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Shon, Hyun Kyong,Yoon, Sohee,Moon, Jeong Hee,Lee, Tae Geol American Vacuum Society 2016 Biointerphases Vol.11 No.2
<P>The popularity of argon gas cluster ion beams (Ar-GCIB) as primary ion beams in time-of-flight secondary ion mass spectrometry (TOF-SIMS) has increased because the molecular ions of large organic-and biomolecules can be detected with less damage to the sample surfaces. However, Ar-GCIB is limited by poor mass resolution as well as poor mass accuracy. The inferior quality of the mass resolution in a TOF-SIMS spectrum obtained by using Ar-GCIB compared to the one obtained by a bismuth liquid metal cluster ion beam and others makes it difficult to identify unknown peaks because of the mass interference from the neighboring peaks. However, in this study, the authors demonstrate improved mass resolution in TOF-SIMS using Ar-GCIB through the delayed extraction of secondary ions, a method typically used in TOF mass spectrometry to increase mass resolution. As for poor mass accuracy, although mass calibration using internal peaks with low mass such as hydrogen and carbon is a common approach in TOF-SIMS, it is unsuited to the present study because of the disappearance of the low-mass peaks in the delayed extraction mode. To resolve this issue, external mass calibration, another regularly used method in TOF-MS, was adapted to enhance mass accuracy in the spectrum and image generated by TOF-SIMS using Ar-GCIB in the delayed extraction mode. By producing spectra analyses of a peptide mixture and bovine serum albumin protein digested with trypsin, along with image analyses of rat brain samples, the authors demonstrate for the first time the enhancement of mass resolution and mass accuracy for the purpose of analyzing large biomolecules in TOF-SIMS using Ar-GCIB through the use of delayed extraction and external mass calibration. (C) 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).</P>
ToF‐SIMS imaging and spectroscopic analyses of PEG‐conjugated AuNPs
Shon, Hyun Kyong,Son, Miyoung,Park, Kyong Mi,Rhee, Choong Kyun,Song, Nam Woong,Park, Hyun Min,Moon, Dae Won,Lee, Tae Geol John Wiley Sons, Ltd. 2011 Surface and interface analysis Vol.43 No.1
<P><B>Abstract</B></P><P>Gold nanoparticles (AuNPs) and poly(ethylene glycol) (PEG) are known safe materials to be used <I>in vivo</I>, and so, are becoming increasingly important in biomedical applications. Here, the stability of PEG‐conjugated AuNPs in an aqueous solution was monitored as a function of time using several techniques, namely dynamic light scattering (DLS)‐size analysis, UV‐visible absorption spectrometry and ToF‐SIMS. Roughly 15‐nm‐sized AuNPs were synthesized and pegylated with mPEG (MW = 5 kDa). Four different samples were synthesized, depending on whether or not a dialysis procedure was performed right after synthesis of the AuNPs or pegylation of the AuNPs. The DLS results show that size of mPEG‐conjugated AuNPs and standard deviation increased in cases where a dialysis procedure was performed after pegylation of the AuNPs, indicating aggregation of the AuNPs due to the detachment of mPEG ligands from the surface of the AuNPs. Also, results from UV‐visible absorption spectra and ToF‐SIMS images point to the likelihood that free mPEG ligands in solution help prevent aggregation by maintaining a dynamic equilibrium between the conjugated ligands on the surface of the AuNPs and the free ligands in the aqueous solution. Conversely, once free, mPEG ligands were eliminated from the solution by dialysis and conjugated mPEG ligands detached from the surface of AuNPs into the solution, suspension stability lowered and the AuNPs showed signs of aggregation. We believe that the ToF‐SIMS imaging analysis with DLS and UV‐visible absorption analyses would be useful to study the stability of PEG‐conjugated AuNPs in different environmental conditions. Copyright © 2010 John Wiley & Sons, Ltd.</P>
Shon, Hyun Kyong,Son, Jin Gyeong,Lee, Kyung-Bok,Kim, Jinmo,Kim, Myung Soo,Choi, Insung S.,Lee, Tae Geol Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.3
Micropatterns of streptavidin and human epidermal carcinoma A431 cells were successfully imaged, as received and without any labeling, using cluster $Au_3{^+}$ ion beam-based time-of-flight secondary ion mass spectrometry (TOF-SIMS) together with a principal component analysis (PCA). Three different analysis ion beams ($Ga^+$, $Au^+$ and $Au_3{^+}$) were compared to obtain label-free TOF-SIMS chemical images of micropatterns of streptavidin, which were subsequently used for generating cell patterns. The image of the total positive ions obtained by the $Au_3{^+}$ primary ion beam corresponded to the actual image of micropatterns of streptavidin, whereas the total positive-ion images by $Ga^+$ or $Au^+$ primary ion beams did not. A PCA of the TOF-SIMS spectra was initially performed to identify characteristic secondary ions of streptavidin. Chemical images of each characteristic ion were reconstructed from the raw data and used in the second PCA run, which resulted in a contrasted - and corrected - image of the micropatterns of streptavidin by the $Ga^+$ and $Au^+$ ion beams. The findings herein suggest that using cluster-ion analysis beams and multivariate data analysis for TOF-SIMS chemical imaging would be an effectual method for producing label-free chemical images of micropatterns of biomolecules, including proteins and cells.
경보현(Boo-Hyun Kyong),손태주(Tae-Ju Shon),전호상(Ho-Sang Jeon),이학찬(Hac-Chan Lee),남성기(Seong-Gi Nam),남궁재찬(Jae-Chan Nam Kung) 한국정보과학회 1999 한국정보과학회 학술발표논문집 Vol.26 No.2Ⅱ
본 논문에서는 디지털 카메라를 통해 얻어진 자동차 영상으로부터 이산코사인변환(Discrete Cosin Transform : DCT)를 이용한 자동차번호판 추출방법을 제안한다. 번호판은 문자와 배경으로 이루어져 있으며 번호판 내에는 문자들이 조밀하게 모여 있다는 특징과 번호판 영역이 직시각형으로 되어있다는 것을 이용하여 DCT에 의해서 자동차영상에서 수직, 수평, 대각선 성분만을 추출한후 이 추출된 에지영상에서 코릴레이션(Correlation) 이용하여 번호판영역을 검출하고 이검출된 번호판영역을 투영 히스토그램(Histogram)에 의해서 번호판영역에서의 문자들을 분리한다. 기존에 연구된 방법들은 번호판을 추출하는데 있어서 날씨가 흐리거나 아주 밝거나 밤에 찍은 영상들에 대해서는 번호판추출이 힘들었다. 그러나 제안된 본논문은 날씨와 낮과 밤에 상관없이 일관된 번호판영상을 추출할수있었다.