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研究グループは、骨欠損部位に照射可能なペンシルタイプの「低温大気圧プラズマ照射装置」を共同で開発し、患部へプラズマ照射することにより骨再生が促進することを明らかにしました。本研究成果は、医療分野において骨折治癒期間の短縮や難治性骨折、巨大骨欠損の確実かつ効率的な治療の実現に貢献することが期待できます。近年、プラズマ発生に関する理論・技術の革新に伴い、幅広い分野でプラズマ照射が応用されるようになり、特に生体組織に直接プラズマを照射することにより皮膚疾患の治癒・再生が促進される現象が報告されるなど、革新的医療技術としての期待が高まってきています。本研究グループはこの現象を骨折部の治癒促進に応用することで骨再生の促進や骨癒合期間の短縮が可能ではないかと考えました。今回、本研究グループは、ウサギで尺骨欠損モデルを用い、骨欠損部へ低温大気圧プラズマ照射をした群としない群で新生骨の再生に違いが出るかどうか比較しました。その結果、プラズマ照射時間を5分、10分、15分と変えたプラズマ照射群では、どれも新生骨の再生が確認されました。また、10分照射した群で、コントロールのプラズマを含まないガスを照射した群に比べて8週間後に最も新生骨量が多くなる結果が得られました。, Medical treatment using non-thermal atmospheric pressure plasma (NTAPP) is rapidly gaining recognition. NTAPP is thought to be a new therapeutic method because it could generate highly reactive species in an ambient atmosphere which could be exposed to biological targets (e.g., cells and tissues). If plasma-generated reactive species could stimulate bone regeneration, NTAPP can provide a new treatment opportunity in regenerative medicine. Here, we investigated the impact of NTAPP on bone regeneration using a large bone defect in New Zealand White rabbits and a simple atmospheric pressure plasma (helium microplasma jet). We observed the recovery progress of the large bone defects by X-ray imaging over eight weeks after surgery. The X-ray results showed a clear difference in the occupancy of the new bone of the large bone defect among groups with different plasma treatment times, whereas the new bone occupancy was not substantial in the untreated control group. According to the results of micro-computed tomography analysis at eight weeks, the most successful bone regeneration was achieved using a plasma treatment time of 10 min, wherein the new bone volume was 1.51 times larger than that in the plasma untreated control group. Using H&E and Masson trichrome stains, nucleated cells were uniformly observed, and no inclusion was confirmed, respectively, in the groups of plasma treatment. We concluded the critical large bone defect were filled with new bone. Overall, these results suggest that NTAPP is promising for fracture treatment.

Total reflection X-ray fluorescence (TXRF) is a powerful technique for trace elemental analysis of various liquid samples. A small volume of the liquid sample is dropped onto a flat substrate, and the dried residue is measured using TXRF. Usually, …

A semi-analytical static sheath (SASS) model can provide a spatial potential profile on a biased surface with microstructures, which can be used for predicting ion trajectories on the surface. However, two- or three-dimensional SASS models require a search procedure for a sheath edge equipotential profile, at which ions have the Bohm velocity, as the starting positions for calculating ion trajectories. This procedure can be troublesome when surface microstructures have complex structures....

We have performed numerical simulations of reaction kinetics and flow dynamics of an atmosphericpressure plasma jet (APPJ) of a gas mixture of 99.9% N_2 and 0.1% O_2 in a two-dimensional flow channel with a height of 5 mm and investigated the effects of a sliding substrate and the substitution of the ambient gas. The sliding substrate in the flow channel produces the gas-drag effect, which results in not only the bending of the APPJ trajectory but also significant loss of atomic oxygen when the ambient gas is air....

We have performed matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) on methylene-blue aqueous solutions treated with three-dimensionally integrated micro-solution plasma, in which we have acquired the time evolution of mass spectra as a function of treatment time. The time evolution of mass spectral peak intensities for major detected species has clearly indicated that the parent methylene-blue molecules are degraded through consecutive reactions. The primary reaction is the oxidation of the parent molecules....

Crosslinked albumin films, to which L929 cells do not attach by nature, acquire the L929-cell-adhesion capability by irradiation of an atmospheric-pressure plasma jet (APPJ) of He gas. The number of attached cells was 2.6 × 10^4 cells/cm^2 after the APPJ irradiation for 180 s, while conventional UV photolithography, which was performed in our previous work, required 2 h to obtain the same order of magnitude of the number of attached cells. The contact angle of samples decreased steeply from 105 to 38◦ in the first 10 s irradiation, but decreased quite gradually from 38 to 32◦ with increasing irradiation time from 10 to 180 s....