Thymine Coordination Chemistry Research Articles

Portable Pumpless 3D-Printed Chip for On-Site Colorimetric Screening of Hg2+ in Lake Water

The early detection of mercury ions in water sources should be emphasized to prevent human exposure to mercury through drinking water or food consumption. Here, we used a three-dimensional (3D)-printed multiarray chip to achieve colorimetric detection of inorganic mercury ions in environmental matrices such as lake water. The chip designed for the multidetection of inorganic mercury did not require an electrical syringe pump or a complex analytical system, thereby making it suitable for on-site detection. The chip could detect inorganic mercury ions via rolling circle amplification, by selectively harnessing thymine-Hg2+-thymine coordination chemistry. Additionally, the activities of rolling circle amplification in simple and environmental matrices were compared. The limits of detection for inorganic mercury ions were 3.4 and 4.1 ??g/L in the simple and environmental matrices, respectively. Further, the chip was successfully applied for the detection of mercury in actual lake water samples collected from locations nearby inland fish farms. The results were quantitatively comparable to those obtained using a conventional mercury analyzer.

Thymine-Hg2+-thymine coordination chemistry induced entropy driven catalytic reaction to form Hemin/G-quadruplex-HRP-mimicking DNAzyme for colorimetric and visual determination of Hg2.

A sensitive and visible colorimetric strategy was proposed for Hg2+ detection by thymine-Hg2+-thymine (T-Hg2+-T) coordination chemistry and entropy driven catalytic reaction. The entropy driven catalytic reaction is induced by T-Hg2+-T coordination chemistry, resulting the releasing of G-riched sequence. Hemin/G-quadruplex-HRP-mimicking DNAzyme can be formed with the help of hemin, catalyzing TMB to TMB+ with a color change from colorless to blue. The sensitivity of this strategy can be reached to 2 pM, which is significantly improved by entropy driven catalytic reaction. In addition, entropy driven catalytic reaction provides a more reliable and accurate results. This method shows great promise for on-site analysis and in-house diagnosis of Hg2+ in water.

On-site quantitative Hg2+ measurements based on selective and sensitive fluorescence biosensor and miniaturized smartphone fluorescence microscope

Mercury is a bio-accumulative and toxic pollutant causing severe damages to human health and environment. Since Hg2+ is the most stable form of mercury, selective and sensitive Hg2+ detection is required. Though classical approaches can realize accurate Hg2+ detection, the complicated instruments and the time-consuming operations inevitably limit their on-site applications. Here, we design a smart Hg2+ detection approach using the fluorescence biosensor, the smartphone fluorescence microscope and the smartphone application for Hg2+ on-site detection. Based on the thymine-Hg2+-thymine coordination chemistry, a selective and sensitive fluorescence biosensor is designed for capturing Hg2+ in aqueous solution; besides, a miniaturized smartphone fluorescence microscope for fluorescence signal collection and an image processing application for quantitative Hg2+ measurements are constructed. A highly specific detection of Hg2+ with a linear relation between 1 nM and 1 μM with a limit of detection of 1 nM is obtained using the smart Hg2+ detection approach. Considering it can realize selective and sensitive quantitative Hg2+ measurements in high precision with simple operations and cost-effective system, it is believed the proposed smart Hg2+ detection approach owns great potentials in Hg2+ detection for routine uses at home and in the field.

Dual-entropy-driven catalytic amplification reaction for ultra-sensitive and visible detection of Hg2+ in water based on thymine-Hg2+-thymine coordination chemistry.

An ultra-sensitive and visible Hg2+ detection strategy was established. It was based on T-Hg2+-T coordination chemistry and a dual-entropy-driven catalytic reaction (EDCR). The dual EDCR was initiated by T-Hg2+-T coordination chemistry, resulting in the release of a G-rich sequence to form a hemin/G-quadruplex-HRP-mimicking DNAzyme, and then catalyzing 3,3',5,5'-tetramethylbenzidine (TMB) into TMB+, with a color change from colorless to blue. This method showed great sensitivity and excellent selectivity, and the limit of detection reached 0.6 pM. The feasibility of this method was demonstrated by real water samples. Moreover, the visible color change provided the possibility of ultra-sensitive detection of Hg2+ by the naked eye.

An evaluation assay for thymine–mercuric–thymine coordination in the molecular beacon-binding system based on microscale thermophoresis

A novel evaluation assay for molecular beacon (MB)-binding system was developed by microscale thermophoresis (MST) and thymine–mercuric–thymine coordination chemistry which was applied for the detection of mercury (II) ion (Hg2+) upon opening the hairpin and facilitating fluorescence recovery through binding with suitable mismatched target. The affinities between the loop of MBs and the complementary ssDNAs in the binding system were varied, determined and optimized by MST in the presence or absence of Hg2+. It suggested that the relative low background could be obtained when the number of mismatches of ssDNA was four and in the present of Hg2+ displayed strong recovery of fluorescence. The lowest detection limit of Hg2+ was 3nM which was below the maximum contaminant level defined by U.S. Environmental Protection Agency (10nM). The working range was 5–320nM with negligible possible interference from the different background composition of water samples by optimization of the binding conditions. Through evaluating by MST, the molecular interaction mechanism was elaborated and the rapid, sensitive and selective detection of Hg2+ was achieved by the designed MB-binding system. It herein has great potential for appraising and analyzing molecular interaction among the interactants.

In Situ-Generated Nano-Gold Plasmon-Enhanced Photoelectrochemical Aptasensing Based on Carboxylated Perylene-Functionalized Graphene

A novel in situ-generated nanogold plasmon-enhanced photoelectrochemical aptasensor for Hg(2+) ions was fabricated using a perylene-3,4,9,10-tetracarboxylic acid/graphene (PTCA-GR) heterojunction. The fabricated photoelectrochemical aptasensor was based on thymine-Hg(2+)-thymine coordination chemistry and the plasmonic near-field absorption enhancement effect of the subsequent specific catalytic formation of nanogold. The energetic electrons from the surface plasmons of the nanogold were injected into the LUMO orbit of the organic PTCA semiconductor and then rapidly transferred to the electrode through GR due to the possible Hg(2+)-DNA molecular wires following irradiation with the visible light (λ > 450 nm) and at a bias voltage of 0.2 V. The fabricated aptasensor was linear in its response to the concentration of Hg(2+) ions in the range of 5-500 pmol L(-1), with a detection limit of 2 pmol L(-1). The presence of up to 200-fold greater concentrations of other common metal ions did not interfere with the detection of Hg(2+) ions in an aqueous system, and the results corresponded well with those obtained by ICP-MS. This novel plasmon-enhanced photoelectrochemical aptasensor exhibited good performance with its high sensitivity, good selectivity, low cost, and portable features. The strategy of the localized surface plasmon resonance through the in situ generation of noble metal nanoparticles paves the way for improvements in PEC aptasensor performance.

Femtomole level photoelectrochemical aptasensing for mercury ions using quercetin–copper(II) complex as the DNA intercalator

An ultrasensitive and selective photoelectrochemical (PEC) aptasensor for mercury ions was first fabricated based on perylene-3, 4, 9, 10-tetracarboxylic acid/graphene oxide (PTCA/GO) heterojunction using quercetin–copper(II) complex intercalated into the poly(dT)–poly(dA) duplexes. Both the PTCA/GO heterojunction and the quercetin–copper(II) complex are in favor of the sensitivity for the fabricated PEC aptasensor due to band alignment and strong reduction capability, respectively. And they efficiently promote the separation of photoexcited carriers and enhance the photocurrent. The formation of thymine–Hg2+–thymine coordination chemistry resulted in the dehybridization of poly(dT)–poly(dA) duplexes and then the intercalator quercetin–copper(II) complex broke away from the surface of the PEC aptasensor. As the concentration of mercury ions increased, the photocurrent gradually decreased. The electrode response for mercury ions detection was in the linear range from 0.01pmolL−1 to 1.00pmolL−1 with the detection limit of 3.33fmolL−1. The label-free PEC aptasensor has excellent performances with ultrasensitivity and good selectivity besides the advantage of economic and facile fabrication. The strategy of quercetin–copper(II) complex as a novel DNA intercalator paves a new way to improve the performances for PEC sensors.

A fishnet electrochemical Hg2+sensing strategy based on gold nanoparticle-bioconjugate and thymine–Hg2+–thymine coordination chemistry

A novel electrochemical biosensing strategy based on a three-dimensional fishnet of DNA-linked nanoparticle supramolecular structure triggered by the analyst for detection of Hg(2+) has been designed. The detection limit is 7.38 pM and the sensor's selectivity and facility have been significantly improved.

Dual polarisation interferometry for real-time, label-free detection of interaction of mercury(ii) with mercury-specific oligonucleotides

A real-time, label-free dual polarisation interferometry technique was used to investigate the interaction of Hg(2+) with a 21-mer T-rich oligonucleotide and further construct a Hg(2+) biosensor based on thymine-Hg(2+)-thymine coordination chemistry.

Phase diagram analysis using a partially associated solution model for III–V binary systems

An ultrasensitive and selective photoelectrochemical (PEC) aptasensor for mercury ions was first fabricated based on perylene-3, 4, 9, 10-tetracarboxylic acid/graphene oxide (PTCA/GO) heterojunction using quercetin–copper(II) complex intercalated into the poly(dT)–poly(dA) duplexes. Both the PTCA/GO heterojunction and the quercetin–copper(II) complex are in favor of the sensitivity for the fabricated PEC aptasensor due to band alignment and strong reduction capability, respectively. And they efficiently promote the separation of photoexcited carriers and enhance the photocurrent. The formation of thymine–Hg2+–thymine coordination chemistry resulted in the dehybridization of poly(dT)–poly(dA) duplexes and then the intercalator quercetin–copper(II) complex broke away from the surface of the PEC aptasensor. As the concentration of mercury ions increased, the photocurrent gradually decreased. The electrode response for mercury ions detection was in the linear range from 0.01 pmol L−1 to 1.00 pmol L−1 with the detection limit of 3.33 fmol L−1. The label-free PEC aptasensor has excellent performances with ultrasensitivity and good selectivity besides the advantage of economic and facile fabrication. The strategy of quercetin–copper(II) complex as a novel DNA intercalator paves a new way to improve the performances for PEC sensors.