Effective and selective removal of 99TcO4-, one of the most nuisance radionuclides in nuclear waste, is highly desirable but remains a significant challenge. Herein, two isostructural MOFs, NCU-3-X ...(X = Cl, Br) were constructed by ZnX2 coordinated to nitrogen-containing neutral ligand tri(4-(1H-imidazole-1-l) phenyl) amine for efficient adsorption ReO4-/TcO4-. Owning to the twofold interpenetrating structure, both of them exhibit strong alkaline resistance. Consequently, NCU-3-Br exhibited superior adsorption performances with a maximum capacity as high as 483 mg/g, which is 2.23 times larger than that of NCU-3-Cl. The primary reasons accounting for the enhanced adsorption performances of NCU-3-Br are that compared to chlorine atoms, the smaller electronegativity of bromine atoms as halogen bonds donor can facilitate the formation of σ-holes, enhance positively charged skeleton, and reduce the adsorption energy associated with ReO4-/TcO4-. In addition, the one-dimensional hydrophobic channels in the NCU-3-Br framework enable NCU-3-Br to have highly selective toward ReO4-, which has a low relative charge density against interfering ions. The SRS simulation removal experiment further confirmed the excellent adsorption capacity of NCU-3-Br to ReO4-/TcO4-. This work illustrated that the halogenated new strategy incorporated different halogen atoms into MOF skeletons can dramatically modulate the adsorption performances for ReO4-/TcO4-.
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•Two halogens isostructural MOFs were designed and synthesized for efficient removal of TcO4-/ReO4-.•The high alkaline resistance was due to the twofold interpenetrating structure of NCU-3-X.•Halogenation in MOFs plays a critical role in modulating the adsorption capacity for ReO4-.•NCU-3-Br showed high-efficiency removal for ReO4-/TcO4- in simulated wastes.
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•We reported a novel colorimetric biosensor for the assay of DNA methyltransferase activity.•Strand displacement amplification was employed for M.SssI activity inhibition assay.•With ...the advantages of SDA, highly sensitive detection of M.SssI activity and inhibition was achieved.
In this paper, we present a colorimetric method for the assay of DNA methyltransferase (MTase) activity based on strand displacement amplification (SDA). In our study, a well-designed hairpin DNA I (HPI) containing the sequence of 5′-CCGG-3′ is specifically recognized by CpG methyltransferase (M.SssI) and HpaII endonuclease. The methylated HPI is able to coexist with all the DNA and enzymes in the solution while the unmethylated HPI can be cleaved into single-stranded DNA (ssDNA) fragments. The amplification can be triggered by the HpaII digestion products hybridization with another hairpin structure DNA II (HPII) to form a duplex, which would be replaced by probe DNA, leading to the aggregation of gold nanoparticles (AuNPs). Simultaneously, ssDNA fragments released from the duplex, and triggered the cycle anew. Varying concentrations of M.SssI in the solution therefore would lead to differences of absorption and color changed from red to pale. A linear response was obtained when the M.SssI concentration ranging from 0.2 to 50UmL−1 with a detection limit of 0.08UmL−1. In addition, the developed assay in this study can also be applied to screen the inhibitors of M.SssI.
A label-free, sensitive and simple method to detect protein kinase based on the selective aggregation of phosphorylated peptide-gold nanoclusters (peptide-AuNCs) triggered by Zr4+ ion coordination is ...developed. The AuNCs were synthesized by peptide without any strong reducing agents, which prevent peptides from being disrupted. Under optimal conditions, a linear relationship between the decreased PL intensity of peptide-AuNCs and the concentration of casein kinase II (CK2) in the range of 0.08–2.0unitmL−1 with a detection limit of 0.027unitmL−1 (3σ) was obtained. The feasibility of this AuNCs-based sensor was further demonstrated by the assessment of kinase inhibition by ellagic acid, 5,6-dichlorobenzimidazole-1-β-d-ribofuranoside, emodin, and quercetin in human serum. As expected, the PL intensity increased with increasing inhibitor efficiency in the presence of inhibitors. The IC50 value (inhibitor concentration producing 50% inhibition) for ellagic acid was estimated to be 0.045μM. With more sophisticated design of the peptide substrate sequences, the detection of other enzymes will be realized. With characteristics of homogeneous, facile, universal, label-free, and applicable for kinase assay, the proposed sensor provides potential application in kinase-related biochemical fundamental research and inhibitor screening.
•We reported a novel fluorescence assay base on peptide-AuNCs for sensitive analysis of protein kinase CK2 activity.•The peptide-AuNCs was synthesized in situ without any coupling and reducing agents.•Sensitive detection of CK2 based on the aggregation quenching mechanism.•Highly sensitive detection of CK2 activity and inhibition was achieved.
•PDA/GO platform for the facile preparation of protein stationary phase was developed.•PDA/GO is endowed with the adhesive nature and high adsorption capacity.•Integrating BSA onto PDA/GO ...platform-based PDMS microchip greatly increased the phase ratio.•This protocol simplified the immobilization methodology of proteins in OT-CEC microdevice.
A novel chip-based enantioselective open-tubular capillary electrochromatography (OT-CEC) was developed employing bovine serum albumin (BSA) conjugated polydopamine–graphene oxide (PDA/GO) nanocomposites (PDA/GO/BSA) as stationary phase. After the poly(dimethylsiloxane) (PDMS) microfluidic chip was filled with a freshly prepared solution containing dopamine and graphene oxide, PDA/GO nanocomposites were formed and deposited on the inner wall of microchannel as permanent coating via the oxidation of dopamine by the oxygen dissolved in the solution. The PDA/GO-coated PDMS microchips not only have the adhesion of PDA that make them easily immobilized in the microchannel, but also have the larger surface and excellent biocompatibility of graphene which can incorporate much more biomolecules and well maintain their biological activity. In addition, incorporation of GO in PDA film can make surface morphology more rough, which is beneficial for enhancing the loading capacity of proteins in the microchannels and increasing sample capacity of OT-CEC columns. BSA was stably immobilized in the PDMS microchannel to fabricate a protein-stationary phase. Compared with the native PDMS microchannels, the modified surfaces exhibited much better wettability, more stable electroosmotic mobility, and less nonspecific adsorption. The efficient separation of chiral amino acids (tryptophan and threonine) and chiral dipeptide demonstrate that the constructed OT-CEC columns own ideal enantioselectivity. The presented strategy using PDA/GO coating as a versatile platform for facile conjugation of proteins may offer new processing strategies to prepare a functional surface designed on microfluidic chips.
In this work, we developed a novel multisignal output for simultaneous detection of multiple proteases by using nanoprobes labeled with distinguishable electrochemical probes. First, biotinylated ...peptide1 (S1) and biotinylated peptide2 (S2) were associated with biotinylated DNA1 and DNA2 via biotin-streptavidin interaction, forming DNA1-S1 and DNA2-S2, respectively. Two distinguishable signal nanoprobes (DNA1'-Au NPs-Thi and DNA2'-Au NPs-Fc) were prepared by initial assembling DNA1' and DNA2' on the Au NPs surface, respectively, and then carrying corresponding thionine (Thi) and 6-(Ferrocenyl)hexanethiol (Fc). Then, the peptide substrates (DNA1-S1 and DNA2-S2) were immobilized on gold electrode surface through Au-S bonds, and the DNA1'-Au NPs-Thi and DNA2'-Au NPs-Fc were assembled to the peptide-DNA-modified electrode surface via DNA hybridization. The targets of trypsin and chymotrypsin can specifically recognize and cleave peptides with different sequences, releasing DNA1'-Au NPs-Thi and DNA2'-Au NPs-Fc from the electrode surface into solution, thus decreasing the current of Thi and Fc. The decrease in the electrochemical currents of the two signal nanoprobes enables us to simultaneously and quantitatively determine the targets trypsin and chymotrypsin. More importantly, this strategy can be extended easily by designing various proteases-specific peptide substrates and utilizing corresponding electrochemical detectable elements for simultaneous multiplex protease assay in various biosystems.
Carbohydrate–protein interactions mediate the important physiological and pathophysiological processes in living organism. Their study has attracted great attention due to its importance in ...understanding these biological processes and in fabricating biosensors for diagnostics and drug development. Here, by using concanavalin A (ConA) as a model protein, a novel surface plasmon resonance (SPR) sensor was developed for sensitive detection ConA. In this sensing platform, dextran (Dex) capped gold nanoparticles (Dex-Au NPs) were initially synthesized in one-pot and utilized as amplification reagent. After deposition of graphene oxide (GO) on the SPR gold film, phenoxy-derivatized dextran (DexP) was assembled onto the GO-modified gold chip surface through π–π interaction. The resultant GO/DexP sensing interface could specifically capture ConA which could further react with Dex-Au NPs through the specific interaction between ConA and Dex, forming a sandwich configuration. The morphologies and the electrochemistry of the formed sensing surface were investigated by using scanning electron microscopy and electrochemical techniques including electrochemical impedance spectroscopy and cyclic voltammogram. Owing to the high surface area of GO and the excellent amplification of Dex-Au NPs, the developed sandwich SPR sensor successfully fulfilled the sensitive detection of ConA in the range of 1.0–20.0μgmL−1 with a detection limit of 0.39μgmL−1. Compared to the direct assay format, the prepared sandwich SPR sensor led to an improvement of 28.7-fold in the sensitivity. The results demonstrated that the proposed method might provide a new direction in designing high-performance SPR biosensors for sensitive and selective detection of a wide spectrum of biomolecules.
•We report a novel sandwich SPR sensor based on GO carrier and Dex-Au amplifier.•The SPR sensing interface can be conveniently constructed through π–π stacking.•Sensitive detection of ConA is achieved via this sandwich assay format.•The strategy can be easily extended to fabricate other GO based SPR biosensors for protein, cell and DNA.
Optical sensors for inorganic arsenic detection Zhang, Li; Chen, Xiao-Rong; Wen, Shao-Hua ...
TrAC, Trends in analytical chemistry (Regular ed.),
September 2019, 2019-09-00, Volume:
118
Journal Article
Peer reviewed
The measurement of arsenic has received considerable attention due to its contaminant to environment and harm on human safety. This paper provides an overview of optical methods on the measurement of ...inorganic arsenic (arsenite and arsenate). We present and discuss the colorimetric, scattering, and fluorimetric strategies for inorganic arsenic detection based on the organic/biological molecules and their coupling with inorganic nanomaterials. The detection mechanism for arsenite and arsenate is summarized and the advantages/limitations are highlighted in the present review. In addition, prospects and future developments of optical sensors for arsenic analysis are also proposed.
•Different optical methods for arsenics were reviewed.•The detection mechanism of optical methods was summarized.•The sensors with organic/biological molecules and nanomaterials were described.•The challenges and prospects in arsenic analysis were discussed.
Protein methylation is predominantly found on lysine and arginine residues, and carries many important biological functions, including gene regulation and signal transduction. Given their important ...involvement in gene expression, protein methylation and their regulatory enzymes are implicated in a variety of human disease states such as cancer, coronary heart disease and neurodegenerative disorders. Thus, identification of methylation sites can be very helpful for the drug designs of various related diseases. In this study, we developed a method called PMeS to improve the prediction of protein methylation sites based on an enhanced feature encoding scheme and support vector machine. The enhanced feature encoding scheme was composed of the sparse property coding, normalized van der Waals volume, position weight amino acid composition and accessible surface area. The PMeS achieved a promising performance with a sensitivity of 92.45%, a specificity of 93.18%, an accuracy of 92.82% and a Matthew's correlation coefficient of 85.69% for arginine as well as a sensitivity of 84.38%, a specificity of 93.94%, an accuracy of 89.16% and a Matthew's correlation coefficient of 78.68% for lysine in 10-fold cross validation. Compared with other existing methods, the PMeS provides better predictive performance and greater robustness. It can be anticipated that the PMeS might be useful to guide future experiments needed to identify potential methylation sites in proteins of interest. The online service is available at http://bioinfo.ncu.edu.cn/inquiries_PMeS.aspx.
An electrochemiluminescence (ECL) sensing approach was designed for sensitive Hg2+ detection based on oligonucleotide hosted silver cluster (DNA-Ag NCs) as effective unit for switching the ECL signal ...of graphite-like carbon nitride nanosheets (g-C3N4 NSs). In this system, g-C3N4 NSs were first immobilized on the glassy carbon electrode surface followed by the chitosan coating and probe DNA assembly. The g-C3N4 NSs exhibited stable ECL intensity which was regarded as first signal switch “on” state. DNA-Ag NCs can be captured onto the g-C3N4 NSs coated electrode surface via DNA hybridization, leading to the ECL signal quenching of g-C3N4 NSs attributed to the ECL resonance energy transfer (ECL-RET) between the luminophore donor g-C3N4 NSs and the acceptor DNA-Ag NCs, turning to signal “off” state. While in the presence of Hg2+, the formation of T-Hg2+-T coordination between DNA-Ag NCs or DNA-Ag NCs themselves would hinder DNA-Ag NCs from embellishing on the electrode surface, resulting in the recovery of the g-C3N4 NSs ECL intensity corresponding to the last signal switch “on” state. Based on this, the biosensor can be demonstrated to quantitatively analyze Hg2+ with a detection of limit of 5 pM. The proposed ECL platform has been utilized to sensitive and selective monitoring Hg2+ in environmental water samples.
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•ECL biosensor based on the ECL-RET between g-C3N4 NSs and Ag NCs has been designed.•A switchable “on-off-on” detection strategy was designed for monitoring Hg2+.•This work presences an excellent Hg2+ biosensor with a low detection limit down to 5 pM.
A bimetal lanthanide coordination polymer nanoparticle (ATP-Ce/Tb-Tris CPNs) with good biocompatibility was synthesized in Tris–HCl buffer using adenosine triphosphate (ATP) molecules as the bridge ...ligands. The large absorption cross section and suitable emission energy of Ce3+ matching to the adsorption energy of Tb3+(4fn) results in the efficient energy transfer from Ce3+ to Tb3+, thus the synthesized ATP-Ce/Tb-Tris CPNs exhibit the characteristic green emission of Tb3+. Such energy transfer from metal to metal in fluorescent lanthanide coordination polymer nanoparticles (Ln-CPNs) has been demonstrated. It is found that the oxidation of Ce3+ in ATP-Ce/Tb-Tris CNPs to Ce4+ would interrupt the energy transfer from Ce3+ to Tb3+, leading to fluorescence quenching of Tb3+. On the basis of this quenching mechanism, ATP-Ce/Tb-Tris CPNs has been successfully used to detect reactive oxygen H2O2 with detection limit as low as 2nM. If glucose oxidase is present in the system, glucose can be determined using the ATP-Ce/Tb-Tris CNPs nanosensor.
•Using ATP as bridge ligand, the lanthanide coordination polymer nanoparticle (ATP-Ce/Tb-Tris CPNs) was synthesized.•The green emission of ATP-Ce/Tb-Tris CNPs was demonstrated to come from the efficient energy transfer from Ce3+ to Tb3+.•The interrupt of energy transfer from Ce3+ to Tb3+ results in the fluorescence quenching of ATP-Ce/Tb-Tris CNPs.
