Editorial

2 pages, 165 KiB

Open AccessEditorial

by Beatriz Jurado-Sánchez

Biosensors 2018, 8(3), 66; https://doi.org/10.3390/bios8030066 - 06 Jul 2018

Cited by 7 | Viewed by 4647

The emerge of nanotechnology along with the success of the microelectronics industry has motivated the miniaturization of biosensors into the nano/microscale. This Special Issue highlights recent advances in microscale and nanoscale biosensors, including self-propelled micromotors: their materials, fabrication, and applications. A total of [...] Read more.

The emerge of nanotechnology along with the success of the microelectronics industry has motivated the miniaturization of biosensors into the nano/microscale. This Special Issue highlights recent advances in microscale and nanoscale biosensors, including self-propelled micromotors: their materials, fabrication, and applications. A total of seven papers (five research and two review papers) are included. Different but related topics are covered, from biosensor design (paper strips and digital microfluidic chips) to integrated configurations that monitor metabolites in cellular environments. The reviews are devoted to protein-based biosensors and moving biosensors based on self-propelled micromotors. Full article

(This article belongs to the Special Issue Micro and Nanoscale Biosensors)

Research

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10 pages, 2162 KiB

Open AccessArticle

New Carrier Made from Glass Nanofibres for the Colorimetric Biosensor of Cholinesterase Inhibitors

by Lukáš Matějovský and Vladimír Pitschmann

Biosensors 2018, 8(2), 51; https://doi.org/10.3390/bios8020051 - 30 May 2018

Cited by 23 | Viewed by 5602

Abstract

Cholinesterase inhibitors are widely used as pesticides in agriculture, but also form a group of organophosphates known as nerve chemical warfare agents. This calls for close attention regarding their detection, including the use of various biosensors. One such biosensor made in the Czech [...] Read more.

Cholinesterase inhibitors are widely used as pesticides in agriculture, but also form a group of organophosphates known as nerve chemical warfare agents. This calls for close attention regarding their detection, including the use of various biosensors. One such biosensor made in the Czech Republic is the Detehit, which is based on a cholinesterase reaction that is assessed using a colour indicator—the Ellman’s reagent—which is anchored on cellulose filter paper together with the substrate. With the use of this biosensor, detection is simple, quick, and sensitive. However, its disadvantage is that a less pronounced yellow discoloration occurs, especially under difficult light conditions. As a possible solution, a new indicator/substrate carrier has been designed. It is made of glass nanofibres, so the physical characteristics of the carrier positively influence reaction conditions, and as a result improve the colour response of the biosensor. The authors present and discuss some of the results of the study of this carrier under various experimental conditions. These findings have been used for the development of a modified Detehit biosensor. Full article

(This article belongs to the Special Issue Micro and Nanoscale Biosensors)

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12 pages, 1447 KiB

Open AccessArticle

Droplet Velocity Measurement Based on Dielectric Layer Thickness Variation Using Digital Microfluidic Devices

by Siti Noor Idora Syafinaz Zulkepli, Nor Hisham Hamid and Vineeta Shukla

Biosensors 2018, 8(2), 45; https://doi.org/10.3390/bios8020045 - 08 May 2018

Cited by 9 | Viewed by 5833

Abstract

In recent years, the number of interdisciplinary research works related to the development of miniaturized systems with integrated chemical and biological analyses is increasing. Digital microfluidic biochips (DMFBs) are one kind of miniaturized systems designed for conducting inexpensive, fast, convenient and reliable biochemical [...] Read more.

In recent years, the number of interdisciplinary research works related to the development of miniaturized systems with integrated chemical and biological analyses is increasing. Digital microfluidic biochips (DMFBs) are one kind of miniaturized systems designed for conducting inexpensive, fast, convenient and reliable biochemical assay procedures focusing on basic scientific research and medical diagnostics. The role of a dielectric layer in the digital microfluidic biochips is prominent as it helps in actuating microliter droplets based on the electrowetting-on-dielectric (EWOD) technique. The advantages of using three different material layers of dielectric such as parafilm, polytetrafluoroethylene (PTFE) and ethylene tetrafluoroethylene (ETFE) were reported in the current work. A simple fabrication process of a digital microfluidic device was performed and good results were obtained. The threshold of the actuation voltage was determined for all dielectric materials of varying thicknesses. Additionally, the OpenDrop device was tested by utilizing a single-plate system to transport microliter droplets for a bioassay operation. With the newly proposed fabrication methods, these dielectric materials showed changes in contact angle and droplet velocity when the actuation voltage was applied. The threshold actuation voltage for the dielectric layers of 10–13 μm was 190 V for the open plate DMFBs. Full article

(This article belongs to the Special Issue Micro and Nanoscale Biosensors)

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11 pages, 7715 KiB

Open AccessFeature PaperArticle

Sensor Access to the Cellular Microenvironment Using the Sensing Cell Culture Flask

by Jochen Kieninger, Yaara Tamari, Barbara Enderle, Gerhard Jobst, Joe A. Sandvik, Erik O. Pettersen and Gerald A. Urban

Biosensors 2018, 8(2), 44; https://doi.org/10.3390/bios8020044 - 26 Apr 2018

Cited by 32 | Viewed by 8070

Abstract

The Sensing Cell Culture Flask (SCCF) is a cell culture monitoring system accessing the cellular microenvironment in 2D cell culture using electrochemical microsensors. The system is based on microfabricated sensor chips embedded in standard cell culture flasks. Ideally, the sensor chips could be [...] Read more.

The Sensing Cell Culture Flask (SCCF) is a cell culture monitoring system accessing the cellular microenvironment in 2D cell culture using electrochemical microsensors. The system is based on microfabricated sensor chips embedded in standard cell culture flasks. Ideally, the sensor chips could be equipped with any electrochemical sensor. Its transparency allows optical inspection of the cells during measurement. The surface of the sensor chip is in-plane with the flask surface allowing undisturbed cell growth on the sensor chip. A custom developed rack system allows easy usage of multiple flasks in parallel within an incubator. The presented data demonstrates the application of the SCCF with brain tumor (T98G) and breast cancer (T-47D) cells. Amperometric oxygen sensors were used to monitor cellular respiration with different incubation conditions. Cellular acidification was accessed with potentiometric pH sensors using electrodeposited iridium oxide films. The system itself provides the foundation for electrochemical monitoring systems in 3D cell culture. Full article

(This article belongs to the Special Issue Micro and Nanoscale Biosensors)

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25 pages, 2251 KiB

Open AccessFeature PaperArticle

S-Layer Protein-Based Biosensors

by Bernhard Schuster

Biosensors 2018, 8(2), 40; https://doi.org/10.3390/bios8020040 - 11 Apr 2018

Cited by 32 | Viewed by 9343

Abstract

The present paper highlights the application of bacterial surface (S-) layer proteins as versatile components for the fabrication of biosensors. One technologically relevant feature of S-layer proteins is their ability to self-assemble on many surfaces and interfaces to form a crystalline two-dimensional (2D) [...] Read more.

The present paper highlights the application of bacterial surface (S-) layer proteins as versatile components for the fabrication of biosensors. One technologically relevant feature of S-layer proteins is their ability to self-assemble on many surfaces and interfaces to form a crystalline two-dimensional (2D) protein lattice. The S-layer lattice on the surface of a biosensor becomes part of the interface architecture linking the bioreceptor to the transducer interface, which may cause signal amplification. The S-layer lattice as ultrathin, highly porous structure with functional groups in a well-defined special distribution and orientation and an overall anti-fouling characteristics can significantly raise the limit in terms of variety and the ease of bioreceptor immobilization, compactness of bioreceptor molecule arrangement, sensitivity, specificity, and detection limit for many types of biosensors. The present paper discusses and summarizes examples for the successful implementation of S-layer lattices on biosensor surfaces in order to give a comprehensive overview on the application potential of these bioinspired S-layer protein-based biosensors. Full article

(This article belongs to the Special Issue Micro and Nanoscale Biosensors)

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9 pages, 238 KiB

Open AccessArticle

The Use of Biosensors to Explore the Potential of Probiotic Strains to Reduce the SOS Response and Mutagenesis in Bacteria

by Vladimir Anatolievich Chistyakov, Evgeniya Valer’evna Prazdnova, Maria Sergeevna Mazanko and Anzhelica Borisovna Bren

Biosensors 2018, 8(1), 25; https://doi.org/10.3390/bios8010025 - 16 Mar 2018

Cited by 15 | Viewed by 5001

Abstract

A model system based on the Escherichia coli MG1655 (pRecA-lux) Lux-biosensor was used to evaluate the ability of the fermentates of eight probiotic strains to reduce the SOS response stimulated by ciprofloxacin in bacteria and mutagenesis mediated by it. Preliminary attempts to estimate [...] Read more.

A model system based on the Escherichia coli MG1655 (pRecA-lux) Lux-biosensor was used to evaluate the ability of the fermentates of eight probiotic strains to reduce the SOS response stimulated by ciprofloxacin in bacteria and mutagenesis mediated by it. Preliminary attempts to estimate the chemical nature of active components of the fermentates were conducted. Full article

(This article belongs to the Special Issue Micro and Nanoscale Biosensors)

11 pages, 1970 KiB

Open AccessCommunication

Self-Organized Nanostructure Modified Microelectrode for Sensitive Electrochemical Glutamate Detection in Stem Cells-Derived Brain Organoids

by Babak Nasr, Rachael Chatterton, Jason Hsien Ming Yong, Pegah Jamshidi, Giovanna Marisa D’Abaco, Andrew Robin Bjorksten, Omid Kavehei, Gursharan Chana, Mirella Dottori and Efstratios Skafidas

Biosensors 2018, 8(1), 14; https://doi.org/10.3390/bios8010014 - 05 Feb 2018

Cited by 30 | Viewed by 7717

Abstract

Neurons release neurotransmitters such as glutamate to communicate with each other and to coordinate brain functioning. As increased glutamate release is indicative of neuronal maturation and activity, a system that can measure glutamate levels over time within the same tissue and/or culture system [...] Read more.

Neurons release neurotransmitters such as glutamate to communicate with each other and to coordinate brain functioning. As increased glutamate release is indicative of neuronal maturation and activity, a system that can measure glutamate levels over time within the same tissue and/or culture system is highly advantageous for neurodevelopmental investigation. To address such challenges, we develop for the first time a convenient method to realize functionalized borosilicate glass capillaries with nanostructured texture as an electrochemical biosensor to detect glutamate release from cerebral organoids generated from human embryonic stem cells (hESC) that mimic various brain regions. The biosensor shows a clear catalytic activity toward the oxidation of glutamate with a sensitivity of 93 ± 9.5 nA·µM⁻¹·cm⁻². It was found that the enzyme-modified microelectrodes can detect glutamate in a wide linear range from 5 µM to 0.5 mM with a limit of detection (LOD) down to 5.6 ± 0.2 µM. Measurements were performed within the organoids at different time points and consistent results were obtained. This data demonstrates the reliability of the biosensor as well as its usefulness in measuring glutamate levels across time within the same culture system. Full article

(This article belongs to the Special Issue Micro and Nanoscale Biosensors)

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Review

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15 pages, 2523 KiB

Open AccessReview

Nanoscale Biosensors Based on Self-Propelled Objects

by Beatriz Jurado-Sánchez

Biosensors 2018, 8(3), 59; https://doi.org/10.3390/bios8030059 - 25 Jun 2018

Cited by 39 | Viewed by 7915

Abstract

This review provides a comprehensive overview of the latest developments (2016–2018 period) in the nano and micromotors field for biosensing applications. Nano and micromotor designs, functionalization, propulsion modes and transduction mechanism are described. A second important part of the review is devoted to [...] Read more.

This review provides a comprehensive overview of the latest developments (2016–2018 period) in the nano and micromotors field for biosensing applications. Nano and micromotor designs, functionalization, propulsion modes and transduction mechanism are described. A second important part of the review is devoted to novel in vitro and in vivo biosensing schemes. The potential and future prospect of such moving nanoscale biosensors are given in the conclusions. Full article

(This article belongs to the Special Issue Micro and Nanoscale Biosensors)

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