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Enhancing performance of a miniaturized surface plasmon resonance sensor in the reflectance detection mode using a waveguide-coupled bimetallic chip.

Lee YK, Jang DH, Lee KS, Kim WM, Sohn YS - Nanoscale Res Lett (2013)

Bottom Line: In the intensity measurement mode, the sensitivity could be improved by reducing the full width at half maximum (FWHM) of the reflectance curve.Enhancement of the sensitivity in the intensity detection mode was achieved using the WcBiM chip compared with the Au chip.Therefore, sufficient sensitivity for the detection of a disease-related biomarker is attainable with the WcBiM chip in the intensity measurement mode using a miniaturized SPR sensor.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering, Catholic University of Daegu, 13-13 Hayang-ro, Hayang-eup, Gyeongsan-si, Gyeongbuk 712-702, Republic of Korea. sohnys@cu.ac.kr.

ABSTRACT
The characteristics of a waveguide-coupled bimetallic (WcBiM) chip in a miniaturized surface plasmon resonance (SPR) sensor and its detection capability for a low molecular weight biomolecule were investigated. The configuration of the WcBiM chip was gold (Au)/waveguide (ZnS-SiO2)/silver (Ag). In the intensity measurement mode, the sensitivity could be improved by reducing the full width at half maximum (FWHM) of the reflectance curve. The FWHM of the WcBiM chip is narrower than that of the Au chip, which suggests that the slope of the reflectance curve for the WcBiM chip is steeper. In order to generate enhanced resolution, the reflectance should be monitored at the specific angle where the slope is the steepest in the reflectance curve. For the detection of biotin that is a low molecular weight biomolecule, streptavidin was formed on the SPR sensor chip surface. The response of the SPR to biotin at various concentrations was then acquired. The sensitivities of the WcBiM chip and the Au chip were 0.0052%/(ng/ml) and 0.0021%/(ng/ml), respectively. The limit of detection of the biotin concentration for both the WcBiM and Au chips was calculated. The values were 2.87 ng/ml for the WcBiM chip and 16.63 ng/ml for the Au chip. Enhancement of the sensitivity in the intensity detection mode was achieved using the WcBiM chip compared with the Au chip. Therefore, sufficient sensitivity for the detection of a disease-related biomarker is attainable with the WcBiM chip in the intensity measurement mode using a miniaturized SPR sensor.

No MeSH data available.


Related in: MedlinePlus

Reflectance curves of the five different WcBiM configurations.
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Figure 2: Reflectance curves of the five different WcBiM configurations.

Mentions: In order to get the optimal configuration, the sensing characteristics of five different configurations of the WcBiM SPR chips were investigated and compared using the commercial optical thin film software (SCI Film Wizard™) as shown in Figure 2. The five configurations were Au (31 nm)/ZnS-SiO2 (190 nm)/Ag (25 nm), Au (25 nm)/ZnS-SiO2 (190 nm)/Ag (25 nm), Au (31 nm)/ZnS-SiO2 (190 nm)/Ag (20 nm), Au (31 nm)/ZnS-SiO2 (190 nm)/Ag (35 nm), and Au (35 nm)/ZnS-SiO2 (190 nm)/Ag (25 nm). The thickness of the waveguide was fixed. In this calculation, the refractive indices of the BK7 and PBS were set to be 1.515 and 1.335, respectively. The line widths of the reflectance curve for each stack were close to each other. When biomolecules are adsorbed onto the sensor chip, then the refractive index is changed. Thus, we assumed that the refractive index was changed from 1.335 to 1.35, and the change in the reflectance was calculated at the angle where the steepest slope is. The largest change in the reflectance among the five configurations occurs at the Au (31 nm)/ZnS-SiO2 (190 nm)/Ag (25 nm) and Au (35 nm)/ZnS-SiO2 (190 nm)/Ag (25 nm) chips as listed in Table 1. However, the Au (31 nm)/ZnS-SiO2 (190 nm)/Ag (25 nm)-configured chip has the deepest dip depth (minimum reflectance = 0.005%) in the reflectance curve compared to the other configuration (minimum reflectance = 1.507%). This deepest dip depth may lead to a larger dynamic range in the sensor application.


Enhancing performance of a miniaturized surface plasmon resonance sensor in the reflectance detection mode using a waveguide-coupled bimetallic chip.

Lee YK, Jang DH, Lee KS, Kim WM, Sohn YS - Nanoscale Res Lett (2013)

Reflectance curves of the five different WcBiM configurations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750426&req=5

Figure 2: Reflectance curves of the five different WcBiM configurations.
Mentions: In order to get the optimal configuration, the sensing characteristics of five different configurations of the WcBiM SPR chips were investigated and compared using the commercial optical thin film software (SCI Film Wizard™) as shown in Figure 2. The five configurations were Au (31 nm)/ZnS-SiO2 (190 nm)/Ag (25 nm), Au (25 nm)/ZnS-SiO2 (190 nm)/Ag (25 nm), Au (31 nm)/ZnS-SiO2 (190 nm)/Ag (20 nm), Au (31 nm)/ZnS-SiO2 (190 nm)/Ag (35 nm), and Au (35 nm)/ZnS-SiO2 (190 nm)/Ag (25 nm). The thickness of the waveguide was fixed. In this calculation, the refractive indices of the BK7 and PBS were set to be 1.515 and 1.335, respectively. The line widths of the reflectance curve for each stack were close to each other. When biomolecules are adsorbed onto the sensor chip, then the refractive index is changed. Thus, we assumed that the refractive index was changed from 1.335 to 1.35, and the change in the reflectance was calculated at the angle where the steepest slope is. The largest change in the reflectance among the five configurations occurs at the Au (31 nm)/ZnS-SiO2 (190 nm)/Ag (25 nm) and Au (35 nm)/ZnS-SiO2 (190 nm)/Ag (25 nm) chips as listed in Table 1. However, the Au (31 nm)/ZnS-SiO2 (190 nm)/Ag (25 nm)-configured chip has the deepest dip depth (minimum reflectance = 0.005%) in the reflectance curve compared to the other configuration (minimum reflectance = 1.507%). This deepest dip depth may lead to a larger dynamic range in the sensor application.

Bottom Line: In the intensity measurement mode, the sensitivity could be improved by reducing the full width at half maximum (FWHM) of the reflectance curve.Enhancement of the sensitivity in the intensity detection mode was achieved using the WcBiM chip compared with the Au chip.Therefore, sufficient sensitivity for the detection of a disease-related biomarker is attainable with the WcBiM chip in the intensity measurement mode using a miniaturized SPR sensor.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biomedical Engineering, Catholic University of Daegu, 13-13 Hayang-ro, Hayang-eup, Gyeongsan-si, Gyeongbuk 712-702, Republic of Korea. sohnys@cu.ac.kr.

ABSTRACT
The characteristics of a waveguide-coupled bimetallic (WcBiM) chip in a miniaturized surface plasmon resonance (SPR) sensor and its detection capability for a low molecular weight biomolecule were investigated. The configuration of the WcBiM chip was gold (Au)/waveguide (ZnS-SiO2)/silver (Ag). In the intensity measurement mode, the sensitivity could be improved by reducing the full width at half maximum (FWHM) of the reflectance curve. The FWHM of the WcBiM chip is narrower than that of the Au chip, which suggests that the slope of the reflectance curve for the WcBiM chip is steeper. In order to generate enhanced resolution, the reflectance should be monitored at the specific angle where the slope is the steepest in the reflectance curve. For the detection of biotin that is a low molecular weight biomolecule, streptavidin was formed on the SPR sensor chip surface. The response of the SPR to biotin at various concentrations was then acquired. The sensitivities of the WcBiM chip and the Au chip were 0.0052%/(ng/ml) and 0.0021%/(ng/ml), respectively. The limit of detection of the biotin concentration for both the WcBiM and Au chips was calculated. The values were 2.87 ng/ml for the WcBiM chip and 16.63 ng/ml for the Au chip. Enhancement of the sensitivity in the intensity detection mode was achieved using the WcBiM chip compared with the Au chip. Therefore, sufficient sensitivity for the detection of a disease-related biomarker is attainable with the WcBiM chip in the intensity measurement mode using a miniaturized SPR sensor.

No MeSH data available.


Related in: MedlinePlus