scholarly journals Impedance-Based Miniaturized Biosensor for Ultrasensitive and Fast Prostate-Specific Antigen Detection

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Ganna Chornokur ◽  
Sunil K. Arya ◽  
Catherine Phelan ◽  
Richard Tanner ◽  
Shekhar Bhansali
Keyword(s):  
Monoclonal Antibodies ◽  
Electrochemical Impedance Spectroscopy ◽  
Detection Limit ◽  
Impedance Spectroscopy ◽  
Prostate Specific Antigen ◽  
Electrochemical Impedance ◽  
Point Of Care ◽  
Specific Antigen ◽  
Nonspecific Binding ◽  
Order Of Magnitude

This paper reports the successful fabrication of an impedance-based miniaturized biosensor and its application for ultrasensitive Prostate-Specific Antigen (PSA) detection in standard and real human plasma solution, spiked with different PSA concentrations. The sensor was fabricated using photolithographic techniques, while monoclonal antibodies specific to human PSA were used as primary capture antibodies. Electrochemical impedance spectroscopy (EIS) was employed as a detection technique. The sensor exhibited a detection limit of 1 pg/ml for PSA with minimal nonspecific binding (NSB). This detection limit is an order of magnitude lower than commercial PSA ELISA assays available on the market. The sensor can be easily modified into an array for the detection of other biomolecules of interest, enabling accurate, ultrasensitive, and inexpensive point-of-care sensing technologies.

Electrochemical Characteristics of Al-Based Coating on Magnesium Alloy Fabricated by Supersonic Particles Deposition

2013 ◽  
Vol 756-759 ◽  
pp. 85-88
Author(s):  
Xiao Ming Wang ◽  
Sheng Zhu ◽  
Qing Chang ◽  
Guo Feng Han
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Magnesium Alloy ◽  
Impedance Spectroscopy ◽  
Current Density ◽  
Corrosion Current Density ◽  
Corrosion Potential ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Electrochemical Characteristics ◽  
Order Of Magnitude

Al-based coating on ZM5 magnesium alloy was prepared by Supersonic Particles Deposition (SPD). Electrochemical working station was utilized to test polarization curve, corrosion potential and electrochemical impedance spectroscopy etc. The results indicted that corrosion potential of Al-Si coating was about-767.6mV, much higher than that of ZM5 Mg-substrate; And corrosion current density of the coating sample decreased three order of magnitude than that of the uncoated. Compared to Mg-substrate, the radius of capacitive impedance arc of the coating enlarged and impedance modulus improved two order of magnitude.

scholarly journals Supersensitive Time-resolved Immunofluorometric Assay of Free Prostate-specific Antigen with Nanoparticle Label Technology

2001 ◽  
Vol 47 (7) ◽  
pp. 1269-1278 ◽  
Author(s):  
Tero Soukka ◽  
Janika Paukkunen ◽  
Harri Härmä ◽  
Stefan Lönnberg ◽  
Hanne Lindroos ◽  
...  
Keyword(s):  
Detection Limit ◽  
Prostate Specific Antigen ◽  
Binding Affinity ◽  
Specific Activity ◽  
Solid Phase ◽  
Specific Antigen ◽  
Nonspecific Binding ◽  
Time Resolved ◽  
Detection Range ◽  
Assay Time

Abstract Background: The extreme specific activity of the long-lifetime fluorescent europium(III) chelate nanoparticles and the enhanced monovalent binding affinity of multivalent nanoparticle-antibody bioconjugates are attractive for noncompetitive immunoassay. Methods: We used a noncompetitive, two-step immunoassay design to measure free prostate-specific antigen (PSA). Europium(III) chelate nanoparticles (107 nm in diameter) were coated with a monoclonal anti-PSA antibody (intrinsic affinity, 6 × 109 L/mol). The nanoparticle-antibody bioconjugates had an average of 214 active binding sites per particle and a monovalent binding affinity of 7 × 1010 L/mol. The assay was performed in a low-fluorescence microtitration well passively coated with an another monoclonal anti-PSA antibody (affinity, 2 × 1010 L/mol), and the europium(III) fluorescence was measured directly from the bottom of the well by a standard time-resolved microtitration plate fluorometer. Results: The detection limit (mean + 2 SD) was 0.040 ng/L (7.3 × 105 molecules/mL), and the dynamic detection range covered four orders of magnitude in a 3-h total assay time. The imprecision (CV) over the whole assay range was 2–10%. The detection limit of the assay was limited by the fractional nonspecific binding of the bioconjugate to the solid phase (0.05%), which was higher than the nonspecific binding of the original antibody (<0.01%). Conclusions: The sensitivity of the new assay is equal to that of the ambient-analyte, microspot immunoassay and will be improved by use of optimized, high binding-site density nanoparticle-antibody bioconjugates with reduced nonspecific binding and improved monovalent binding affinity.

scholarly journals A Graphene-PEDOT:PSS Modified Paper-Based Aptasensor for Electrochemical Impedance Spectroscopy Detection of Tumor Marker

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1372 ◽  
Author(s):  
Yi-Kuang Yen ◽  
Chen-Hsiang Chao ◽  
Ya-Shin Yeh
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
Point Of Care ◽  
Low Cost ◽  
Serum Samples ◽  
Analytical Instruments ◽  
Buffer Solutions ◽  
Early Cancer Diagnosis

A graphene and poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) modified conductive paper-based electrochemical impedance spectroscopy (EIS) aptasensor has been successfully fabricated by a simple and continuous coating process. A graphene/PEDOT:PSS modified paper electrode forms the nanocomposite providing a conductive and sensitive substrate for further aptamer functionalization of the biosensor. This low-cost paper-based aptasensor exhibits its sensitivity to carcinoembryonic antigens (CEA) in standard buffer solutions and human serum samples in a linear range of 0.77–14 ng·mL−1. The limit of detection (LOD) is found to be 0.45 ng·mL−1 and 1.06 ng·mL−1 for CEA in both samples, separately. This aptamer-based sensing device was also evaluated and received a good correlation with the immunoassay detection method. The proposed paper-based aptasensor has demonstrated its potential as a rapid simple point-of-care analytical platform for early cancer diagnosis in less developed areas where manufacturing facilities, analytical instruments, and trained specialists are limited.

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