitate such liquid biopsies. In this study, we further developed glass filters (with various patterns of holes, pitches, and non-adhesive coating) that can capture CTCs, but not white blood cells. We optimized the glass filters to capture CTCs, and demonstrated that they could be used to detect CTCs from lung cancer patients. We also used the optimized glass filters for detecting CAFs. Additionally, we further developed a system for visualizing the captured cells on the glass filters. Finally, we demonstrated that we could directly culture the captured cells on the glass filters. Based on these results, our high-performance glass filters appear to be useful for capturing and culturing CTCs and CAFs for further examinations.

DOI： 10.1038/s41598-023-31265-9

Generation and measurement of low-temperature plasma for cancer therapy: a historical review Reviewed Open Access

Ishikawa, K; Takeda, K; Yoshimura, S; Kondo, T; Tanaka, H; Toyokuni, S; Nakamura, K; Kajiyama, H; Mizuno, M; Hori, M

FREE RADICAL RESEARCH Vol. 57 ( 3 ) page： 239 - 270 2023.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Free Radical Research

This review provides a description of the historical background of the development of biological applications of low-temperature plasmas. The generation of plasma, methods and devices, plasma sources, and measurements of plasma properties, such as electron dynamics and chemical species generation in both gaseous and aqueous phases, were assessed. Currently, direct irradiation methods for plasma discharges contacting biological surfaces, such as the skin and teeth, are related to plasma biological interactions. Indirect methods using plasma-treated liquids are based on plasma–liquid interactions. The use of these two methods is rapidly increasing in preclinical studies and cancer therapy. The authors address the prospects for further developments in cancer therapeutic applications by understanding the interactions between the plasma and living organisms.

DOI： 10.1080/10715762.2023.2230351

Efficacy of periodic cold plasma treatment in a paddy to produce white-core grains in brewer's rice cultivar Yamadanishiki Reviewed

Hashizume, H; Kitano, H; Mizuno, H; Abe, A; Yuasa, G; Tohno, S; Tanaka, H; Ishikawa, K; Matsumoto, S; Sakakibara, H; Hirosue, Y; Maeshima, M; Mizuno, M; Hori, M

FREE RADICAL RESEARCH Vol. 57 ( 3 ) page： 161 - 173 2023.3

Language：English Publishing type：Research paper (scientific journal) Publisher：Free Radical Research

We investigated the effect of cold plasma application on the yield and grain quality of rice (Oryza sativa L.), focusing on the brewer’s rice cultivar, Yamadanishiki. Two treatment methods were examined in a paddy; direct plasma irradiation of seedlings and indirect treatment with plasma-activated Ringer’s lactate solution (PAL) during the vegetative growth phase. Periodic direct irradiation for 30 s increased whole plant weight and grain yield. Treatment with PAL promoted some growth of panicles relatively and partially suppressed the growth of culms and leaves. Both treatments affected the grain quality; an increase of the ratio of white-core grains to total number of grains, which is suited for producing Japanese sake rice, as well as a decrease of the ratio of immature grains. The results showed that the effective production of rice grains for sake production can be improved by the application of cold plasma treatment of rice seedlings in a paddy.Highlight Rice plants of brewer’s rice cultivar in a paddy were treated with cold plasma, by the direct irradiation of plants and the immersed of plants in plasma-activated Ringer’s lactate (PAL). Direct plasma irradiation promoted plant weight, grain ripening, and increased yield. PAL treatment affected the growth of main stem and promoted the growth of panicles relatively. Both treatments improved the producing white-core grains, in addition to promotion of grain ripening. Cold plasma treatment can be applied to produce stable and high-quality food in various agriculture and food industries, which can achieve the sustainable developmental goals (SDGs).

DOI： 10.1080/10715762.2023.2215914

Cancer-specific cytotoxicity of Ringer's acetate solution irradiated by cold atmospheric pressure plasma Reviewed

Miron, C; Ishikawa, K; Kashiwagura, S; Suda, Y; Tanaka, H; Nakamura, K; Kajiyama, H; Toyokuni, S; Mizuno, M; Hori, M

FREE RADICAL RESEARCH Vol. 57 ( 2 ) page： 91 - 104 2023.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Free Radical Research

Cold atmospheric pressure plasmas are promising medical tools that can assist in cancer treatment. While the medical pathology mechanism is substantially understood, knowledge of the contribution of reactive species formed in plasma and the mode of activation of biochemical pathways is insufficient. Herein, we present a concept involving antitumoral plasma-activated organics, which is envisaged to increase cytotoxicity levels against cancer cells. Ringer′s acetate solution was irradiated by low-temperature plasma at atmospheric pressure and possible reaction pathways of the compound generation are presented. The chemical compounds formed by plasma treatment and their effects on non-tumorigenic breast epithelial cells (MCF-10A) and breast cancer cells (MCF-7) were investigated. The cell viability results have shown that plasma-derived compounds have both, stimulatory and inhibitory effects on cell viability, depending on the concentration of the generated compounds in the irradiated liquids. Previous studies have shown that oxidative stresses involving reactive oxygen and nitrogen species (RONS) can be used to kill cancer cells. Hence, while RONS offers promising first-step killing effects, cell viability results have shown that plasma-derived compounds, such as acetic anhydride and ethyl acetate, have the potential to play important roles in plasma-based cancer therapy.

DOI： 10.1080/10715762.2023.2201390

Plasma-Assisted Priming: Improved Germination and Seedling Performance of Papaya Reviewed Open Access

Xi, DK; Yap, SL; Kumar, NN; Toh, CC; Ishikawa, K; Hori, M

SAINS MALAYSIANA Vol. 52 ( 2 ) page： 599 - 611 2023.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Sains Malaysiana

Papaya is a one of the important tropical fruit crops with a global export of 353 ktonnne reported in 2020. The germination of papaya seed is erratic and often non-uniform. Plasma assisted priming of seed was performed at atmospheric pressure in a parallel plate dielectric barrier discharge system. The germination rate of papaya seeds and the growth performance of the seedling were monitored for several treatment plans combining the atmospheric pressure plasma treatment with soaking of seed in deionized water. An enhanced germination rate of 92% was obtained by the plasma assisted priming, compared to the untreated of 60%. The plasma assisted priming performed by plasma treatment and soaking in an opposite sequence showed different requirement and possibly involved different mechanisms. The treatment time was reduced to only 4 minutes for pre-soaked seeds, otherwise the germination rate increased with the plasma treatment time from 3 to 30 min treatment. The plasma assisted priming approaches were also found enhancing seedling growth performance. The treated seedling grows about two times bigger and the dried mass measured after 30 days was more than 100% compared to that of the untreated and hot water treated seeds.

DOI： 10.17576/jsm-2023-5202-21

Cooperation of Poly(rC)-binding Proteins 1/2 and Glutathione in Ferroptosis Induced by Plasma-activated Ringer's Lactate Reviewed

Zheng, H; Jiang, L; Lyu, QY; Akatsuka, S; Motooka, Y; Sekido, Y; Nakamura, K; Tanaka, H; Ishikawa, K; Kajiyama, H; Mizuno, M; Hori, M; Toyokuni, S

CANCER SCIENCE Vol. 114 page： 749 - 749 2023.2

Cooperation of Poly(rC)-binding Proteins 1/2 and Glutathione in Ferroptosis Induced by Plasmaactivated Ringer's Lactate Reviewed

Zheng, H; Jiang, L; Lyu, QY; Akatsuka, S; Motooka, Y; Sekido, Y; Nakamura, K; Tanaka, H; Ishikawa, K; Kajiyama, H; Mizuno, M; Hori, M; Toyokuni, S

CANCER SCIENCE Vol. 114 page： 1340 - 1340 2023.2

GaN damage-free cyclic etching by sequential exposure to Cl2 plasma and Ar plasma with low Ar+-ion energy at substrate temperature of 400 °C Reviewed

Nakamura, S; Tanide, A; Kimura, T; Nadahara, S; Ishikawa, K; Oda, O; Hori, M

JOURNAL OF APPLIED PHYSICS Vol. 133 ( 4 ) 2023.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Applied Physics

Damage-free atomic layer etching (ALE) of GaN was demonstrated using a cyclic process in which the chlorinated layer formed by Cl2 plasma exposure was removed by exposure to Ar plasma with energy-controlled ions when the substrate temperature was maintained at 400 °C. The layer chlorinated at 400 °C by Cl2 plasma exposure was found to be thinner than that chlorinated at 25 °C. Therefore, in the case of an Ar+-ion energy of 70 eV, the "ALE synergy"parameter, which quantifies the degree to which a process approaches the ideal ALE regime, decreased from 86% at a substrate temperature of 25 °C to 24% at a substrate temperature of 400 °C. A substrate temperature of 400 °C promoted etching even at the lower ion energy of 40 eV, thereby resulting in a higher ALE synergy of 62%. The vertical etching profile with no degradation of photoluminescence near the band edge on the etched surface was then observed. The proposed high-temperature ALE method is promising for realizing a vertical pattern profile via damage-free etching of GaN.

DOI： 10.1063/5.0131685

Mechanical properties of maze-like carbon nanowalls synthesized by the radial injection plasma enhanced chemical vapor deposition method Reviewed Open Access

Ghodke, S; Murashima, M; Christy, D; Van Nong, N; Ishikawa, K; Oda, O; Umehara, N; Hori, M

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING Vol. 862 2023.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Materials Science and Engineering A

The unique structural properties of vertically aligned graphene sheets or Carbon Nanowalls (CNWs) have attracted great interests for their potential for various applications in microelectronic devices, energy storage, and catalyst support materials. During the handling or operation of the devices, tension and/or pressure are often needed. Under such conditions, CNWs must undergo compression and stress. Therefore, the deformation mechanism and evolution behavior of the CNW structures under load play a critical role in the performance and reliability of the devices. In this study, the mechanical properties of a typical maze-like CNW structure synthesized by a Radial Injection Plasma Enhanced Chemical Vapor Deposition (RI-PECVD) technique were analyzed by employing the nanoindentation method. The measured compressive strength of the CNW structure was 50 MPa with an average modulus E value of ∼28 GPa, which is significantly higher than that of pyrolytic graphite and other graphene-based materials such as 3D graphene-derived carbon, commercial graphene, and reduced graphene oxide films. An elastoplastic behavior of a soft material was observed in high-resolution microscopy and a mechanism of deformation for CNWs is elucidated.

DOI： 10.1016/j.msea.2022.144428

Effects of plasma-activated Ringer's lactate solution on cancer cells: evaluation of genotoxicity Reviewed Open Access

Liu, Y; Nakatsu, Y; Tanaka, H; Koga, K; Ishikawa, K; Shiratani, M; Hori, M

GENES AND ENVIRONMENT Vol. 45 ( 1 ) page： 3 2023.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Genes and Environment

Background: Non-thermal atmospheric pressure plasma technologies form the core of many scientific advances, including in the electronic, industrial, and biotechnological fields. The use of plasma as a cancer therapy has recently attracted significant attention due to its cancer cell killing activity. Plasma-activated Ringer’s lactate solution (PAL) exhibits such activity. In addition to ROS, PAL contains active compounds or species that cause cancer cell death, but the potential mutagenic risks of PAL have not been studied. Results: PAL has a low pH value and a high concentration of H<inf>2</inf>O<inf>2</inf>. H<inf>2</inf>O<inf>2</inf> was removed from PAL using catalase and catalase-treated PAL with a pH of 5.9 retained a killing effect on HeLa cells whereas this effect was not observed if the PAL was adjusted to pH 7.2. Catalase-treated PAL at pH 5.9 had no significant effect on mutation frequency, the expression of γH2AX, or G2 arrest in HeLa cells. Conclusion: PAL contains one or more active compounds or species in addition to H<inf>2</inf>O<inf>2</inf> that have a killing effect on HeLa cells. The compound(s) is active at lower pH conditions and apparently exhibits no genotoxicity. This study suggested that identification of the active compound(s) in PAL could lead to the development of novel anticancer drugs for future cancer therapy.

DOI： 10.1186/s41021-023-00260-x

Editorial: Prospects of plasma generated species interaction with organic and inorganic materials Reviewed Open Access

Attri, P; Koga, K; Kurita, H; Ishikawa, K; Shiratani, M

FRONTIERS IN PHYSICS Vol. 10 2023.1

Plasma activated Ringer's lactate solution Reviewed

Tanaka, H; Mizuno, M; Ishikawa, K; Miron, C; Okazaki, Y; Toyokuni, S; Nakamura, K; Kajiyama, H; Hori, M

FREE RADICAL RESEARCH Vol. 57 ( 1 ) page： 14 - 20 2023.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Free Radical Research

Low-temperature plasma (LTP) has been widely used in life science. Plasma-activated solutions were defined as solutions irradiated with LTP, and water, medium, and Ringer’s solutions have been irradiated with LTP to produce plasma-activated solutions. They contain chemical compounds produced by reactions among LTP, air, and solutions. Reactive oxygen and nitrogen species (RONS) are major components in plasma-activated solutions and recent studies revealed that plasma-activated organic compounds are produced in plasma-activated Ringer’s lactate solution (PAL). Many in vitro and in vivo studies demonstrated that PAL exhibits anti-tumor effects on cancers, and biochemical analyses revealed intracellular molecular mechanisms of cancer cell death by PAL.

DOI： 10.1080/10715762.2023.2182663

Biocompatibility of conformal silicon carbide on carbon nanowall scaffolds Reviewed Open Access

Ono, K; Koide, T; Ishikawa, K; Tanaka, H; Kondo, H; Sugawara-Narutaki, A; Jin, Y; Yasuhara, S; Hori, M; Takeuchi, W

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 62 ( SA ) 2023.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics

Silicon carbide (SiC) was coated onto carbon nanowall (CNW) scaffolds using chemical vapor deposition with a vinylsilane precursor at 700 °C to investigate the influence of the wall edge width, wall-to-wall distance, and surface morphology. The wall edge width ranged from 10 nm to those filling the wall-to-wall space without disrupting the CNW morphology. When SiC-coated CNWs (SiC/CNWs) were used as scaffolds for cell culture, cell viability increased until the edge area ratio reached 40%. In over 40% of edge area ratio, cell viability was saturate and comparable to flat surfaces such as SiC films on the Si substrate (SiC/Si) and control samples prepared using polystyrene. Calcification was suppressed in the CNWs, SiC/CNWs, and SiC/Si scaffolds compared to polystyrene. Our results suggest that SiC-coated CNW scaffolds could suppress calcification and promote cell proliferation.

DOI： 10.35848/1347-4065/ac9319

Science-based, data-driven developments in plasma processing for material synthesis and device-integration technologies Reviewed Open Access

Kambara, M; Kawaguchi, S; Lee, HJ; Ikuse, K; Hamaguchi, S; Ohmori, T; Ishikawa, K

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 62 ( SA ) 2023.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Journal of Applied Physics

Low-temperature plasma-processing technologies are essential for material synthesis and device fabrication. Not only the utilization but also the development of plasma-related products and services requires an understanding of the multiscale hierarchies of complex behaviors of plasma-related phenomena, including plasma generation in physics and chemistry, transport of energy and mass through the sheath region, and morphology- and geometry-dependent surface reactions. Low-temperature plasma science and technology play a pivotal role in the exploration of new applications and in the development and control of plasma-processing methods. Presently, science-based and data-driven approaches to control systems are progressing with the state-of-the-art deep learning, machine learning, and artificial intelligence. In this review, researchers in material science and plasma processing, review and discuss the requirements and challenges of research and development in these fields. In particular, the prediction of plasma parameters and the discovery of processing recipes are asserted by outlining the emerging science-based, data-driven approaches, which are called plasma informatics.

DOI： 10.35848/1347-4065/ac9189

Effects of High-Quality Carbon Nanowalls Ionization-Assisting Substrates on Surface-Assisted Laser Desorption/Ionization Mass Spectrometry Performance Reviewed Open Access

Sakai, R; Kondo, H; Ishikawa, K; Ohta, T; Hiramatsu, M; Tanaka, H; Hori, M

NANOMATERIALS Vol. 13 ( 1 ) 2023.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Nanomaterials

Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is performed using carbon nanowalls (CNWs) for ionization-assisting substrates. The CNWs (referred to as high-quality CNWs) in the present study were grown using a radical-injection plasma-enhanced chemical vapor deposition (RI-PECVD) system with the addition of oxygen in a mixture of CH<inf>4</inf> and H<inf>2</inf> gases. High-quality CNWs were different with respect to crystallinity and C–OH groups, while showing similar wall-to-wall distances and a wettability comparable to CNWs (referred to as normal CNWs) grown without O<inf>2</inf>. The efficiency of SALDI was tested with both parameters of ion intensity and fragmental efficiency (survival yield (SY)) using N-benzylpyridinuim chloride (N-BP-CI). At a laser fluence of 4 mJ/cm<sup>2</sup>, normal CNWs had an SY of 0.97 and an ion intensity of 0.13, while 5-sccm-O<inf>2</inf>– high-quality CNWs had an SY of 0.89 and an ion intensity of 2.55. As a result, the sensitivity for the detection of low-molecular-weight analytes was improved with the high-quality CNWs compared to the normal CNWs, while an SY of 0.89 was maintained at a low laser fluence of 4 mJ/cm<sup>2</sup>. SALDI-MS measurements available with the high-quality CNWs ionization-assisting substrate provided high ionization and SY values.

DOI： 10.3390/nano13010063

Selective isotropic atomic-layer etching of thin films by using dry chemical removal tool Reviewed

Shinoda K., Miyoshi N., Kobayashi H., Izawa M., Ishikawa K., Hori M.

Proceedings of SPIE the International Society for Optical Engineering Vol. 12499 2023

Language：English Publishing type：Research paper (scientific journal) Publisher：Proceedings of SPIE the International Society for Optical Engineering

There has been considerable interest in the development of isotropic atomic layer etching (ALE) for the conformal removal of thin films. Material selectivity is crucial for the development of isotropic ALE because the next generation of semiconductor devices will be constructed with miniaturized 3D structures using a variety of very thin films. We developed plasma-assisted thermal-cyclic ALE, which is a repetition of surface modification by plasma exposure and removal of the modified surface by infrared heating. We developed a 300-mm tool, namely, dry chemical removal (DCR), which is equipped with an inductively coupled plasma (ICP) source and infrared lamps, to facilitate rapid thermal desorption of the modified surface. An important feature of the plasma-assisted thermal-cyclic ALE is that it has more tuning knobs than that of conventional ALE because it uses two temperatures: a low temperature for surface modification and an elevated temperature for the removal of the modified surface. This paper presents the selective ALE of various materials, i.e., Si3N4, TiN, W, and SiGe using the developed tool. The mechanisms of the selectivity are divided into two categories: formation of an ammonium salt-based modified layer and selectivity control by adjusting the infrared heating time. This paper reviews the selective ALE mechanisms, focusing on the results of in situ analysis of surface reactions, and presents some of the latest findings.

DOI： 10.1117/12.2664547

Free radical formation induced by cold atmospheric plasma and its biological implications-Comparison with ionizing radiation- Reviewed

Kondo Taakshi, Tanaka Hiromasa, Ishikawa Kenji, Hori Masaru

Vol. 74 ( 2 ) page： 120 - 126 2023

総説：プラズマなどで処理された水の多様性 Reviewed

石川健治

静電気学会誌 Vol. 46 page： 209 2023

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