Lumei Wang

A mini-review on functional nucleic acids-based heavy metal ion detection.

Recent years have witnessed great progress in developing functional nucleic acids (FNAs)-based sensors for the detection of heavy metal ion. In this review, four types of the FNAs that most widely-used in heavy metal ions detection were briefly introduced and a dozen of recently published review articles which summarized those FNAs-based sensors were introduced. Particularly, according to the degree of automation and system integration, those FNAs-based sensors which belong to the lab-on-a-chip (LOC) category were reviewed in more detail by classifying them into six types such as microfluidic LOC system, microchip, lateral flow dipstick, personal glucose meter, microfluidic paper-based analytical devices (μPADs) and disc-based analytical platform. After gave a brief description of the sensing strategies, properties, advantages or disadvantages of these FNAs-based sensors, existing problems and future perspectives were also discussed.

Fluorescent detection of Hg2+ and Pb2+ using GeneFinder™ and an integrated functional nucleic acid.

This paper reports a simple fluorescent assay for the determination of Hg(2+) and Pb(2+) by using a DNA intercalator GeneFinder™ (GF) and an integrated functional nucleic acid (FNA). In the absence of Hg(2+) and Pb(2+), GF intercalated with the FNA and released moderate strong fluorescence. While in the presence of Hg(2+) or Pb(2+), the FNA would be induced to form T-Hg(2+)-T or G-quadruplex structure, interacted with which the GF would exhibit extremely strong or very weak fluorescence. By monitoring the fluorescence changes upon addition of these two ions, the Hg(2+) and Pb(2+) could be selectively detected as low as 3.23 ppb and 2.62 ppb. As the main advantage of this assay is simplicity and the feasibility was demonstrated by detecting Hg(2+) and Pb(2+) in spiked water samples, this assay holds great potential for the development of a cost effective and useful tool for environmental monitoring.

Sensitive fluorescent assay for copper (II) determination in aqueous solution using copper-specific ssDNA and Sybr Green I.

This paper reports a fluorescent turn-off assay for sensitive detection of Cu(2+) in an aqueous solution by using a copper-specific ssDNA Cu100 and Sybr Green I. By monitoring the fluorescence changes arose from different interactions of Sybr Green I with Cu100 and Cu100/Cu(2+) complex, the Cu(2+) could be linearly detected from 5.57 to 250 ppb, with a detection limit of 5.57 ppb. The feasibility of this assay was demonstrated by detecting Cu(2+) in certified reference materials and spiked water samples with satisfactory results.

A Label-Free Colorimetric Biosensor for 17β-Estradiol Detection Using Nanoparticles Assembled by Aptamer and Cationic Polymer

Concern is mounting regarding the human health and environment effects of 17β-estradiol (E2), a natural oestrogen excreted by human beings and animals. In this paper, a sensitive and selective biosensor for the detection of E2 using gold nanoparticles (AuNPs), label-free E2-specific aptamer, and poly(diallyldimethylammonium chloride) (PDDA) was developed. In the absence of E2, PDDA can electrostatically interact with E2-specific aptamer, and the charge responsible for inducing AuNPs aggregation was destroyed. However, the introduction of E2 can specifically interact with the aptamer to form E2–aptamer complex so that PDDA can aggregate AuNPs and cause a remarkable change in colour from wine red to blue, which enables colorimetric detection of E2 with selectivity and a detection limit of 1.57 nM.

A label-free fluorescent sensor for the detection of Pb2+ and Hg2+

A label-free fluorescent DNA-based sensor for the detection of Pb2+ and Hg2+ has been reported in this paper. A single-stranded DNA named modified T30695 was used as a recognition probe and SYBR Green I (SG) was used as a signal reporter. This sensor consisted of two interaction sections: Pb2+ interacts with modified T30695 to form a G-quadruplex and Hg2+ interacts with modified T30695 to form a T–Hg(II)–T hairpin conformation. Circular dichroism confirmed the interactions between modified T30695 and Pb2+ or Hg2+. Based on this, a sensor for the detection of Pb2+ and Hg2+ with limits of detection of 2.09 ppb and 1.14 ppb was constructed.

Insight into a novel β-1,4-glucosidase from Streptomyces griseorubens JSD-1

Streptomyces griseorubens JSD-1 is novel isolate utilizing cellulose as a sole carbon source for growth, and cellulytic genes related to this proceßs were expected to be crucial. To investigate the molecular mechanism of cellulose metabolism, bacterial genome sequencing was carried out. As a result, its draft genome map was obtained which has been deposited at GenBank. ß-1,4-glucosidase (Glu) was acquired following with characterization of its cellular localization and expression profiles. Glu from S. griseorubens JSD-1 was suggested to be an intracellular enzyme which was different from those obtained from similar species through the combined analysis of multiple sequences alignment and putative 3D structure modeling. Expression of recombinant enzyme was optimized in heterogeneous hosts for the further determination of its optimum pH and temperature as well as the residual activity in the presence of metal ions and inhibitors. Novel Glu expected to have promising potential in the degradation of cellulosic materials.