Stephanos Karapetis

Lipid Membrane Nanosensors for Environmental Monitoring: The Art, the Opportunities, and the Challenges

The advent of nanotechnology has brought along new materials, techniques, and concepts, readily adaptable to lipid membrane-based biosensing. The transition from micro-sensors to nano-sensors is neither straightforward nor effortless, yet it leads to devices with superior analytical characteristics: ultra-low detectability, small sample volumes, better capabilities for integration, and more available bioelements and processes. Environmental monitoring remains a complicated field dealing with a large variety of pollutants, several decomposition products, or secondary chemicals produced ad hoc in the short- or medium term, many sub-systems affected variously, and many processes largely unknown. The new generation of lipid membranes, i.e., nanosensors, has the potential for developing monitors with site-specific analytical performance and operational stability, as well as analyte-tailored types of responses. This review presents the state-of-the art, the opportunities for niche applicability, and the challenges that lie ahead.

Novel Biosensors for the Rapid Detection of Toxicants in Foods

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.

Point-of-Care and Implantable Biosensors in Cancer Research and Diagnosis

Continuous, real-time in vivo monitoring in cancer would undoubtedly provide much needed information in early disease diagnosis, drug efficacy, or even drug delivery without the need for inconclusive imaging or lengthy biopsies. Towards that end, biosensor systems have the background and potential to provide real-time and personalized health monitoring. Numerous biosensor platforms have been developed for the detection of cancer biomarkers and lately some suggestions have been made on implantable systems for disease control and monitoring. Fast responses, miniaturized sensor size, rapid label-free detection, easy device tailoring, ultra-low detection limits, high reliability of measurements, and low development costs are appealing to patients, physicians, and the medical industry. This chapter critically reviews the field and highlights the potential of the emerging technology as well as the barriers that have to be overcome before implantable integrated sensors can become a reliable diagnostic tool in point-of-care cancer management.

Prototype Biosensing Devices

Abstract 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.

Nanobiosensors Based on Graphene Electrodes: Recent Trends and Future Applications

Abstract 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.

Biosensors Based on Microfluidic Devices Lab-on-a-Chip and Microfluidic Technology

Abstract 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.

Application of Biosensors Based on Lipid Membranes for the Rapid Detection of Toxins

Lipid assemblies in the form of two dimensional films have been used extensively as biosensing platforms. These films exhibit certain similarities with cell membranes, thus providing a suitable means for the immobilization of proteinaceous moieties and, further, a number of intrinsic signal amplification mechanisms. Their implementation in the detection of toxins yielded reliable and fast detectors for in field analyses of environmental and clinical samples. Some examples are presented herein, including aflatoxin and cholera toxin detection. The conditions and parameters that determine the analytical specifications of the lipid membrane sensors are discussed, advantages and technology bottlenecks are reviewed, and possible further developments are highlighted.

Biosensors for Security and Bioterrorism: Definitions, History, Types of Agents, New Trends and Applications

Biosensors are making a large impact in environmental, food, biomedical, and in many other applications. They provide many advantages. in comparison to standard analytical detection methods (i.e., chromatographic techniques) such as minimal sample preparation and handling, faster time analysis, simpler steps of analysis, rapid detection of the analytes of concern, use of non-skilled personnel, and portability for uses in the field applications. The aim of this chapter is to focus on novel research related to the rapid detection of agents and weapons of bioterrorism and provide a comprehensive review of the research topics most pertinent to advancing devices applicable to the rapid real-time detection of toxicants and bioterrorism weapons such as microbes, pathogens, toxins, virus, or nerve gases. The ongoing war on terrorism and the rising security concerns are driving the need for newer faster biosensing devices against bio-warfare agents for both military and civil defense applications. Readers of these review article will learn new schemes of biological weapons that can lead to the construction of devices that will minimize the risk of bio-terrorism.