64 research outputs found

    Polymers and plastics modified electrodes for biosensors: a review

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    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

    Recent progress in biomedical sensors based on conducting polymer hydrogels

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    Biosensors are increasingly taking a more active role in health science. The current needs for the constant monitoring of biomedical signals, as well as the growing spending on public health, make it necessary to search for materials with a combination of properties such as biocompatibility, electroactivity, resorption, and high selectivity to certain bioanalytes. Conducting polymer hydrogels seem to be a very promising materials, since they present many of the necessary properties to be used as biosensors. Furthermore, their properties can be shaped and enhanced by designing conductive polymer hydrogel-based composites with more specific functionalities depending on the end application. This work will review the recent state of the art of different biological hydrogels for biosensor applications, discuss the properties of the different components alone and in combination, and reveal their high potential as candidate materials in the fabrication of all-organic diagnostic, wearable, and implantable sensor devices.Peer ReviewedPostprint (published version

    Nanomaterials for Healthcare Biosensing Applications

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    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

    Nanocellulose-based sensors in medical/clinical applications: The state-of-the-art review

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    In recent years, the considerable importance of healthcare and the indispensable appeal of curative issues, particularly the diagnosis of diseases, have propelled the invention of sensing platforms. With the development of nanotechnology, the integration of nanomaterials in such platforms has been much focused on, boosting their functionality in many fields. In this direction, there has been rapid growth in the utilisation of nanocellulose in sensors with medical applications. Indeed, this natural nanomaterial benefits from striking features, such as biocompatibility, cytocompatibility and low toxicity, as well as unprecedented physical and chemical properties. In this review, different classifications of nanocellulose-based sensors (biosensors, chemical and physical sensors), alongside some subcategories manufactured for health monitoring, stand out. Moreover, the types of nanocellulose and their roles in such sensors are discussed.This work was supported by the University of the Basque Country (Training of Researcher Staff, PIF 20/197)

    Semiconducting Polymers for Electronic Biosensors and Biological Interfaces

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    Bioeletronics aims at the direct coupling of biomolecular function units with standard electronic devices. The main limitations of this field are the material needed to interface soft living entities with hard inorganic devices. Conducting polymers enabled the bridging between these two separate worlds, owing to their biocompatibility, soft nature and the ability to be tailored according to the required application. In particular, the intrinsically conductive poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) is one of the most promising polymers, having an excellent chemical and thermal stability, reversible doping state and high conductivity. This thesis relies on the use of PEDOT:PSS as semiconducting material for biological interfaces and biosensors. In detail, OECTs were demonstrated to be able to real-time monitor growth and detachment of both strong-barrier and no-barrier cells, according to the patterning of the device active area and the selected geometry. Thus, these devices were employed to assess silver nanoparticles (AgNPs) toxicity effects on cell lines, allowing further insights on citrate-coated AgNPs uptake by the cells and their toxic action, while demonstrating no cytotoxic activity of EG6OH-coated AgNPs. Moreover, PEDOT:PSS OECTs were proved to be capable of detecting oxygen dissolved in KCl or even cell culture medium, in the oxygen partial pressure range of 0-5%. Furthermore, PEDOT:PSS OECTs were biofunctionalized to impart specificity on the device sensing capabilities, through a biochemical functionalization strategy, electrically characterized. The resulting devices showed a proof of concept detection of a fundamental cytokine for cells undergoing osteogenic differentiation. Finally, PEDOT:PSS thickness-controlled films were employed as biocompatible, low-impedance and soft interfaces between the animal nerve and a gold electrode. The introduction of the plasticizer polyethylene glycol (PEG) enhanced the elasticity of the polymer, while keeping good conductivity and low-impedance properties. An in-vivo, chronic recording of the renal sympathetic nerve activity in rats demonstrated the efficiency of the device

    Organic electrochemical transistors with PVA hydrogels/PEDOT:PSS channel

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    Most organic electrochemical transistor (OECT)-based biosensors currently rely solely on the generation of electronic signals upon sensor-analyte interaction which has limited the range of analytes to those with distinct electronic properties or those that rely on specific biological materials with poor environmental stability, such as redox enzymes and antibodies. The development of durable stimuli-responsive hydrogels, which exhibit changes in ionic conductivity upon interacting with specific analytes, has significantly expanded the potential for ionic-based sensing as an alternative to electronic-based sensing. Although OECTs are suitable for measuring ionic signals, there have been only a few instances where these materials have been utilized within an OECT platform. This study investigates the applicability of OECTs for ionic-based sensing using poly(vinyl alcohol) (PVA) hydrogels and PEDOT:PSS based OECTs. Through varying macromer percentage alone, a set of hydrogels was fabricated that mimics the network properties seen in complex analyte-responsive systems. These hydrogels offer a cheap alternative, without the use of biorecognition elements, for probing OECT sensitivity to ionic signals. A system based on four electrode impedance spectroscopy was also developed to independently measure their ionic conductivity, with preliminary results consistent with values reported in literature. To enhance device reproducibility and improve compatibility with hydrogel deposition, a novel OECT geometry was designed. This involved incorporating larger features such as wider channels and thicker electrode contacts to minimize fabrication artifacts which ultimately improved OECT transconductance. Additionally, the impact of 3 direct polymerization of hydrogels on PEDOT:PSS was explored using Raman spectroscopy. The findings revealed that a high degree of adherence between the hydrogel and PEDOT:PSS may significantly reduce the dedoping capacity of PEDOT:PSS. Overall, this work represents a valuable first step in exploring the suitability of OECTs to ionic flow based sensing using hydrogels.Open Acces

    New analytical applications of gold nanoparticles

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    The work includes improvements of surface technology, new analytical applications of metallic nanoparticles and optimization of technological steps for production of different types of metallic nanoparticles in discrete and continuous modes. The technology of LbL deposition was optimized and applied for immobilization of metallic nanoparticles. SPR detection was used for the determination of optimal deposition conditions and on-line monitoring of the deposition process. Simple approach for automation of LbL deposition allowing one to deposit up to hundreds of layers was developed. The technology was proved by electrochemical analysis for deposition of electrochemically active polymers. A new diffusion based semi-quantitative assay for detection of sugars was suggested. Electrochemical oxidation of glucose and dopamine on electrodes modified with gold nanoparticles was studied. Conditions for electrochemical analysis of these substances in the presence of typical natural interferents were evaluated. A combination of voltammetry and impedance spectroscopy was used to demonstrate a formation of insulating layer on gold surface, this resulted in explanation of anomalous shape of voltammetric curves. A combination of electrochemical and SPR measurements demonstrated directly a formation of an insulating layer on the electrode surface and was used for optimization of the assay conditions. The results indicate a possibility to develop an enzyme free sensors for glucose and dopamine. It was discovered that gold nanoparticles are effective nucleating agents for protein crystallization. Nanoparticles induce protein crystallization at lower supersaturation and increase the number of protein crystals formed at higher supersaturation. The fact that this technology works with so different proteins as lysozyme and ferritin allows one to suggest that it may be also applied for many other proteins including the ones which are reluctant to crystallization by known technologies. Irreversible freezing indicators based on gold nanoparticles were developed. The filling suspension containing nanoparticles, nucleation and stabilization agents were optimized in sense of stability and irreversibility of color changes. A large scale production of this indicator will be started in spring 2008

    Study and achievement of organic-inorganic innovative materials through electrochemical techniques

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    The functionalization of conductors and semiconductors using organic molecules is a very important issue in the development of novel organic/inorganic heterostructures suitable as materials in sensors, biosensors, clinical diagnostics, biological sensing and energy storage and conversion. In this context, to obtain a stable, durable bond with the surface and controllable process, the electroreduction of aryldiazonium salts is a promising alternative to conventional techniques (as Self Assembled Monolayer), also to ensure conductivity and homogeneity of the organic coating. This work, focused on the achievement of innovative materials developed for a wide range of applications that include biosensors, energy storage and metal-free sensors, is divided in four main topics: 1. Polyaniline electropolimerization on gold surface 2. Polyaniline electropolimerization on nanoporous silicon surface 3. DNA immobilization on gold 4. Polyaniline electropolimerization on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate The common theme about the achievement of these devices is the functionalization of the metal or polymeric electrode base by means diazonium salt (4-nitrobenzenediazonium) electrochemical reduction, prior to further modification with polyaniline or DNA. All these functionalization are realized using electrochemical techniques: organic molecules are grafted on the electrode surface using cyclic voltammetry, as well as aniline electropolimerization. Furthermore, all electrode functionalization step are characterized by Electrochemical Impedance Spectroscopy (EIS), which can give fast and useful information about the surface state. In this thesis results of sensor functionalization and performance varying electrochemical parameter and preparation conditions are presented and discussed, giving a well-developed starting point for following applications

    Study and achievement of organic-inorganic innovative materials through electrochemical techniques

    Get PDF
    The functionalization of conductors and semiconductors using organic molecules is a very important issue in the development of novel organic/inorganic heterostructures suitable as materials in sensors, biosensors, clinical diagnostics, biological sensing and energy storage and conversion. In this context, to obtain a stable, durable bond with the surface and controllable process, the electroreduction of aryldiazonium salts is a promising alternative to conventional techniques (as Self Assembled Monolayer), also to ensure conductivity and homogeneity of the organic coating. This work, focused on the achievement of innovative materials developed for a wide range of applications that include biosensors, energy storage and metal-free sensors, is divided in four main topics: 1. Polyaniline electropolimerization on gold surface 2. Polyaniline electropolimerization on nanoporous silicon surface 3. DNA immobilization on gold 4. Polyaniline electropolimerization on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate The common theme about the achievement of these devices is the functionalization of the metal or polymeric electrode base by means diazonium salt (4-nitrobenzenediazonium) electrochemical reduction, prior to further modification with polyaniline or DNA. All these functionalization are realized using electrochemical techniques: organic molecules are grafted on the electrode surface using cyclic voltammetry, as well as aniline electropolimerization. Furthermore, all electrode functionalization step are characterized by Electrochemical Impedance Spectroscopy (EIS), which can give fast and useful information about the surface state. In this thesis results of sensor functionalization and performance varying electrochemical parameter and preparation conditions are presented and discussed, giving a well-developed starting point for following applications

    Microneedle based electrochemical (bio)sensing: towards decentralized and continuous health status monitoring

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    Microneedle (MN) based electrochemical (bio)sensing has become a growing field within the discipline of analytical chemistry as a result of its unique capacity for continuous, decentralized health status monitoring. There are two significant advantages to this exclusive feature: i) the ability to directly analyze interstitial fluid (ISF), a body fluid with a similar enough composition to plasma (and blood) to be considered a plentiful source of information related to biologically relevant molecules and biomarkers; and ii) the capacity to overcome some of the major limitations of blood analysis including painful extraction, high interferant concentrations, and incompatibility with diagnosis of infants (and especially newborns). Recent publications have demonstrated important advancements in electrochemical MN sensor technology, among which are included new MN fabrication methods and various modification strategies, providing different architectures and allowing for the integration of electronics. This versatility highlights the undeniable need for interdisciplinary efforts towards tangible progress in the field. In a context evidently dominated by glucose sensing, which is slowly being expanded towards other analytes, the following crucial questions arise: to what extent are electrochemical MN (bio)sensors a reliable analytical tool for continuous ISF monitoring? Which is the best calibration protocol to be followed for in vivo assays? Which strategies can be employed to protect the sensing element during skin penetration? Is there an appropriate validation methodology to assess the accuracy of electrochemical MN (bio)sensors? How significant is the distinction between successful achievements in the laboratory and the real commercial feasibility of products? This paper aims to reflect on those previous questions while reviewing the progress of electrochemical MN (bio)sensors in the last decade with a focus on the analytical aspects. Overall, we describe the current state of electrochemical MN (bio)sensors, the benefits and challenges associated to ISF monitoring, as well as key features (and bottlenecks) regarding its implementation for in vivo assays
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