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Sensitive and molecular size-selective detection of proteins using a chip-based and heteroliganded gold nanoisland by localized surface plasmon resonance spectroscopy.

Hong S, Lee S, Yi J - Nanoscale Res Lett (2011)

Bottom Line: Their ratios on gold nanoisland were optimized for the sensitive detection of superoxide dismutase (SOD1).This protein has been implicated in the pathology of amyotrophic lateral sclerosis (ALS).Upon exposure of the optimized gold nanoisland to a solution of SOD1 and aggregates thereof, changes in the LSPR spectra were observed which are attributed to the size-selective and covalent chemical binding of SOD1 to the nanoholes.

View Article: PubMed Central - HTML - PubMed

Affiliation: World Class University (WCU) Program of Chemical Convergence for Energy & Environment (C2E2), School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 151-744, Korea. jyi@snu.ac.kr.

ABSTRACT
A highly sensitive and molecular size-selective method for the detection of proteins using heteroliganded gold nanoislands and localized surface plasmon resonance (LSPR) is described. Two different heteroligands with different chain lengths (3-mercaptopionicacid and decanethiol) were used in fabricating nanoholes for the size-dependent separation of a protein in comparison with its aggregate. Their ratios on gold nanoisland were optimized for the sensitive detection of superoxide dismutase (SOD1). This protein has been implicated in the pathology of amyotrophic lateral sclerosis (ALS). Upon exposure of the optimized gold nanoisland to a solution of SOD1 and aggregates thereof, changes in the LSPR spectra were observed which are attributed to the size-selective and covalent chemical binding of SOD1 to the nanoholes. With a lower detection limit of 1.0 ng/ml, the method can be used to selectively detect SOD1 in the presence of aggregates at the molecular level.

No MeSH data available.


Related in: MedlinePlus

(A) Representative absorption spectra of SOD1 concentration-dependent response. (B) Changes in the maximum absorbance peak as a function of SOD1 concentration.
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Figure 3: (A) Representative absorption spectra of SOD1 concentration-dependent response. (B) Changes in the maximum absorbance peak as a function of SOD1 concentration.

Mentions: To explore the sensitivity of the method using a homogeneous protein solution, changes in maximum absoprtion at the surface plasmon peak after a 1-h exposure were determined for SOD1 protein concentrations in the range of 1.0 to 0.1 mg/ml. Figure 3A shows representative absorption spectra for the SOD1 concentration-dependent response. When the gold nanoisland substrate is exposed to an SOD1 solution, the peak position is red and shifted upward, compared to the spectra of the native gold nanoisland substrate. Overall in these experiments, the wavelength shift at the centroid peak (the signal of red shift) was not sensitive at low concentrations of SOD1. Thus, the change in absorption near the surface plasmon peak is the preferred optical signal. As seen in Figure 3B, upon increasing the protein cencentration, the changes in the absorption also increase. Concerning signal noise, the limit of detection was determined to be 1.0 ng/ml. It should be noted that there is linear increase in the absorbance changes for the concentration range of 1.0 ng/ml to 10 μg/ml (semi-log scale). At higher concentrations, the binding of SOD1 became saturated, leading to a nonlinear response and a plateau for concentrations in excess of 50 μg/ml. The reason for the non-linear response at higher SOD1 concentrations is that the binding site of the gold nanoisland was nearly saturated with SOD1 protein. That is, the operational amplitude of absorption change (ΔA) increases in proportion to the SOD1 concentration, reaching a limiting value (ΔA = 0.058). The calibration curve also shows that the heteroliganded gold nanoisland can detect roughly a five- to tenfold lower concentration of the protein than other metallic nanoparticle systems [38,39].


Sensitive and molecular size-selective detection of proteins using a chip-based and heteroliganded gold nanoisland by localized surface plasmon resonance spectroscopy.

Hong S, Lee S, Yi J - Nanoscale Res Lett (2011)

(A) Representative absorption spectra of SOD1 concentration-dependent response. (B) Changes in the maximum absorbance peak as a function of SOD1 concentration.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211424&req=5

Figure 3: (A) Representative absorption spectra of SOD1 concentration-dependent response. (B) Changes in the maximum absorbance peak as a function of SOD1 concentration.
Mentions: To explore the sensitivity of the method using a homogeneous protein solution, changes in maximum absoprtion at the surface plasmon peak after a 1-h exposure were determined for SOD1 protein concentrations in the range of 1.0 to 0.1 mg/ml. Figure 3A shows representative absorption spectra for the SOD1 concentration-dependent response. When the gold nanoisland substrate is exposed to an SOD1 solution, the peak position is red and shifted upward, compared to the spectra of the native gold nanoisland substrate. Overall in these experiments, the wavelength shift at the centroid peak (the signal of red shift) was not sensitive at low concentrations of SOD1. Thus, the change in absorption near the surface plasmon peak is the preferred optical signal. As seen in Figure 3B, upon increasing the protein cencentration, the changes in the absorption also increase. Concerning signal noise, the limit of detection was determined to be 1.0 ng/ml. It should be noted that there is linear increase in the absorbance changes for the concentration range of 1.0 ng/ml to 10 μg/ml (semi-log scale). At higher concentrations, the binding of SOD1 became saturated, leading to a nonlinear response and a plateau for concentrations in excess of 50 μg/ml. The reason for the non-linear response at higher SOD1 concentrations is that the binding site of the gold nanoisland was nearly saturated with SOD1 protein. That is, the operational amplitude of absorption change (ΔA) increases in proportion to the SOD1 concentration, reaching a limiting value (ΔA = 0.058). The calibration curve also shows that the heteroliganded gold nanoisland can detect roughly a five- to tenfold lower concentration of the protein than other metallic nanoparticle systems [38,39].

Bottom Line: Their ratios on gold nanoisland were optimized for the sensitive detection of superoxide dismutase (SOD1).This protein has been implicated in the pathology of amyotrophic lateral sclerosis (ALS).Upon exposure of the optimized gold nanoisland to a solution of SOD1 and aggregates thereof, changes in the LSPR spectra were observed which are attributed to the size-selective and covalent chemical binding of SOD1 to the nanoholes.

View Article: PubMed Central - HTML - PubMed

Affiliation: World Class University (WCU) Program of Chemical Convergence for Energy & Environment (C2E2), School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 151-744, Korea. jyi@snu.ac.kr.

ABSTRACT
A highly sensitive and molecular size-selective method for the detection of proteins using heteroliganded gold nanoislands and localized surface plasmon resonance (LSPR) is described. Two different heteroligands with different chain lengths (3-mercaptopionicacid and decanethiol) were used in fabricating nanoholes for the size-dependent separation of a protein in comparison with its aggregate. Their ratios on gold nanoisland were optimized for the sensitive detection of superoxide dismutase (SOD1). This protein has been implicated in the pathology of amyotrophic lateral sclerosis (ALS). Upon exposure of the optimized gold nanoisland to a solution of SOD1 and aggregates thereof, changes in the LSPR spectra were observed which are attributed to the size-selective and covalent chemical binding of SOD1 to the nanoholes. With a lower detection limit of 1.0 ng/ml, the method can be used to selectively detect SOD1 in the presence of aggregates at the molecular level.

No MeSH data available.


Related in: MedlinePlus