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Lateral-flow tests were first launched commercially in 1984, as a simple urine-based pregnancy test for home use. The simplicity of the visual readout delivered by the basic lateral-flow format proved to be a very popular. However, the recent apparently unstoppable trend towards portable and wearable technology is driving the lateral-flow strip towards an industrial interface that will enable it to interface with big data and expert systems, and where ready transmission of data is essential. In this review, we chart the inevitable evolution of the visually-read lateral-flow strip to more advanced instrumented versions and consider the future of this very flexible approach to delivering simple affinity assays. We examine recent labelling strategies, the relative merits of optical and electrochemical transducers and explore the evolution of recognition elements that are now being incorporated into these systems. [ABSTRACT FROM AUTHOR]

The discovery of graphene and its unique properties has inspired researchers to try to invent other two-dimensional (2D) materials. After considerable research effort, a distinct "beyond graphene" domain has been established, comprising the library of non-graphene 2D materials. It is significant that some 2D non-graphene materials possess solid advantages over their predecessor, such as having a direct band gap, and therefore are highly promising for a number of applications. These applications are not limited to nano- and opto-electronics, but have a strong potential in biosensing technologies, as one example. However, since most of the 2D non-graphene materials have been newly discovered, most of the research efforts are concentrated on material synthesis and the investigation of the properties of the material. Applications of 2D non-graphene materials are still at the embryonic stage, and the integration of 2D non-graphene materials into devices is scarcely reported. However, in recent years, numerous reports have blossomed about 2D material-based biosensors, evidencing the growing potential of 2D non-graphene materials for biosensing applications. This review highlights the recent progress in research on the potential of using 2D non-graphene materials and similar oxide nanostructures for different types of biosensors (optical and electrochemical). A wide range of biological targets, such as glucose, dopamine, cortisol, DNA, IgG, bisphenol, ascorbic acid, cytochrome and estradiol, has been reported to be successfully detected by biosensors with transducers made of 2D non-graphene materials. [ABSTRACT FROM AUTHOR]

Abstract: The detection of dopamine by differential pulse voltammetry (DPV) and square wave voltammetry (SWV) at the interface between two immiscible electrolyte solutions (ITIES) has been studied. Voltammetry at the liquid/liquid (water/1,2-dichloroethane) interface provides a simple method for overcoming the major problem associated with dopamine detection by voltammetry at solid electrodes: the co-existence of ascorbate at higher concentrations. Selectivity for dopamine was achieved by the use of dibenzo-18-crown-6 as an ionophore for the facilitated transfer voltammetry of protonated dopamine across the ITIES. Under these conditions, ascorbate is not transferred and hence does not interfere in the ion transfer current for dopamine. By use of DPV and SWV, the lowest concentration detectable can be lowered from ca. 0.1mM (obtained with cyclic voltammetry) to 2μM. Evaluation of the effect of some other physiologically important species (acetylcholine, sodium, potassium and ammonium ions) on the dopamine transfer voltammetry has been studied, indicating the need for improved ionophore designs in order to achieve practically useful selectivity. [Copyright &y& Elsevier]

Infectious diseases are a potential risk for public health and the global economy. Fast and accurate detection of the pathogens that cause these infections is important to avoid the transmission of the diseases. Conventional methods for the detection of these microorganisms are time-consuming, costly, and not applicable for on-site monitoring. Biosensors can provide a fast, reliable, and point of care diagnostic. Nanomaterials, due to their outstanding electrical, chemical, and optical features, have become key players in the area of biosensors. This review will cover different nanomaterials that employed in electrochemical, optical, and instrumental biosensors for infectious disease diagnosis and how these contributed to enhancing the sensitivity and rapidity of the various sensing platforms. Examples of nanomaterial synthesis methods as well as a comprehensive description of their properties are explained. Moreover, when available, comparative data, in the presence and absence of the nanomaterials, have been reported to further highlight how the usage of nanomaterials enhances the performances of the sensor. [Display omitted] • Fast detection of infectious disease is crucial to avoid fast human to human transmission. • We provide a comprehensive overview of most applicable nanomaterials in biosensors. • The review covered electrochemical, colorimetric, fluorescence, SERS, and lateral flow biosensor used antibodies and aptamers. • We emphasis how the usage of nanomaterials can influences the performances of the immunosensors and aptasensors. [ABSTRACT FROM AUTHOR]

There is a profound need in bioprocess manufacturing for low-cost single-use sensors that allow timely monitoring of critical product and production attributes. One such opportunity is screen-printed enzyme-based electrochemical sensors, which have the potential to enable low-cost online and/or off-line monitoring of specific parameters in bioprocesses. In this study, such a single-use electrochemical biosensor for lactate monitoring is designed and evaluated. Several aspects of its fabrication and use are addressed, including enzyme immobilization, stability, shelf-life and reproducibility. Applicability of the biosensor to off-line monitoring of bioprocesses was shown by testing in two common industrial bioprocesses in which lactate is a critical quality attribute (Corynebacterium fermentation and mammalian Chinese hamster ovary (CHO) cell cultivation). The specific response to lactate of the screen-printed biosensor was characterized by amperometric measurements. The usability of the sensor at typical industrial culture conditions was favorably evaluated and benchmarked with commonly used standard methods (HPLC and enzymatic kits). The single-use biosensor allowed fast and accurate detection of lactate in prediluted culture media used in industrial practice. The design and fabrication of the biosensor could most likely be adapted to several other critical bioprocess analytes using other specific enzymes. This makes this single-use screen-printed biosensor concept a potentially interesting and versatile tool for further applications in bioprocess monitoring. [ABSTRACT FROM AUTHOR]

The key step in the construction of efficient and selective analytical separations or sensors is the design of the recognition interface. Biomimicry of the recognition features typically found in biological molecules, using amino acids, peptides and nucleic acids, provides plausible opportunities to integrate biological molecules or their active sites into a synthetic polymeric backbone. Given the basic role of functional amino acids in biorecognition, we focused on the synthesis of polymerizable amino acid derivatives and their incorporation into a polymer-based biohybrid interface to construct generic bioinspired analytical tools. We also utilized polyvinyl alcohol (PVA) as a sacrificial polymer to adjust the porosity of these biohybrid interfaces. The surface morphologies of the interfaces on gold electrodes were characterized by using scanning electron (SEM) and atomic force (AFM) microscopies. The electrochemical behavior of the polymeric films was systematically investigated using differential pulse voltammetry (DPV) to demonstrate the high affinity of the biohybrid interfaces for Cu(II) ions. The presence of macropores also significantly improved the recognition performance of the interfaces while enhancing interactions between the target [Cu(II) ions] and the functional groups. As a final step, we showed the applicability of the proposed analytical platform to create a Cu(II) ion-mediated supramolecular self-assembly on a quartz crystal microbalance (QCM) electrode surface in real time. [ABSTRACT FROM AUTHOR]

The mediation of oxidases glucose oxidase (GOx), lactate oxidase (LOx) and cholesterol oxidase (ChOx) by a new electron shuttling mediator, unsubstituted phenothiazine (PTZ), was studied. Cyclic voltammetry and rotating-disk electrode measurements in nonaqueous media were used to determine the diffusion characteristics of the mediator and the kinetics of its reaction with GOx, giving a second-order rate constant of 7.6×103–2.1×104 M−1 s−1 for water–acetonitrile solutions containing 5–15% water. These values are in the range reported for commonly used azine-type mediators, indicating that PTZ is able to function as an efficient mediator. PTZ and GOx, LOx and ChOx were successfully co-immobilised in sol–gel membrane on a screen-printed electrode to construct glucose, lactate and cholesterol biosensors, respectively, which were then optimised in terms of stability and sensitivity. The electrocatalytic oxidation responses showed a dependence on substrate concentration ranging from 0.6 to 32mM for glucose, from 19 to 565mM for lactate and from 0.015 to 1.0mM for cholesterol detection. Oxidation of substrates on the surface of electrodes modified with PTZ and enzyme membrane was investigated with double-step chronoamperometry and the results showed that the PTZ displays excellent electrochemical catalytic activities even when immobilised on the surface of the electrode. [ABSTRACT FROM AUTHOR]

Fast and accurate detection of microorganisms is of key importance in clinical analysis and in food and water quality monitoring. Salmonella typhimurium is responsible for about a third of all cases of foodborne diseases and consequently, its fast detection is of great importance for ensuring the safety of foodstuffs. We report the development of a label-free impedimetric aptamer-based biosensor for S. typhimurium detection. The aptamer biosensor was fabricated by grafting a diazonium-supporting layer onto screen-printed carbon electrodes (SPEs), via electrochemical or chemical approaches, followed by chemical immobilisation of aminated-aptamer. FTIR-ATR, contact angle and electrochemical measurements were used to monitor the fabrication process. Results showed that electrochemical immobilisation of the diazonium-grafting layer allowed the formation of a denser aptamer layer, which resulted in higher sensitivity. The developed aptamer-biosensor responded linearly, on a logarithm scale, over the concentration range 1×10 1 to 1×10 8 CFU mL −1 , with a limit of quantification (LOQ) of 1×10 1 CFU mL −1 and a limit of detection (LOD) of 6 CFU mL −1 . Selectivity studies showed that the aptamer biosensor could discriminate S. typhimurium from 6 other model bacteria strains. Finally, recovery studies demonstrated its suitability for the detection of S. typhimurium in spiked (1×10 2 , 1×10 4 and 1×10 6 CFU mL −1 ) apple juice samples. [ABSTRACT FROM AUTHOR]