Chemosensors

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Open AccessReview

Novel Signal-Enhancing Approaches for Optical Detection of Nucleic Acids—Going beyond Target Amplification

by Laura Miotke, Maria Carla Barducci and Kira Astakhova

Chemosensors 2015, 3(3), 224-240; https://doi.org/10.3390/chemosensors3030224 - 23 Sep 2015

Cited by 13 | Viewed by 11337

Detection of low-abundance nucleic acids is a challenging task, which over the last two decades has been solved using enzymatic target amplification. Enzymatic synthesis enhances the signal so that diverse, scientifically and clinically relevant molecules can be identified and studied, including cancer DNA, [...] Read more.

Detection of low-abundance nucleic acids is a challenging task, which over the last two decades has been solved using enzymatic target amplification. Enzymatic synthesis enhances the signal so that diverse, scientifically and clinically relevant molecules can be identified and studied, including cancer DNA, viral nucleic acids, and regulatory RNAs. However, using enzymes increases the detection time and cost, not to mention the high risk of mistakes with amplification and data alignment. These limitations have stimulated a growing interest in enzyme-free methods within researchers and industry. In this review we discuss recent advances in signal-enhancing approaches aimed at nucleic acid diagnostics that do not require target amplification. Regardless of enzyme usage, signal enhancement is crucial for the reliable detection of nucleic acids at low concentrations. We pay special attention to novel nanomaterials, fluorescence microscopy, and technical advances in detectors for optical assessment. We summarize sensitivity parameters of the currently available assays and devices which makes this review relevant to the broad spectrum of researchers working in fields from biophysics, to engineering, to synthetic biology and bioorganic chemistry. Full article

(This article belongs to the Special Issue Feature Paper)

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895 KiB

Open AccessArticle

Steady-State Fluorescence and Lifetime Emission Study of pH-Sensitive Probes Based on i-motif Forming Oligonucleotides Single and Double Labeled with Pyrene

by Anna Dembska, Patrycja Rzepecka and Bernard Juskowiak

Chemosensors 2015, 3(3), 211-223; https://doi.org/10.3390/chemosensors3030211 - 23 Sep 2015

Cited by 6 | Viewed by 6800

Abstract

Cytosine-rich nucleic acids undergo pH-stimulated structural transitions leading to formation of an i-motif architecture at an acidic pH. Thus, i-motifs are good foundation for designing simple pH-sensitive fluorescent probes. We report here steady-state and time-resolved fluorescence studies of pyrene-labeled probes based on RET [...] Read more.

Cytosine-rich nucleic acids undergo pH-stimulated structural transitions leading to formation of an i-motif architecture at an acidic pH. Thus, i-motifs are good foundation for designing simple pH-sensitive fluorescent probes. We report here steady-state and time-resolved fluorescence studies of pyrene-labeled probes based on RET sequence: C₄GC₄GC₄GC₄TA (RET21), AC₄GC₄GC₄GC₄TA (RET21A) and C₄GC₄GC₄GC₄T (RET20). Comparative studies with single- and double-labeled i-motif probes were carried out. For each probe, we have measured fluorescence spectra and decays for emission wavelength of 390 nm over a wide range of pH (from 4.0 to 8.0). Effect of the oligonucleotide sequence and the number of pyrene labels on the spectral characteristics of probes were discussed. Full article

(This article belongs to the Special Issue Feature Paper)

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381 KiB

Open AccessArticle

Carbon Nanotubes-Based Potentiometric Bio-Sensors for Determination of Urea

by Ewa Jaworska, Krzysztof Maksymiuk and Agata Michalska

Chemosensors 2015, 3(3), 200-210; https://doi.org/10.3390/chemosensors3030200 - 24 Jul 2015

Cited by 11 | Viewed by 5888

Abstract

The possibility of using disposable plastic-carbon potentiometric sensors as enzyme biosensors was examined. Urease enzyme was immobilized on poly(vinyl chloride) based H⁺- or NH₄⁺-selective membranes using cellulose acetate. This approach has resulted in a potentiometric response on changing [...] Read more.

The possibility of using disposable plastic-carbon potentiometric sensors as enzyme biosensors was examined. Urease enzyme was immobilized on poly(vinyl chloride) based H⁺- or NH₄⁺-selective membranes using cellulose acetate. This approach has resulted in a potentiometric response on changing the pH of the solution or NH₄⁺ ion content due to an enzymatic reaction that occurs between urease and urea. Both types of potentiometric biosensors for urea were characterized by good analytical parameters as high sensitivity and fast response time. Full article

(This article belongs to the Special Issue Ionophore-Based Potentiometric Sensors)

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Chemosensors, Volume 3, Issue 3 (September 2015) – 3 articles , Pages 200-240

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