777 research outputs found

    Biosensors for cardiac biomarkers detection: a review

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    The cardiovascular disease (CVD) is considered as a major threat to global health. Therefore, there is a growing demand for a range of portable, rapid and low cost biosensing devices for the detection of CVD. Biosensors can play an important role in the early diagnosis of CVD without having to rely on hospital visits where expensive and time-consuming laboratory tests are recommended. Over the last decade, many biosensors have been developed to detect a wide range of cardiac marker to reduce the costs for healthcare. One of the major challenges is to find a way of predicting the risk that an individual can suffer from CVD. There has been considerable interest in finding diagnostic and prognostic biomarkers that can be detected in blood and predict CVD risk. Of these, C-reactive protein (CRP) is the best known biomarker followed by cardiac troponin I or T (cTnI/T), myoglobin, lipoprotein-associated phospholipase A(2), interlukin-6 (IL-6), interlukin-1 (IL-1), low-density lipoprotein (LDL), myeloperoxidase (MPO) and tumor necrosis factor alpha (TNF-α) has been used to predict cardiovascular events. This review provides an overview of the available biosensor platforms for the detection of various CVD markers and considerations of future prospects for the technology are addressed

    Rapid and selective concentration of bacteria, viruses, and proteins using alternating current signal superimposition on two coplanar electrodes

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    Dielectrophoresis (DEP) is usually effective close to the electrode surface. Several techniques have been developed to overcome its drawbacks and to enhance dielectrophoretic particle capture. Here we present a simple technique of superimposing alternating current DEP (high-frequency signals) and electroosmosis (EO; low-frequency signals) between two coplanar electrodes (gap: 25 mu m) using a lab-made voltage adder for rapid and selective concentration of bacteria, viruses, and proteins, where we controlled the voltages and frequencies of DEP and EO separately. This signal superimposition technique enhanced bacterial capture (Escherichia coli K-12 against 1-mu m-diameter polystyrene beads) more selectively (>99%) and rapidly (similar to 30 s) at lower DEP (5 Vpp) and EO (1.2 Vpp) potentials than those used in the conventional DEP capture studies. Nanometer-sized MS2 viruses and troponin I antibody proteins were also concentrated using the superimposed signals, and significantly more MS2 and cTnI-Ab were captured using the superimposed signals than the DEP (10 Vpp) or EO (2 Vpp) signals alone (p < 0.035) between the two coplanar electrodes and at a short exposure time (1 min). This technique has several advantages, such as simplicity and low cost of electrode fabrication, rapid and large collection without electrolysis

    Impedimetric Sensors for Bacteria Detection

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    The application of electrochemical biosensors based on impedance detection has grown during the past years due to their high sensitivity and rapid response, making this technique extremely useful to detect biological interactions with biosensor platforms. This chapter is focused on the use of electrochemical impedance spectroscopy (EIS) for bacterial detection in two ways. On one hand, bacteria presence may be determined by the detection of metabolites produced by bacterial growth involving the media conductivity changes. On the other hand, faster and more selective bacterial detection may be achieved by the immobilization of bacteria on a sensor surface using biorecognition elements (antibodies, antimicrobial peptides, aptamers, etc.) and registering changes produced in the charge transfer resistance (faradic process) or interfacial impedance (nonfaradic process). Here we discuss different types of impedimetric biosensors for microbiological applications, making stress on their most important parameters, such as detection limits, detection times, selectivity, and sensitivity. The aim of the paper was to give a critical review of recent publications in the field and mark the future trends

    Diamond MEMS Biosensors: Development and applications

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    This research focuses on the development a dielectrophoresis-enhanced microfluidic impedance biosensor (DEP-e-MIB) to enable fast response, real-time, label-free, and highly sensitive sensor for bacterial detection in clinical sample. The proposed design consists of application of dielectrophoresis (DEP) across a microfluidic channel to one of the impedance spectroscopy electrodes in order to improve the existent bacterial detection limits with impedance spectroscopy. In order to realize such a design, choice of electrode material with a wide electrochemical potential window for water is very important. Conventional electrode material, such as gold, are typically insulated for the application of DEP, and they fail when used open because the DEP voltages avoiding electrolysis do not provide enough force to move the bacteria. First, the use of nanodiamonds (ND) seeding gold surface to widen the electrochemical potential window is examined, since diamond has a wider potential window. ND seed coverage is a function of sonication time, ND concentration, and solvent of ND dispersion. Examining these parameters allowed us to increase the ND surface coverage to ~35%. With the highest ND coverage achievable, such electrodes are still susceptible to damage from electrolysis, however yield a unique leverage for impedance biosensing. When NDs is seeded at a 3x3 interdigitated electrode array, which act as electrically conductive islands between the electrodes and reduce the effective gap between the electrodes, thus allowing to perform impedance spectroscopy in solutions with low electrical conductivity such as ITS. The changes obtained in resistance to charge transfer with bacterial capture is nearly twice than that obtained with plain electrodes. Secondly, the feasibility of using boron-doped ultra nanocrystalline diamond (BD-UNCD) to apply DEP is tested without constructing a 3x3 IDE array. BD-UNCD electrodes can be used for DEP through tagging of the bacteria with immunolatex beads. This allows applying a larger DEP force on the bacteria. Since historically bead based assays are plagued with problems with non-specific binding, the role of different parameters including bead bioconjugation chemistry, bead PEGylation, BD-UNCD surface PEGylation, and DEP on specific and non-specific binding are tested. Most importantly DEP increases the specific binding and PEGylation of beads decreases the specific binding. Finally, a 3x3 IDE array with BD-UNCD was fabricated, and used impedance spectroscopy to test the suitability of BD-UNCD IDEs for impedance biosensing. The huge electrode resistance and the charge transfer resistance at BD-UNCD IDEs poses a problem for impedance biosensing as it will lead to lower sensitivity. BD-UNCD is the material of choice for applying DEP at open electrodes however gold is the choice of material for designing the chip interconnects. So the BD-UNCD layer should be as thin as possible and the interface between gold IDEs and the solution phase during DEP. The findings in this dissertation put us closer to realizing a DEP-eMIB

    A review on impedimetric immunosensors for pathogen and biomarker detection

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    Since the discovery of antibiotics in the first quarter of the twentieth century, their use has been the principal approach to treat bacterial infection. Modernized medicine such as cancer therapy, organ transplantation or advanced major surgeries require effective antibiotics to manage bacterial infections. However, the irresponsible use of antibiotics along with the lack of development has led to the emergence of antimicrobial resistance which is considered a serious global threat due to the rise of multidrug-resistant bacteria (Wang et al. in Antibiotic resistance: a rundown of a global crisis, pp. 1645–1658, 2018). Currently employed diagnostics techniques are microscopy, colony counting, ELISA, PCR, RT-PCR, surface-enhanced Raman scattering and others. These techniques provide satisfactory selectivity and sensitivity (Joung et al. in Sens Actuators B Chem 161:824–831, 2012). Nevertheless, they demand specialized personnel and expensive and sophisticated machinery which can be labour-intensive and time-consuming, (Malvano et al. in Sensors (Switzerland) 18:1–11, 2018; Mantzila et al. in Anal Chem 80:1169–1175, 2008). To get around these problems, new technologies such as biosensing and lab-on-a-chip devices have emerged in the last two decades. Impedimetric immunosensors function by applying electrochemical impedance spectroscopy to a biosensor platform using antibodies or other affinity proteins such as Affimers (Tiede et al. in Elife 6(c):1–35, 2017) or other binding proteins (Weiss et al. in Electrochim Acta 50:4248–4256, 2005) as bioreceptors, which provide excellent sensitivity and selectivity. Pre-enrichment steps are not required and this allows miniaturization and low-cost. In this review different types of impedimetric immunosensors are reported according to the type of electrode and their base layer materials, either self-assembled monolayers or polymeric layers, composition and functionalization for different types of bacteria, viruses, fungi and disease biomarkers. Additionally, novel protein scaffolds, both antibody derived and non-antibody derived, used to specifically target the analyte are considered

    An Overview of Recent Strategies in Pathogen Sensing

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    Pathogenic bacteria are one of the major concerns in food industries and water treatment facilities because of their rapid growth and deleterious effects on human health. The development of fast and accurate detection and identification systems for bacterial strains has long been an important issue to researchers. Although confirmative for the identification of bacteria, conventional methods require time-consuming process involving either the test of characteristic metabolites or cellular reproductive cycles. In this paper, we review recent sensing strategies based on micro- and nano-fabrication technology. These technologies allow for a great improvement of detection limit, therefore, reduce the time required for sample preparation. The paper will be focused on newly developed nano- and micro-scaled biosensors, novel sensing modalities utilizing microfluidic lab-on-a-chip, and array technology for the detection of pathogenic bacteria

    Multilayered Nanostructures Integrated with Emerging Technologies

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    Surface and interface functionalization are crucial steps to introduce new functionalities in numerous applications, as faster dynamics occur on surfaces rather than bulk. Within this context, the layer-by-layer (LbL) technique is a versatile methodology to controllably form organized nanostructures from the spontaneous adsorption of charged molecules. It enables the assembly of multilayered LbL films on virtually any surface using non-covalent molecular interactions, allowing the nanoengineering of interfaces and creation of multifunctional systems with distinct building blocks (polymers, clays, metal nanoparticles, enzymes, organic macromolecules, etc.). Several applications require thin films on electrodes for sensing/biosensing, and here we explore LbL films deposited on interdigitated electrodes (IDEs) that were 3D-printed using the fusing deposition modeling (FDM) technique. IDEs covered with LbL films can be used to form multisensory systems employed in the analysis of complex liquids transforming raw data into specific patterns easily recognized by computational and statistical methods. We extend the FDM 3D-printing methodology to simplify the manufacturing of electrodes and microchannels, thus integrating an e-tongue system in a microfluidic device. Moreover, the continuous flow within microchannels contributes to faster and more accurate analysis, reducing the amount of sample, waste, and costs

    New Trends in Impedimetric Biosensors for the Detection of Foodborne Pathogenic Bacteria

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    The development of a rapid, sensitive, specific method for the foodborne pathogenic bacteria detection is of great importance to ensure food safety and security. In recent years impedimetric biosensors which integrate biological recognition technology and impedance have gained widespread application in the field of bacteria detection. This paper presents an overview on the progress and application of impedimetric biosensors for detection of foodborne pathogenic bacteria, particularly the new trends in the past few years, including the new specific bio-recognition elements such as bacteriophage and lectin, the use of nanomaterials and microfluidics techniques. The applications of these new materials or techniques have provided unprecedented opportunities for the development of high-performance impedance bacteria biosensors. The significant developments of impedimetric biosensors for bacteria detection in the last five years have been reviewed according to the classification of with or without specific bio-recognition element. In addition, some microfluidics systems, which were used in the construction of impedimetric biosensors to improve analytical performance, are introduced in this review

    A Bifunctional Nanocomposites Based Electrochemical Biosensor for In-field Detection of Pathogenic Bacteria in Food

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    This research focused on the application of electrochemical biosensors for the rapid detection of pathogenic bacteria, Escherichia coli O157:H7 and Salmonella Typhimurium, in foods. The possible presence of pathogenic bacteria in foods has always been a great threat to the wellbeing of people and the revenue of food companies. Therefore, the demand for rapid and sensitive methods to detect foodborne pathogens is growing. In this research, an impedimetric immunosensor was first developed for the rapid detection of E. coli O157:H7 and S. Typhimurium in foods. It was based on the techniques of immunomagnetic separation, enzyme labelling, and electrochemical impedance spectroscopy (EIS). This impedimetric immunosensor was capable of specifically detecting E. coli O157:H7 and S. Typhimurium within the range of 102 to 106 colony forming unit (cfu)/ml in the pure culture. The limits of detection (LODs) of E. coli O157:H7 in ground beef and S. Typhimurium in chicken carcass rinse water were 2.05 x 103 cfu/g and 1.04 x 103 cfu/ml, respectively. The second electrochemical biosensor was designed for rapid detection of E. coli O157:H7. This biosensor integrated magnetic GOx-polydopamine (PDA) based polymeric nanocomposites (PMNCs) which served dual functions as both the carrier and the label, and Prussian blue (PB) modified SP-IDMEs for measurement. The core-shell Abs/GOxext/gold nanoparticles (AuNPs)/magnetic beads (MBs)-GOx@PDA PMNCs acted efficiently to get a high load of enzyme onto the surface of bacterial cells. A filtration step separated the free PMNCs from the bonded ones and reduce the background noise to achieve better sensitivity. The constructed biosensor had been proved to be able to detect E. coli O157:H7 with the LOD of 52 cfu/ml in the pure culture. The third electrochemical aptasensor was developed to detect S. Typhimurium based on the concept of the bifunctional nanocomposites. The ssDNA aptamers were used as the biorecognition element. The achieved LOD in the pure culture was 96 cfu/ml. The biosensors developed in this research exhibited good specificity, reproducibility, and easy-to-operate, and are expected to find broad applications in the detection, especially in-field detection, of foodborne pathogens

    Developments in nanoparticles for use in biosensors to assess food safety and quality

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    The following will provide an overview on how advances in nanoparticle technology have contributed towards developing biosensors to screen for safety and quality markers associated with foods. The novel properties of nanoparticles will be described and how such characteristics have been exploited in sensor design will be provided. All the biosensor formats were initially developed for the health care sector to meet the demand for point-of-care diagnostics. As a consequence, research has been directed towards miniaturization thereby reducing the sample volume to nanolitres. However, the needs of the food sector are very different which may ultimately limit commercial application of nanoparticle based nanosensors. © 2014 Elsevier Ltd
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