Advances in lipid film based biosensors

© 2016 Elsevier B.V. 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

Advances in lipid film based biosensors

© 2016 Elsevier B.V.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

HapBead: on-skin microfluidic haptic interface using tunable bead

On-skin haptic interfaces using soft elastomers which are thin and flexible have significantly improved in recent years. Many are focused on vibrotactile feedback that requires complicated parameter tuning. Another approach is based on mechanical forces created via piezoelectric devices and other methods for non-vibratory haptic sensations like stretching, twisting. These are often bulky with electronic components and associated drivers are complicated with limited control of timing and precision. This paper proposes HapBead, a new on-skin haptic interface that is capable of rendering vibration like tactile feedback using microfluidics. HapBead leverages a microfluidic channel to precisely and agilely oscillate a small bead via liquid flow, which then generates various motion patterns in channel that creates highly tunable haptic sensations on skin. We developed a proof-of-concept design to implement thin, flexible and easily affordable HapBead platform, and verified its haptic rendering capabilities via attaching it to users’ fingertips. A study was carried out and confirmed that participants could accurately tell six different haptic patterns rendered by HapBead. HapBead enables new wearable display applications with multiple integrated functionalities such as on-skin haptic doodles, mixed reality haptics and visual-haptic displays

Biosensors for security and bioterrorism applications

This book offers comprehensive coverage of biomarker/biosensor interactions for the rapid detection of weapons of bioterrorism, as well as current research trends and future developments and applications. It will be useful to researchers in this field who are interested in new developments in the early detection of such. The authors have collected very valuable and, in some aspects indispensable experience in the area i.e. in the development and application of portable biosensors for the detection of potential hazards. Most efforts are centered on the development of immunochemical assays including flow-lateral systems and engineered antibodies and their fragments. In addition, new approaches to the detection of enzyme inhibitors, direct enzymatic and microbial detection of metabolites and nutrients are elaborated. Some realized prototypes and concept devices applicable for the further use as a basis for the cooperation programs are also discussed. There is a particular focus on electrochemical and optical detection systems, including those employing carbon nanotubes, quantum dots and metal nanoparticles. The authors are well-known scientists and most of them are editors of respected international scientific journals. Although recently developed biosensors utilize known principles, the biosensing devices described can significantly shorten the time required for successful detection and enhance efforts in more time-consuming directions, e.g. remote sensing systems and validation in real-sample analysis. The authors describe advances in all stages of biosensor development: the selection of biochemical components, their use in biosensor assembly, detection principles and improvements and applications for real sample assays

Portable biosensors for the rapid detection of biochemical weapons of terrorism

The present review article describes the weapons of bioterrorism, history, types of agents used and recent advances of chemical sensors for the rapid detection of chemical and biological agents and other weapons of terrorism. The release of viruses, bacteria, or other germs used to cause illness or death in people mainly, animals, or plants can be found in nature and mainly are prepared to cause diseases or death. These biological weapons are used by terrorists as a method of creating mass panic and disruption to a society. Therefore it is of primary concern to develop biosensors to detect these terrorism weapons prior to their use. Novel recent biosensor technology has significant technological advantages when compared to that of the traditional detection methods. However, biosensor technology still needs to construct a portable device for the rapid detection of bioterrorism weapons that can be used in airports and other cases. © 2012 Springer Science+Business Media B.V

Development of chemical sensors for the detection of toxic compounds

The present dissertation was focused on the topic of chemical sensors for rapid detection of toxic substances, an investigation that was made for first time in the literature. For this purpose, biosensors using printed circuits composed from graphene microelectrodes using stabilized lipid membranes were constructed and developed.A number of particular methodologies were used to embody various receptors such as enzymes (urease and cholesterol oxidase) and an antibody (antibody D-dimer) in the sensors.Various physicochemical and instrumental methods of analysis, eg., differential scanning calorimetry (DSC), scanning electron microscopy (SEM), Raman spectrophotometry, etc., were used to locate the position of the receptor (eg. antibody, enzyme, etc.) into the stabilized lipid membrane of the sensor and the mechanism of signal generation.The response of the sensor to various potentially toxic substrates eg. urea (urease immobilization), cholesterol (cholesterol oxidase immobilization) and D-dimer (immobilizing antibody D-dimer) and its stability with time were studied.For example, the response of urea biosensor towards various urea concentrations was found to have high sensitivity (ca. 70 mV/ concentration decade) over a range of urea concentrations between 1 Χ 10−6 Μ - 1 Χ 10−3 Μ. The response of cholesterol biosensor towards various concentrations of the substrate were also found to be highly sensitive (ca. 64 mV/ concentration decade) over a concentration range between 1 Χ 10−6 Μ - 1 Χ 10−3 Μ; this sensitivity is larger than those provided up to date in the literature. Finally the response of the D-dimer immunosensor was found satisfactory over a wide concentration range of analyte (10-6 μg/ mL - 10-3 μg/ mL) with a sensitivity of ca. 59 mV/ concentration decade with a rapid response of 15 s.The selectivity of the sensor construction method and on how to limit interferences were studied so that the sensor could be applied in real samples. The conditions for satisfactory stability and reproducibility of the chemical sensors were thoroughly studied and their construction into nanoscale was investigated.The results of the implementation of the constructed devices in real samples were satisfactory and show the possibility of construction of portable chemical sensors for the detection of toxicants for first time in the literature with many advantages, which can be used in the future as alternative systems instead of the time consuming, costly and complex chromatographic methods of analysis.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