Optimized diagnostic assays based on redox tagged bio-receptive interfaces (original) (raw)

Fundamentals and Applications of Impedimetric and Redox Capacitive Biosensors

Journal of Analytical & Bioanalytical Techniques, 2014

Electroanalyses have brought a huge amount to our understanding of interfaces generally. When applied to surfaces which have been specifically engineered so as to recruit targets from an analytical solution, potent sensors can be derived. These may be based on a multitude of different analytical methods all typified by specific requirements and surface configurations. This short review examines the application of amperometric and impedimetric methods to the detection of biomarkers of clinical relevance. Basic principles are introduced with examples at both planar and "nanofunctionalised" interfaces comprising immobilized antibodies/antigens and oligonucleotide receptors. A particular focus is made of new developments in impedance and impedance derived capacitance spectroscopy.

Direct detection of biomolecules by electrochemical impedance measurements

Sensors and Actuators B: Chemical, 1994

Accurate, early, fast diagnosis of many diseases requires the direct detection of biomolecules such as immunospecies. Until now, in situ studies have consisted in analysing capacitance variations or optical properties. In this work, electrochemical impedance measurements at various frequencies have been performed on p-Si/SiO,/polymer/ grafted antibody/solution heterostructures with or without an antigen. The in-phase impedance change appears to be a specific signal correlated to the antibody/antigen binding, This key parameter is consistent with the specificity, reversrbility and kinetics of that interaction. Higb signal sensitivity will allow the direct titration of the antigen and better knowledge of the structural parameters involved in the antibody/antigen interaction. 0925-4005/94/$07.00 0 1994 Elsevier Science S.A. All rights reserved SSDI 0925-4005(93)01165-Z

Electrochemical impedance spectroscopy as a platform for reagentless bioaffinity sensing

Sensors and Actuators B: Chemical, 2001

Simple reagentless immunosensor formats have been dif®cult to achieve, particularly for electrochemical devices, since antigen/hapten recognition by an antibody does not directly lead to a reaction cascade. A direct reading electrochemical immunosensor would have major advantages with respect to speed, de-skilled analysis and the development of multi-analyte sensors.

The use of electrochemical impedance spectroscopy for biosensing

Analytical and Bioanalytical Chemistry, 2008

This review introduces the basic concepts and terms associated with impedance and techniques of measuring impedance. The focus of this review is on the application of this transduction method for sensing purposes. Examples of its use in combination with enzymes, antibodies, DNA and with cells will be described. Important fields of application include immune and nucleic acid analysis. Special attention is devoted to the various electrode design and amplification schemes developed for sensitivity enhancement. Electrolyte insulator semiconductor (EIS) structures will be treated separately.

Label-free capacitive assaying of biomarkers for molecular diagnostics

Nature Protocols, 2020

The label-free analysis of biomarkers offers important advantages in developing point-of-care (PoC) biosensors. In contrast to label-based methodologies, such as ELISA, label-free analysis enables direct detection of targets without additional steps and labeled reagents. Nonetheless, label-free approaches require high sensitivity to detect the intrinsic features of a biomarker and low levels of nonspecific signals. Electrochemical capacitance, C μ , is a feature of electroactive nanoscale films that can be measured using electrochemical impedance spectroscopy. C μ is promising as an electrochemical transducing signal for the development of high-sensitivity, reagentless and label-free molecular diagnostic assays. We used a proprietary ferrocene (Fc)-tagged peptide that is able to self-assemble onto gold electrodes (thicknesses <2 nm) to which any biological receptor can be coupled. When coupled with biological receptors (e.g., a monoclonal antibody), C μ exhibited by the redox-tagged peptide changes as a function of the target concentration. We provide herein the steps for the qualitative and quantitative detection of dengue non-structural protein 1 (NS1) biomarker. Detection of NS1 can be used to diagnose dengue virus infection, which causes epidemics each year in tropical and subtropical regions of the world. Including the pre-treatment of the electrode surface, the analysis takes~25 h. This time can be reduced to minutes if the electrode surface is fabricated separately, demonstrating that C μ is promising for PoC applications. We hope this protocol will serve as a reference point for researchers and companies that intend to further develop capacitive devices for molecular diagnostic assays.

Label free redox capacitive biosensing

Biosensors and Bioelectronics, 2013

A surface confined redox group contributes to an interfacial charging (quantifiable by redox capacitance) that can be sensitively probed by impedance derived capacitance spectroscopy. In generating mixed molecular films comprising such redox groups, together with specific recognition elements (here antibodies), this charging signal is able to sensitively transduce the recognition and binding of specific analytes. This novel transduction method, exemplified here with C-reactive protein, an important biomarker of cardiac status and general trauma, is equally applicable to any suitably prepared interfacial combination of redox reporter and receptor. The assays are label free, ultrasensitive, highly specific and accompanied by a good linear range.

Redox-tagged peptide for capacitive diagnostic assays

Biosensors and Bioelectronics, 2015

Early detection assays play a key role in the successful treatment of most diseases. Redox capacitive biosensors were recently introduced as a potential electroanalytical assay platform for point-of-care applications but alternative surfaces (besides a mixed layer containing ferrocene and antibody receptive component) for recruiting important clinical biomarkers are still needed. Aiming to develop alternative receptive surfaces for this novel electrochemical biosensing platform, we synthesized a ferrocene redoxtagged peptide capable of self-assembly into metallic interfaces, a potentially useful biological surface functionalization for bedside diagnostic assays. As a proof of concept we used C-reactive protein (CRP), as a model biomarker, and compared the obtained results to those of previously reported capacitive assays. The redox-tagged peptide approach shows a limit of detection of 0.8 nmol L-1 (same as 94 ng mL-1) and a linear range (R 2 ~ 98%) with the logarithm of the concentration of the analyte comprising 0.5 to 10.0 nmol L-1 , within a clinical relevant range for CRP.

The use of electrochemical impedance spectroscopie for biosensing

Analytical and Bioanalytical Chemistry

Label-free Capacitive Diagnostics: Exploiting Local Redox Probe State Occupancy

Analytical Chemistry, 2014

An electrode surface confined redox group contributes to a substantial potential-dependent interfacial charging that can be sensitively probed and frequency-resolved by impedance-derived capacitance spectroscopy. In utilizing the sensitivity of this charging fingerprint to redox group environment, one can seek to generate derived sensory configurations. Exemplified here through the generation of mixed molecular films comprising ferrocene and antibody receptors to two clinically important targets, the label-free methodology is able to report on human prostatic acid phosphatase (PAP), a tumor marker, with a limit of detection of 11 pM and C-reactive protein with a limit of detection of 28 pM. Both assays exhibit linear ranges encompassing those of clinical value.

Optimized diagnostic assays based on redox tagged bio-receptive interfaces (original) (raw)

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