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Enzyme stabilization using pectin as a novel entrapment matrix in biosensors

ANALYTICAL LETTERS 2002年第13期35卷 2077-2091页

作者： Jawaheer, S White, SF Rughooputh, SDDV Cullen, DC Cranfield Univ Cranfield Biotechnol Ctr Inst BioSci & Technol Bedford MK45 4DT England Univ Mauritius Fac Sci Reduit Mauritius

The development of biosensors is often based on the use of enzymes that commonly display an inherent lack of suitable stability. We report the use of pectin as a novel material for enzyme entrapment and stabilisation. This work relates to the development of an electrochemical enzyme-sensor array for the monitoring of fruit quality. The enzymes investigated are glucose oxidase, mutarotase, invertase and ascorbate oxidase. Sensors were constructed by screen-printing, with a metallised (rhodium) carbon working electrode, silver/silver chloride printed reference electrode and carbon counter electrode. Enzymes were dispensed in a pectin-based gel over the working electrode and retained by a cellulose acetate membrane. Enzyme stability as a function of dry storage time was assessed by the attained steady-state response of the single-use sensors upon removal from storage. Except for ascorbate oxidase, all enzyme sensors functioned via the detection of enzymatically generated hydrogen peroxide. Ascorbate oxidase stability was assessed by the efficacy of enzymatic elimination of ascorbic acid. All the measurements were carried out at +350mV vs. Ag/AgCl. Pectin was compared to the established polymer hydroxyethyl cellulose (HEC) as an immobilisation matrix. The use of a pectin immobilisation matrix demonstrated either similar stability (glucose oxidase) or increased stability (mutarotase, invertase, ascorbate oxidase) with respect to HEC during a twenty-five week storage test period. Pectin immobilised enzymes demonstrated a greater stabilising effect and reduced response variability while larger signal currents were often observed for HEC immobilised enzymes.

关键词： enzyme stabilization enzyme immobilization pectin enzyme electrode biosensor array

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Multichannel Boron Doped Nanocrystalline Diamond Ultramicroelectrode arrays: Design, Fabrication and Characterization

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SENSORS 2012年第6期12卷 7669-7681页

作者： Kiran, Raphael Rousseau, Lionel Lissorgues, Gaelle Scorsone, Emmanuel Bongrain, Alexandre Yvert, Blaise Picaud, Serge Mailley, Pascal Bergonzo, Philippe CEA LIST Diamond Sensors Lab F-91191 Gif Sur Yvette France Univ Paris Est ESYCOM EA2552 ESIEE Cite Descartes F-93162 Noisy Le Grand France Univ Bordeaux UMR 5287 INCIA F-33000 Bordeaux France INSERM U968 Inst Vis F-75012 Paris France Univ Paris 06 UMR S968 UPMC Inst Vis F-75012 Paris France CEA LITEN DTS Lab Stockage Elect F-73377 Le Bourget Du Lac France

We report on the fabrication and characterization of an 8 x 8 multichannel Boron Doped Diamond (BDD) ultramicro-electrode array (UMEA). The device combines both the assets of microelectrodes, resulting from conditions in mass transport from the bulk solution toward the electrode, and of BDD's remarkable intrinsic electrochemical properties. The UMEAs were fabricated using an original approach relying on the selective growth of diamond over pre-processed 4 inches silicon substrates. The prepared UMEAs were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results demonstrated that the electrodes have exhibited a very fast electrode transfer rate (k(0)) up to 0.05 cm.s(-1) (in a fast redox couple) and on average, a steady state limiting current (in a 0.5 M potassium chloride aqueous solution containing 1 mM Fe(CN)(6)(4-) ion at 100 mV.s(-1)) of 1.8 nA. The UMEAs are targeted for electrophysiological as well as analytical applications.

关键词： ultramicroelectrode boron doped diamond electrochemical impedance spectroscopy biosensor array statistical study of microelectrode arrays

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Surface plasmon resonance imaging of microstructured monolayers

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JOURNAL OF MOLECULAR STRUCTURE 1999年第1-3期509卷 265-273页

作者： Steiner, G Sablinskas, V Hübner, A Kuhne, C Salzer, R Tech Univ Dresden Inst Analyt Chem D-01062 Dresden Germany Vilnius State Univ Dept Gen Phys & Spect Vilnius Lithuania

Surface plasmon resonance (SPR) is one of the most sensitive detection methods for changes of thickness and refractive index in ultra-thin films. We developed a SPR imaging system in order to characterise patterned organic monolayers, a basic commodity for the development of biochemical sensor arrays. The SPR image contrast could be enhanced by chemical modifications of the patterned monolayers. High quality SPR images of microstuctured monolayers were obtained. The lateral resolution achieved by an SPR imaging device with a HeNe laser source and a Kretschmann ATR prism coupler is 2 mu m. The potential of SPR imaging consists in the in-situ investigations of smallest changes in individual elements of arrays of the patterned ultra-thin film. (C) 1999 Elsevier Science B.V. All rights reserved.

关键词： surface plasmon resonance surface plasmon resonance imaging biosensor array ultra-thin polymer film

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Development of a microfluidic biochip for online monitoring of fungal biofilm dynamics

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LAB ON A CHIP 2007年第12期7卷 1723-1731页

作者： Richter, Lukas Stepper, Christoph Mak, Andy Reinthaler, Alessa Heer, Rudolf Kast, Michael Brueckl, Hubert Ertl, Peter Austrian Res Ctr GmbH ARC Div Nano Syst Technol A-1220 Vienna Austria

Microfabricated biochips are developed to continuously monitor cell population dynamics in a non-invasive manner. In the presented work we describe the novel combination of contact-less dielectric microsensors and microfluidics to promote biofilm formation for quantitative cell analysis. The cell chip consists of a polymeric fluidic (PDMS) system bonded to a glass wafer containing the electrodes while temperature and fluid flow are controlled by external heating and pumping stations. The high-density interdigitated capacitors (mu IDES) are isolated by a 550 nm multi-passivation layer of defined dielectric property and provide stable, robust and non-drifting measurement conditions. The performance of this detector is evaluated using various bacterial and yeast strains. The high sensitivity of the developed dielectric microsensors allows direct identification of microbial strains based on morphological differences and biological composition. The novel biofilm analysis platform is used to continuously monitor the dynamic responses of C. albicans and P. pastoris biofilms to increased shear stress and antimicrobial agent concentration. While the presence of shear stress triggers significant changes in yeast growth profiles, the addition of 0.5 mu g mL(-1) amphotericin B revealed two distinct dynamic behaviors of the C. albicans biofilm. Initially, impedance spectra increased linearly at 30 Omega h(-1) for two hours followed by 10 Omega h(-1) (at 50 kHz) over 10 hours while cell viability remained above 95% during fungicide administration. These results demonstrate the ability to directly monitor dielectric changes of sub-cellular components within a living cell population.

关键词： TOTAL ANALYSIS SYSTEMS ON-A-CHIP DIELECTRIC-SPECTROSCOPY CANDIDA-ALBICANS IMPEDANCE MEASUREMENT BIOLOGICAL CELLS biosensor array BACTERIA IDENTIFICATION CULTURE

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Disposable Smart lab on a chip for point-of-care clinical diagnostics

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PROCEEDINGS OF THE IEEE 2004年第1期92卷 154-173页

作者： Ahn, CH Choi, JW Beaucage, G Nevin, JH Lee, JB Puntambekar, A Lee, JY Univ Cincinnati Cincinnati OH 45221 USA Louisiana State Univ Baton Rouge LA 70801 USA Univ Texas Richardson TX 75083 USA Ohio State Univ Columbus OH 45221 USA

This paper presents the development of a disposable plastic biochip incorporating smart passive microfluidics with embedded on-chip power sources and integrated biosensor array for applications in clinical diagnostics and point-of-care testing. The fully integrated disposable biochip is capable of precise volume control with smart microfluidic manipulation without costly on-chip microfluidic components. The biochip has a unique power source using on-chip pressurized air reservoirs, for microfluidic manipulation, avoiding the need for complex microfluidic pumps. In addition, the disposable plastic biochip has successfully been tested for the measurements of partial oxygen concentration, glucose, and lactate level in human blood using an integrated biosensor array. This paper presents details of the smart passive microfluidic system, the on-chip power source, and the biosensor array together with a detailed discussion of the plastic micromachining techniques used. for chip fabrication. A handheld analyzer capable of multiparameter detection of clinically relevant parameters has also been developed to detect the signals from the cartridge type disposable biochip. The handheld analyzer developed in this work is currently the smallest analyzer capable of multiparameter detection for point-of-care testing.

关键词： biosensor array clinical diagnostics lab on a chip on-chip power source smart passive microfluidics

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Influence of statistical variations in cell distribution on the proliferation kinetics of Madin-Darby canine kidney cells on quartz crystal resonator

Influence of statistical variations in cell distribution on ...

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23rd Eurosensors Conference

作者： Cama, G. Bolaeva, K. Jacobs, T. Hartmann, M. Hirsch, S. Naumann, M. Hauptmann, P. Otto VonGuericke Univ Magdegurg Inst Micro & Sensor Syst D-39106 Magdeburg Germany Otto VonGuericke Univ Magdegurg Inst Expt Internal Med D-39106 Magdeburg Germany

The influence of statistical variations in cell distribution on the proliferation of Madin-Darby canine kidney (MDCK-II) cells was analyzed. MDCK-II cells were cultivated in parallel on 4 quartz crystal resonators in a bioreactor chip. Results of proliferation experiments with different initial grade of confluence were compared. Light microscope pictures of the sensor surface and impedance spectra were continuously acquired. CFD simulation results of the bioreactor chip were employed to verify experimental conditions. Results show that especially at low confluency dissimilar development of non-confluent MDCK-II cell layers and resulting changes in acoustic load depend significantly on initial cell distribution.

关键词： biosensor array Cell adhesion Cell distribution Impedance analysis Quartz Crystal Resonator Acoustic load

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An Integrated Circuit for Galvanostatic Electrodeposition of on-chip Electrochemical Sensors 29

An Integrated Circuit for Galvanostatic Electrodeposition of...

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29th IEEE International Conference on Electronics, Circuits and Systems (IEEE ICECS)

作者： Li, Minghao Gill, Atal A. S. Vanhoestenberghe, Anne Ghoreishizadeh, Sara S. UCL Div Surg & Intervent Sci London England UCL Dept Elect & Elect Engn London England Kings Coll London Sch Biomed Engn & Imaging Sci London England

ISBN: (数字)9781665488235

ISBN: (纸本)9781665488235

This paper presents the design of an integrated circuit (IC) for (i) galvanostatic deposition of sensor layers on the on-chip pads, which serve as the sensor's base layer, and (ii) amperometric readout of electrochemical sensors. The system consists of three main circuit blocks: the electrochemical cell including a 4x4 electrode array, two Beta-multiplier based current generators and one pA-size current generator for galvanostatic electrodeposition, and a switch-capacitor based amperometric readout circuit for sensor current measurement. The circuits are designed and simulated in a 180-nm CMOS process. The three current reference circuits generate a stable current from 7.2 pA to 88 mu A with low process, power supply voltage and temperature (PVT) sensitivity. The pA-size current generator has a temperature coefficient of 517.8 ppm/degrees C on average (across corners) in the range of 0 to 60 degrees C. The line regulation is 4.4 %/V over a supply voltage range of 0.8-3 V. The feasibility of galvanostatic deposition on on-chip pads is validated by applying a fixed current of 300 nA to electrochemically deposit a gold layer on top of electrodes with nickel/zinc as the adhesive layer for gold. Successful deposition of gold was confirmed using optical microscope images of the on-chip electrodes.

关键词： current reference subthreshold region sensor fabrication potentiostat biosensor array complementary metal-oxide semiconductor (CMOS) electrochemical sensor

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Electrochemical biosensors for Blood-Borne Viruses Detection: A Review

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CHEMNANOMAT 2024年第9期10卷

作者： Ketabi, Kiana Mohammadinejad, Arash Soleimanjahi, Hoorieh Rezayi, Majid Meshkat, Zahra Tarbiat Modares Univ Fac Med Sci Dept Virol Tehran Iran Mashhad Univ Med Sci Sch Med Dept Med Biotechnol & Nanotechnol Mashhad Iran Mashhad Univ Med Sci Med Toxicol Res Ctr Mashhad Iran Mashhad Univ Med Sci Antimicrobial Resistance Res Ctr Mashhad Iran

This review article discusses the advancements in electrochemical biosensors for detecting blood-borne viruses. Infections like HBV, HCV, HIV, and HTLV transmitted through blood can be life-threatening and have significant impact on both the health and social life. Therefore, timely diagnosis of these infections is crucial. Various effective diagnostic methods have been developed to detect these infections. The combination of nanotechnology and biology has led to creation of new diagnostic techniques using electrodes to detect microorganisms. This review aims to summarize recent studies on the performance of electrochemical biosensors for detecting blood-borne viruses in the last five years, comparing their characteristics, limits of detection, and other relevant parameters. Blood-borne viral infections can be lethal to humans. The use of diagnostic electrochemical biosensors for the detection of blood-borne viruses has attracted scientists' attention due to these positive features. In this review, a research evaluation has been done on the last five years of studies in the field of using electrochemical biosensors for the detection of blood-borne viral infections. image

关键词： Electrochemistry biosensors Blood-borne viruses Clinical diagnosis biosensor array

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Magnetoresistive biosensors with on-chip pulsed excitation and magnetic correlated double sampling

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SCIENTIFIC REPORTS 2018年第1期8卷 16493-16493页

作者： Kim, Kyunglok Hall, Drew A. Yao, Chengyang Lee, Jung-Rok Ooi, Chin C. Bechstein, Daniel J. B. Guo, Yue Wang, Shan X. Stanford Univ Dept Elect Engn Stanford CA 94305 USA Univ Calif San Diego Dept Elect & Comp Engn La Jolla CA 92093 USA Ewha Womans Univ Div Mech & Biomed Engn Seoul South Korea Stanford Univ Dept Chem Engn Stanford CA 94305 USA Stanford Univ Dept Mech Engn Stanford CA 94305 USA Stanford Univ Dept Mat Sci & Engn Stanford CA 94305 USA

Giant magnetoresistive (GMR) sensors have been shown to be among the most sensitive biosensors reported. While high-density and scalable sensor arrays are desirable for achieving multiplex detection, scalability remains challenging because of long data acquisition time using conventional readout methods. In this paper, we present a scalable magnetoresistive biosensor array with an on-chip magnetic field generator and a high-speed data acquisition method. The on-chip field generators enable magnetic correlated double sampling (MCDS) and global chopper stabilization to suppress 1/f noise and offset. A measurement with the proposed system takes only 20 ms, approximately 50x faster than conventional frequency domain analysis. A corresponding time domain temperature correction technique is also presented and shown to be able to remove temperature dependence from the measured signal without extra measurements or reference sensors. Measurements demonstrate detection of magnetic nanoparticles (MNPs) at a signal level as low as 6.92 ppm. The small form factor enables the proposed platform to be portable as well as having high sensitivity and rapid readout, desirable features for next generation diagnostic systems, especially in point-of-care (POC) settings.

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Design of a bioelectronic tongue for glucose monitoring using zinc oxide nanofibers and graphene derivatives

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SENSORS AND ACTUATORS REPORTS 2021年 3卷

作者： Mercante, Luiza A. Andre, Rafaela S. Facure, Murilo H. M. Fugikawa-Santos, Lucas Correa, Daniel S. Fed Univ Bahia UFBA Inst Chem BR-40170280 Salvador BA Brazil Embrapa Instrumentacao Nanotechnol Natl Lab Agr LNNA BR-13560970 Sao Carlos SP Brazil Fed Univ Sao Carlos UFSCar Ctr Exact Sci & Technol Dept Chem PPGQ BR-13565905 Sao Carlos SP Brazil Sao Paulo State Univ Inst Geosci & Exact Sci Phys Dept UNESP BR-13506900 Rio Claro SP Brazil

Monitoring glucose levels is critical for diabetes management and might be a key step in the development of individualized treatment strategies. In this scenario, tracking salivary glucose has been recognized as a promising strategy due to its merits of ease sampling and non-invasive nature. In this paper, we report on the development of an electrical impedance-based biosensor array to distinguish glucose at different concentrations in saliva. The enzymatic biosensors were made of gold interdigitated electrodes coated with pristine electrospun zinc oxide nanofibers (NFZ) and NFZ combined with graphene-based nanomaterials (i.e., reduced graphene oxide - rGO and graphene quantum dots - GQDs), on which a layer of glucose oxidase (GOx) enzyme was adsorbed. Electrical impedance measurements indicate that the NFZ-GQDs@GOx and NFZ-rGO@GOx platforms presented good linear relationship with glucose concentration in the range of 0.1 to 6 mM. The highest sensitivity was reached for NFZ-rGO@GOx with a detection limit (LOD) of 14 mu M, while the LOD was 32 mu M for NFZ-GQDs@GOx. Both biosensors were also capable of detecting glucose in artificial saliva using aliquots of 10 mu L, with recovery between 87.3 and 106.8%. Furthermore, the three sensing units (NFZ@GOx, NFZ-rGO@GOx and NFZ-GQDs@GOx) were employed to build a bioelectronic tongue. Using Principal Component Analysis (PCA) technique to project the electrical impedance data of all sensing units allowed the discrimination of the different glucose concentrations and interferents. This study reveals the applicability of the developed bioelectronic tongue as noninvasive glucose sensors, which approach could also be pottentially adapted to detect other disease biomarkers present in saliva.

关键词： Electrospinning Electrospun nanofibers Reduced graphene oxide Graphene quantum dots Glucose detection biosensor array

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