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장승철 ( Seung Cheol Chang ) 한국센서학회 2011 센서학회지 Vol.20 No.1
A disposable electrochemical immunosensor system has been developed for the detection of herbicide in aqueous samples. Disposable screen printed carbon electrodes(SPCE) were used as basic electrodes and an enzyme, horseradish peroxidase (HRP), and anti-herbicide antibodies was immobilised on to the working electrode of SPCE by using avidin-biotin coupling reactions. An herbicide-glucose oxidase conjugates have been used for the competitive immunoreaction with sample herbicides. The enzymatic reaction between the conjugated glucose oxidase and glucose added generates hydrogen peroxide, which was reduced by the peroxidase immobilised. The latter process caused an electrical current change, due to direct re-reduction of peroxidase by a direct electron transfer mechanism, which was measured to determine the herbicides in the sample. The optimal operational condition was found to be: 20 μgl-1 deglycosylated avidin loading to the working electrode and working potential +50 mV vs. Ag/AgCl. The total assay time was 15 min after sample addition. The detection limits for herbicides, atrazine and simazine, were found to be 3 ppb and 10 ppb, respectively.
최지혜 ( Ji Hye Choi ),이승재 ( Seung Jae Yi ),장승철 ( Seung Cheol Chang ),김경천 ( Kyung Chun Kim ) 한국센서학회 2011 센서학회지 Vol.20 No.6
This study introduced the development of a strip type disposable enzyme-linked immunosensor platform for the detection of IgG. Strips of the strip sensor were fabricated by using commercial nitrocellulose filter membranes and a housing holder for the strips was manufactured by using a standard injection molding process for a plastic material. An IgG-urease conjugate was prepared and used for the competitive immune-binding with sample IgG. From the enzymatic reaction between the conjugated urease and urea added, ammonia was generated and caused a localized alkaline pH change on the immobilized antibody band which was coated onto the sensor strips. This pH increase subsequently caused a color change of the antibody band in the presence of a pH indicator, phenol red. Used in conjunction with a competitive immunoassay format, the intensity of the color produced is directly linked with the concentration of target analyte, IgG, and specific measurement of IgG in a lateral flow immunoassay format was achieved over the range 100 ppb to 2000 ppb IgG.
Thirumalai Dinakaran,Subramani Devaraju,Bosung Shin(신보성),Hyun-jong Paik(백현종),Seung-Cheol Chang(장승철) 한국고분자학회 2017 폴리머 Vol.41 No.6
탄소섬유전극을 기반으로 효소가 불필요한 과산화수소(H₂O₂) 센서를 분산된 은 나노와이어와 단일벽 탄소나노튜브를 탄소섬유전극 표면에 드롭캐스팅법으로 고정화하여 제작하였다. 센서 제작에 사용된 탄소나노튜브는 고분자 분산제인 술폰화 폴리(에테르 술폰)에 의하여 효과적인 길이/직경의 종횡비를 나타낼 수 있도록 개별 분산되었으며 센서의 성능 향상을 위하여 은 나노와이어와 더불어 컴포지트 형태로 제작되어 새로운 센서 제작법에 활용되었다. 제작된 센서는 H₂O₂에 대하여 높은 전기촉매활성과 재현성, 빠른 분석 시간 및 우수한 감도를 나타냄을 확인하였다(센서 감도: 1.3 μA·mM<SUP>-1</SUP>, 검출 한계: 0.69 μM (S/N=3) 및 검출 시간: 3초 미만). 따라서 본 연구에서 개발된 고분자 분산제를 사용한 단일벽 탄소나노튜브의 수용액 내에서의 분산도 향상은 효소가 불필요한 H₂O₂ 센서의 설계 및 제작에 활용될 것으로 기대된다. A new non-enzymatic hydrogen peroxide (H₂O₂) sensor based on carbon fiber microelectrodes (CFMEs) has been developed. The CFMEs were modified using a simple drop casting procedure with effectively dispersed silver nanowires (AgNWs) and debundled single-walled carbon nanotubes (SWCNTs). In aqueous solution, the SWCNTs were debundled with a high length/diameter aspect ratio using a synthesized polymer dispersant, sulfonated poly(ether sulfone) (SPES). Enhanced electrocatalytic activity of the sensor for the reduction of H₂O₂ was obtained with the sensor sensitivity of 1.3 μA·mM<SUP>-1</SUP> and the detection limit of 0.69 μM (S/N=3) with a quick turnaround time (less than 3 s). The results clearly reveal that the AgNW-SWCNTs/CFMEs possess high electro-catalytic activity and efficient sensitivity with high reproducibility and fast amperometric response production. Therefore, the proposed debundling approach can be expanded to design and develop nonenzymatic hydrogen peroxide sensors.