Yoshinori Sasaki

Publications (4)8.71 Total impact

• Article: Low drift and small hysteresis characteristics of diamond electrolyte-solution-gate FET

  Yoshinori Sasaki, Hiroshi Kawarada
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  ABSTRACT: We have investigated drift and hysteresis characteristics on an electrolyte-solution-gate field-effect transistor (SGFET) with a unique structure using polycrystalline diamond and verified the possibility as chemical sensors and biosensors. Silicon-based ion-sensitive field effect transistors (ISFETs) have not yet solved such time-related issues due to the chemical instability of the passivation layer covering on SiO2 and that is why the Si-ISFET is not wide spread. First of all, we have confirmed that the pH sensitivities of oxygen- and amine-terminated diamond surfaces are 20 mV/pH and 48 mV/pH, respectively, whereas that of hydrogen-terminated surface is only 7 mV/pH. Drift characteristics measurement on diamond SGFET reveals that diamond SGFETs with any surface termination are more stable in electrolyte solution than Si-ISFETs with typical passivation membranes. Hysteresis width, which is known to be a more serious cause of measurement error than drift, proves to be 0.39 mV on amine-terminated SGFET. This is less than 1/10 compared with common Si3N4-ISFET. These results can be explained by high tolerance of diamond against ions in solution due to intrinsic chemical stability and densely packed structure of diamond itself. In this work, we bear out that diamond SGFET is a promising platform for highly sensitive biosensor application owing to the superiority in terms of time response and resulting measurement accuracy.
  Journal of Physics D Applied Physics 09/2010; 43(37):374020. · 2.54 Impact Factor
• Article: Characterization of DNA hybridization on partially aminated diamond by aromatic compounds.

  Jung-Hoon Yang, Kwang-Soup Song, Guo-Jun Zhang, Munenori Degawa, Yoshinori Sasaki, Iwao Ohdomari, Hiroshi Kawarada
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  ABSTRACT: Here, we report a novel method of micropatterning oligonucleotides via aromatic groups as linkers on partially amino-terminated diamond and the inherence on subsequent hybridization. The covalent immobilization of probe oligonucleotides and characterization of immobilized probe oligonucleotides with carboxylic compounds were investigated by X-ray photoelectron spectroscopy (XPS). To confirm the effects of linker flexibility in a low amino group on diamond for probe oligonucleotides, three kinds of dicarboxylic compound--adipic acid, terephthalic acid, and trimesic acid--were used for immobilization of probe oligonucleotides, like linkers; and these oligonucleotides were hybridized with target oligonucleotides labeled with Cy 5 on the micropatterned diamond surface. The hybridization intensities determined by epifluorescence microscopy were compared and analyzed.
  Langmuir 01/2007; 22(26):11245-50. · 4.19 Impact Factor
• Article: [A case of liposarcoma of the sigmoid colon mesenterium successfully treated with chemotherapy].

  Yoshinori Sasaki, Masato Moritani, Toshifumi Wada, Yasuo Mizumura, Mari Kondo, Keiichiro Yamamoto, Akihiko Tsuchida, Tatsuya Aoki
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  ABSTRACT: We report a case of postoperative recurrence of liposarcoma of the mesenterium successfully treated by chemotherapy using ifosfamide (IFM) and cisplatin (CDDP). A 58-year-old man presented with a strange feeling in the lower abdomen. Enhanced computed tomography showed enhanced non-epithelial tumor in the pelvic space. The tumor moved on palpation, so we diagnosed liposarcoma from the mesenterium, and resected the tumor on 22 August, 2002. The pleomorphic liposarcoma was 11 x 14 x 7 cm, growing from the mesenterium of the sigmoid colon, and weighed 640 g. We performed re-operation due to pelvic recurrence on 24 March, 2003. On 18 September of the same year, when we performed re-operation again for pelvic recurrence, there were so many recurrences on the mesenterium of small intestine that resection was impossible. We started chemotherapy 3 days later using 3.0 g/body IFM from 1 October 2003, together with 1,800 mg/body mesna for prevention of hemorrhage cystitis. We continued chemotherapy using 3.0 g/body/day IFM together with 1, 800 mg/body/day mesna on an outpatient basis, upon his weekly visit to the hospital. Patient remission was shown by abdominal enhanced computed tomography on 10 December. Some grade 2 alopecia and grade 2 leukopenia occurred, so we changed to chemotherapy once every two weeks. Then, it continued to decrease, without any side effects. The response appeared to be complete on computed tomography in August 2004, and we have been continuing the same chemotherapy without recurrence.
  Gan to kagaku ryoho. Cancer & chemotherapy 06/2006; 33(5):679-82.
• Article: Suppression of tumor growth through introduction of an antisense plasmid of macrophage migration inhibitory factor.

  Yoshinori Sasaki, Kazuhiko Kasuya, Jun Nishihira, Yasushi Magami, Akihiko Tsuchida, Tatsuya Aoki, Yasuhisa Koyanagi
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  ABSTRACT: The potential role in cell growth of Macrophage migration inhibitory factor (MIF) has been studied, however, the mechanism of its anti-tumor effect is poorly understood. Antisense-MIF plasmids were directly injected into colon 26 tumors embedded in the back of mice. Furthermore, the role of MIF in the cell cycle was assessed with regard to retinoblastoma (Rb) protein and transcription factor E2F. Plasmids containing sense- and antisense-MIF genes were transfected into human colon cancer KM12SM cells in vitro. To examine the Rb protein-E2F pathway, plasmids containing each specific cis-acting enhancer for Rb protein and E2F with luciferase reporter genes, pRB-luc and pE2F-luc, respectively, were used. Antisense MIF treatment significantly reduced the tumor size. In vitro cell proliferation was significantly suppressed by the antisense treatment as examined by BrdU uptake. Transcriptions of Rb protein were 8.4x10(3) (RLU), 9.5x10(3) and 24.3x10(3) in the antisense MIF, PBK, and the sense MIF, respectively. As for E2F, transcription activities were 3.8x10(3), 3.6x10(3) and 7.7x10(3), respectively. These results indicate the possibility that MIF may promote tumor growth, in which the activation-inactivation mechanism of the Rb protein-E2F pathway could be profoundly involved.
  International Journal of Molecular Medicine 12/2002; 10(5):579-83. · 1.98 Impact Factor