Bithiophene-based fluorescent sensor for highly sensitive and ultrarapid detection of Hg2+ in water, seafood, urine and live cells

Thiourea Functionalised Receptor for Selective Detection of Mercury Ions and its Application in Serum Sample

A thiourea functionalised fluorescent probe 1-phenyl-3-(pyridin-4-yl)thiourea was synthesized and utilised as a fluorescent turn-on chemosensor for the selective recognition of Hg2+ ion over competitive metal ions including Na+, Mn2+, Li+, Cr2+, Ni2+, Ca2+, Cd2+, Mg2+, K+, Co2+, Cu2+, Zn2+, Al3+ and Fe2+ ions based on the inter-molecular charge transfer (ICT). Intriguingly, the receptor demonstrated unique sensing capabilities for Hg2+ in DMSO: H2O (10:90, v/v). The addition of Hg2+ ions to the sensor resulted in a blue shift in the absorption intensity and also enhancement in fluorescence intensity at 435 nm. Fluorescence emission intensity increased linearly with Hg2+ concentration ranging from 0 to 80 µL. The detection limit and binding constant were determined as 0.134 × 10-6 M and 1.733 × 107 M-1, respectively. The sensing behavior of Hg2+ was further examined using DLS, SEM and FTIR. The probe could detect Hg2+ ions across a wide pH range. Furthermore, the receptor L demonstrated good sensing performance for Hg2+ in bovine serum albumin and actual water samples.

An efficient chitosan-naphthalimide fluorescent probe for simultaneous detection and adsorption of Hg2+ and its application in seafood, water and soil environments

As a virulent heavy metal ion, Hg2+ will lead to a serious threat to ecosystem and human health. In this work, we reported a chitosan-naphthalimide fluorescent probe CS-NA-ITC for specific recognition and efficient adsorption of Hg2+. CS-NA-ITC showed no fluorescence in solution state, while the fluorescence intensity increased obviously at the presence of Hg2+, accompanied by the fluorescence color becomes from colorless to bright yellow. It displayed favorable properties like low detection limit (73 nM), extensive pH detection range (5-10) and excellent anti-interference ability. The binding pattern of CS-NA-ITC to Hg2+ was verified by Job's plot, XPS analysis and FT-IR test. In addition, CS-NA-ITC was utilized to recognition of Hg2+ in actual water and soil samples and seafood products. Furthermore, the CS-NA-ITC hydrogel could be employed as an efficient Hg2+ adsorbent with good reusability, which adsorption ability was enhanced compared to chitosan hydrogel.

Molecular docking and optical sensor studies based on 2,4-diamino pyrimidine-5-carbonitriles for detection of Hg2

An organic chemical sensor based on pyrimidine was successfully produced through the green reaction between aromatic aldehyde, malononitrile, and guanidine carbonate using SBA-Pr-SO₃H. This fluorescence intensity of chemosensor (2,4-diamino-6-(phenyl)pyrimidine-5-carbonitrile) decreases by the addition of Hg²⁺ and its detection limit is about 14.89 × 10^-5 M, in fact, through the green synthesis, the ligand was yielded to detect Hg²⁺ and the importance of ligand was considered in docking studies. The molecular docking of 2,4-diamino-6-(phenyl)pyrimidine-5-carbonitrile compound has been done with the protein selective estrogen receptor 5ACC complexed with (Azd9496), Human Anaplastic Lymphoma Kinase Pdb; 2xp2 complex with crizotinib (PF-02341066) and human wee1 kinase Pdb; 5vc3 complexed with bosutinib. The ligands 2,4-diamino-6-(phenyl)pyrimidine-5-carbonitrile generate very good docking results with the protein Pdb; 2xp2, which is responsible for effective tumor growth inhibition.

Colorimetric screening of elevated urinary mercury levels by a novel Hg2+-selective probe of resorufin phosphinothioate

Urinary mercury levels are the most reliable indicators of mercury exposure but identifying them requires complex techniques and heavy instruments. In this research, we reported a simple and convenient urinary mercury analysis method using a readily available office scanner. Probe MP-1 synthesized by the reaction of resorufin and dimethylthiophosphinoyl chloride revealed Hg²⁺-selective chromogenic and fluorescent signaling behavior. Signaling was realized through Hg²⁺-induced deprotection of the phosphinothioate protecting group in the resorufin-based probe MP-1 to yield the parent fluorochrome. A pronounced colorimetric response of color change from light yellow to pink alongside a turn-on type fluorescence enhancement was perceived exclusively toward Hg²⁺ ions over other metal ions and anions. The colorimetry provided a more advantageous ratiometric approach than the simple fluorometric analysis exhibiting an off–on type response, with a detection limit of 12 nM (2.4 ppb). The Hg²⁺ signaling of the MP-1 probe was not disturbed by the presence of coexisting metal ions and anions. The sensitive and convenient diagnosis of clinically important neurological symptoms and fatal inorganic mercury levels in urine was successfully demonstrated using a standard office scanner.

A Hg²⁺ selective signaling probe, resorufin phosphinothioate, for the colorimetric diagnosis of clinically elevated mercury levels in urine samples using an office scanner was developed.

A novel chemosensor for the distinguishable detections of Cu2+ and Hg2+ by off-on fluorescence and ratiometric UV-visible absorption

A novel dual-functional chemosensor, derived from the conjugation of rhodamine B with a quinoline derivative (RHQ), was firstly synthesized with high efficiency and cost-effectiveness for the distinguishable detections of Cu²⁺ and Hg²⁺ via ring-opening and ring-forming mechanism. The chemosensor exhibits highly selective and distinguishable responses for Cu²⁺ and Hg²⁺ in CH₃CN-H₂O (4:1, v/v) with off-on fluorescence and ratiometric ultraviolet-visible (UV-Vis) absorption changes. Additionally, Cu²⁺ is identified by opening a rhodamine spirocycle with a UV-Vis absorption band, at around 560 nm and fluorescence turn-on. Interestingly, Hg²⁺ is discerned by opening the rhodamine spirocycle and by generating a new special cycle for the quinoline unit. Resultantly, there were two UV-Vis absorption bands at around 365 nm and 560 nm, which were accompanied by fluorescence turn-on. Moreover, the chemosensor can quantitatively detect Cu²⁺ and Hg²⁺ by off-on fluorescence and ratiometric UV-Vis absorption changes, respectively. Furthermore, the chemosensor with low cytotoxicity could be successfully administered to monitor Cu²⁺ and Hg²⁺ in living cells. This work may pay the way for the development of dual-functional chemosensor for quantificationally detecting metal ions in environmental and biological systems.

High-efficient liquid exfoliation of 2D metal-organic framework using deep-eutectic solvents

The exfoliation of bulk two-dimensional metal-organic framework (MOF) into few-layered nanosheets has attracted much attention recently. In this work, an environmental-friendly route has been developed for layered-MOF (MAMS-1) delamination using deep eutectic solvent (DES), which is more sustainable and efficient alternative than conventional organic solvents for MOF nanosheet preparation. Under sonication condition, DES as solvents, the highest exfoliation rate of MAMS-1 is up to 70% with two host layers via poly(vinylpyrrolidone) (PVP) surfactant-assisted method. The presence of tert-butyl exteriors and the atomically thickness endow the MOF nanosheets stable suspension for at least one month. Due to the 2D structure and excellent stability, MAMS-1 nanosheet (MAMS-1-NS) was chosen as a good candidate to encapsulate Eu3+ cations. The obtained Eu3+@MAMS-1-NS acts as a multi-responsive luminescent sensor through fluorescence quenching, and can specifically recognize Fe3+ (LOD = 0.40 μM, KSV = 1.05 × 105 M-l), Hg2+ (LOD = 0.038 μM, KSV = 5.78 × 106 M-l), Cr2O72- (LOD = 0.33 μM, KSV = 1.55 × 105 M-l) and MnO4- (LOD = 0.088 μM, KSV = 4.49 × 105 M-l). Compared with bulk Eu3+@MAMS-1, the sensitivity of Eu3+@MAMS-1-NS is greatly improved owing to its ultrathin nanosheet morphology and highly accessible active sites on the surface.

Mercury Toxicity and Detection Using Chromo-Fluorogenic Chemosensors

Mercury (Hg), this non-essential heavy metal released from both industrial and natural sources entered into living bodies, and cause grievous detrimental effects to the human health and ecosystem. The monitoring of Hg2+ excessive accumulation can be beneficial to fight against the risk associated with mercury toxicity to living systems. Therefore, there is an emergent need of novel and facile analytical approaches for the monitoring of mercury levels in various environmental, industrial, and biological samples. The chromo-fluorogenic chemosensors possess the attractive analytical parameters of low-cost, enhanced detection ability with high sensitivity, simplicity, rapid on-site monitoring ability, etc. This review was narrated to summarize the mercuric ion selective chromo-fluorogenic chemosensors reported in the year 2020. The design of sensors, mechanisms, fluorophores used, analytical performance, etc. are summarized and discussed.

The preparation of novel triphenylamine-based AIE-effect fluorescent probe for selectively detecting mercury(ii) ion in aqueous solution

A novel triphenylamine-based TPA-ME exhibits good AIE fluorescence in a DMF/Water system and excellent probe property for detecting Hg²⁺ in solution.

New thiophene hydrazide dual-functional chemosensor: Colorimetric sensor for Cu2+ & fluorescent sensor for Al3

A new thiophene hydrazide derivative TSB was synthesized and utilized as naked-eye colorimetric sensor for Cu²⁺ by the color changed from colorless to yellow as well as green fluorescent turn on sensor for Al³⁺ in DMSO/H₂O (1/1, V/V) solution. The dual-functional chemosensor TSB for Cu²⁺/Al³⁺ sensing displayed excellent properties of special selectivity, superior sensitivity, outstanding anti-interference performance, instantaneous response, wide pH working range and good reversibility. The detection limits of TSB for Cu²⁺/Al³⁺ were determined as low as 46.5 nM and 32.7 nM, respectively. The 1:1 binding mode of TSB with Cu²⁺/Al³⁺ was proved by spectrometric titrations, Job's plots, FTIR, ¹H NMR and HRMS analysis. Moreover, chemosensor TSB was successfully utilized for detection of Cu²⁺ and Al³⁺ in real environmental water and food samples with high reliability, demonstrating its practical applicability.

Recent Developments in Fluorescent Materials for Heavy Metal Ions Analysis From the Perspective of Forensic Chemistry

Forensic chemistry deals with the analysis of various types of physical evidences related to crime, corresponding to the detection of target substances or elements in complex matrices. There is a vital need for highly selective, rapid, and sensitive biosensing technologies in heavy metal ions analysis especially those from living persons, autopsy, food, water, soil, and other identified substances at very preliminary stages. Fluorescent materials-based method for heavy metal ions detection is one of the most important analytical methods, resulting in the ability to measure analytes in complex matrices with unsurpassed selectivity and sensitivity. In this mini review, different fluorescent materials-based analytical methods aiming at several heavy metal ions detection are exclusively reviewed through a comprehensive literature survey. In addition, current challenges to achieve integrated evidence analysis process are briefly discussed to provide an outlook for heavy metal ions detection based on fluorescent analytical methods in the forensic chemistry field.

Acenaphtoquinoxaline as a selective fluorescent sensor for Hg (II) detection: experimental and theoretical studies

A new fluorescent chemosensor based on quinoxaline was successfully synthesized through a facile and green catalytic reaction of ortho-phenylenediamine (O-PDA) and acenaphthylene-1,2-dione in the presence of SBA-Pr-SO3H. Prepared a "switch-off" quinoxaline-based receptor to recognized Hg2+ ion in high selectively and, without any interference from other metal ions, was developed. The photophysical behavior of this fluorophore was studied in acetonitrile by using fluorescence spectra. The fluorescence properties of several cations to acenaphtoquinoxaline were investigated in acetonitrile, and the competition test displayed that the probe fluorescence changes were specific for Hg2+ ion. The obtained results have shown high selectivity and sensitivity only for Hg2+. Also, the detection limit was as low as 42 ppb, and a top linear trend was observed between the concentration of Hg2+ ions and fluorescence intensity. The binding stoichiometry between chemosensor L and Hg2+ was found to be 1:1. Moreover, a computational study was performed to obtain an electronic description of the fluorescence emission and quenching mechanisms. The optimized structures and binding mechanisms were supported with a high correlation and agreement by spectroscopy and DFT calculations.

RNA-responsive fluorescent carbon dots for fast and wash-free nucleolus imaging

RNA as a carrier of genetic information plays a critical role in various physiological processes. RNA-rich nucleolus is usually employed as an important biomarker for many malignant diseases. Herein, RNA-responsive fluorescent carbon dots (CDs) were synthesized by a simple microwave method. Due to the presence of cationic benzothiazolium groups in the CDs, a "turn-on" fluorescence signal was achieved between CDs and RNA. The CDs exhibit excellent RNA selectivity and a good linear relationship with a detection limit of 0.62 μg/mL. The small particle size, polarity sensitivity and RNA response behavior of CDs realized fast and wash-free nucleolus imaging effectively. Overall, these CDs provide a powerful potential tool for monitoring cell nucleus activity and elucidating RNA dynamics.

Rapid and selective detection of Hg(ii) in water using AuNP in situ-modified filter paper by a head-space solid phase extraction Zeeman atomic absorption spectroscopy method

AuNPs modified filter paper as sensitive mercury sensor was applied in the head-space solid phase extraction (HS-SPE) of Hg(ii). With negative pressure sampling, it can achieve in situ sampling and detection rapidly in a complex environment.