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Special Issue "Aptasensors 2016"

A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Biosensors".

Deadline for manuscript submissions: closed (15 February 2017)

Special Issue Editor

Guest Editor
Dr. Beate Strehlitz

Department Environmental and Biotechnology Centre, Helmholtz Centre for Environmental Research - UFZ, Permoserstr. 15, 04318 Leipzig, Germany
E-Mail
Phone: +49 341 2351764
Fax: +49 341 2351764
Interests: biosensor development and application; aptamer selection and characterization; aptamer based sensors and assays

Special Issue Information

Dear Colleagues,

The last year was the 25th anniversary of the ‘aptamer’ termed functional biomacromolecules and of the in vitro selection and amplification technology (SELEX) used for their development. In 1990, Tuerk & Gold and Ellington & Szostak, independently described their discoveries to generate RNA aptamers able to bind a protein molecule (Science 249, 1990, 505–510) and synthetic organic dyes (Nature 346, 1990, 818–822), respectively. Aptamers are still very attractive functional molecules that are applied by researchers from different disciplines in areas such as nanotechnology, synthetic and chemical biology, analytics, clinical diagnostics, and therapy. The discovery of high-quality aptamers for relevant targets proceeds. The first commercial products based on aptamers are on the market, such as Macugen® (Pfizer Inc., US) as a therapeutic aptamer to treat wet macular degeneration; the ELISA-like assays for detection of Ochratoxin A and aflatoxin (NeoVentures Biotechnologies, Canada); and others. In addition to these applications, aptamers are in great demand in the development of new biosensors, the so-called aptasensors. The aptamers are used as sensitive and selective bio-receptors coupled with a variety of transducer principles, such as optical, mass-sensitive, and electrochemical detection. The analytes cover a wide range from small molecules, such as nucleotides, cofactors, amino acids, organic molecules over peptides, polysaccharides and proteins to complex structures such as whole cells, viruses, and single cell organisms. Aptasensors offer great potential to measure substances in clinical diagnostics, environmental analytics, food and biotechnology industries, process engineering, and others.

With this re-opening of the Special Issue, we invite you again to contribute with your full research papers and review articles showing the highly-dynamic evolvements in the field of aptasensor development. We look forward to and welcome your participation in this Special Issue.

Dr. Beate Strehlitz
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • aptamers
  • biosensor
  • affinity sensor
  • electrochemical
  • optical
  • mass sensitive
  • label- and label-free detection

Published Papers (7 papers)

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Research

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Open AccessArticle The Optimization and Characterization of an RNA-Cleaving Fluorogenic DNAzyme Probe for MDA-MB-231 Cell Detection
Sensors 2017, 17(3), 650; doi:10.3390/s17030650
Received: 20 January 2017 / Revised: 28 February 2017 / Accepted: 1 March 2017 / Published: 21 March 2017
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Abstract
Breast cancer is one of the most frequently diagnosed cancers in females worldwide and lacks specific biomarkers for early detection. In a previous study, we obtained a selective RNA-cleaving Fluorogenic DNAzyme (RFD) probe against MDA-MB-231 cells, typical breast cancer cells, through the systematic
[...] Read more.
Breast cancer is one of the most frequently diagnosed cancers in females worldwide and lacks specific biomarkers for early detection. In a previous study, we obtained a selective RNA-cleaving Fluorogenic DNAzyme (RFD) probe against MDA-MB-231 cells, typical breast cancer cells, through the systematic evolution of ligands by exponential process (SELEX). To improve the performance of this probe for actual application, we carried out a series of optimization experiments on the pH value of a reaction buffer, the type and concentration of cofactor ions, and sequence minimization. The length of the active domain of the probe reduced to 25 nt from 40 nt after optimization, which was synthesized more easily and economically. The detection limit of the optimized assay system was 2000 MDA-MB-231 cells in 30 min, which is more sensitive than the previous one (almost 5000 cells). The DNAzyme probe was also capable of distinguishing MDA-MB-231 cell specifically from 3 normal cells and 10 other tumor cells. This probe with high sensitivity, selectivity, and economic efficiency enhances the feasibility for further clinical application in breast cancer diagnosis. Herein, we developed an optimization system to produce a general strategy to establish an easy-to-use DNAzyme-based assay for other targets. Full article
(This article belongs to the Special Issue Aptasensors 2016)
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Open AccessArticle Single-Step Purification of Monomeric l-Selectin via Aptamer Affinity Chromatography
Sensors 2017, 17(2), 226; doi:10.3390/s17020226
Received: 22 December 2016 / Revised: 19 January 2017 / Accepted: 20 January 2017 / Published: 24 January 2017
Cited by 3 | PDF Full-text (2240 KB) | HTML Full-text | XML Full-text
Abstract
l-selectin is a transmembrane receptor expressed on the surface of white blood cells and responsible for the tethering of leukocytes to vascular endothelial cells. This initial intercellular contact is the first step of the complex leukocyte adhesion cascade that ultimately permits extravasation
[...] Read more.
l-selectin is a transmembrane receptor expressed on the surface of white blood cells and responsible for the tethering of leukocytes to vascular endothelial cells. This initial intercellular contact is the first step of the complex leukocyte adhesion cascade that ultimately permits extravasation of leukocytes into the surrounding tissue in case of inflammation. Here we show the binding of a soluble histidine tagged l-selectin to a recently described shortened variant of an l-selectin specific DNA aptamer with surface plasmon resonance. The high specificity of this aptamer in combination with its high binding affinity of ~12 nM, allows for a single-step protein purification from cell culture supernatants. In comparison to the well-established Ni-NTA based technology, aptamer affinity chromatography (AAC) was easier to establish, resulted in a 3.6-fold higher protein yield, and increased protein purity. Moreover, due to target specificity, the DNA aptamer facilitated binding studies directly from cell culture supernatant, a helpful characteristic to quickly monitor successful expression of biological active l-selectin. Full article
(This article belongs to the Special Issue Aptasensors 2016)
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Open AccessArticle Electrochemical Aptatoxisensor Responses on Nanocomposites Containing Electro-Deposited Silver Nanoparticles on Poly(Propyleneimine) Dendrimer for the Detection of Microcystin-LR in Freshwater
Sensors 2016, 16(11), 1901; doi:10.3390/s16111901
Received: 7 August 2016 / Revised: 19 October 2016 / Accepted: 20 October 2016 / Published: 11 November 2016
Cited by 2 | PDF Full-text (1738 KB) | HTML Full-text | XML Full-text
Abstract
A sensitive and reagentless electrochemical aptatoxisensor was developed on cobalt (II) salicylaldiimine metallodendrimer (SDD–Co(II)) doped with electro-synthesized silver nanoparticles (AgNPs) for microcystin-LR (L, l-leucine; R, l-arginine), or MC-LR, detection in the nanomolar range. The GCE|SDD–Co(II)|AgNPs aptatoxisensor was fabricated with 5’ thiolated
[...] Read more.
A sensitive and reagentless electrochemical aptatoxisensor was developed on cobalt (II) salicylaldiimine metallodendrimer (SDD–Co(II)) doped with electro-synthesized silver nanoparticles (AgNPs) for microcystin-LR (L, l-leucine; R, l-arginine), or MC-LR, detection in the nanomolar range. The GCE|SDD–Co(II)|AgNPs aptatoxisensor was fabricated with 5’ thiolated aptamer through self-assembly on the modified surface of the glassy carbon electrode (GCE) and the electronic response was measured using cyclic voltammetry (CV). Specific binding of MC-LR with the aptamer on GCE|SDD–Co(II)|AgNPs aptatoxisensor caused the formation of a complex that resulted in steric hindrance and electrostatic repulsion culminating in variation of the corresponding peak current of the electrochemical probe. The aptatoxisensor showed a linear response for MC-LR between 0.1 and 1.1 µg·L−1 and the calculated limit of detection (LOD) was 0.04 µg·L−1. In the detection of MC-LR in water samples, the aptatoxisensor proved to be highly sensitive and stable, performed well in the presence of interfering analog and was comparable to the conventional analytical techniques. The results demonstrate that the constructed MC-LR aptatoxisensor is a suitable device for routine quantification of MC-LR in freshwater and environmental samples. Full article
(This article belongs to the Special Issue Aptasensors 2016)
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Open AccessArticle One Step Assembly of Thin Films of Carbon Nanotubes on Screen Printed Interface for Electrochemical Aptasensing of Breast Cancer Biomarker
Sensors 2016, 16(10), 1651; doi:10.3390/s16101651
Received: 17 August 2016 / Accepted: 29 September 2016 / Published: 6 October 2016
Cited by 5 | PDF Full-text (2519 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Thin films of organic moiety functionalized carbon nanotubes (CNTs) from a very well-dispersed aqueous solution were designed on a screen printed transducer surface through a single step directed assembly methodology. Very high density of CNTs was obtained on the screen printed electrode surface,
[...] Read more.
Thin films of organic moiety functionalized carbon nanotubes (CNTs) from a very well-dispersed aqueous solution were designed on a screen printed transducer surface through a single step directed assembly methodology. Very high density of CNTs was obtained on the screen printed electrode surface, with the formation of a thin and uniform layer on transducer substrate. Functionalized CNTs were characterized by X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and Brunauer–Emmett– Teller (BET) surface area analyzer methodologies, while CNT coated screen printed transducer platform was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The proposed methodology makes use of a minimum amount of CNTs and toxic solvents, and is successfully demonstrated to form thin films over macroscopic areas of screen printed carbon transducer surface. The CNT coated screen printed transducer surface was integrated in the fabrication of electrochemical aptasensors for breast cancer biomarker analysis. This CNT coated platform can be applied to immobilize enzymes, antibodies and DNA in the construction of biosensor for a broad spectrum of applications. Full article
(This article belongs to the Special Issue Aptasensors 2016)
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Review

Jump to: Research

Open AccessReview Design of Artificial Riboswitches as Biosensors
Sensors 2017, 17(9), 1990; doi:10.3390/s17091990
Received: 8 August 2017 / Revised: 23 August 2017 / Accepted: 25 August 2017 / Published: 30 August 2017
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Abstract
RNA aptamers readily recognize small organic molecules, polypeptides, as well as other nucleic acids in a highly specific manner. Many such aptamers have evolved as parts of regulatory systems in nature. Experimental selection techniques such as SELEX have been very successful in finding
[...] Read more.
RNA aptamers readily recognize small organic molecules, polypeptides, as well as other nucleic acids in a highly specific manner. Many such aptamers have evolved as parts of regulatory systems in nature. Experimental selection techniques such as SELEX have been very successful in finding artificial aptamers for a wide variety of natural and synthetic ligands. Changes in structure and/or stability of aptamers upon ligand binding can propagate through larger RNA constructs and cause specific structural changes at distal positions. In turn, these may affect transcription, translation, splicing, or binding events. The RNA secondary structure model realistically describes both thermodynamic and kinetic aspects of RNA structure formation and refolding at a single, consistent level of modelling. Thus, this framework allows studying the function of natural riboswitches in silico. Moreover, it enables rationally designing artificial switches, combining essentially arbitrary sensors with a broad choice of read-out systems. Eventually, this approach sets the stage for constructing versatile biosensors. Full article
(This article belongs to the Special Issue Aptasensors 2016)
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Open AccessReview Current and Potential Developments of Cortisol Aptasensing towards Point-of-Care Diagnostics (POTC)
Sensors 2017, 17(5), 1180; doi:10.3390/s17051180
Received: 10 March 2017 / Revised: 17 April 2017 / Accepted: 18 April 2017 / Published: 22 May 2017
Cited by 1 | PDF Full-text (2128 KB) | HTML Full-text | XML Full-text
Abstract
Anxiety is a psychological problem that often emerges during the normal course of human life. The detection of anxiety often involves a physical exam and a self-reporting questionnaire. However, these approaches have limitations, as the data might lack reliability and consistency upon application
[...] Read more.
Anxiety is a psychological problem that often emerges during the normal course of human life. The detection of anxiety often involves a physical exam and a self-reporting questionnaire. However, these approaches have limitations, as the data might lack reliability and consistency upon application to the same population over time. Furthermore, there might be varying understanding and interpretations of the particular question by the participant, which necessitating the approach of using biomarker-based measurement for stress diagnosis. The most prominent biomarker related to stress, hormone cortisol, plays a key role in the fight-or-flight situation, alters the immune response, and suppresses the digestive and the reproductive systems. We have taken the endeavour to review the available aptamer-based biosensor (aptasensor) for cortisol detection. The potential point-of-care diagnostic strategies that could be harnessed for the aptasensing of cortisol were also envisaged. Full article
(This article belongs to the Special Issue Aptasensors 2016)
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Open AccessReview Label-Free Aptasensors for the Detection of Mycotoxins
Sensors 2016, 16(12), 2178; doi:10.3390/s16122178
Received: 31 October 2016 / Revised: 8 December 2016 / Accepted: 14 December 2016 / Published: 18 December 2016
Cited by 2 | PDF Full-text (2566 KB) | HTML Full-text | XML Full-text
Abstract
Various methodologies have been reported in the literature for the qualitative and quantitative monitoring of mycotoxins in food and feed samples. Based on their enhanced specificity, selectivity and versatility, bio-affinity assays have inspired many researchers to develop sensors by exploring bio-recognition phenomena. However,
[...] Read more.
Various methodologies have been reported in the literature for the qualitative and quantitative monitoring of mycotoxins in food and feed samples. Based on their enhanced specificity, selectivity and versatility, bio-affinity assays have inspired many researchers to develop sensors by exploring bio-recognition phenomena. However, a significant problem in the fabrication of these devices is that most of the biomolecules do not generate an easily measurable signal upon binding to the target analytes, and signal-generating labels are required to perform the measurements. In this context, aptamers have been emerged as a potential and attractive bio-recognition element to design label-free aptasensors for various target analytes. Contrary to other bioreceptor-based approaches, the aptamer-based assays rely on antigen binding-induced conformational changes or oligomerization states rather than binding-assisted changes in adsorbed mass or charge. This review will focus on current designs in label-free conformational switchable design strategies, with a particular focus on applications in the detection of mycotoxins. Full article
(This article belongs to the Special Issue Aptasensors 2016)
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