寡聚核苷酸稳定银纳米簇荧光探针的合成及含巯基药物的高选择性分析测定

金属纳米团簇具有很好的光电特性,但因其化学活性高而不易稳定存在于水介质中.根据核苷酸的所有碱基中胞嘧啶与Ag+的结合能力最强,寡聚鸟苷酸易折叠和序列中同时存在腺嘌呤和胸腺嘧啶易发生杂交导致自身团聚等因素,本文设计了胞嘧啶和腺嘌呤各占50%的寡聚核苷酸序列模板分子用于合成稳定性好、荧光性能优异的银纳米簇,并进一步应用于含巯基药物的分析测定.研究表明,含巯基药物通过巯基能高选择性地与银纳米簇发生相互作用形成Ag?S键,使得银纳米簇的荧光发生静态猝灭.据此,本文建立了以抗高血压药物卡托普利为代表的含巯基物质的分析方法.该方法快速、准确、选择性好、灵敏度高,可成功应用于卡托普利片剂的分析.     

Optical detection of cyanide by palladium(II)-dithiazolopyridine probe at the parts per billion level

Abstract

The ensemble of 2,6-bis(2-chlorophenyl)dithiazolo[4,5-b:5',4'-e]pyridine 1 with Pd²⁺ ions (1?Pd²⁺) was prepared for the detection of cyanide ions (CN^¯) in 50% aqueous methanol. Among the tested metal ions, only Pd²⁺ sensitively induced the red shift of the absorption bands and the complete decrease of fluorescence emission. The detection limit toward Pd²⁺ was 2?ppb. The ensemble 1?Pd²⁺ selectively and rapidly detected a low concentration of cyanide ions by a colorimetric change (40?ppb) as well as a “turn-on” fluorescent response (5?ppb). Job’s plot revealed the complex formation with 1:1 stoichiometry. The binding and replacement mode of 1?Pd²⁺ and CN^¯ were also confirmed by ¹H NMR titrations and IR analysis. In general, a fast and selective recognition of CN^¯ is reported.     

Synthesis of organic nanoparticles of naphthalene-thiourea-thiadiazole-linked molecule as highly selective fluorescent and colorimetric sensor for Ag(I)

A novel fluorescent and colorimetric sensor was synthesized by a reprecipitation to probe Ag⁺ ions in water on naphthalene-thiourea-thiadiazole (NTTA) molecular nanocrystals. The fluorescent organic nanoparticles (FONs) allowed a highly sensitive determination of free Ag⁺ ions in aqueous media. The possible mechanism was discussed.     

A highly selective fluorescent chemosensor for silver(I) in water/ethanol mixture

Synthesis, photophysical, and complexation properties of fluorescent chemosensors, L¹ and L², with ‘receptor-spacer-fluorophore’ motif (L¹: NS₂O₂-cyclic receptor, L²: acyclic analogue receptor) are described. Maximum chelation-enhanced fluorescence effect (TURN-ON type) was observed in the presence of Ag⁺ for both fluoroionophores in a 1:1 (v/v) aqueous ethanol solution: remarkably superior selectivity of L¹ (150-fold) with cyclic receptor than that of the L² (50-fold) with acyclic analogue was found. According to the fluorescence and NMR titrations, the excellent selectivity of L¹ is attributed to its topology-based higher affinity in complexation.     

DNAzyme-based fluorescent microarray for highly selective and sensitive detection of lead(II)

A facile microarray-based fluorescent sensor for the detection of lead (II) was developed based on the catalytic cleavages of the substrates by a DNAzyme upon its binding to Pb(2+). The release of the fluorophore labelled substrates resulted in the decrease of fluorescence intensity. The sensor had a quantifiable detection range from 1 nM to 1 μM and a selectivity of >20 fold for Pb(2+) over other metal ions.     

Self-assembled poly(imidazole-palladium): highly active, reusable catalyst at parts per million to parts per billion levels

Metalloenzymes are essential proteins with vital activity that promote high-efficiency enzymatic reactions. To ensure catalytic activity, stability, and reusability for safe, nontoxic, sustainable chemistry, and green organic synthesis, it is important to develop metalloenzyme-inspired polymer-supported metal catalysts. Here, we present a highly active, reusable, self-assembled catalyst of poly(imidazole-acrylamide) and palladium species inspired by metalloenzymes and apply our convolution methodology to the preparation of polymeric metal catalysts. Thus, a metalloenzyme-inspired polymeric imidazole Pd catalyst (MEPI-Pd) was readily prepared by the coordinative convolution of (NH(4))(2)PdCl(4) and poly[(N-vinylimidazole)-co-(N-isopropylacrylamide)(5)] in a methanol-water solution at 80 °C for 30 min. SEM observation revealed that MEPI-Pd has a globular-aggregated, self-assembled structure. TEM observation and XPS and EDX analyses indicated that PdCl(2) and Pd(0) nanoparticles were uniformly dispersed in MEPI-Pd. MEPI-Pd was utilized for the allylic arylation/alkenylation/vinylation of allylic esters and carbonates with aryl/alkenylboronic acids, vinylboronic acid esters, and tetraaryl borates. Even 0.8-40 mol ppm Pd of MEPI-Pd efficiently promoted allylic arylation/alkenylation/vinylation in alcohol and/or water with a catalytic turnover number (TON) of 20,000-1,250,000. Furthermore, MEPI-Pd efficiently promoted the Suzuki-Miyaura reaction of a variety of inactivated aryl chlorides as well as aryl bromides and iodides in water with a TON of up to 3,570,000. MEPI-Pd was reused for the allylic arylation and Suzuki-Miyaura reaction of an aryl chloride without loss of catalytic activity.     

Rosamine-based fluorescent chemosensor for selective detection of silver(I) in an aqueous solution

The synthesis and photophysical properties of a rosamine-based fluorescent chemosensor, RosAg, for detecting Ag ion in an aqueous solution are described. This fluorescent sensor has a negligible quantum yield (<0.005) in the absence of Ag(+), whereas a significant increase in fluorescence is observed upon complexation with Ag(+) under physiological conditions. The crystal structure of the silver complex with the chelator moiety of RosAg reveals a trigonal-planar coordination geometry in which three S atoms occupy the metal center. Although a strong coordinative interaction of Ag-N is not observed in the crystal structure, the (1)H NMR experiments suggest that aniline nitrogen is likely to be associated with the Ag(+) center in the solution state. This may inhibit the photoinduced electron transfer process and result in the enhancement of fluorescence.     

Label-free fluorescent detection of copper(II) using DNA-templated highly luminescent silver nanoclusters

Novel luminescent silver nanoclusters (AgNCs) were synthesized utilizing DNA as templates by a simple, rapid and one-pot procedure. Luminescence studies indicated that these DNA-AgNCs exhibited strong emission with peak maximum at 624 nm. The fluorescence of the DNA-AgNCs was found to be quenched by Cu(2+) enabling its detection with high sensitivity and selectivity.     

Synthesis and functionalization of a highly fluorescent and completely water-soluble poly(para-phenyleneethynylene) copolymer for bioconjugation

Bioconjugation of a highly fluorescent water-soluble poly(para-phenyleneethynylene) (PPE) copolymer with ionic and non-ionic side chains is achieved by means of chain-end modification, providing a design principle for biosensor development.     

Electrode kinetics of amperometric hydrogen sensors for hydrogen detection at low parts per million level

Hydrogen gas detection at low parts per million concentration levels in sensors based on polymer membrane electrolytes and catalytically active electrodes, operating at room temperature, is sensitively dependent on the morphology of the electrode. This effect has been investigated using Nafion^® as polymeric proton-conducting membrane onto which a catalytic electrode was deposited by an in situ impregnation–reduction technique. In this work, Pt was selected as active catalyst for hydrogen oxidation. The deposition conditions were modified to optimise the parameters with regard to the application of the electrode in low-level hydrogen sensors in the 10–1,000 ppm range and to improve the metal utilisation for reduced electrode loading without loss of electrochemical performance. Models of electrode kinetics are proposed and compared with experimental results. Increasing porosity as a result of decreased reductant concentrations was observed by scanning electron microscopy and other surface characterisation methods. The response time of the hydrogen sensor was in the range of 10–30 s and a stable linear current output was observed under short-circuit conditions.     

Novel highly selective fluorescent chemosensors for Zn(II)

Two novel fluorescent Zn²⁺ chemosensors were synthesized in four steps from inexpensive starting materials. They exhibited very strong fluorescence responses to Zn²⁺ and had remarkably high selectivity to Zn²⁺ than other metal ions including Mg²⁺, Ca²⁺, Ni²⁺, Cu²⁺, and Cd²⁺. These two new molecules could be used as low-priced yet high-quality Zn²⁺ chemosensors.     

A seminaphthofluorescein-based fluorescent chemodosimeter for the highly selective detection of cysteine

A fluorescent chemodosimeter for cysteine detection was developed based on a tandem conjugate addition and intramolecular cyclization reaction. The method exhibited an excellent selectivity for cysteine over other biothiols such as homocysteine and glutathione.     

A selective fluorescent sensor for Pb(II) in water

A new fluorescent sensor (1) containing bis(2-pyridylmethyl)amine group as a binding moiety for Pb²⁺ was developed. Compound 1 shows selective response to Pb²⁺ over other metal ions in pH 7.0 HEPES buffer solution. The fluorescence intensity enhancement was ascribed to the complex formation between Pb²⁺ and 1 which blocked the photo-induced electron transfer process.     

One‐pot synthesis of highly fluorescent silicon nanoparticles for sensitive and selective detection of hemoglobin

In this work, a simple, selective, and sensitive probe for hemoglobin based on the quenched fluorescence of silicon nanoparticles (SiNPs) was fabricated. The SiNPs were synthesized by a simple hydrothermal treatment from N‐[3‐(trimethoxysilyl)propyl]ethylenediamine and sodium citrate. The as‐prepared SiNPs exhibited good water‐solubility and high fluorescence with the quantum yield of 70%. The fluorescence of the SiNPs could be remarkably quenched by hemoglobin. A wide linear range was obtained from 50 nM to 4000 nM with a LOD of 40 nM. The quenching mechanism was investigated by UV‐Vis absorption spectrometry and time‐resolved fluorescence spectrometry.     

An ultrasensitive rapid-response fluorescent probe for highly selective detection of HSA

A fluorescent probe HCAB based on twisted intramolecular charge transfer (TICT) mechanism has been designed and synthesized by introducing benzoyl moiety to 4-dimethylamino-2′-hydroxychalcone. HCAB showed excellent selectivity towards human serum albumin (HSA) among different proteins with a remarkable 160-fold fluorescence enhancement and a wider linear range 0–100?mg/L of HSA. Job’s Plot analysis suggested that the formation of HCAB-HSA complex followed a 1:1 stoichiometry. Molecular docking and the displacement assay demonstrated the binding site of HCAB was subdomain IIA and IB of HSA. We also tested HSA levels in human plasma for practical application, the results obtained from HCAB method were similar to those obtained from the standard clinical method.     

A highly selective fluorescent probe for the detection of palladium(II) ion in cells and aqueous media

We report on a fluorescent probe for the optical (and even bare eye) detection of palladium(II) ion which causes the probe to undergo a strong increase in absorbance and fluorescence. The probe is easily synthesized from rhodamine B hydrazide and 9-anthraldehyde and displays high selectivity over other metal ions. Fluorescence intensity and absorbance are linearly proportional to the concentration of Pd(II) in the 0–7 μM and 0–1 μM concentration range, respectively, with detection limits of 0.21 μM and 0.03 μM. The probe can detect Pd(II) with virtually no interferences by other metal ions and anions. It was applied to intracellular imaging of Pd(II) in living cells and to its determination in a palladium-containing catalyst and in spiked water samples.

A highly selective turn-on fluorescent chemosensor for copper(II) ion

A new pyrene derivative (1) containing a diaminomaleonitrile moiety exhibits high selectivity for Cu²⁺ detection. Significant fluorescence enhancement was observed with chemosensor 1 in the presence of Cu²⁺. However, the metal ions Ag⁺, Ca²⁺, Cd²⁺, Co²⁺, Fe²⁺, Fe³⁺, Hg²⁺, Mg²⁺, Mn²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ produced only minor changes in fluorescence values for the system. The apparent association constant (K_a) of Cu²⁺ binding in chemosensor 1 was found to be 5.55×10³ M⁻¹. The maximum fluorescence enhancement caused by Cu²⁺ binding in chemosensor 1 was observed over the pH range 5-7.5.     

The water-soluble bicyclic 2-pyridone-based fluorescent probe for fast and selective detection of hypochlorite

As a strong oxidizer, hypochlorite (ClO^–) are widely employed as bleaching agents and disinfectants. Determination of ClO^– is required to ensure bactericidal effects and avoid hazards caused by excessive residual chlorine. Herein, the derivative bicyclic 2-pyridone, namely DHIP-Py, was prepared successfully to establish a new ClO^–-quantitative method. The probe exhibits excellent ClO^– selectivity over other ROS and anions/cations, high sensitivity (LOD = 1.32 µmol/L), fast response (<5 s), and wide-pH tolerance (pH 4∼10). Benefit from its good water solubility, DHIP-Py is well suited for water sample analysis and has been successfully applied to detect ClO^– in real-world food and environmental samples, including tap water, bottled water and river water. The detection results were essentially identical to that of obtained from traditional DPD method. Moreover, visual detection of ClO^– via filter paper-based solid sensor and imaging of ClO^– in Escherichia coli were also achieved by DHIP-Py. These satisfactory results demonstrate that this bicyclic 2-pyridone-based hypochlorite probe is a promising free chlorine chemosensor with great potential for analytical applications.