Metal−organic frameworks (MOFs), synthesized by assembling metal nods with organic linkers, are highly ordered crystalline materials. MOFs have attracted much attention for applications in ...electrochemical sensors, because of their unique chemical and physical properties including ultrahigh porosity, large surface area, tunable structure, and high thermal and chemical stability. In particular, redox and catalytic active sites introduced by use of active metal ions and/or ligands endow MOFs with the functions required in electrochemical sensing. Moreover, precise chemical modification of functional molecules and immobilization with metal nanoparticles, carbon nanostructures, and biomolecules could promote their electrochemical performances. In this Review, we focus on recent progress achieved in MOF research with respect to general sensing principles and analytical performances of electrochemical sensors. The evaluation and challenges governing the detection of the assays are also discussed.
Making sense of it all: Recent progress in the development of techniques for electrochemical sensors based on metal−organic framework (MOF) materials are summarized. With the advancement of nanotechnology, MOF‐based materials will display promising applications and offer a proof‐of‐concept in electrochemical sensing.
In-depth insights into the oligomers of carbon dots (CDs) prepared from small-molecule precursors are important in the study of the carbonization mechanism of CDs and for our knowledge of their ...complex structure. Herein, citric acid (CA) and ethylenediamine (EDA) were used as small-molecule precursors to prepare CDs in an aqueous solution. The structure of oligomers acquired from CA and EDA in different molar ratios and their formation process were first studied using density functional theory, including the dispersion correction (DFT-D3) method. The results showed that the energy barrier of dimer cyclization was higher than that of its linear polymerization, but the free energy of the cyclized product was much lower than that of its reactant, and IPCA (5-oxo-1,-2,3,5-tetrahydroimidazo 1,2-apyridine-7-carboxylic acid) could therefore be obtained under certain conditions. The oligomers obtained from different molar ratios of EDA and CA were molecular clusters formed by short polyamide chains through intermolecular forces; with the exception of when the molar ratio of EDA to CA was 0.5, excessive CA did not undergo an amidation reaction but rather attained molecular clusters directly through intermolecular forces. These oligomers exhibited significant differences in their surface functional groups, which would affect the carbonization process and the surface structure of CDs.
A facile, selective, and sensitive strategy for colorimetric sensor of mercury ions has been presented based on anti-aggregation of gold nanoparticles via self-dehydration condensation of boronic ...acid.
•We reported a simple colorimetric sensor for Hg2+ based on anti-aggregation of AuNPs.•High sensitivity was obtained due to the unique mechanism of the assay.•The sensor was extremely specific for Hg2+ in the presence of other metal ions.•The analysis of Hg2+ in water samples showed a satisfactory result.
A simple and rapid colorimetric sensor for Hg2+ in aqueous solution was developed based on the observation that the detection target, Hg2+, could inhibit the aggregation of gold nanoparticles (AuNPs) induced by 4-mercaptophenylboronic acid (MPBA). Without a potent competitor, MPBA can bind to the AuNPs via Au-S bonds and induces the aggregation of AuNPs by self-dehydration condensation of boronic acid groups, resulting in a visible color change of the AuNPs solution from red to blue. In the presence of Hg2+, the thiol group of MPBA preferentially binds to Hg2+ and thus MPBA loses the ability to induce aggregation of AuNPs, which is mechanism behind the color change of the solution from blue to red. Our results showed that the absorbance ratio (A520/A690) was linear with the Hg2+ concentration in the range of 0.01–5μM (R=0.998). The detection limit of the colorimetric sensor was 8nM (S/N=3). The colorimetric changes of the sensor were extremely specific for Hg2+ and no obvious color change was observed when adding other competitive metal ions in parallel. Further promising results from Hg2+ detection in water samples indicated that our newly developed assay might open a new assay avenue for Hg2+ determination.
Split aptamer strategy was often used to improve the sensitivity of aptasensor. However, traditional split aptamer strategy can not be directly used to improve the label-free aptamer based Thioflavin ...T (ThT) displacement assay for ATP because the split ATP aptamer display much lower enhancement effects on the fluorescence of ThT than intact aptamer. In order to address this issue, this is the first report using G-rich DNA sequence to enhance the affinity of the two split ATP aptamer halves to ThT and offer lower limit of detection (LOD), wider linear range and higher selectivity through the enhanced molecular recognition. Compared to the intact aptamer/ThT complex, the ensemble of two G-rich split ATP aptamer fragments/ThT are higher fluorescent. Consequently, G-rich sequences would improve the fluorescent signal and thus the sensing performance of the proposed assay. In the optimized conditions, the LOD of the proposed fluorescent ATP aptasensor is 2 nM, which is lower than the reported ThT/ATP aptamer based methods. Additionally, our aptasensor has a wider dynamic linear range (0.1 μM - 120 μM) and higher selectivity. The proposed aptasensor has been successfully applied to detect ATP in 15% human serum. More importantly, the current study not only provides a novel method for ATP assay but also presents a way to construct a label-free split aptamer based fluorescent sensor for other species where aptamer can be generated.
•G-rich sequence enhances the molecular recognition between split ATP aptamer and ThT.•G-rich sequence improves the performances of the split aptamer based ThT displacement ATP assay.•The split aptamer based ThT displacement ATP assay was successfully constructed and applied to detect ATP in human serum.
Graphene (GR) was synthesized through electrochemical reduction of graphene oxide and characterized by spectroscopic and electrochemical techniques. Polyvinylpyrrolidone (PVP)/graphene modified ...glassy carbon electrode (PVP/GR/GCE) was prepared and applied for the fabrication of dopamine (DA) sensors without the interference of ascorbic acid (AA). Compared to bare GCE, an increase of current signal was observed, demonstrating that PVP/GR/GCE exhibited favorable electron transfer kinetics and electrocatalytic activity towards the oxidation of dopamine. Furthermore, PVP/GR/GCE exhibited good ability to suppress the background current from large excess ascorbic acid. Amperometric response results show that the PVP based sensor displayed a wide linear range of 5×10−10 to 1.13×10−3mol/L DA with a correlation coefficient of 0.9990 and a detection limit of 0.2nM (S/N=3). The determination of dopamine in urine and human serum samples were studied.
► PVP/GR/GCE showed good sensitivity, selectivity and reproducibility towards the detection of DA. ► The modified electrode can eliminate the interference of AA, UA and some co-existing substances. ► The modified electrode can determine DA in urine and human serum samples without pretreatment.
Thiophenol (PhSH) belongs to a class of highly reactive and toxic aromatic thiols with widespread applications in the chemical industry for preparing pesticides, polymers, and pharmaceuticals. In ...this review, we comprehensively summarize recent progress in the development of fluorescent probes for detecting and imaging PhSH. These probes are classified according to recognition moieties and are detailed on the basis of their structures and sensing performances. In addition, prospects for future research are also discussed.
Oxidative stress plays an important role in the pathogenesis of many diseases, while the exact mechanism that hydrogen peroxide (H2O2) as one of the most abundant reactive oxygen species (ROS) exerts ...its influence on oxidative stress remains unclear. We developed a novel turn-on ratiometric electrochemical sensor for the detection of H2O2 in blood samples. The electrochemical probe 5-(1,2-dithiolan-3-yl)-N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)pent-anamide (BA) was designed and synthesized for the selective detection of H2O2 via a one-step amide reaction. Meanwhile, Nile Blue A (NB) was optimized as an internal reference molecule, thus enabling accurate quantification of H2O2 in a complex environment. BA and NB were then co-assembled onto a carbon fiber microelectrode (CFME) coated with Au cones. The oxidation peak current ratio between BA and NB demonstrated good linearity with the logarithm of the H2O2 concentration values ranging from 0.5 μM to 400 μM with a low detection limit of 0.02 μM. The developed sensor showed remarkable selectivity against potential interferences in whole blood samples, especially for ascorbic acid, uric acid, and dopamine. In combination with the unique characteristics of CFME, such as a small size and good biocompatibility, the microsensor was used for rapid analysis of one drop of whole blood sample. This sensor not only creates a new platform for the detection of H2O2 in whole blood samples, but also provides a new design strategy of other ROS analysis for early diagnosis of ROS-related diseases, drug discovery processes, and pathological mechanisms.
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•A novel electrochemical probe molecule for H2O2 were designed and synthesized.•Au nanocones was the first time synthesized for H2O2 detection with high sensitivity.•NB as internal reference improved accuracy, reproducibility and stable.•The sensor was a turn-on system with low background.•Promising for a drop of blood detection by CFME.
The simply constructed fluorescent sensor with inexpensive reagents and low toxicity has attracted increasing attention contributing to its practical application. However, the common construction ...methods usually required a few building blocks and complex procedures, which is inconvenient for their further application. Herein, a simply constructed fluorescent Hg
2+
sensor has been developed based on the intrinsic fluorescence quenching power of G-quadruplex. Two components, AGRO 100 and AMT, were used to construct the sensor. AMT was selected as the fluorescent probe because of its distinct merits. The free AMT emits strongly. However, the fluorescence of AMT could be quenched by G-quadruplex DNA. Additionally, AMT is less toxic and inexpensive. AGRO 100 acts as both the quencher and the capture sequence because it consists of G-rich sequences and T-T mismatched base pairs. The fluorescence of AMT could be quenched by the formed G-quadruplex structure of AGRO 100 in the presence of K
+
. In the presence of Hg
2+
, G-quadruplex structure of AGRO 100 was switched to hairpin DNA structure because T-T mismatched base pairs in AGRO 100 could specifically recognize and capture Hg
2+
with high affinity. Thus, AMT was released and the fluorescence of AMT was recovered. The developed sensing system was successfully applied to detect Hg
2+
in human serum with good recovery and reproducibility.
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Formaldehyde, a ubiquitous indoor air pollutant, plays a significant role in various biological processes, posing both environmental and health challenges. This comprehensive review delves into the ...latest advancements in electrochemical methods for detecting formaldehyde, a compound of growing concern due to its widespread use and potential health hazards. This review underscores the inherent advantages of electrochemical techniques, such as high sensitivity, selectivity, and capability for real-time analysis, making them highly effective for formaldehyde monitoring. We explore the fundamental principles, mechanisms, and diverse methodologies employed in electrochemical formaldehyde detection, highlighting the role of innovative sensing materials and electrodes. Special attention is given to recent developments in nanotechnology and sensor design, which significantly enhance the sensitivity and selectivity of these detection systems. Moreover, this review identifies current challenges and discusses future research directions. Our aim is to encourage ongoing research and innovation in this field, ultimately leading to the development of advanced, practical solutions for formaldehyde detection in various environmental and biological contexts.
Antimony (Sb) is a potential candidate anode for potassium-ion batteries (PIBs) owing to its high theoretical capacity. However; in the process of potassium alloying reaction; the huge volume ...expansion (about 407%) leads to pulverization of active substance as well as loss of electrical contact resulting in rapidly declining capacity. Herein; uniformly dispersed Sb-Nanodot in carbon frameworks (Sb-ND@C) were constructed by in situ confined polymerization of ionic liquids. Attributed to the uniformly dispersed Sb-ND and confinement effect of carbon frameworks; as anode for PIBs; Sb-ND@C delivered a superior rate capability (320.1 mA h g
at 5 A g
) and an outstanding cycling stability (486 mA h g
after 1000 cycles; achieving 89.8% capacity retention). This work offers a facile route to prepare highly dispersed metal-Nanodot via the in situ polymerization of ionic liquid for high-performance metal-ion batteries.
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