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Author : Nihan Aydemir
Publisher :
ISBN 13 :
Total Pages : 246 pages
Book Rating : 4.:/5 (957 download)
Download or read book Development of Highly Sensitive and Selective DNA Sensors Based on Conducting Polymers written by Nihan Aydemir and published by . This book was released on 2016 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Bhuvaneswari Kannan
Publisher :
ISBN 13 :
Total Pages : 358 pages
Book Rating : 4.:/5 (87 download)
Download or read book Development of Highly Sensitive, Label-free DNA Sensors Based on Conducting Polymers written by Bhuvaneswari Kannan and published by . This book was released on 2012 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Lingyin Meng
Publisher : Linköping University Electronic Press
ISBN 13 : 9179298001
Total Pages : 101 pages
Book Rating : 4.1/5 (792 download)
Download or read book Tailoring Conducting Polymer Interface for Sensing and Biosensing written by Lingyin Meng and published by Linköping University Electronic Press. This book was released on 2020-09-17 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: The routine measurement of significant physiological and biochemical parameters has become increasingly important for health monitoring especially in the cases of elderly people, infants, patients with chronic diseases, athletes and soldiers etc. Monitoring is used to assess both physical fitness level and for disease diagnosis and treatment. Considerable attention has been paid to electrochemical sensors and biosensors as point-of-care diagnostic devices for healthcare management because of their fast response, low-cost, high specificity and ease of operation. The analytical performance of such devices is significantly driven by the high-quality sensing interface, involving signal transduction at the transducer interface and efficient coupling of biomolecules at the transducer bio-interface for specific analyte recognition. The discovery of functional and structured materials, such as metallic and carbon nanomaterials (e.g. gold and graphene), has facilitated the construction of high-performance transducer interfaces which benefit from their unique physicochemical properties. Further exploration of advanced materials remains highly attractive to achieve well-designed and tailored interfaces for electrochemical sensing and biosensing driven by the emerging needs and demands of the “Internet of Things” and wearable sensors. Conducting polymers (CPs) are emerging functional polymers with extraordinary redox reversibility, electronic/ionic conductivity and mechanical properties, and show considerable potential as a transducer material in sensing and biosensing. While the intrinsic electrocatalytic property of the CPs is limited, especially for the bulk polymer, tailoring of CPs with controlled structure and efficient dopants could improve the electrochemical performance of a transducer interface by delivering a larger surface area and enhanced electrocatalytic property. In addition, the rich synthetic chemistry of CPs endows them with versatile functional groups to modulate the interfacial properties of the polymer for effective biomolecule coupling, thus bridging organic electronics and bioelectrochemistry. Moreover, the soft-material characteristics of CPs enable their use for the development of flexible and wearable sensing platforms which are inexpensive and light-weight, compared to conventional rigid materials, such as carbons, metals and semiconductors. This thesis focuses on the exploration of CPs for electrochemical sensing and biosensing with improved sensitivity, selectivity and stability by tailoring CP interfaces at different levels, including the CP-based transduction interface, CP-based bio-interface and CP-based device interface. First, we demonstrate different strategies for tailoring the physicochemical properties of poly (3,4-ethylenedioxythiophene) (PEDOT) beyond its intrinsic properties, via charge effects, structural effects and by the use of hybrid materials, as a CP-based transduction interface to improve sensing performance of various analytes. 1) A positively-charged PEDOT interface, and a negatively-charged carboxylic-acid-functionalised PEDOT (PEDOT:COOH) interface were developed to modulate the electrode kinetics for oppositely-charged analytes, e.g. negatively-charged nicotinamide adenine dinucleotide (NADH) and positively-charged dopamine (DA), respectively. These interfaces displayed high sensitivity and wide linear range towards the analytes due to the electrostatic attraction effect. 2) Various structured PEDOT including porous microspheres and nanofibres were synthesised via hard-template and soft-template methods, respectively, and were employed as building blocks for a hierarchical PEDOT and 3D nanofibrous PEDOT transduction interface, that facilitated signal transduction for NADH. 3) A PEDOT hybrid material interface was developed via using a novel bi-functional graphene oxide derivative with high reduction degree and negatively-charged sulphonate terminal functionality (S-RGO) as dopant to create PEDOT:S-RGO which delivered an enhanced electrochemical performance for various analytes. Based on the established CP-based transduction interface, biomolecules (e.g. enzymes) could be coupled to the CP surface to create CP-based bio-interfaces for biosensing. The immobilisation of enzyme was realised via either covalent bonding to a PEDOT derivative bearing a -COOH group (PEDOT-COOH) through EDC/NHS chemistry, or by physical absorption into the 3D porous PEDOT structure. The CP-based bio-interfaces were used to demonstrate the stable immobilisation of two different types of enzymes, i.e. lactate dehydrogenase and lactate oxidase, achieving the biosensing of analytes by relay bioelectrochemical signal transduction. Together, CP was employed as the CP-based device interface for the fabrication of a flexible and wearable biosensing device. A 3D honeycomb-structured graphene network was generated in-situ on a flexible polyimide surface by mask-free patterning using laser irradiation. The substrate was then reinforced with PEDOT as a polymeric binder to stabilise the 3D porous network by adhesion and binding, thus minimising the delamination of the biosensing interface under deformation and enhancing the mechanical behaviours for use in flexible and wearable devices. The subsequent nanoscale-coating of Prussian blue and immobilisation of enzyme into the 3D porous network provided a flexible platform for wearable electrochemical biosensors to detect lactate in sweat. Rutinmässig övervakning av hälsorelaterade fysiologiska och biokemiska parametrar har blivit allt viktigare för ett stort antal människor bland annat seniorer, spädbarn, patienter med kroniska sjukdomar, idrottare, soldater och med flera, på både en fysisk nivå för förebyggande av sjukdomar samt på en medicinsk nivå för diagnos och behandling av sjukdomar. Stor uppmärksamhet har lagts på utveckling av elektrokemiska sensorer och biosensorer som point-of-care (PoC) diagnostiska enheter for rutinmässig sjukvårdsledning genom deras snabba svar, låga kostnad, höga specificitet och enkla drift. Deras analytiska funktioner drivs av avkänningsgranssnittet vilket involverar signaltransduktion vid transducer-gränssnittet och effektiv koppling av biomolekyler till transducer-biogränssnittet för specifik analytigenkänning. Upptäckten av konventionella funktionella och strukturerade material, t.ex. metalliska nanopartiklar, kolnanorör och grafen, har underlättat konstruktionen av transducergränssnitt med hög prestanda på grund av deras unika fysiokemiska egenskaper. Ytterligare forskning av avancerade material ar önskvärt for att uppnå ett väldesignat och skräddarsytt gränsnitt for elektrokemisk avkänning och biosensering for Internet of Things och klädd sensorer. Ledande polymerer (LP) ar en typ av nya funktionella polymerer med extraordinär redoxomvändbarhet, elektronisk/jonisk ledningsförmåga och mekaniska egenskaper, som uppvisar betydande potential som ett givarmaterial vid avkänning och biosensering. Medan de inneboende elektrokatalytiska egenskaperna i LP:er är begränsade, speciellt for den skrymmande polymeren, kan skräddarsydda LP:er med kontrollerad struktur och effektiva dopmedel förbättra den elektrokemiska prestandan hos ett givargränssnitt med större ytarea och förbättrade elektrokatalytiska egenskaper. Dessutom ger den syntetiska kemin LP:er mångsidiga funktionella grupper för att modulera gränssnittsegenskaperna för LP:er för att förbättra selektivitet for analytdetektering, såväl som för effektiv biomolekylkoppling som ett biogränssnitt som överbryggar den organiska elektroniken och det biologiska system som stöds av de LP:s organkemiska natur. Dessutom möjliggör de mjuka materialegenskaperna för LP:er för användning i utveckling av en flexibla och bärbara avkänningsplattformar med låg kostnad och lätt vikt, jämfört med konventionella styva material, såsom metaller och halvledare. Denna avhandling fokuserar på utforskning av LP:er för elektrokemisk avkänning och biosensering med förbättrad känslighet, selektivitet och stabilitet genom att skräddarsy LP:s gränssnitt i olika nivåer, inklusive LP-baserat transduktionsgränssnitt, LP-baserat bio-gränssnitt och LP-baserat enhetsgränssnitt. Först demonstrerar vi olika strategier for att skräddarsy fysikalisk-kemiska egenskaper hos poly (3,4-etylendioxytiofen) (PEDOT) som ett LP-baserat transduktionsgränssnitt för avkänning via laddningseffekter, struktureffekter och hybridmaterialeffekter för förbättrad prestanda för olika analyser utöver dess inre egenskaper. 1) Ett positivt laddat hierarkiskt PEDOT-gränssnitt och ett negativt laddat karboxylsyra-funktionaliserad PEDOT (PEDOT: COOH) gränssnitt utvecklades for att modulera gränssnittets kinetik for de motsatt laddade analyterna, t.ex. negativt laddad s-Nicotinamidadeninudukleotid (NADH) respektive positivt laddat dopamin (DA). Den elektrokemiska avkänningsprestandan hos dessa analyser förbättrades baserat på laddningseffekten med högre känslighet och ett bredare linjärt intervall. 2) Med tanke på den väl skrymmande filmbildande egenskapen och den resulterande låga tillgängliga aktiva ytan för PEDOT, syntetiserades olika strukturerade PEDOT inklusive porösa mikrosfärer och nanofibrer via en hård mall respektive en mjuk mall och användes sedan som byggstenar för hierarkiska PEDOT och 3D nanofibrosa PEDOT-transduktionsgränssnitt, vilket underlättar signaltransduktion for NADH. 3) Ett LP-hybridmaterialgränssnitt utvecklades med användning av ett nytt bi-funktionellt grafenoxidderivat med hög reduktionsgrad och negativt laddad sulfonatterminal funktionalitet (S-RGO) med förbättrad elektrokemisk prestanda fär olika analyser. Baserat på det etablerade LP-baserade transduktionsgränssnittet utvecklades sedan de LP-baserade bio-gränssnitten med immobilisering av biomolekyler (t.ex. enzym) för biosensering. Immobiliseringen av enzym på LP-gränssnittet realiserades via antingen kovalent bindning till PEDOT-derivatbärande -COOH-grupper (PEDOT-COOH) genom EDC/NHS-kemi eller fysisk absorption i porösa 3D-PEDOT-strukturer. De LP-biobaserade gränssnitten visar stabil immobilisering av två olika typer av enzymer, d.v.s. laktatdehydrogenas och laktatoxidas, vilket uppnår biosensering av analyter genom en successiv bioelektrokemisk signaltransduktion. Tillsammans användes LP:er som det LP-baserade enhetsgränssnittet för tillverkning av en flexibel och bärbar biosenseringsanordning. Ett tredimensionellt bikakestrukturerat grafennatverk genererades in-situ på den flexibla polyimidytan genom maskfri mönstring med laserbestrålningsteknik. Substratet förstärktes sedan med nanodeponerat PEDOT som ett polymert bindemedel for att stabilisera det porösa 3D-nätverket genom vidhäftning och bindning, vilket sålunda förbättrade det mekaniska beteendet för flexibla och bärbara anordningar. Den sekventiella beläggningen på nanoskala av Preussiskt blått (PB) och immobiliseringen av enzym i det porösa 3Dnatverket minimerade delaminering av biosenseringsgränssnittet vid deformation, vilket försedde en flexibel plattform för en bärbar elektrokemisk biosensor för detektering av laktat i svett med det monterade treelektrodsystemet.
Author : John B. Spires
Publisher :
ISBN 13 :
Total Pages : 472 pages
Book Rating : 4.:/5 (695 download)
Download or read book Synthesis, Characterisation and Application of Functionalised Thiophene-based Conducting Polymers as DNA Sensors written by John B. Spires and published by . This book was released on 2010 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Specific DNA detection is important for many applications in areas such as biology, forensics and medical diagnostics which all share the need for fast and inexpensive detection technology. Conducting polymers are now widely investigated as alternative substrates for rapid and label-free DNA sensors. Previous work in this laboratory investigated DNA sensors based on conducting polymer films made from pyrrole but the chemical versatility of thiophene motivated the study of thiophene based conducting polymer substrates in this thesis. Four thiophene conducting polymers were synthesized wherein two of these (TAA and TPDA) shared structural features with pyrrole homologues for comparison of their sensing properties. The following thiophene-containing monomers and the conducting polymers were synthesised and characterised: TAA (5'':2'''- terthiophene)-3''-yl) acrylic acid), TPDA (5'(2':2'', 5'':2'''-terthiophene)-3''-yl)] (2E,4E)penta-2,4-dienoic acid ), HTAA (3-[3',3'''-bis(hydroxymethyl)-2':2'',5'':2'''-terthiophene)-3''-yl (E)acrylic acid ) and AAE ((E)-3-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)acrylic acid). All polymers were studied by electrochemical impedance spectroscopy (EIS) which was used as the sensor readout to allow rapid and label-free detection. Initial results using PTAA and PTPDA film as DNA sensors in aqueous solution showed poor hybridisation responses that were difficult to consistently reproduce. This prompted a comprehensive EIS study investigating the change of polymers properties when immersed (20 hours) in aqueous electrolytes before attachment of DNA. EIS revealed that the microstructure of these films collapses in aqueous solution for about three hours accompanied by a dramatically decreased capacitance and hindered redox activity and conductivity. Subsequently, a gradual increase in film capacitance resulted from the oxidizing potential applied during the EIS experiment. Discovery of this microstructure collapse in aqueous solution explained the difficulty in obtaining reproducible hybridisation responses. This finding runs contrary to the usual assumption in the literature that conducting polymers are electrochemically stable and may be used straight after preparation for DNA sensing [1-7]. The collapse was largely ameliorated in PHTAA films and the increased electrochemical stability of this polymer was attributed to its greater hydrophilicity endowed by its hydrophilic group (CH2OH). The slight gradual capacitance increase due to film charging induced by the oxidizing potential applied during EIS was also observed in PHTAA film. Poor DNA selectivity of PTAA and PTPDA films originated partly from the collapse and the consequent disruption of the TT-bonded "highway" of the polymer backbone. Another contribution towards poor selectivity was the charge storage region that built up underneath the film surface during the time (20 hours) the films were allowed to adjust their microstructure in aqueous solution. EIS was optimized for DNA sensing by examining the effect of the Fe(CN)6 3-/4- redox couple on the DNA sensing of PTAA film which was found to enhance sensing. Additionally, the effect of the oxidation state of PTAA film on its DNA-sensing ability was examined where the oxidized state best detected DNA compared to the reduced state. An alternative modelling scheme that measures the hybridisation response from the change in phase angle on the phase angle plot (rather than the change in real impedance) was also demonstrated. This scheme can be adapted for other electrochemical DNA sensors where the Nyquist plot does not sufficiently characterize the hybridisation response. Unlike the Nyquist plot, the phase angle plot sensitively conveyed useful information about film microstructure changes and oligonucleotide attachment on the film surface for the entire frequency range studied although frequencies in the 103-105 Hz region provided the best indicator of hybridisation"--Abstract.
Author : Youssef Lattach
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (8 download)
Download or read book Development and Characterization of Sensing Layers Based on Molecularly Imprinted Conducting Polymers for the Electrochemical and Gravimetrical Detection of Small Organic Molecules written by Youssef Lattach and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the field of chemical and biological sensors, the increased need for better sensitivity, faster response and higher selectivity during an analysis process, requires the development of more and more efficient transducing sensing layers. In this context, and with the aim to detect small non-electroactive molecules, such as atrazine (ATZ), we designed, characterized and developed sensing layers constituted by functionalized Molecularly Imprinted Conducting Polymers (MICP) and we integrated them into electrochemical and gravimetrical sensors. Starting from acetonitrile pre-polymerization media containing ATZ as template molecules in the presence of thiophene-based functional monomers (FM, namely TMA, TAA, EDOT, TMeOH or Th), differently functionalized and structurally different polythiophene-based FM-MICP films were electrosynthesized onto gold substrates and used for ATZ detection. The sensing properties of FM-MICP layers were shown to result from the presence in their backbones of pre-shaped FM-functionalized imprinted cavities which keep the memory of the targets. Nevertheless, non-specific adsorption onto the surface of the sensing layers takes place systematically, which affects the selectivity of the recognition process. Thanks to surface characterization techniques, we highlighted the influence of the thickness and of the structural properties of the layers on the efficiency of the recognition process. Besides, this latter was shown to operate in the bulk of the polymer matrixes thanks to layers porosity. On another hand, electrochemical measurements correlated with semi-empirical calculations demonstrated the influence of the nature of FM on the strength of the ATZ-FM interaction in the pre-polymerization medium, and then on the number of ATZ molecular imprints and on the sensitivity towards ATZ of the FM-MICP layers. We showed that TAA-MICP, which presents a low limit of detection (10-9 mol L-1) and a large dynamic range (10-8 to 10-4 mol L-1), is the best sensing layer since it offers the best compromise between high level of specific detection of ATZ and low level of non-specific adsorption. Finally, TAA-MICP was used as sensitive layer in an original Electrochemical Surface Acoustic Wave sensor (ESAW) which enabled simultaneous coupled gravimetric and electrochemical measurements.
Author : Anupama Rao Gular Srinivas
Publisher :
ISBN 13 :
Total Pages : 340 pages
Book Rating : 4.:/5 (865 download)
Download or read book Miniaturized Optical DNA Sensors Based on Conjugated Polymers written by Anupama Rao Gular Srinivas and published by . This book was released on 2013 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of highly sensitive and selective DNA sensors has fuelled applications in a wide range of fields including medical diagnostics, forensics, biodefense, food contamination and environment monitoring. Recently, conjugated polymers (CPs) have drawn attention as attractive novel materials for biosensors due to their tuneable optical and electronic properties and ability to respond to minor changes in their environment. The aim of this research was to develop miniaturised optical DNA sensors based on photoluminescent CPs. Investigations towards the effect of systematically substituting carboxylic acid functionalized CPs with polar methoxy, mono-ethylene glycol, di-ethylene glycol and tri-ethylene glycol sidechains on the solubility, optical and electrochemical properties were conducted. The resultant CPs were characterised using a range of techniques such as nuclear magnetic resonance (NMR), fourier infrared spectroscopy (FTIR), ultra-violet (UV-Vis) visible spectroscopy and fluorescence spectroscopy. Furthermore, three different novel optical DNA sensors on magnetic beads were designed and developed using the synthesized CPs. DNA hybridisation was monitored using fluorescence resonance energy transfer (FRET) and superquenching readout methodologies. These sensors exhibit desirable characteristics such as ease of handling (through magnetic deployment). All the three different sensing platforms were able to discriminate mismatches in the target sequences, theoretical detection limits to target DNA concentrations were calculated between 0.01 pM and 18.8 pM, improving resistance to non-specific interactions with DNA and proteins, fulfilling the requirements for a selective, sensitive, mobile, cost effective miniaturised DNA sensor.
Author : Akin Augustine Iyogun
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (135 download)
Download or read book Chemically Diverse Sensor Arrays Based on Conducting Polymers in Sensing Characterization and Application written by Akin Augustine Iyogun and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: There has been a growing need to develop an artificial mimic of mammalian olfaction in a manner analogous to charged coupled device (CCD) chip in machine vision. This need is motivated by the existence of devices to mimic the five senses except the sense of smell and taste, generally known as perception. One major challenge is the limited number of chemically different sensing surfaces that are to be useful as multi sensor array in a device, comparable with olfaction in its capacity to engage ≈1000 unique olfactory receptors to discriminate odorants. To be technically viable, such a device will involve the development and incorporation of several chemically distinct sensors to perform similar functions as its natural counterpart. An approach to create such a multi sensor array was explored in this research involving the electrosynthesis of homopolymers and copolymers sensor films. The modification of these polymers was performed through the growth of sensor films at different oxidation potentials, or holding the individual 'as grown' sensor films to different redox potential after growth. While variable signature resistance responses were generated from sensors interaction with analytes, differential response patterns were created to discriminate between them. The task of identifying unique patterns for analytes and the classification of each analyte as A or B hence, the uniqueness of each sensor was also investigated to ascertain that chemical variation of these sensors occurred. Pattern recognition algorithms involving techniques such as principal component analysis and linear discriminant analysis were relevant to relate the measured resistance responses in the form of clusters or numerical separation of clusters to differentiate patterns as a function of the sensor analyte interactions. This created the needed discrimination, as the resolving power of the arrays was investigated with linear discriminant analysis as a function of analytes or sensors. An ensemble of all the homopolymer, copolymer and conducting polymer composites created in this research resulted in broadly responsive, partially selective arrays which progressively tend towards realizing the number of olfactory receptors utilized by mammalian olfaction in performing odor discriminatory function. A real world application of these arrays as 'fuel sensor' has been investigated and is included in this thesis.
Author : Kelly M. Millan
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (13 download)
Download or read book The Development and Application of a Sequence-selective DNA Sensor written by Kelly M. Millan and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Dounia el-Fadil
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (143 download)
Download or read book Development of Highly Sensitive and Selective Molecularly Imprinted Polymers Based Sensing Systems written by Dounia el-Fadil and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 249 pages
Book Rating : 4.:/5 (914 download)
Download or read book Conducting Polymers for Micro and Nano Electrodes written by and published by . This book was released on 2015 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis aims at providing a better understanding of the micro- and nanofabrication of conducting polymers for biomedical devices and presents novel processes that widen the application range of conducting polymers in this field. The thesis is divided in four chapters, namely "Materials and Methods", "Biocatalytically-produced polypyrrole thin films and microelectrodes on insulating surfaces", "Azide-PEDOT electrodes. Application to DNA sensors" and "Fabrication of polypyrrole single nanowire devices". Chapter 1, entitled "Materials and Methods", describes the materials used in this work and the fabrication and characterization methods required for the development of the thesis. Here, theoretical and experimental details about the techniques employed, are provided. Chapter 2, entitled "Biocatalytically-produced polypyrrole thin films and microelectrodes on insulating surfaces", presents a new on-surface biocatalytical procedure for the fabrication of polypyrrole microelectrodes on insulating surfaces, with resolutions comparable to the ones of conventional photolitography. This is an environmentally respectful microfabrication method that allows the entrapment of biomolecules during the polymer synthesis in a single step. As a proof of concept, biotin was trapped in the polypyrrole matrix and then released in a controlled way through electrical stimulation. It was proven that the polymer keeps its electroactivity after the fabrication and functionalization processes. This biocatalytical-based technique represents a straightforward method for the microfabrication of biological-active conducting polymers, which could be implemented in implantable devices for remotely controlled tissue interactions. Chapter 3, entitled "Azide-PEDOT electrodes. Application to DNA sensors", describes the fabrication and testing of an electrochemical label-free DNA hybridization sensor, based on novel azidomethyl-modified poly(3,4-ethylenedioxythiophene) electrodes (azide-PEDOT electrodes). These azide-PEDOT electrodes were used as platforms for the immobilization of acetylene-DNA probes, complementary to the "Hepatitis C" virus. The acetylene-DNA probes were covalently grafted to the polymer backbone via the robust "Click" reaction, which a part from being a very selective functionalization method, preserves DNA from denaturation during the synthesis of the polymer. DNA hybridization was detected by Differential Pulse Voltammetry (DPV), where the electrochemical change of the polymer behaviour, produced by the recognition event, was directly evaluated. This fabrication procedure is a powerful tool for the preparation of label-free DNA sensors able to selectively recognize a specific DNA sequence, down to the nanomolar range. Finally, Chapter 4, entitled "Fabrication of polypyrrole single nanowire devices", discusses the fabrication of polypyrrole at the nanoscale. Two fabrication techniques were investigated here, namely dip pen nanolithography and electrochemical polymerization on template-assisted surfaces. On one hand, the dip pen nanolithography proved to be a simple deposition technique with good control over size and location of the polypyrrole nanowires. On the other hand, the electrochemical polymerization on template-assisted surfaces provided as well nanoscaled polypyrrole, but added the possibility to chemically manipulate the polymer. This chemical manipulation was translated into polymer devices with different electrical properties. By the use of these techniques, the capability of fabricating single nanowire devices (ready to use in different applications) and arrays of ordered nanowires based on conducting polymers is demonstrated. Additionally, two appendixes can be found at the end of the thesis: Appendix A: "Fabrication of azide-PEDOT microwire-based devices" and Appendix B: "Fabrication of nanopatterns by electron-sensitive silanes". They provide short experimental results obtained during the course of this work, which are first steps for future investigations. A general conclusions section can be found at the end of the thesis, where a summary of the main achievements and contributions of this thesis are listed.
Author : Katherine Mariann Elizabeth Stewart
Publisher :
ISBN 13 :
Total Pages : 292 pages
Book Rating : 4.:/5 (988 download)
Download or read book Design of Polymeric Sensing Materials for Volatile Organic Compounds written by Katherine Mariann Elizabeth Stewart and published by . This book was released on 2016 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are many applications in which sensing and monitoring volatile organic compounds (VOCs) and other gas analytes are important. This thesis focusses on finding suitable sensing materials for ethanol to reduce the instances of people driving while intoxicated. To find suitable sensing materials, many constraints must be taken into consideration. For example, a sensing material and sensor must have the appropriate sensitivity and selectivity required. The goal is to create a sensing material or multiple materials capable of detecting ethanol that is emitted from the skin (transdermally). This requires highly sensitive sensing materials and sensors capable of detecting ethanol close to 5 ppm. This limit of 5 ppm was confirmed by measuring transdermal ethanol. In addition, to avoid false positives, the sensor must be able to selectively identify ethanol (i.e. respond preferentially to ethanol). To achieve this goal, polymeric sensing materials were used because of their ability to be tailored towards a target analyte. Multiple polymeric sensing materials were designed, synthesized, and evaluated as a sensing material for ethanol. Both the sensitivity and selectivity of the sensing materials were evaluated using a specially designed experimental test set-up that included a highly sensitive gas chromatograph (GC) capable of detecting down to the ppb range. In total, over thirty potential sensing materials were evaluated for ethanol. These sensing materials, which include polyaniline (PANI) and two of its derivatives, poly (o-anisidine) (PoANI) and poly (2,5-dimethyl aniline) (P25DMA), doped with various concentrations of five different metal oxide nanoparticles (Al2O3, CuO, NiO, TiO2, and ZnO), were synthesized and evaluated for sensitivity and selectivity to ethanol. In addition, specialized siloxane-based polymers and other polymers such as poly (methyl methacrylate) (PMMA) and polypyrrole (PPy) were evaluated. From these thirty plus sensing materials, P25DMA doped with TiO2, NiO, and Al2O3, along with PPy, had the best sensitivity towards ethanol. Most of the materials tested, with the exception of the CuO doped P25DMA, P25DMA doped with 20% ZnO, poly (ethylene imine) (PEI), and the siloxane-based sensing materials, were able to sorb, and therefore detect, 5 ppm of ethanol. Therefore, the sensitivity requirement of 5 ppm was satisfied. In terms of selectivity, P25DMA doped with 5% Al2O3 and P25DMA doped with 10% TiO2 had the best selectivity towards ethanol with respect to five typical interferent gases (acetaldehyde, acetone, benzene, formaldehyde, and methanol). Some of the most promising polymeric sensing materials were then deposited onto two different kinds of sensors: a capacitive radio frequency identification (RFID) sensor and a mass-based microcantilever microelectromechanical systems (MEMS) sensor. These sensors were evaluated for sensitivity, selectivity, and response and recovery times. It was found that P25DMA doped with 20% NiO had a detection limit of 3 ppm on the RFID sensor, whereas P25DMA had a detection limit of 5 ppm on the MEMS sensor. It should be noted that not all sensing materials work well on all sensors. To improve the selectivity of a sensor, a sensor array or electronic nose can be used. These use a pattern-recognition algorithm to separate the responses for different gas analytes. A proof-of-principle study was done using principal component analysis that was capable of distinguishing between six different VOCs using five different polymeric sensing materials. In addition, a three sensor array was evaluated on the RFID platform. Using PCA as the filtering algorithm, four gas analytes (ethanol, methanol, acetone, and benzene) were able to be identified. These four analytes could also be identified even when in gas mixtures of twos and threes and when all four gas analytes were present. After this wide experimentation, and based on the knowledge gained from the sorption responses between various VOCs and polymers, along with what has been reported in the literature, various sensing mechanisms were proposed. These sensing mechanisms explain why certain VOCs sorb more preferentially onto certain polymers. Therefore, identifying the dominant sensing mechanisms for a target analyte can improve sensing material selection. Based on these sensing mechanisms, potential sensing materials can be chosen for a target analyte. By including other constraints from the specific application target and sensor, this list of potential sensing materials can be further narrowed. From here, these sensing materials can be evaluated for sensitivity and selectivity, before the most promising ones are deposited onto sensors for further testing. This has led to prescriptions that can be followed when designing a new sensing material for a target application. These prescriptions take into consideration the chemical nature of the target analyte (and thus, the dominant mechanisms by which it is likely to interact), any constraints of the target application (including operational temperature and type of sensor), and the chemical nature of the common interferents present with the target analyte. These prescriptions allow one to narrow down a list of hundreds or thousands of potential sensing materials to a manageable few, which can then be evaluated.
Author : Vijay Kumar
Publisher : Springer
ISBN 13 : 3319464582
Total Pages : 338 pages
Book Rating : 4.3/5 (194 download)
Download or read book Conducting Polymer Hybrids written by Vijay Kumar and published by Springer. This book was released on 2016-11-02 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a comprehensive survey about conducting polymers and their hybrids with different materials. It highlights the topics pertinent to research and development in academia and in the industry. The book thus discusses the preparation and characterization of these materials, as well as materials properties and their processing. The current challenges in the field are addressed, and an outline on new and even futuristic approaches is given. “Conducting Polymer Hybrids” is concerned with a fascinating class of materials with the promise for wide-ranging applications, including energy generation and storage, supercapacitors, electronics, display technologies, sensing, environmental and biomedical applications. The book covers a large variety of systems: one-, two-, and three-dimenstional composites and hybrids, mixed at micro- and nanolevel.
Author : Hui Zhu
Publisher :
ISBN 13 :
Total Pages : 29 pages
Book Rating : 4.:/5 (129 download)
Download or read book Three Luminescent Cd(Ii) Coordination Polymers as Highly Sensitive and Selective Sensors for Detection of Cr2o72- Oxoanions in Water written by Hui Zhu and published by . This book was released on 2020 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Di Kang (Chemist)
Publisher :
ISBN 13 : 9781369340846
Total Pages : 138 pages
Book Rating : 4.3/5 (48 download)
Download or read book Improvement of DNA-based and Protein-based Electrochemical Biosensors written by Di Kang (Chemist) and published by . This book was released on 2016 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent years have seen the development of a number of reagentless, electrochemical sensors based on the target-induced folding or other target-induced conformational changes in electrode-bound oligonucleotides, with examples reported to date including sensors for the detection of specific nucleic acids, proteins, small molecules and inorganic ions. These of sensors, termed Electrochemical DNA-based (E-DNA) sensors, are comprised of an electrode modified with surface immobilized, redox-reporter-tagged DNA probes. This technique has emerged as a promising new biosensor platform due to its sensitive and selective measurement of specific molecular targets without the need for additional reagents, wash steps or complex and costly equipment. My thesis work has focused on expanding and improving this increasingly important sensing platform. We have expanded the number of signaling redox reporter for multiplexing and ratiometric auto-calibration sensing. As well as we developed a simple strategy to rationally edit the useful dynamic range of our electrochemical DNA sensors. To make our platform more generic for sensing, we designed a novel protein-based electrochemical sensing architecture achieves good specificity and sensitivity, providing a new approach for the quantitative, single-step measurement of protein-macromolecule interactions. At the end, we have used surface forces apparatus (SFA) to study the behavior of surface grafted single-stranded and double-stranded DNAs.
Author : William Cheung
Publisher :
ISBN 13 :
Total Pages : 202 pages
Book Rating : 4.:/5 (83 download)
Download or read book Carbon Nanotube/polymer Composites written by William Cheung and published by . This book was released on 2012 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is well known that carbon nanotubes (CNT) exhibit remarkable electrical, mechanical and optical properties. In addition, conducting polymers have also been used for molecular sensors, electronic energy generation and storage devices due to their interesting electronic and electrochemical properties. In an effort to synergistically combine the advantages of both materials, conducting CNT/polymer composites have been fabricated. However, due to the highly hydrophobic surface and their strong intertube interactions, it is necessary to properly modify the carbon nanotube surface either covalently or non-covalently to prevent them from forming bundles and disperse them into solutions or polymer matrices to fabricate genuine polymer/CNT composites. Blending pre-formed polymers with carbon nanotubes has been demonstrated to be the most straightforward approach to fabricate carbon nanotube composites. However, recent studies in our group have demonstrated that in-situ polymerization of the respective monomers in the presence of dispersed and functionalized carbon nanotubes could form conducting polymer/CNT composites with much more enhanced functions. Different surface modification imparts carbon nanotubes with different electronic structures and surface chemistries. This can greatly impact the monomer/CNT interaction, and therefore influence the polymerization process and the CNT/polymer interaction after polymerization. Extensive studies reported have shown that the enhanced functions of a composite are largely determined by the interactions between the polymer and the CNTs. Studies on the impact of electronic structure and surface chemistry on the monomer/CNT interaction and its subsequent effect on the polymerization kinetics as well as the quality of the formed composites are limited. These studies are essential for developing more efficient and green fabrication approaches of high quality composites with enhanced functions. In this thesis, we will also systematically study how the surface chemistry and electronic structures of carbon nanotubes influence the electronic performance of carbon nanotube/conducting polymer composites and their stabilizing effect against UV degradation. The knowledge learned from these fundamental studies will be used to fabricate highly conductive and stable composites for constructing efficient biofuel cells. Along the same line, we will also study how the electronic structures of carbon nanotubes influence the development of sensitive and selective molecular detection devices. Chapter 1 will be a general introduction to carbon nanotubes, their structure, properties, and surface chemistry. Conducting polymers such as polyaniline and their properties will also be introduced. The available approaches to fabricate conducting polymer/CNT composites, their application for biofuel cells, and the current issues of biofuel cells will be summarized. In this chapter electrical and optical approaches for molecule detections based on carbon nanotubes are also elaborated. The aim of Chapter 2 is to systematically study how the electronic structure and surface chemistry of carbon nanotubes influence the kinetics of ABA polymerization. The electronic properties of CNTs will be altered through surface modification using double stranded DNA and single stranded DNA with different sequences. After surface modification, their effect on the polymerization process and the formed composites will be studied. Chapter 3 will be focused on a detailed study of the stabilizing effects that carbon nanotubes have in self doped polyaniline composites. CNTs have been shown to mitigate the environmental degradation effects imposed on conducting polymers. This study is important for developing stable devices such as biofuel cells using conducting polymer composites. In this work, a new stabilization mechanism against UV irradiation will also be proposed. Slow electron transfer rate is a fundamental problem that exists in biosensors and biological fuel cells. This is usually due to the lack or inefficient direct electron transfer between redox enzymes and the electrode support. Chapter 4 applies the knowledge gained from chapters 2 and 3 to modify an electrode surface with highly conductive CNT/polymer composites to construct an efficient anode for a biofuel cell. Optimization was performed to realize direct electron transfer between the redox center of glucose oxidase and the electrode surface with a dramatic enhancement in electron transfer rate and glucose oxidation efficiency. Furthermore, the enzyme will be reconstructed onto the surface of the electrode in different orientations and their electrobiocatalytic oxidation of glucose will be studied. In Chapter 5, the strong plasmon absorption of single walled carbon nanotubes (SWNTs) was explored to develop a new sensing platform for metallic ions. Compared to previously reported electronic and NIR fluorescence detection approaches, the new sensing platform can reach the same or better detection sensitivity and detection limits simply by using UV absorption spectroscopy. The detection sensitivity was studied using modified SWNTs with different electronic structures. The detection selectivity is realized by modifying the surface of SWNTs with molecular ligands with high specificity for metal ions. As a demonstration, the new method is applied to selectively detect iron ions (Fe3+) in aqueous solution. Fe3+ was chosen because it is an essential element for the growth and metabolism of all marine organisms. Therefore the ability to selectively and sensitively detection Fe3+ is critical to study of carbon sequestration in the ocean and consequently climate change. Chapter 6 is a preliminary study on how the electronic structures of SWNTs can influence its Raman scattering properties, which in turn influence their sensitivity for the detection of cancer cells and their capability to destroy them using NIR light radiation.
Author : M. Aldissi
Publisher : Springer Science & Business Media
ISBN 13 : 9401719527
Total Pages : 233 pages
Book Rating : 4.4/5 (17 download)
Download or read book Intrinsically Conducting Polymers: An Emerging Technology written by M. Aldissi and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the majority of the papers presented at the NATO Ad vanced Research Workshop (ARW) held in Burlington, Vermont, USA on October 12-15, 1992. This ARW was the first of its kind to address the subject of intrinsically conducting polymers with an emphasis on processing and technological applications. The NATO ARW format was followed in that the subjects addressed here were limited in number but discussed in detail with the attendance being limited to a small number of selected scientists. The ARW brought together lecturers who are leaders in their respective fields from a wide range of NATO and non-NATO countries (a total of 11 countries) with the support of the NATO Scientific Affairs Division and some support from Champlain Cable Corporation. The total number of par ticipants was 33 and the number of presentations was 24. The speakers were chosen based on the topics selected for this workshop and repre sented industry, universities and government laboratories. The field of conducting polymers has grown rapidly during the past few years with important developments in materials processing and fabrica tion that brought about active research programs focusing on the use of these polymers as "smart" materials in technological applications and devices in academic and industrial research laboratories.
Author : Ahmadi, Mohammad Taghi
Publisher : IGI Global
ISBN 13 : 152250737X
Total Pages : 601 pages
Book Rating : 4.5/5 (225 download)
Download or read book Handbook of Research on Nanoelectronic Sensor Modeling and Applications written by Ahmadi, Mohammad Taghi and published by IGI Global. This book was released on 2016-09-20 with total page 601 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoelectronics are a diverse set of materials and devices that are so small that quantum mechanics need to be applied to their function. The possibilities these devices present outweigh the difficulties associated with their development, as biosensors and similar devices have the potential to vastly improve our technological reach. The Handbook of Research on Nanoelectronic Sensor Modeling and Applications begins with an introduction of the fundamental concepts of nanoelectronic sensors, then proceeds to outline in great detail the concepts of nanoscale device modeling and nanoquantum fundamentals. Recent advances in the field such as graphene technology are discussed at length in this comprehensive handbook, ideal for electrical engineers, advanced engineering students, researchers, and academics.
