100 research outputs found
Microfabricated potentiometric electrodes and their in vivo applications
No full textNew technologies that yield mass-produced, miniature, ion-selective electrodes for biology and medicine are described by Erno Lindner of the University of Memphis and Richard P. Buck of the University of North Carolina-Chapel Hill
To the Memory of Ernő Pungor: A Subjective View on the History of Ion‐Selective Electrodes
No full textIn the Mátraf red 08 Symposium on Electrochemical Sensors a session was dedicated to the memory of late Professor Erno{double acute accent} Pungor, the founder and long-term organizer of the Mátrafüred conference series. We all remember him as an inventive scientist with an enthusiastic and witty personality, rich in ideas. Erno{double acute accent} Pungor left his mark in science and on many scientists worldwide. With this contribution, the authors would like to pay tribute to him and acknowledge his outstanding contributions to analytical chemistry, but especially his pioneering works in the field of ion-selective electrodes. © 2009 WILEY-VCH Verlag GmbH&Co
Surface plasmon resonance aided electrochemical immunosensor for CK-MB determination in undiluted serum samples
No full textThis article presents a simple chronoamperometric immunosensor for the quantitative assessment of creatine kinase MB (CK-MB) in 50 μL undiluted serum samples. The immunosensor consists of gold working and counter electrodes patterned onto a glass chip by thin-film photolithography and an external Ag|AgCl reference electrode. The detection limit (DL) of the chronoamperometric method is 13 ng mL-1 (DL = 2×RMSD/S, where RMSD is the residual mean standard deviation of the measured points around a calibration curve with a slope of S). In spiked serum samples, the response was linear up to 300 ng mL-1 of CK-MB. A surface plasmon resonance (SPR) system with simultaneous electrochemical detection (EC-SPR) aided the development of the sandwich immunoassay. Real-time monitoring of the SPR signal was used to optimize the capture antibody immobilization, CK-MB and detection antibody binding, as well as to minimize the nonspecific adsorption of serum proteins to the sensor surface. The detection antibody has been labeled with alkaline phosphatase (ALP) enzyme for sensitive electrochemical detection. ALP catalyzes the hydrolysis of ascorbic acid phosphate and generates ascorbic acid, which is measured chronoamperometrically. The electrochemical immunoassay for CK-MB was less sensitive to nonspecific adsorption related interferences, had a better detection limit, and required a lower volume of sample than the SPR method. © 2010 Springer-Verlag.Fil: Garay, Fernando Sebastian. University of Memphis; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Kisiel, Greggory. University of Memphis; Estados Unidos. Institut National de la Recherche Agronomique; FranciaFil: Fang, Aiping. University of Memphis; Estados UnidosFil: Lindner, Erno. University of Memphis; Estados Unido
Electrochemical quantification of 2,6-diisopropylphenol (propofol)
No full text2,6-Diisopropylphenol (propofol) is a potent anesthetic drug with fast onset of the anesthetic effect and short recovery time for the patients. Outside of the United States, propofol is widely used in performing target controlled infusion anesthesia. With the long term vision of an electrochemical sensor for in vivo monitoring and feedback controlled dosing of propofol in blood, different alternatives for the electrochemical quantification of propofol using diverse working electrodes and experimental conditions are presented in this contribution.When the electrochemical oxidation of propofol takes place on a glassy carbon working electrode, an electrochemically active film grows on the electrode surface. The reduction current of the film is proportional to the propofol concentration and the accumulation time. Based on these findings a stripping analytical method was developed for the detection of propofol in acidic solutions between 0 and 30 μM, with a detection limit of 5.5 ± 0.4 μM.By restricting the scanned potential window between 0.5. V and 1.0. V in cyclic voltammetric experiments, the formation of the electrochemically active polymer can be prevented. This allowed the development of a direct voltammetric method for assessing propofol in acidic solutions between 0 and 30 μM, with a 3.2 ± 0.1 μM (n= 3) detection limit.The stripping method has a better sensitivity but somewhat worse reproducibility because the electrode surface has to be renewed between each experiment. The direct method does not require the renewal of the electrode surface between measurements but has no adequate selectivity towards the common interfering compounds. © 2011 Elsevier B.V.Fil: Langmaier, Jan. University of Memphis; Estados Unidos. Academy of Sciences of the Czech Republic; República ChecaFil: Garay, Fernando Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. University of Memphis; Estados UnidosFil: Kivlehan, Francine. University of Memphis; Estados UnidosFil: Chaum, Edward. University of Tennessee; Estados UnidosFil: Lindner, Erno. University of Memphis; Estados Unido
Theoretical interpretation of transient signals obtained with precipitate-based ion-selective electrodes in the presence of interfering ions
No full textPrecipitate-based ion-selective electrodes respond to sudden changes in the interfering ion activity with nonmonotonic, overshoot-type transient signals, when a certain amount of primary ion is also present in the solution and when the respective selectivity factor is much less than one. A simplified and more detailed quantitative description of these signals is presented in terms of diffusion processes in the adherent solution layer and of adsorption/desorption equilibria on the electrode membrane surface. The validity of this description is proved by excellent fittings to experimental signals in cases of (I) increasing and decreasing interfering ion activity steps, (ii) subsequent changes in interfering ion activity, (Hi) interfering ion activity steps at different primary ion activity levels. The selectivity factor, the diffusion layer thickness values, and the amount of ions adsorbed or desorbed providing good fitting were in agreement with the experimental values determined by other methods, within the respective experimental and calculation errors. © 1985, American Chemical Society. All rights reserved
Medical Sensors for the Diagnosis and Management of Disease: The Physician Perspective
No full textThe objective of this paper is to assist developers of medical sensors to better formulate the clinically relevant design criteria and required performance characteristics of their novel sensor based on an understanding of how these devices will be used by physicians. Sensor technologies play a central role in medicine, and the most critical aspect of the sensor\u27s clinical utility relates to these design decisions. Clinically, sensors are used by health care providers to make both diagnostic and management decisions, and the sensors that aid in these decisions are evaluated by certain clinical, as well as analytical, criteria. Failure to adequately address these end-user requirements can lead to the development of sensors without clinical utility
Designing Medical, Point of Care Sensors to Aid Health Care Providers in Diagnosing and Managing Diseases: Addressing Pertinent Issues and Some Contemporary Opportunities
No full textPoint of care sensors play an important role in clinical medicine and are used daily to guide clinical decisions. This paper discusses clinical considerations in designing such devices for both the diagnosis and management of diseases as well as two contemporary needs for sensor development
A Smart Biosensor-Enabled Intravascular Catheter and Platform for Dynamic Delivery of Propofol to Close the Loop for Total Intravenous Anesthesia
No full textBackground: Target-controlled infusion anesthesia is used worldwide to provide user-defined, stable, blood concentrations of propofol for sedation and anesthesia. The drug infusion is controlled by a microprocessor that uses population-based pharmacokinetic data and patient biometrics to estimate the required infusion rate to replace losses from the blood compartment due to drug distribution and metabolism. The objective of the research was to develop and validate a method to detect and quantify propofol levels in the blood, to improve the safety of propofol use, and to demonstrate a pathway for regulatory approval for its use in the USA. Methods: We conceptualized and prototyped a novel smart biosensor-enabled intravenous catheter capable of quantifying propofol at physiologic levels in the blood, in real time. The clinical embodiment of the platform is comprised of a smart biosensor-enabled catheter prototype, a signal generation/detection readout display, and a driving electronics software. The biosensor was validated in vitro using a variety of electrochemical methods in both static and flow systems with biofluids, including blood. Results: We present data demonstrating the experimental detection and quantification of propofol at sub-micromolar concentrations using this biosensor and method. Detection of the drug is rapid and stable with negligible biofouling due to the sensor coating. It shows a linear correlation with mass spectroscopy methods. An intuitive graphical user interface was developed to: (1) detect and quantify the propofol sensor signal, (2) determine the difference between targeted and actual propofol concentration, (3) communicate the variance in real time, and (4) use the output of the controller to drive drug delivery from an in-line syringe pump. The automated delivery and maintenance of propofol levels was demonstrated in a modeled benchtop patient applying the known pharmacokinetics of the drug using published algorithms. Conclusions: We present a proof-of-concept and in vitro validation of accurate electrochemical quantification of propofol directly from the blood and the design and prototyping of a smart, indwelling, biosensor-enabled catheter and demonstrate feedback hardware and software architecture permitting accurate measurement of propofol in blood in real time. The controller platform is shown to permit autonomous, closed-loop delivery of the drug and maintenance of user-defined propofol levels in a dynamic flow model
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