• 센서학회지
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• 제20권6호
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• pp.434-438
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• 2011

A portable surface plasmon resonance(SPR) based immunosensor using thiolated protein G and protein G was developed for the detection of immunoglobulin G(IgG). The protein G has specific affinity with Fc fragment of IgG and was thiolated by 2-Iminothiolane for introduction of thiol groups. Anti-IgG, bovine serum albumin(BSA), and IgG have been sequently injected after surface modification of gold sensor chip with protein G and thiolated protein G. The output signal was increased with the injection of each protein and the actual signal was measured by subtracting signal of reference channel from signal of sample injected channel. The experimental results showed the higher detection capability of IgG using thiolated protein G compared with protein G. From these results, we can conclude that the current surface modification technique and the portable SPR sensor system can be applied to various immunosensors for diagnosis.

• 한국어병학회지
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• 제27권2호
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• pp.99-105
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• 2014

Biosensors consist of biochemical recognition agents like antibodies immobilized on the surfaces of transducers that change the recognition into a measurable electronic signal. Here we report a piezoelectric immunosensor made to detect Vibrio vulnificus. A 9MHz AT-cut piezoelectric wafer attached with two gold electrodes of 5mm diameter was used as the transducer of the QCM biosensor with a reproducibility of ${\pm}0.1Hz$ in frequency response. We have tried different approaches to immobilize antibody on the sensor chip. Concerning the orientation of antibody for the best antigen binding capacity, the antibody was immobilized by specific binding to protein G or by cross-linking through hydrazine. In addition, protein G was cross-linked on glutaraldehyde activated immine layer (PEI) or EDC/NHS activated sulfide monolayer (MPA). PEI was found to be more effective to immobilize protein G following glutaraldehyde activation than MPA. However, hydrazine chip showed a better capability to immobilize more IgG than protein G chip and a higher sensitivity. The sensor system was able to detect V. vulnificus in dose dependent manner and was able to detect bacterial cells within 5 minutes by monitoring frequency shifts in real time. The detection limit can be improved by preincubation to enrich the bacterial cell number.

• 센서학회지
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• 제20권1호
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• pp.35-39
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• 2011

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: $20\;{\mu}gl-1$ 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.

• KSBB Journal
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• 제24권3호
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• pp.253-258
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• 2009

본 연구에서는 ELISA와 면역-크로마토그래피 스트립기술을 결합하여 E. coli O157 : H7을 탐지할 수 있는 면역스트립 센서를 제작하기 위한 제작조건의 최적화 연구를 수행하였다. 포획항체 농도, 탐지항체 농도, 완충용액 첨가제 조성의 면역스트립 제작 또는 운전인자들의 최적화 조건을 결정하였다. 포획항체의 농도는 1 mg/mL를 최적 조건으로 선정하였고, 탐지항체의 최적 농도도 1 mg/mL로 결정하였다. 비특이적 결합을 방지하기 위한 시료 희석용 완충용액의 첨가제 조성으로는 0.5% Tween 20와 3% BSA 혼합 사용을 선정하였다.

• 센서학회지
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• 제17권5호
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• pp.380-386
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• 2008

Quartz crystal microbalance immunosensor has a capacity to perform a label-free and real time detection of a trace amount of analyte through the specific interaction between antibody and antigen. However, immobilization of antibody molecules on the sensor surface is a troublesome procedure for researchers who are not experienced in chemistry. Protein G has a specific affinity to antibody and would serve as a capturing agent for antibody when immobilized on the sensor surface. In this work, we prepared a protein G sensor chip by immobilizing protein G on the surface of quartz crystal microbalance and examined its capability to detect human haptoglobin or human transferrin with unpurified corresponding antiserum. Specific and dose dependent response was observed when the protein G chip was used for detection of antigens after saturated with antiserum. We also verified several advantageous aspects of the protein G chip such as improved flexibility and sensitivity.

• 한국식품위생안전성학회지
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• 제18권3호
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• pp.101-106
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• 2003

냉장식품의 주요한 변패원일균으로서 저온세균인 Pseudomonas aeruhinosa를 최소 전처리한 후 신속히 검출할 수 있는 비표지 면역센서 시스템을 개발하였다. 수정결정전극상으로의 생물요소인 항체의 고정화는 이형이기능성 가교화제인 sulfosuccinimidyl 6-[3-(2-pyridyldithio)propionamido] hexanoate를 사용하여 항체를 티올화시킨 후 티올화된 항체를 화학흡착하여 행하였고, P. aeruginosa flagella에 대한 단클론항체를 사용하였을 때 다클론항체를 사용한 경우보다 센서감응이 우수한 것으로 나타났다. 항체가 고정화된 센서 chip과 flow형 quart crystal microbalance 계측 시스템을 이용하여 균 첨가 및 증균을 행한 10종의 모델시료에 대한 계측을 행하였다. 이 때, 시료자체에 의한 진동수변화가 52~89 Hz 범위인 반면 균 첨가 시에 나타난 진동수변화는 108~200 Hz이었고 증균시료에 의한 진동수변화는 162~222 Hz 범위로 나타났다. 시스템 안정화, 시료주입 및 정상상태이 센서반응 획득, 시스템 세척으로 이루어지는 한 주기의 센서계측에 소요된 시간은 모든 시료에 있어 30분 이내였다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.713-714
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• 2000

Six monoclonal antibodies to human cardiac troponin I (hcTnI) were produced to eventually develop an immunosensor for acute myocardial infarction (AMI). For the characterization of these antibodies, a set of 11 different peptides covering selected ranges of the complete amino acid sequence of hcTnI was prepared and used for epitope mapping. Such analysis allowed to select an appropriate pair of antibodies that can form a sandwich type of immune complexes and was consequently used for an immunoassay.

• Journal of Microbiology and Biotechnology
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• 제11권6호
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• pp.979-985
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• 2001

A fluorometric detection technique for HDL (High Density Lipoprotein) and LDL (Low Density Lipoprotein) was developed for application in a fiber-optic immunosensor using a protein A Langmuir-Blodgget (LB) film. For the fluorescence immunoassay, antibodies specific to HDL or LDL were imobilied on the protein A LB film, and a fluorescence amplification method was developed to overcome their weak fluorescence. The deposition of protein A using the LB technique was monitored using a surface pressure-are $({\pi}-A)$ curve, and the antibody immobilization of the protein A LB film was experimentally verified. The immobilized antibody was used to separate only HDL and LDL from a sample, then the fluorescence of he separated HDL or LDL was amplified. The amount of LDL or HDL was measured using the developed fiber optic fluorescence detection system. The optical properties resulting from the reaction of HDL or LDL with o-phtaldialdehyde, detection range, response time, and stability of the immunoassay were all investigated. The respective detection ranges for HDL and LDL were sufficient to diagnose the risk of coronary heart disease. The amplification step increased the sensitivity, while selective separation using the immobilized antibody led to linearity in the sensor signal. The regeneration of the antibody-immobilized substrate could produce a stable and reproducible immunosensor.

• 센서학회지
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• 제6권5호
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• pp.356-361
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• 1997

광섬유 소산파 센서(fiber-optic evanescent wave sensor)를 제작하였다. 클래드층을 제거한 광섬유 코아 표면에 anti-mouse immunoglobulin G(IgG)를 결합시키고, 형광이 표지된 mouse IgG와의 반응을 직접적인 방법과 경쟁적인 방법을 통하여 측정하였다. 직접적인 방법과 경쟁적인 방법 모두 $1{\mu}g/m{\ell}$이하의 mouse IgG를 측정할 수 있는 감도를 얻을 수 있었다. Anti-mouse IgG는 단순 흡착 방법에 의하여 광섬유 코아 표면의 93.9%에 고정되었고 비특이적 결합반응을 제거하기 위하여 실시한 소혈청 알부민(bovine serum albumin : BSA)을 이용한 표면 코팅 효과는 없었다. Mouse IgG에 결합된 fluorescein의 비율이 높을수록 형광 발생량이 많았으나 관계는 직선적이지 않았다. 본 연구에서 제작된 광섬유 소산파 센서는 $1{\mu}g/m{\ell}$ 이하의 항원 항체 반응을 소산파 여기에 의한 형광량으로 측정할 수 있어 면역센서로의 응용이 가능할 것으로 판단된다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제9권2호
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• pp.107-111
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• 2004

A comparative study was performed to evaluate the signal amplification strategies in electrochemical affinity sensing, which included the direct electron transfer and diffusible-group mediated electron transfer between label enzymes that were specifically bound to target proteins and chemically modified electrode surfaces. As a platform surface for affinity recognition reactions, a double functionalized poly(amidoamine) dendrimer monolayer that was modified with ferrocene and biotin groups was constructed on a gold surface. With the chemically modified electrode, a model affinity sensing with avidin was investigated. The advantages of adopting the diffusible-group mediated signaling strategy were demonstrated in terms of signal sensitivity and stability.