897 research outputs found

    Polymer Nanocomposite-Based Electrochemical Sensors and Biosensors

    Get PDF
    Polymer nanocomposites (PNCs) play a significant role in modern day life and are widely studied for extensive properties which make them appealing to numerous applications. They are synthesized with scalable processing procedures with several nanoscale variations of fillers and forms leading to specific sensing applications. In this chapter, PNC-based electrochemical sensors and biosensors like DNA biosensors and immunosensors are discussed. These sensors related PNC applications uses nanofillers of various combinations like conductive polymers with graphene (Grp), carbon nanotubes (CNTs), and metal nanoparticles, which endow high electrical conductivity, effective surface area, and fast electron transfer rate. Currently, wearable devices based on electrochemical Sensors and biosensors have been of great interest in the detection of both physiological and environmental analytes

    Impedimetric Immunosensor for Pesticide Detection

    Get PDF

    Applications of Graphene Quantum Dots in Biomedical Sensors

    Get PDF
    Due to the proliferative cancer rates, cardiovascular diseases, neurodegenerative disorders, autoimmune diseases and a plethora of infections across the globe, it is essential to introduce strategies that can rapidly and specifically detect the ultralow concentrations of relevant biomarkers, pathogens, toxins and pharmaceuticals in biological matrices. Considering these pathophysiologies, various research works have become necessary to fabricate biosensors for their early diagnosis and treatment, using nanomaterials like quantum dots (QDs). These nanomaterials effectively ameliorate the sensor performance with respect to their reproducibility, selectivity as well as sensitivity. In particular, graphene quantum dots (GQDs), which are ideally graphene fragments of nanometer size, constitute discrete features such as acting as attractive fluorophores and excellent electro-catalysts owing to their photo-stability, water-solubility, biocompatibility, non-toxicity and lucrativeness that make them favorable candidates for a wide range of novel biomedical applications. Herein, we reviewed about 300 biomedical studies reported over the last five years which entail the state of art as well as some pioneering ideas with respect to the prominent role of GQDs, especially in the development of optical, electrochemical and photoelectrochemical biosensors. Additionally, we outline the ideal properties of GQDs, their eclectic methods of synthesis, and the general principle behind several biosensing techniques.DFG, 428780268, Biomimetische Rezeptoren auf NanoMIP-Basis zur Virenerkennung und -entfernung mittels integrierter AnsÀtz

    Polymers and plastics modified electrodes for biosensors: a review

    Get PDF
    Polymer materials offer several advantages as supports of biosensing platforms in terms of flexibility, weight, conformability, portability, cost, disposability and scope for integration. The present study reviews the field of electrochemical biosensors fabricated on modified plastics and polymers, focusing the attention, in the first part, on modified conducting polymers to improve sensitivity, selectivity, biocompatibility and mechanical properties, whereas the second part is dedicated to modified “environmentally friendly” polymers to improve the electrical properties. These ecofriendly polymers are divided into three main classes: bioplastics made from natural sources, biodegradable plastics made from traditional petrochemicals and eco/recycled plastics, which are made from recycled plastic materials rather than from raw petrochemicals. Finally, flexible and wearable lab-on-a-chip (LOC) biosensing devices, based on plastic supports, are also discussed. This review is timely due to the significant advances achieved over the last few years in the area of electrochemical biosensors based on modified polymers and aims to direct the readers to emerging trends in this field.Peer ReviewedPostprint (published version

    A cellulose-based bioassay for the colorimetric detection of pathogen DNA

    Get PDF
    Cellulose-paper-based colorimetric bioassays may be used at the point of sampling without sophisticated equipment. This study reports the development of a colorimetric bioassay based on cellulose that can detect pathogen DNA. The detection was based on covalently attached single-stranded DNA probes and visual analysis. A cellulose surface functionalized with tosyl groups was prepared by the N,N-dimethylacetamide-lithium chloride method. Tosylation of cellulose was confirmed by scanning electron microscopy, Fourier transform infrared spectroscopy and elemental analysis. Sulfhydryl-modified oligonucleotide probes complementary to a segment of the DNA sequence IS6110 of Mycobacterium tuberculosis were covalently immobilized on the tosylated cellulose. On hybridization of biotin-labelled DNA oligonucleotides with these probes, a colorimetric signal was obtained with streptavidin-conjugated horseradish peroxidase catalysing the oxidation of tetramethylbenzamidine by H2O2. The colour intensity was significantly reduced when the bioassay was subjected to DNA oligonucleotide of randomized base composition. Initial experiments have shown a sensitivity of 0.1 ÎŒM. A high probe immobilization efficiency (more than 90 %) was observed with a detection limit of 0.1 ÎŒM, corresponding to an absolute amount of 10 pmol. The detection of M. tuberculosis DNA was demonstrated using this technique coupled with PCR for biotinylation of the DNA. This work shows the potential use of tosylated cellulose as the basis for point-of-sampling bioassays.Peer reviewedFinal Accepted Versio

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

    Get PDF
    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

    The application of functionalized nanocarbon materials as bio-interfaces in early diagnosis support

    Get PDF
    The aim of this study is to design and develop novel carbon nanotube and graphene based platforms as biosensors for electrochemically detecting dopamine. The use of such novel nanostructure, which was introduced with functional groups or bio-recognizition molecular, will enable the development of affinity-based biosensors for disease diagnostics and therapy monitoring. The electrical devices are extremely useful for dopamine determination in a fast and simple way. In this study, a Nafion/MWCNT chip prepared by inkjet printing was developed for rapid dopamine determination in human serum. A well dispersed Nafion/MWCNT composite was investigated with homogeneous double layers which increased the efficiency of dopamine detection, producing a measurable current change at the underlying sensor electrode. This platform as described successfully demonstrated detection of dopamine concentrations (0.1 M to 10 M, R=0.999) using DPV and amperometry methods. This direct measurement of dopamine in serum samples without pretreatment and dilution is reported for the first time in a Nafion/MWCNT system. In addition, to improve the specificity of the detecting probe, the direct electrochemical detection of antibody-antigen recognition was developed. Graphene can be used as an electrode surface for sensitive detection of a label. Graphene sheets were modified with gold nanoparticles or the dopamine antibody fragments (Fab’) loaded with sulphur binding with gold. Unfortunately, such bio-sensing systems did not perform sensitively and selectively for detection of the neurotransmitters/neurochemicals by utilizing certain nanostructure and introducing various functional groups. Further study will be conducted on analysing fragments’ and the whole antibodies’ activity and affinity of specific recognition

    Aspects on Fundaments and Applications of Conducting Polymers

    Get PDF
    Since the establishment of the conductive properties of intrinsic conductive polymers, a huge variety of basic and applied research has been carried out, involving different polymers, copolymers, blends, mixtures and composites. Thus, fundamental understanding of physical and chemical properties of these materials has been sought, while the applied aspects have advanced very rapidly, crossing the boundaries between disciplines. Today, the applications of conducting polymers in various fields such as neuroscience, nanotechnology and green chemistry, are easily found. This development is dynamic and it needs to be updated and hence the motivation for the set of results presented in this book; which provides information about the development of fundamentals, and about some applications of conductive polymers

    Functional polypyrrole core-shell particles and flexible membranes for biomedical applications

    Get PDF
    Le polypyrrole (PPy), l'un des polymĂšres conducteurs de type p, a dĂ©montrĂ© un potentiel considĂ©rable dans les applications biomĂ©dicales et le stockage d'Ă©nergie en raison de sa conductivitĂ© Ă©lectrique intrinsĂšque, sa facilitĂ© de synthĂšse, son potentiel de modification chimique et sa biocompatibilitĂ©. En raison de la conjugaison Ă©tendue dans ses chaĂźnes molĂ©culaires et de son Ă©tat d'agrĂ©gation, les mauvaises propriĂ©tĂ©s mĂ©caniques et le manque de processabilitĂ© du PPy ont Ă©tĂ© des dĂ©fis scientifiques et technologiques exceptionnels. En outre, le PPy possĂšde une bioconductivitĂ©, mais aucune bioinductivitĂ©, c'est-Ă -dire une absence de biofonctionnalitĂ©, ce qui constitue un autre dĂ©fi pour le PPy lorsqu'il est utilisĂ© pour des applications biomĂ©dicales. Cette thĂšse se concentre principalement sur ces deux dĂ©fis auxquels le PPy fait face, c’est-Ă -dire le manque de biofonctionnalitĂ© et la mauvaise performance mĂ©canique. En se basant sur la diffĂ©rence des rĂ©activitĂ©s chimiques des comonomĂšres, les particules de poly(pyrrole-co-(1- (2-carboxyĂ©thyl)pyrrole structurĂ©es en noyaux-coquilles (P(Py-PyCOOH)) ont Ă©tĂ© synthĂ©tisĂ©es. Elles sont constituĂ©es d'un noyau composĂ© d’un copolymĂšre de P(Py-PyCOOH) riche en PPy et d'une coque composĂ©e de PPy-COOH. Les paramĂštres expĂ©rimentaux de polymĂ©risation en Ă©mulsion ont Ă©tĂ© Ă©tudiĂ©s pour dĂ©finir les conditions optimales. L'anticorps d’albumine de sĂ©rum humain (anHSA), en tant que molĂ©cule modĂšle a Ă©tĂ© immobilisĂ© par des liaisons covalentes sur la surface des particules et a Ă©tĂ© prouvĂ© rĂ©actif aux antigĂšnes. Un schĂ©ma a Ă©tĂ© proposĂ© pour illustrer la formation des particules de cƓur-coquille (P(Py-PyCOOH)) selon un nouveau mĂ©canisme basĂ© sur les rĂ©activitĂ©s du comonomĂšre. Cette mĂ©thode de fabrication peut permettre de prĂ©parer des particules de PPy fonctionnelles en grande quantitĂ©. La chimie de surface et de masse, la conductivitĂ© et le rendement global des particules peuvent ĂȘtre rĂ©gulĂ©s. Pour la premiĂšre fois, une membrane en PPy souple et mĂ©caniquement traitable (PPy-N) a Ă©tĂ© prĂ©parĂ©e par polymĂ©risation interfaciale assistĂ©e par modĂšle (TIP) sans modification chimique des monomĂšres ni autres matĂ©riaux. Les structures uniquement interconnectĂ©es et multicouches ont Ă©tĂ© considĂ©rĂ©es comme responsables de l'excellente souplesse aux tempĂ©ratures ambiante et Ă  -196 °C. Un mĂ©canisme basĂ© sur la nature exothermique de la polymĂ©risation du pyrrole a Ă©tĂ© suggĂ©rĂ© pour expliquer les morphologies du PPy-N. Cette membrane en PPy flexible a un poids lĂ©ger (9 g m-2), une grande surface (14,5 m2 g-1), un comportement Ă©lectrothermique stable, une amphiphilicitĂ© et une excellente cytocompatibilitĂ©. Enfin, une nouvelle approche modulaire a Ă©tĂ© proposĂ©e pour immobiliser les protĂ©ines sur une surface micro/nano structurĂ©e. L'albumine de sĂ©rum bovin (BSA) et la HSA ont Ă©tĂ© immobilisĂ©es de maniĂšre covalente sur la surface des particules (P(Py-PyCOOH) avant qu’elles soient assemblĂ©es sur la surface de la membrane PPy-N pour construire une surface biofonctionnĂ©e avec la coexistence de deux types de biomolĂ©cules. Cette approche sĂ©pare la greffe de protĂ©ines et l'immobilisation en deux Ă©tapes indĂ©pendantes, fournissant ainsi une mĂ©thode simple et hautement flexible pour concevoir et fabriquer une surface ou un Ă©chafaudage multi-biofonctionnalisĂ©.Polypyrrole (PPy), one of p-type conducting polymers, has shown considerable potential in biomedical applications and energy storage owing to its inherent electrical conductivity, ease of synthesis, possibility of further chemical modification, and biocompatibility. Due to the extensive conjugation in PPy chains and the aggregation state, the poor mechanical property and processability of pristine heterocyclic PPy have been the outstanding scientific and technological challenges. Moreover, PPy only possesses bioconductivity but no bioinductivity, i.e., lack of biofunction, which is another challenge for PPy when it is applied in biomedical applications. This thesis mainly focuses on these two issues of PPy, i.e., the lack of biofunctionality and the poor mechanical performance. Based on the difference in comonomer reactivity, the core-shell structured poly(pyrrole-co-(1-(2-carboxyethyl)pyrrole)) (P(Py-PyCOOH)) particles were synthesized, comprising the pyrrole (Py) dominated P(Py-PyCOOH) copolymer as the core and PPyCOOH homopolymer as the shell. Experimental parameters of emulsion polymerization were investigated to define the optimal conditions. Anti-human serum albumin antibody (anHSA) as a model molecule was covalently immobilized onto the particle surface and proven reactive to its antigen. A schema was proposed to illustrate the formation of the core-shell (P(Py-PyCOOH)) particles based on a new reactivity-driven mechanism. This fabrication method can be used to prepare functional PPy particles in large-scale. The surface and bulk chemistry, conductivity, and the overall yield of the particles can be regulated. For the first time, a soft and mechanically processable PPy membrane (PPy-N) was prepared by template assisted interfacial polymerization (TIP) with neither chemical modification of the monomers nor compounding with any other materials. The uniquely interconnected and multilayered structures were considered responsible for the excellent flexibility at both room temperature and -196 °C. A mechanism based on the exothermic nature of pyrrole polymerization was suggested to explain the morphology of the PPy-N. Such a flexible PPy membrane has lightweight (9 g m-2), large surface area (14.5 m2 g-1), stable electrothermal behavior, amphiphilicity, and excellent cytocompatibility. Finally, a novel modular approach was proposed to immobilize proteins to a micro/nano structured surface. Bovine serum albumin (BSA) and HSA were covalently immobilized onto the surface of the (P(Py-PyCOOH)) particles prior to their assembly onto the surface of the PPy-N membrane, to construct a biofunctionalized surface with the coexistence of two types of biomolecules. This approach separates protein grafting and immobilization into two independent steps, providing an easy and highly flexible method to design and fabricate multi-biofunctionalized surface or scaffold

    Nanomaterials for Healthcare Biosensing Applications

    Get PDF
    In recent years, an increasing number of nanomaterials have been explored for their applications in biomedical diagnostics, making their applications in healthcare biosensing a rapidly evolving field. Nanomaterials introduce versatility to the sensing platforms and may even allow mobility between different detection mechanisms. The prospect of a combination of different nanomaterials allows an exploitation of their synergistic additive and novel properties for sensor development. This paper covers more than 290 research works since 2015, elaborating the diverse roles played by various nanomaterials in the biosensing field. Hence, we provide a comprehensive review of the healthcare sensing applications of nanomaterials, covering carbon allotrope-based, inorganic, and organic nanomaterials. These sensing systems are able to detect a wide variety of clinically relevant molecules, like nucleic acids, viruses, bacteria, cancer antigens, pharmaceuticals and narcotic drugs, toxins, contaminants, as well as entire cells in various sensing media, ranging from buffers to more complex environments such as urine, blood or sputum. Thus, the latest advancements reviewed in this paper hold tremendous potential for the application of nanomaterials in the early screening of diseases and point-of-care testing
    • 

    corecore