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Η παρούσα διατριβή εμβάθυνε για πρώτη φορά στην κατασκευή χημικών αισθητήρων για την ταχεία ανίχνευση τοξικών ουσιών. Για το σκοπό αυτό κατασκευάσθηκαν και αναπτύχθηκαν βιαισθητήρες που στηρίζονται σε τυπωμένα κυκλώματα γραφενίου με ακινητοποιημένες σταθεροποιημένες λιπιδικές μεμβράνες.Χρησιμοποιώντας συγκεκριμένες μεθοδολογίες, έγινε ενσωμάτωση στους αισθητήρες διαφόρων υποδοχέων, όπως ενζύμων (ουρεάση και οξειδάση της χοληστερόλης) και αντισωμάτων (αντισώματος του D-dimer).Στη συνέχεια, με χρήση ενόργανων μεθόδων ανάλυσης όπως, διαφορικής θερμιδομετρίας σαρώσεως (DSC), ηλεκτρονικής μικροσκοπίας σαρώσεως (SEM), φασματοφωτομετρίας Raman, κλπ., προσδιορίστηκε πειραματικά η θέση του υποδοχέα (π.χ. αντίσωμα, ένζυμο, κτλ.) μέσα στη σταθεροποιημένη λιπιδική μεμβράνη του αισθητήρα και εξερευνήθηκε ο μηχανισμός παραγωγής του σήματος.Μελετήθηκε η απόκριση σε διάφορα υποστρώματα με τοξικές εν δυνάμει ενώσεις π.χ. ουρία (ακινητοποίηση ουρεάσης), χοληστερόλη (ακινητοποίηση οξειδάσης της χοληστερόλης) και D-dimer (ακινητοποίηση αντισώματος D-dimer), καθώς και η σταθερότητα του συστήματος των αισθητήρων με το χρόνο.Χαρακτηριστικά αναφέρεται ότι η απόκριση του αισθητήρα της ουρίας σε διάφορες συγκεντρώσεις ουρίας, βρέθηκε να παρουσίαζει υψηλή ευαισθησία (~70 mV/ δεκάδα συγκεντρώσεων) για μια ευρεία περιοχή συγκεντρώσεων της ουρίας που κυμαινόταν από 1 Χ 10−6 Μ ως 1 Χ 10−3 Μ. Επίσης η απόκριση του αισθητήρα της χοληστερόλης σε διάφορες συγκεντρώσεις χοληστερόλης, βρέθηκε να παρουσιάζει υψηλή ευαισθησία (~64 mV/ δεκάδα συγκεντρώσεων) για μια ευρεία περιοχή συγκεντρώσεων της χοληστερόλης που κυμαινόταν από 1 Χ 10−6 Μ ως 1 Χ 10−3 Μ, και είναι καλύτερη από βιβλιογραφικά αναφερθέντες συσκευές βιοαισθητήρες χοληστερόλης. Τέλος η απόκριση του ανοσοαισθητήρα του D-dimer βρέθηκε ικανοποιητική για ένα ευρύ συγκέντρωσεων D-dimer (10-6 μg/ mL έως 10-3 μg/ mL) με ευαισθησία ~59 mV/ δεκάδα συγκεντρώσεων και με μια γρήγορη απόκριση 15s.Εν συνεχεία μελετήθηκε η εκλεκτικότητα της μεθόδου της κατασκευής των αισθητήρων και η άρση των παρεμποδίσεων για να εφαρμοστούν σε πραγματικά δείγματα. Παράλληλα μελετήθηκαν οι συνθήκες για ύπαρξη ικανοποιητικής σταθερότητας και επαναληπτικότητας των χημικών αισθητήρων και ερευνήθηκε η κατασκευή τους σε νανοκλίμακα.Τα αποτελέσματα της εφαρμογής των αισθητήρων που κατασκευάστηκαν σε πραγματικά δείγματα ήταν ικανοποιητικά με αποτέλεσμα για πρώτη φορά στην παγκόσμια βιβλιογραφία να υπάρχει η δυνατότητα να κατασκευαστούν φορητοί χημικοί αισθητήρες για την ανίχνευση τοξικών ουσιών με πολλά πλεονεκτήματα και στο μέλλον να μπορούν να χρησιμοποιηθούν σαν εναλλακτικά συστήματα αντί των χρονοβόρων, πανάκριβων και πολύπλοκων χρωματογραφικών μεθόδων ανάλυσης.

The exploration of lipid membranes for the construction of nanobiosensors has recently provided the opportunity to construct devices to monitor a wide range of compounds of biological interest. Nanobiosensor miniaturization using nanotechnological tools has given novel ways to attach a wide range of “receptors” in the lipid membrane. The lipids used to construct a lipid film-based device are dipalmiloylphosphatidylcholine {DPPC} and in some cases dipalmitoylphosphatidic acid (DPPA) which is an anionic lipid and is used to increase the sensitivity of detection. Most common “receptors” used in lipid film biosensors are enzymes such as urease, cholesterol oxidase, urecase, etc, antibodies such as D-dimer antibody and artificial or natural receptors such as saxitoxin, cholera toxin, calyx [4] arene phospjoryl receptor, etc. This chapter reviews and investigates the construction of nanobiosensors based on lipid membranes that are used to monitor various toxicants. It also exploits examples of applications with an emphasis on novel devices, new nanobiosensing techniques and nanotechnology-based transduction schemes. The compounds that can be detected are insecticides, toxins, hormones, dioxins, etc. Keywords:Lipid membrane based nanosensors; Nanoyechology; Graphene and ZnO electrodes; Food toxicants; Environmental pollutants; Clinical analysis

The application of lipid film biosensor devices has created the opportunity to reconstitute a considerable part of their functionality to detect traces of food toxicants. Nanotechnology-enabled sensor miniaturization has extended the range of biological moieties that could be immobilized within a lipid bilayer device. This chapter reviews the recent progress in biosensor technologies for food-quality monitoring. A large number of applications are described herein, placing emphasis on size reduction of novel systems of lipid film devices, new sensing techniques, and nanotechnology-based transduction schemes. The range of analytes that can be currently detected include insecticides, pesticides, herbicides, toxins, hormones, dioxins, and genetically modified foods. Technology limitations and future prospects are discussed, with a focus on the commercialization capabilities of the proposed sensors.

The recent advances in lipid membrane biosensors gave the ability to provide devices to detect trace of environmental pollutants in real samples. Nanotechnology provided sensors with increased selectivity and sensitivity, portability, ease of construction, rapid response times, etc. This chapter reviews recent advances in biosensor technologies for environmental pollutant monitoring. A large number of applications are described herein, clarifying some recent advances in the technology of these devices such as miniaturization, new sensing techniques, and nanotechnology-based transduction schemes. A wide range of environmental toxicants can be monitored and these compounds include toxins, hormones, dioxins, PAHs, etc. As a result, the commercialization capabilities of these biosensors are given in the present chapter.

The investigation of lipid films for the construction of nanosensors has recently given the opportunity to manufacture devices to selectively determine a wide range of food toxicants. Biosensor miniaturization using recent advances in nanotechnology has given the opportunity to investigate novel techniques to immobilize a wide range of enzymes, antibodies and receptors within the lipid film. This chapter reviews novel revent platforms in nanobiosensors based on lipid membranes that are used in food chemistry to determine various food toxicants. Examples of applications are described with an emphasis on novel systems, sensing techniques and nanotechnology-based transduction schemes. The compounds that can be monitored are insecticides, pesticides, herbicides, metals, toxins, hormones, etc. Finally, limitations and future prospects are presented herein on the evaluation/validation and eventually commercialization of the proposed sensors.

The investigation of lipid films for the construction of nanosensors has recently given the opportunity to manufacture devices to selectively determine a wide range of food toxicants. Biosensor miniaturization using recent advances in nanotechnology has given the opportunity to investigate novel techniques to immobilize a wide range of enzymes, antibodies and receptors within the lipid film. This chapter reviews novel revent platforms in nanobiosensors based on lipid membranes that are used in food chemistry to determine various food toxicants. Examples of applications are described with an emphasis on novel systems, sensing techniques and nanotechnology-based transduction schemes. The compounds that can be monitored are insecticides, pesticides, herbicides, metals, toxins, hormones, etc. Finally, limitations and future prospects are presented herein on the evaluation/validation and eventually commercialization of the proposed sensors.

The investigation of lipid films for the construction of biosensors has recently given the opportunity to manufacture devices to selectively detect a wide range of compounds of clinical interest. Biosensor miniaturization using nanotechnological tools has provided novel routes to immobilize various “receptors” within the lipid film. This chapter reviews and exploits platforms in biosensors based on lipid membrane technology that are used to detect various analytes of clinical interest. Examples of applications are described with an emphasis on novel systems, new sensing techniques, and nanotechnology-based transduction schemes. The compounds that can be monitored are urea, cholesterol, glucose, toxins, antibiotics, microorganisms, hormones, etc. Finally, limitations and future prospects are presented herein on the evaluation/validation and eventually commercialization of the proposed sensors.

A miniaturized potentiometric saxitoxin sensor on graphene nanosheets with incorporated lipid films and Anti-STX, the natural saxitoxin receptor, immobilized on the stabilized lipid films is described in the present paper. An adequate selectivity for detection over a wide range of toxin concentrations, fast response time of ca. 5–20 min, and detection limit of 1 nM have been achieved. The proposed sensor is easy to construct and exhibits good reproducibility, reusability, selectivity, long shelf life and high sensitivity of ca. 60 mV/decade of toxin concentration. The method was implemented and evaluated in lake water and shellfish samples. This novel ultrathin film technology is currently adapted to the rapid detection of other toxins that could be used in bioterrorism.

The present work describes a miniaturized potentiometric naphthalene acetic acid (NAA) sensor on graphene nanosheets with incorporated lipid films. Auxin-binding protein 1 receptor immobilized on the stabilized lipid films provided adequate selectivity for detection over a wide range of hormone concentrations, fast response time of ca. 5 min, and detection limit of 10 nM. The proposed sensor is easy to construct and exhibits good reproducibility, reusability, selectivity, long shelf life and high sensitivity of ca. 56 mV/decade of hormone concentration. The reliability of the biosensor was successfully evaluated using a wide range of NAA-spiked fruits and vegetables.

Since first report on formation stable free standing bilayer lipid membranes (BLM) in 1962 by Mueller et al. [1] these systems became very popular in modeling various membrane processes at molecular level, such as ionic transport, ligand-receptor interactions or lipid-protein interactions. Despite of advantage of BLM in respect of variation in lipid composition and their modifications by receptors and proteins, the work with these systems was rather difficult due to their limited stability. The situation has been considerably improved by introduction of supported bilayer lipid membranes (sBLM) in 1980 by Thompson et al. [2] for possible applications in biosensors. Recent advances in stabilization of supported lipid membranes, appearance of novel nanomaterials such as carbon nanotubes has increased the number of publications on this topic. This review summarizes latest achievements in the field of biosensors utilizing sBLMs.

The present work describes a miniaturized potentiometric cholera toxin sensor on graphene nanosheets with incorporated lipid films. Ganglioside GM1, the natural cholera toxin receptor, immobilized on the stabilized lipid films, provided adequate selectivity for detection over a wide range of toxin concentrations, fast response time of ca. 5 min, and detection limit of 1 nM. The proposed sensor is easy to construct and exhibits good reproducibility, reusability, selectivity, long shelf life and high sensitivity of ca. 60 mV/decade of toxin concentration. The method was implemented and validated in lake water samples. This novel ultrathin film technology is currently adapted to the rapid detection of other toxins that could be used in bioterrorism.

The implementation of nanotechnology concepts, processes, and tools in the design and development of sensors is intriguing, indeed, and considered as the means to optimize analytical performance and move bench setups to the market. During the past decade, novel concepts have materialized into molecular electronics, synthetic biochemistry, DNA-based self-assembly, or manipulation of individual atoms via scanning tunneling microscopy. The development of nanoplatforms for chemical sensors and biosensors has received much attention, extending the range of strategies, architectures, and materials for biomedical and environment-friendly applications. The use of nanomaterials harmonized the scale between biological species and transduction platforms, thus resulting in the development of devices with higher rates of information flow. Despite these advantages, size reduction to nanodimensions is neither straightforward nor problem-free. This chapter presents, in brief, the principle directions of research in the field and justifies their practical implementation in sensing with a view to highlight current challenges and future prospects.

The exploitation of lipid membranes in biosensors has provided the ability to reconstitute a considerable part of their functionality to detect trace of food toxicants and environmental pollutants. Nanotechnology enabled sensor miniaturization and extended the range of biological moieties that could be immobilized within a lipid bilayer device. This chapter reviews recent progress in biosensor technologies suitable for environmental applications and food quality monitoring. Numerous biosensing applications are presented, putting emphasis on novel systems, new sensing techniques, and nanotechnology-based transduction schemes. The range of analytes that can be currently detected include phenols, insecticides, pesticides, herbicides, heavy metals, toxins, allergens, antibiotics, microorganisms, hormones, dioxins, genetically modified foods, etc. Technology limitations and future prospects are discussed, focused on the commercialization capabilities of the proposed sensors.

The exploitation of lipid membranes in biosensors has provided the ability to reconstitute a considerable part of their functionality to detect trace of food toxicants and environmental pollutants. Nanotechnology enabled sensor miniaturization and extended the range of biological moieties that could be immobilized within a lipid bilayer device. This chapter reviews recent progress in biosensor technologies based on lipid membranes suitable for environmental applications and food quality monitoring. Numerous biosensing applications are presented, putting emphasis on novel systems, new sensing techniques and nanotechnology-based transduction schemes. The range of analytes that can be currently detected include, insecticides, pesticides, herbicides, metals, toxins, antibiotics, microorganisms, hormones, dioxins, etc. Technology limitations and future prospects are discussed, focused on the evaluation/ validation and eventually commercialization of the proposed sensors.

This review provides informations and details for the fabrication of biosensors that are composed from lipid membranes and have been utilized and applied to rapidly detect food toxic compounds, environmental pollutants and analytes of clinical interest. Biosensors based on polymeric lipid membranes have been used to rapidly detect a wide range of these analytes and offer several advantages such as fast response, high sensitivity and selectivity, can be portable for in the field applications, and small size. A description of the construction of these devices and their applications for the rapid detection of food toxic substance, environmental pollutants and analytes of clinical interest is provided in this review.

The modern environmental and food analysis requires sensitive, accurate, and rapid methods. The growing field of biosensors represents an answer to this demand. Unfortunately, most biosensor systems have been tested only on distilled water or buffered solutions, although applications to real samples are increasingly appearing in recent years. In this context, biosensors for potential food applications continue to show advances in areas such as genetic modification of enzymes and microorganisms, improvement of recognition element immobilization, and sensor interfaces. This chapter investigates the progress in the development of biosensors for the rapid detection of food toxicants for online applications. Recent progress in nanotechnology has produced affordable, mass-produced devices, and to integrate these into components and systems (including portable ones) for mass market applications for food toxicants monitoring. Sensing includes chemical and microbiological food toxicants, such as toxins, insecticides, pesticides, herbicides, microorganisms, bacteria, viruses and other microorganisms, phenolic compounds, allergens, genetically modified foods, hormones, dioxins, etc. Therefore, the state of the art of recent advances and future targets in the development of biosensors for food monitoring is summarized as follows: biosensors for food analysis will be highly sensitive, selective, rapidly responding, real time, massively parallel, with no or minimum sample preparation, and platform suited to portable and handheld nanosensors for the rapid detection of food toxicants for online uses even by nonskilled personnel.

The present article describes a miniaturized potentiometric carbofuran chemical sensor on graphene nanosheets with incorporated lipid films. The graphene electrode was used for the development of a very selective and sensitive chemical sensor for the detection of carbofuran by immobilizing an artificial selective receptor on stabilized lipid films. The artificial receptor was synthesized by transformation of the hydroxyl groups of resorcin[4]arene receptor into phosphoryl groups. This chemical sensor responded for the wide range of carbofuran concentrations with fast response time of ca. 20 s. The presented potentiometric carbofuran chemical sensor is easy to construct and exhibits good reproducibility, reusability, selectivity, rapid response times, long shelf life and high sensitivity of ca. 59 mV/decade over the carbofuran logarithmic concentration range from 10−6 to 10−3 M.

Nanotechnology is playing an increasingly important role in the development of biosensors. Use of nanomaterials in biosensors allows the use of many new signal transduction technologies in their manufacture. Because of their submicron size, nanosensors, nanoprobes, and other nanosystems are revolutionizing the fields of chemical and biological analysis, to enable rapid analysis of multiple substances in food and environmental samples. Recent progress in nanotechnology has resulted in producing affordable, mass-produced devices and in integrating these into components and systems (including portable ones) for mass market applications for food toxicants monitoring. Sensing includes chemical and microbiological food toxicants, such as toxins, insecticides, pesticides, herbicides, microorganisms, bacteria, viruses, and other microorganisms, phenolic compounds, allergens, genetically modified foods, hormones, and dioxins. The sensitivity and performance of biosensors is being improved by using nanomaterials for their construction. The use of these nanomaterials has allowed the introduction of many new signal transduction technologies in biosensors. Because of their submicron dimensions, nanosensors, nanoprobes, and other nanosystems have allowed simple and rapid analyses in vivo. Portable instruments capable of analyzing multiple components are becoming available. This chapter reviews the status of the various nanostructure-based biosensors and investigates prototype biosensing devices: design and microfabrication based on nanotechnological tools yield devices suitable for the rapid in the field detection of food toxicants and environmental pollutants.

A biosensor is an analytical device that is constructed by incorporating a biological recognition element immobilized on a physicochemical transducer and measures one or more analytes. Microfluidics is a generalized term that denotes, individually or in combination, fluids behavior, precise control, and manipulation at the sub-millimeter scale. Microfluidic systems provide throughput processing, enhance transport for controlling the flow conditions, increase the mixing rate of different reagents, reduce sample and reagents volume (down to nanoliter scale), and increase the sensitivity of detection. Therefore in the scope of these advantages, the integration of microfluidics in biosensor technology offers new opportunities for future biosensing applications including portability, real-time detection, improved accuracy, increased sensitivity and selectivity, and simultaneous analysis of different analytes in a single device. A lab-on-a-chip (LOC) is an integrated device that offers several laboratory functions on a single platform; areas typically ranging from square millimeters to a few square centimeters. LOCs deal with the handling of extremely small fluid volumes down of less than a picolitre. The present review is targeted at representing the advances and applications in the area of microfluidic-based biosensing. The fabrication and designing of microfluidics platform technology for biosensors is described herein. The review provides examples from applications of microfluidics-based devices in the literature and demonstrates the advantages of merging microfluidic and biosensing technologies. Such integration promises in the future, biosensing for emerging areas of biological engineering, biomedical studies, point-of-care diagnostics, environmental monitoring, and precision agriculture.

The modern environmental and food analysis requires sensitive, accurate, and rapid methods. The growing field of biosensors represents an answer to this demand. Unfortunately, most biosensor systems have been tested only on distilled water or buffered solutions, although applications to real samples are increasingly appearing in recent years. In this context, biosensors for potential food applications continue to show advances in areas such as genetic modification of enzymes and microorganisms, improvement of recognition element immobilization, and sensor interfaces. This chapter investigates the progress in the development of biosensors for the rapid detection of food toxicants for online applications. Recent progress in nanotechnology has produced affordable, mass-produced devices, and to integrate these into components and systems (including portable ones) for mass market applications for food toxicants monitoring. Sensing includes chemical and microbiological food toxicants, such as toxins, insecticides, pesticides, herbicides, microorganisms, bacteria, viruses and other microorganisms, phenolic compounds, allergens, genetically modified foods, hormones, dioxins, etc. Therefore, the state of the art of recent advances and future targets in the development of biosensors for food monitoring is summarized as follows: biosensors for food analysis will be highly sensitive, selective, rapidly responding, real time, massively parallel, with no or minimum sample preparation, and platform suited to portable and handheld nanosensors for the rapid detection of food toxicants for online uses even by nonskilled personnel.

Graphene nanomaterials have received an enormous amount of attention for their technological applications in biosensing, due to advantages such as good sensing ability, excellent mechanical, thermal, and electrical properties, large surface-area-to-volume ratio, and biocompatibility. The present chapter describes recent trends in and future applications of the development of miniaturized amperometric and potentiometric biosensors by integrating “receptors” (i.e., enzymes, antibodies, and natural receptors) in graphene nanoelectrodes. The latest trends are related to the application of these systems to rapidly detecting clinically important substrates, such as glucose, urea, uric acid, cholesterol, etc. The presented biosensors exhibit good reproducibility, reusability, selectivity, rapid response times, long shelf life, and high sensitivity, while not suffering from interference by coexisting oxidable substances. The electrochemical nanobiosensors are prepared through the integration of biomolecules with graphene and have demonstrated capabilities to compare with conventional platforms. Miniaturization, reagent-less biosensing, and single-molecule detection are their obvious advantages. This chapter highlights the significant milestones already achieved and elucidates emerging trends in this area.

The present article describes a miniaturized potentiometric D-dimer biosensor on graphene nanosheets with incorporated lipid films. The graphene electrode was used for the development of a very selective and sensitive immunosensor for the detection of D-dimer by immobilizing the mouse anti human D-dimer antibody on stabilized lipid films. The immunosensor responded for the wide range of D-dimer concentrations with fast response time of ca. 15 s. The presented potentiometric D-dimer biosensor is easy to construct and exhibits good reproducibility, reusability, selectivity, rapid response times, long shelf life and high sensitivity of ca. 59 mV/decade over the D-dimer logarithmic concentration range from 10−6 μg/L to 10−3 μg/L.

This article describes the development of a calcium solid minisensor based on lipid films on ZnO nanorods. The lipid film was composed from dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylcic acid (DPPA). The calibration graph was logarithmically related to the concentration of calcium ions in the range from 10−6 to 10−3 M. The response times of the electrode were less than 5 s. No memory effects were observed for this electrode. The reproducibility of the electrode was less than 5 %. The electrode has shown good stability for a period of 1 month. The influence of a wide range of metals and anions as potential interferences was checked. The method was applied to the rapid detection of calcium ions in mineral waters.

ZnO nanorods were grown on gold coated glass substrate by low temperature aqueous chemical growth method. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used for the characterization of ZnO nanorods. ZnO nanorods are highly dense, uniform, well aligned and perpendicular-oriented to the substrate. ZnO nanorods exhibited good crystal quality. The well aligned ZnO nanorods were potentially used for the development of selective and sensitive immunosensor for the detection of D-dimer by immobilizing antibody on stabilized lipid films. The ZnO nanorods based immunosensor responded to a wide range of D-dimer concentrations with fast response time of ca. 20 s.

Abstract A novel potentiometric cholesterol biosensor has been fabricated through the immobilization of the stabilized polymeric lipid membrane onto graphene electrode. The stabilized polymeric lipid membrane is composed of cholesterol oxidase enzyme and polymerization mixture; which holds paramount influence on the properties of the cholesterol biosensor. The presented biosensor reveals an appreciable reproducibility, good selectivity and high sensing capability with a linear slope curve of ∼64 mV per decade. The strong biocompatibility among stabilized polymeric lipid membranes and human biofluids provides the possibility to use for real blood samples and other biological applications. Graphical abstract

An electrochemical biosensor based on a supported polymerized lipid film with incorporated sheep anti-3,3′,4,4′ tetrachlorobiphenyl (PCB congener 77) antibody using flow injection analysis was developed. The polymerized lipid film contained 85% (w/w) dipalmitoylphosphatidylcholine (DPPC) and 15% (w/w) dipalmitoylphosphatidic acid (DPPA), methacrylic acid, ethylene glycol dimethacrylate, AIBN and sheep anti-congener 77 antiserum. Congener 77 was injected into flowing carrier electrolyte and the flow stopped to detect the antigen. These membranes gave only a single transient proportional to log [congener 77] from 10−8 to 10−5 M, with a detection limit of ca. 10−8 M. A membrane containing 35% (w/w) DPPA was used to examine regeneration. The maximum number of cycles was about 5.