• Journal of Microbiology and Biotechnology
• /
• 제12권5호
• /
• pp.780-786
• /
• 2002

An immunosensor based on surface plasmon resonance (SPR) with a self-assembled protein G layer was developed for the detection of Escherichia coli O157:H7. A self-assembled protein C layer on a gold (Au) surface was fabricated by adsorbing the mixture of 11-mercaptoundecanoic acid (MUA) and hexanethiol at various molar ratios and by activating chemical binding between free amine (-$NH_2$) of protein G and 11-(MUA) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDAC) in series. The formation of a self-assembled protein G layer on an Au substrate and the binding of the antibody and antigen in series were confirmed by SPR spectroscopy. The surface morphology analyses of the self-assembled protein G layer on the Au substrate, monoclonal antibody (Mab) against E. coli O157:H7 which was immobilized on protein G, and bound E. coli O157:H7 extracts on Immobilized Mab against E. coii O157:H7 were performed by atomic force microscopy (AFM). The detection limit of the SPR-based immunosensor for E. coli O157:H7 was found to be about $10^4$ cells/ml.

• Current Optics and Photonics
• /
• 제7권4호
• /
• pp.449-456
• /
• 2023

The localized surface-plasmon resonance has drawn great attention, due to its unique optical properties. In this work a general theoretical description of the dipole mode is proposed, using the forced damped harmonic oscillator model of free charges in an ellipsoid. The restoring force and driving force are derived in the quasistatic approximation under general conditions. In this model, metal is regarded as composed of free charges and bound charges. The bound charges form the dielectric background which has a dielectric function. Those free charges undergo a collective motion in the dielectric background under the driving force. The response of free charges will not be included in the dielectric function like the Drude model. The extinction and scattering cross sections as well as the damping coefficient from our model are verified to be consistent with those based on the Drude model. We introduce size effects and modify the restoring and driving forces by adding the dynamic depolarization factor and the radiation damping term to the depolarization factor. This model provides an intuitive physical picture as well as a simple theoretical description of the dipole mode of the localized surface-plasmon resonance based on free-charge collective motion.

• 분석과학
• /
• 제19권1호
• /
• pp.9-17
• /
• 2006

생체 물질의 농도, 두께 및 특정 생체 물질의 분석을 위한 반응 속도론적 자료를 검출하는 능력 그리고 antigen/antibody, ligand/receptor, protein/protein 및 DNA/DNA 상호작용을 포함하는 다양한 생체물질간의 상호작용에 대한 분석에 적용되고, 자연 환경중 오염물질의 분석 등 다양하게 적용되는 표면 플라즈몬 공명 센서를 제작하였다. 또한 표면 플라즈몬 공명 센서를 제어하고 검출기로부터의 데이타(data)를 personal computer로 받아들이기 위해 data acquisition board를 이용하여 LabVIEW program을 만들었다.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
• /
• pp.601-604
• /
• 2008

We report on the Ag thickness effect on the electrical and optical properties of indium zinc tin oxide (IZTO)-Ag-IZTO multilayer electrode grown on a PET substrate and the surface plasmon effect of Ag layer on the optical properties of IZTO-Ag-IZTO electrode. Using an IZTO-Ag-IZTO multilayer with a total thickness below ~80 nm, we can obtain high-quality flexible electrode with very low sheet resistance, high transmittance, high work function and superior flexibility.

• Journal of Electrochemical Science and Technology
• /
• 제3권2호
• /
• pp.57-62
• /
• 2012

In this report, we demonstrate that the longitudinal localized surface plasmon resonance mode can be suppressed when the nanorods were in dumbbell shape. The seed nanorods were synthesized by electrochemical deposition of metals into the pores of anodic aluminum oxide templates. The dumbbell-like nanorods were grown from seed Au-Ni-Au nanorods by a rate-controlled seed-mediated growth strategy. The selective deposition of Au atoms onto Au blocks of Au-Ni-Au nanorods produced larger diameter of Au nanorods with bumpy surface resulting in dumbbell-like nanorods. The morphology of nanorods depended on the reduction rate of $AuCl_4^-$, slow rate producing smooth surface of Au nanorods, but high reduction rate producing bumpy surface morphology. Through systematic investigation into the UV-Vis-NIR spectroscopy, we found that the multiple localized surface plasmon resonance (LSPR) modes were available from single-component Au nanorods. And, their LSPR modes of Au NRs with bumpy surface, compared to the smooth seed Au NRs, were red-shifted, which was obviously attributed to the increased electron oscillation pathways. While the longitudinal LSPR modes of smoothly grown Au NRs were blue-shifted except for a dipole transverse LSPR mode, which can be interpreted by decreased aspect ratio. In addition, dumbbell-like nanorods showed an almost disappeared longitudinal LSPR mode. It reflects that the plasmonic properties can be engineered using complex nanorods structure.

• 대한금속재료학회지
• /
• 제46권7호
• /
• pp.464-470
• /
• 2008

Metallic nanostructures have great potential for bio-chemical sensor applications due to the excitation of localized surface plasmon and its sensitive response to environmental change. Unlike the commonly explored absorption-based sensing, the optical scattering provides single particle detection scheme. For the localized surface plasmon resonance spectroscopy, the metallic nanostructures with controlled shape and size have been usually fabricated on adhesion-layer pre-coated transparent glass substrates. In this study, we calculated the optical scattering properties of plasmonic Au nanodisc using a discrete dipole approximation method and analyzed the effect of adhesion layer on them. Our result also indicates that there is a trade-off between the surface plasmon damping and the capability of supporting nanostructures in determining the optimal thickness of adhesion layer. Marginal thickness of Ti adhesion layer for supporting Au nanostructures fabricated on a silica glass substrate was experimentally analyzed by an adhesion strength test using a nano-indentation technique.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.133.2-133.2
• /
• 2014

A gap surface plasmon resonator have received considerable attention because it can dramatically enhance the absorption of the electromagnetic field. However, whereas most of studies were just focused on the absorption within a narrow range of wavelength, few studies have been performed for the broadband absorption in the visible range. Therefore, in this study, we discuss methods that can induce broadband light absorption using gap plasmon resonance in visible regime. The gap plasmon resonator will offer great potential for appplications to solar cells and bioimaging.

• 센서학회지
• /
• 제28권6호
• /
• pp.355-359
• /
• 2019

Exosomes, known as nanoscale extracellular vesicles in the range of 30-150 nm, are known to contain clinically significant information. However, there is still insufficient information on exosomal membrane proteins for cancer diagnosis. In this work, we investigated the characteristics of the membrane proteins of exosomes shed by cultured breast cancer cell lines using a surface plasmon resonance (SPR) spectroscopy and pre-activated alkanethiols modified sensor chips. The antibodies of breast cancer biomarkers such as MCU-16, EpCAM, CD24, ErbB2, and CA19-9 were immobilized on the pre-activated alkanethiols surfaces without any activation steps. The purified exosomes were loaded onto each antibody surface. The affinity rank of the antibody surfaces was decided by the relative capture efficiency factors for the exosomes. In addition, an antibody with a relative capture efficiency close to 100% was tested with exosome concentration levels of 10⁴/µl, 10⁵/µl, and 10⁶/µl for quantitative analysis.

• Journal of Biosystems Engineering
• /
• 제35권2호
• /
• pp.116-123
• /
• 2010

Rapid detection of foodborne pathogens has been a major challenge for the food industry. Salmonella contamination is well known in all foods including pasteurised milk. The possibility of specific detection of Salmonella Enteritidis by surface plasmon resonance (SPR) biosensor was explored using a commercially available portable SPR sensor. Self assembly technique was adopted to immobilize anti-Salmonella antibodies on the gold sensing surface of the SPR sensor. The concentration of polyclonal antibody for use in the SPR biosensor was chosen to 1.0 mg/mL. Experiments were conducted at near real-time with results obtained for one SPR biosensor assay within 1 hour. The limit of detection for Salmonella Enteritidis was determined to be $10^6$ CFU/mL in both PBS buffer and milk samples. The assay sensitivity was not significantly affected by milk matrix. Our results showed that it would be possible for employing the SPR biosensor to detect Salmonella Enteritidis in near real-time.

• 센서학회지
• /
• 제30권5호
• /
• pp.326-330
• /
• 2021

Reactions between gold (Au) surface plasmon resonance (SPR) chips and bovine serum albumin (BSA) dissolved in solutions of different pH were investigated. The charge on the BSA depends on the pH of the solution in which it is dissolved. Thus, dissolving BSA in different pH solutions resulted in different charges of BSA. Among the BSA dissolved in solutions with pH 4.01, 7.4, and 10.01, the SPR response was the highest for BSA dissolved in the solution of pH 4.01. To eliminate the response variation owing to the difference in the refractive indices of the solutions, phosphate buffered saline (PBS) was injected into the system after the reaction of BSA with the Au SPR chip had happened. In this case too, the BSA dissolved in the solution with pH 4.01 exhibited the highest response. This may be attributed to the non-uniform distribution of ionic patches on the BSA, which can induce electrostatic attraction to the surface even though BSA has a positive charge at pH 4.01, and the absolute values of the net charge of BSA at pH 4.01 and 7.4 were very close.