193 research outputs found
Controlled Potential techniques in amperometric sensing
No full textThermodynamics should strictly govern every reliable surement
supposedly performed in equilibrium conditions, as it is the case of potentiometry, in such a way that a measure that is not in agreement with thermodynamics is actually of poor meaning, if any. On the other hand, if an external power source controls the occurrence of a redox process at an electrode, as it happens in the controlled potential techniques, thermodynamics tries to manage what is going on, though not always successfully. Sometimes it happens that it does, sometimes that the
system “runs after” equilibrium conditions, only approaching them more or less closely
Electrochemical Immunosensors and Aptasensors
No full textThe possibility to integrate biorecognition elements into electrochemical detection systems has opened the way to a new class of powerful analytical devices named electrochemical (EC) biosensors. The first EC biosensors employed enzymes as recognition elements; however this limited their application to redox enzymes and natural or artificial redox substrates or inhibitors. Broadening this to include non-electroactive analytes was later possible thanks to the development of affinity sensors in which specific interactions between biomolecules are exploited for developing highly selective and sensitive biosensors. Presently, the combination of the exceptional molecular recognition capabilities of antibodies and aptamers with the sensitivity, low cost, practicality of use and handiness of electrochemical devices is leading to an impressive development of EC immunosensors and aptasensors that are potentially suitable to detect a wide range of analytes, following a path that is moving alongside the most recent advances in proteomics. Interestingly, with continued improvements and refinements in EC immunosensors based on the use of labels, together with intrinsically electroactive, or those with the ability to interact with electroactive molecules, a new generation of label-free sensors is being developed. This Special Issue takes stock of the state of the art and identifies prospects for EC immuno- and aptasensors, both labeled and label-free. Emphasis is placed on analytical applications for the rapid detection of disease markers and for toxicological and food analyses
Pyrolyzed Photoresist Carbon Electrodes for Trace Electroanalysis of Nickel(II)
No full textNovel pyrolyzed photoresist carbon electrodes for electroanalytical applications have been produced by photolithographic technology followed by pyrolysis of the photoresist. A study of the determination of Ni(II) dimethylglyoximate (Ni-DMG) through adsorptive cathodic stripping voltammetry at an in situ bismuth-modified pyrolyzed photoresist electrode (Bi-PPCE) is reported. The experimental conditions for the deposition of a bismuth film on the PPCE were optimized. The Bi-PPCE allowed the analysis of trace concentrations of Ni(II), even in the presence of Co(II), which is the main interference in this analysis, with cathodic stripping square wave voltammograms characterized by well-separated stripping peaks. The calculated limits of detection (LOD) were 20 ng∙L−1 for Ni(II) alone and 500 ng∙L−1 in the presence of Co(II). The optimized method was finally applied to the analysis of certified spring water (NIST1640a)
Nanobiosensing with arrays and ensembles of nanoelectrodes
No full textSince the first reports dating back to the mid-1990s, ensembles and arrays of nanoelectrodes (NEEs and NEAs, respectively) have gained an important role as advanced electroanalytical tools thank to their unique characteristics which include, among others, dramatically improved signal/noise ratios, enhanced mass transport and suitability for extreme miniaturization. From the year 2000 onward, these properties have been exploited to develop electrochemical biosensors in which the surfaces of NEEs/NEAs have been functionalized with biorecognition layers using immobilization modes able to take the maximum advantage from the special morphology and composite nature of their surface. This paper presents an updated overview of this field. It consists of two parts. In the first, we discuss nanofabrication methods and the principles of functioning of NEEs/NEAs, focusing, in particular, on those features which are important for the development of highly sensitive and miniaturized biosensors. In the second part, we review literature references dealing the bioanalytical and biosensing applications of sensors based on biofunctionalized arrays/ensembles of nanoelectrodes, focusing our attention on the most recent advances, published in the last five years. The goal of this review is both to furnish fundamental knowledge to researchers starting their activity in this field and provide critical information on recent achievements which can stimulate new ideas for future developments to experienced scientists
Ion-exchange voltammetry at polymer-coated electrodes: Principles and analytical prospects.
No full text
Molecular Diagnostics with Electrochemical Biosensors and Arrays
No full textBiosensors are self-contained analytical devices in which a bioreceptor is integrated with a transducer. The interaction between the bioreceptor and a target analyte generates a signal suitable for analytical purposes. In electrochemical biosensors, a change in the redox state of the biorecognition/analyte system generates a change in an electrochemical quantity which can be monitored by electroanalytical techniques. Electrochemical sensors can be miniaturized using ultramicroelectrodes and nanoelectrodes and their arrays as transducers. These devices are characterized by high specificity and sensitivity and improved detection limits. Biosensors can be used by non-specialist operators at the point of care. For the above reasons, within the frame of the Trans2care project, the Laboratory of Electrochemical Sensors of the University Ca' Foscari of Venice will collaborate with the project partners to develop electrochemical sensors suitable for specific clinical needs
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