查看更多>>摘要：Reactive oxygen species (ROS) play an essential role in regulating various physiological functions of living organisms. Superoxide anion (O2- .), one kind of ROS, is the single-electron reduction product of oxygen molecules, which mainly exists in plants and animals, and is closely related to many inflammatory diseases. In the field of biomedicine, with the deepening understanding of superoxide anion, more and more detection methods have been developed. This review mainly introduces the detection techniques for superoxide anion in recent years.
查看更多>>摘要：A novel fluorometric assay for selective and sensitive determination of formalin (FA) was developed based on nitrogen-doped carbon dots (N-CDs) coupled with silver mirror reaction. N-CDs was synthesized using the hydrothermal method with the ethylene glycol and ammonia solution as carbon and nitrogen precursors, respectively. The detection principle was based on "off-on" fluorescence switching. Specifically, the fluorescence signal of N-CDs was first turned off after incorporating the Ag+ and Tollens' reagents. Then, in the presence of FA, the Ag+ species on the N-CDs surface were reduced to Ag0 species and the fluorescence signal of N-CDs was switched back on. The fluorescence intensity due to the N-CDs signal linearly increased with the increasing FA concentrations in the range of 5-100 mg L-1, with the detection limit of 1.5 mg L-1. The proposed approach provides rapid, simple, sensitive, and selective detection of FA in various food samples.
查看更多>>摘要：A new fluorescent probe for ratiometric detection of phosgene is reported. This probe was constructed with classic 1,8-naphthalimide and 2-(2-aminophenyl)benzimidazole by Ullmann coupling reaction. After exposure to phosgene, yellow fluorescence weakened while blue fluorescence enhanced significantly. There was a ratiometric response between 542 nm and 490 nm. The detection limit (LOD) was 6.7 nM and the response time was within 200 s in CHCl3. Meaningfully, a new chromophore, benzo [4,5]imidazo[1,2-c]quinazolin-6(5H)-one, was formed after 2-(2-aminophenyl)benzimidazole unit reacted with phosgene, and the ratiometric response was achieved by two chromophores in which the mechanism was confirmed by 1H NMR spectra, HRMS and theoretical calculation. Furthermore, test papers and nanofibers were fabricated with the probe, which could sensitive detection of phosgene within 10 min and 1 min respectively.
查看更多>>摘要：A conjugated microporous organic polymer (TPA-Bp) comprised of triphenylamine (TPA) and 2,2'-bipyridine5,5'-diformaldehyde (Bp) was prepared via the Schiff-base reaction under ambient conditions. TPA-Bp is an amorphous and microporous spherical nanoparticle with very high stability. TPA-Bp suspension in DMF displayed strong fluorescence emission and selective fluorescence quenching response towards Fe3+ and Fe2+ ions. The fluorescence intensity of TPA-Bp at 331 nm presents linear relationship with the concentrations of both Fe3+ and Fe2+ with low detection limits of 1.02 x 10(-5) M for Fe3+ and 5.37 x 10(-6) M for Fe2+. The results of X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy (FTIR) confirm the selective coordination of N atoms of pyridine unit with Fe ions. The fluorescence quenching of TPA-Bp upon the addition of Fe3+/Fe2+ ions can be attributed to the absorption competition quenching (ACQ) mechanism and the energy transfer between TPA-Bp and Fe3+/Fe2+ ions. This work demonstrates that the conjugated microporous polymers are promising candidates as luminescent sensor for detection of the special analytes in practical applications.
查看更多>>摘要：A covalent organic framework (named as TpDq) linked by beta-ketoamine was prepared by imine condensation reaction with 1,3,5-triformylphloroglucinol (TFP) and 2,6-diaminoanthraquinone (DAAQ) as building blocks. Via employing a functionalized modification strategy, a new lanthanide complex Eu3+-beta-diketone functionalized covalent organic framework hybrid material, Eu-TTA@TpDq (TTA = 2-thenoyltrifluoroacetone), has been synthesized. After post-synthetic modification (PSM), the shape and structure of the parent framework is well preserved and the modified material shows remarkable luminescence properties. Based on this, we designed it as a fluorescent probe and tried to use it to sense common aldehydes. The results indicate that Eu-TTA@TpDq exhibits a turn-off response toward glutaraldehyde which can distinguish from other common aldehydes. The fluorescent probe has the advantages of reusability, pH stability (4.50-8.52), fast luminescence response (<1 min) and low detection limit. The linear range of this method was 0-100 mu M; the detection limit was 4.55 mu M; the relative standard deviation was 2.16%. Furthermore, it has broad application prospect in both practical sensing of glutaraldehyde in water environment and simple detection of glutaraldehyde vapor. In addition, we preliminarily discussed the possible sensing mechanism.
查看更多>>摘要：Ultrasensitive detection of biomarkers at an early stage is generally limited by external influence factors such as high reaction temperature, complex operations, and sophisticated instruments. Here, we circumvent these problems by using nicotinamide adenine dinucleotide (NAD+) to control electroinitiated reversible addition fragmentation chain transfer (electro-RAFT) polymerization for biosensing that enables the detection of a few molecules of target DNA. In this coenzyme-catalyzed electro-RAFT polymerization, numerous ferrocenylmethyl methacrylate (FCMMA) as monomer with electrochemistry signal were linked to the biomarker on Au electrode. Afterwards, a strong oxidation peak appears at the potential of about 0.3 V that represents a typical oxidation potential of FCMMA. The sensitivity of this methodology was presented by detecting DNA from 10-1 to 104 fM concentration and detection limit (LOD) being down to 4.39 aM in 10 mu L samples. This is lower by factors than detection limits of most other ultra-sensitive electrochemical DNA assays.
查看更多>>摘要：Molecularly imprinted polymers (MIPs) have aroused great attention as a new material for the removal or detection of pharmaceuticals and personal care products (PPCPs). However, it is not clear about the superiority and deficiency of MIPs in the process of removing or detecting PPCPs. Herein, we evaluated the performance of MIPs in the aspects of adsorption capacity, binding affinity, adsorption rate, and compatibility to other tech-niques, and proposed ways to improve its performance. Without regard to the selectivity of MIPs, for the PPCPs adsorption, MIPs surprisingly did not always perform better than the conventional adsorbents (non-imprinted polymers, biochar, activated carbon and resin), indicating that MIPs should be used where selectivity is crucial, for example recovery of specific PPCPs in an environmental sample extraction process. Compared to the tradi-tional solid-phase extraction for PPCPs detection pretreatment, the usage of MIPs as substitute extraction agents could obtain high selectivity of specific substance, due to the uniformity and effectiveness of the specific sites. A promising development in the future would be to combine other simple and rapid quantitative technologies, such as electro/photochemical sensor and catalytic degradation, to realize rapid and sensitive detection of trace PPCPs.
Jose Lopez-Mayan, Juandel-Angel-Monroy, SergioPena-Vazquez, ElenaCarmen Barciela-Alonso, Maria...
8页
查看更多>>摘要：In this study, a first attempt for isolating and determining (characterising) background levels of titanium dioxide nanoparticles (TiO2 NPs) in seaweed has been developed by using single particle inductively coupled plasma mass spectrometry (SP-ICP-MS). Seaweeds were processed using an optimised ultrasound assisted extraction (UAE) procedure based on tetramethylammonium hydroxide (TMAH) before dilution and SP-ICP-MS analysis. The effect of the TMAH percentage in the extracting solution, as well as the volume of extracting solution and sonication (extraction) time, has been fully assessed. Additional experiments also showed that TiO2 NPs were quantitatively released from the seaweed matrix in one UAE step since the analysis of residues gave TiO2 NPs concentrations lower than the limit of quantification (LOQ) of the method. Validation of the method with 50 and 100 nm TiO2 NPs (10 mu g L-1 as Ti) showed good analytical recovery (115% and 112% for 50 and 100 nm TiO2 NPs, respectively), and good reproducibility (2% for size and 16% for number of TiO2 NPs). Experiments regarding TiO2 NPs stability showed that the extracted NPs are stable since there were not changes on the number of TiO2 NPs and TiO2 NPs size distributions when exposing TiO2 NPs standards to the optimised extractive conditions.
Chen, David D. Y.Semail, Nadhiratul-FarihinKeyon, Aemi Syazwani AbdulSaad, Bahruddin...
8页
查看更多>>摘要：A dynamic pH junction was used in capillary electrophoresis (CE-DAD) to on-line preconcentrate, separate, and determine trace amounts of sulfonamide antibiotics (SAs) in milk and yoghurt samples in this study. A sample matrix with 0.15% acetic acid and 10% methanol (MeOH) at a pH of 4.0, and a background electrolyte (BGE) that contained 35 mM sodium citrate with 10% MeOH at a pH of 8.5, and an acidic barrage of 0.4% acetic acid with 10% MeOH at a pH of 2.5 were utilised to achieve a stacking effect for SAs through a dynamic pH junction. Under optimised conditions, the proposed preconcentration method showed good linearity (30-500 ng/mL, r(2) >= 0.9940), low limits of detection (LODs) of 4.1-6.3 ng/mL, and acceptable analytes recovery (81.2-106.9%) with relative standard deviations (RSDs) within 5.3-13.7 (n = 9). The limits of quantification (LOQs) were below the maximum residue limit approved by the European Union (EU) in this type of matrices. Sensitivity enhancement factors of up to 129 were reached with the optimised dynamic pH junction using CE with a diode array detector (DAD). The method was used to determine SAs in fresh milk, low-fat milk, full-cream milk, and yoghurt samples.
查看更多>>摘要：This work describes (Z)-N-((Z)-2-(1,3,3-trimethylindolin-2ylidene)ethylidene)quinoline-8-amine (LYSO-QF), a high-performing and biocompatible dye comprised of quinoline and Fisher aldehyde moieties linked via an imine vinyl backbone with lysosome targeting ability that can be used to quantitatively detect the mercury ion (Hg2+) in biosystems and the natural environment. This is achieved by forming three different tetrameric, trimeric and dimeric complexes between Hg2+ and LYSO-QF with the limit of detection (LOD) of 11 nm. The complexes formed were analyzed with the aid of time-dependent density functional theory (TD-DFT) calculations. The concentration dependence of the Hg2+ complex fluorescence emission changes from grey-green to jade green and then to red as the different types of complex are formed. The favorable sensor properties of the LYSO-QF probe are demonstrated by monitoring different Hg2+ concentrations in buffer solutions, HeLa cells, zebrafish model samples and several different types of water sample. Experiments with Whatman paper strips demonstrate that the cost-effective LYSO-QF also has considerable potential for use in on-site Hg2+ detection with the naked eye.
NSTL
Elsevier