Damrongsak, Pattareeya

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Apparatus for inspection of low-coercivity magnetic force microscopy tips
(2018-08-13)
Damrongsak, Badin
;
Photaram, Worachote
;
Saengkaew, Karnt
;
Cheowanish, Ittipon
;
Damrongsak, Pattareeya
In hard disk drive manufacturing, magnetic force microscopy (MFM) is employed to provide feedback for process control. This requires accurate and precise measurement of the intensity and the width of the write field generated from fabricated recording heads. Thus, the response of MFM tips when exposed to the write field must be consistency, run to run and machine to machine; however, no specific tool that can inspect and separate out-of-spec or defective MFM tips is available so far. In this present work, we designed and developed a new apparatus that is suitable to quantitatively evaluate the performance of low-coercivity MFM tips. The detailed discussion of the design of the proposed system is given as well as the inspection algorithm. Basically, a solenoid coil is used as a magnetic field generator which can generate the field strength up to 500 Oe, enough to saturate the tip magnetization. When the tip was exposed, a phase difference of the oscillating MFM tip, which is directly proportional to the field intensity, is employed as a measure of the tip response. In addition, the capability of the implemented apparatus to inspect low-coercivity MFM tips was demonstrated. Results were then compared with those obtained from a conventional MFM machine with the reference magnetic write head as a test sample. Several tests with different sets of low-coercivity MFM tips were carried out to evaluate the implemented system. Results showed that it can distinguish the response of different MFM tips; however, as the results were not too different, only three samples were selected to present here, including the tips with typical magnetic response, low response and out-of-spec response. The measured phase shifts of those samples were 54.5 ± 0.3, 36.3 ± 0.3 and 15.4 ± 0.2 degrees, respectively.
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Antitumor activities of carboplatin–doxorubicin–ZnO complexes in different human cancer cell lines (breast, cervix uteri, colon, liver and oral) under UV exposition
(2021-01-01)
Pairoj, Suttirak
;
Damrongsak, Pattareeya
;
Damrongsak, Badin
;
Jinawath, Natini
;
Kaewkhaw, Rossukon
This study aimed to examine the pharmacological profiles of multiple chemo drug candidates in systematic circulation to enhance their specific interactions with five human cancer cell lines. ZnO nanoparticles were successfully bound with chemo drugs via physical adsorption. The drug loading capacity was confirmed by FTIR, whereas the loading efficiency was determined via UV–vis spectrometry. The mean hydrodynamic size increased to 69–82 nm after chemo-drug immobilization via non-covalent interaction with ZnO. Among the nine formulated chemo drugs, the carboplatin (CP)–doxorubicin (DOX)–ZnO complex under UV light irradiation exhibited high sensitivity towards human breast adenocarcinoma cells without affecting human keratinocyte immortal cells with an IC<inf>50</inf> of 0.137 µg/mL, whereas the loading capacity and efficiency of CP–DOX–ZnO were 77.81% and 99.05%, respectively. Fluorescence images confirmed that CP–DOX–ZnO using DOX served as a fluorescence enhancer specifically bound onto the cell membranes, which became almost saturated after 24 h incubation. Carboplatin–DOX–ZnO was possibly endocytosed by cancer cells and was selectively internalized into the target cells; thus, free chemo drug was released in the cytoplasm, which induced acute apoptosis. This resulted in complete inhabitation of growth signal of target cancer cells.
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Antiradical properties of chemo drug, carboplatin, in cooperation with ZnO nanoparticles under UV irradiation in putative model of cancer cells
(2019-07-01)
Pairoj, Suttirak
;
Damrongsak, Pattareeya
;
Damrongsak, Badin
;
Jinawath, Natini
;
Kaewkhaw, Rossukon
The main objective of this study was to assess the antiradical properties of zinc oxide (ZnO) nanoparticles upon exposure to ultraviolet radiation with carboplatin, an anti-proliferative drug used in the treatment of retinoblastoma. For the purpose of this study, the decomposition of 2,2(diphenyl-1-picryhydrazyl) radical (DPPH*) was used to assess the free radical capacity of antioxidants and was followed by MTT measurements. To test the antiradical capacity, the effective concentration, antiradical power, stoichiometry, and number of reduced DPPH* were investigated. DPPH* has a peak absorbance at a wavelength of 515 nm, which disappears upon the introduction of the antiradical agents. Four agents were reacted with DPPH* and represented the possible reaction kinetic categories. ZnO nanoparticles and carboplatin-loaded ZnO nanoparticles reacted more strongly with DPPH* and approached a saturation state at 420 min. The remaining two antiradical agents, ZnO nanoparticles under UV radiation and carboplatin-loaded ZnO nanoparticles under UV radiation, reacted a bit slower with DPPH* and approached a steady state at 1440 min. Among the different four antiradical agents, carboplatin-loaded ZnO nanoparticles under UV light had the highest antiradical response with the lowest effective concentration value to the reduced DPPH* molecules. ZnO nanoparticles alone were found to be poor antiradical agent. Possible mechanisms were attributed to the number of hydroxyl groups available to decrease the number of DPPH*.
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Damrongsak, Pattareeya

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