Ratiometric Detection of ATP by Fluorescent Cyclophanes with Bellows-Type Sensing Mechanism

Pyrene-based cyclophanes have been synthesized with the aim to realize a bellows-type sensing mechanism for the ratiometric detection of nucleotide concentrations in a buffered aqueous solution. The sensing mechanism involves the encapsulation of a nucleobase between two pyrene rings, which affects the monomer-excimer equilibrium of the receptor in the excited state. The nature of the spacer and its connection pattern to pyrene rings have been varied to achieve high selectivity for ATP. The 1,8-substituted pyrene-based cyclophane with the 2,2’-diaminodiethylamine spacer demonstrates the best selectivity for ATP showing a 50-fold increase in the monomer-excimer emission ratio upon saturation with the nucleotide. The receptor can detect ATP within the biological concentrations range over a wide pH range. NMR and spectroscopic studies have revealed the importance of hydrogen bonding and stacking interactions for achieving a required receptor selectivity. The probe has been successfully applied for the real-time monitoring of creatine kinase activity.     

High performance ethylene sensor based on palladium-loaded tin oxide: Application in fruit quality detection

Ethylene (C₂H₄), as a plant hormone, its emission can be served as an indicator to measure fruit quality. Due to the limited physiochemical reactivity of C₂H₄, it is a challenge to develop high performance C₂H₄ sensors for fruit detection. Herein, this paper presents a resistive-type C₂H₄ sensor based on Pd-loaded tin oxide (SnO₂). The C₂H₄ sensing performance of proposed sensor are tested at optimum operating temperature (250 °C) with ambient relative humidity (51.9% RH). The results show that the response of Pd-loaded SnO₂ sensor (11.1, R_a/R_g) is about 3 times higher than that of pristine SnO₂ (3.5) for 100 ppm C₂H₄. The response time is also significantly shortened from 7 s to 1 s compared with pristine SnO₂. Especially, the Pd-loaded SnO₂ sensor possesses good sensitivity (0.58 ppm⁻¹) at low concentration (0.05–1 ppm) with excellent linearity (R² = 0.9963) and low detection limit (50 ppb). The high sensing performance of Pd-loaded SnO₂ are attributed to the excellent adsorption and catalysis effects of Pd nanoparticle. Meaningfully, the potential applications of C₂H₄ sensor are performed for monitoring the maturity and freshness of fruits, which presents a promising prospect in fruit quality evaluation.     

Semiconductor Quantum Dots as Components of Photoactive Supramolecular Architectures

Luminescent quantum dots (QDs) are colloidal semiconductor nanocrystals consisting of an inorganic core covered by a molecular layer of organic surfactants. Although QDs have been known for more than thirty years, they are still attracting the interest of researchers because of their unique size-tunable optical and electrical properties arising from quantum confinement. Moreover, the controlled decoration of the QD surface with suitable molecular species enables the rational design of inorganic-organic multicomponent architectures that can show a vast array of functionalities. This minireview highlights the recent progress in the use of surface-modified QDs – in particular, those based on cadmium chalcogenides – as supramolecular platforms for light-related applications such as optical sensing, triplet photosensitization, photocatalysis and phototherapy.     

Highly Sensitive Upconverting Nanoplatform for Luminescent Thermometry from Ambient to Cryogenic Temperature

Precise assessment of temperature is crucial in many physical, technological, and biological applications where optical thermometry has attracted considerable attention primarily due to fast response, contactless measurement route, and electromagnetic passivity. Rare-earth-doped thermographic phosphors that rely on ratiometric sensing are very efficient near and above room temperature. However, being dependent on the thermally-assisted migration of carriers to higher excited states, they are largely limited by the quenching of the activation mechanism at low temperatures. In this paper, we demonstrate a strategy to pass through this bottleneck by designing a linear colorimetric thermometer by which we could estimate down to 4 K. The change in perceptual color fidelity metric provides an accurate measure for the sensitivity of the thermometer that attains a maximum value of 0.86 K⁻¹. Thermally coupled states in Er³⁺ are also used as a ratiometric sensor from room temperature to ∼140 K. The results obtained in this work clearly show that Yb³⁺−Er³⁺ co-doped NaGdF₄ microcrystals are a promising system that enables reliable bimodal thermometry in a very wide temperature range from ultralow (4 K) to ambient (290 K) conditions.     

薄膜基荧光传感检测的研究进展

薄膜基荧光传感器是继离子迁移谱之后,业界公认的一种最具发展潜力的微痕量物质探测技术.由于其具有灵敏性、便携性、实时检测、响应速度快、易于制造、不污染待测体系等优点,在食品检测、环境监测、质量控制和生物医学分析等领域引起了广泛的关注和研究.本文主要综述了近年来薄膜基荧光传感在挥发性气体检测、有毒化学品检测、爆炸物检测、溶液相离子检测以及生物监测等领域的研究进展,并提出了薄膜基荧光传感所面临的挑战与未来的发展方向.     

囊泡型荧光纳米界面的构建及其对CD44蛋白的比例型传感

本文设计合成了两亲性Eu(Ⅲ)配合物(Eu L^3+)、两亲性香豆素衍生物(CA)以及荧光素修饰的透明质酸(HA-FA).Eu L^3+和CA可在水中共组装形成带正电荷的囊泡型荧光纳米界面(Eu L^3+/CA).HA-FA可通过静电引力络合在Eu L^3+/CA表面,促使CA与FA之间发生有效的荧光共振能量转移,体系的荧光发射以荧光素的绿色荧光为主.当肿瘤细胞标识物CD44蛋白与络合在囊泡表面上的透明质酸发生特异相互作用后,降低了CA与FA之间的能量转移效率,体系的荧光发射从绿色转变为蓝色.据此,实现了对CD44的高灵敏检测(DL=1.79×10^-7g/m L),而所测试的氨基酸、蛋白质等生物分子几乎不对荧光纳米界面的荧光性质产生影响.基于此,我们成功地将Eu L^3+/CA/HA-FA用于人乳腺癌细胞MCF-7和MDA-MB-231悬浮液中CD44蛋白的高效检测,该工作为构建新型CD44蛋白荧光探针提供了思路,为癌症早期诊断和治疗奠定了基础.     

Electrochemistry in Carbon‐based Quantum Dots

Electrochemistry belongs to an important branch of chemistry that deals with the chemical changes produced by electricity and the production of electricity by chemical changes. Therefore, it can not only act a powerful tool for materials synthesis, but also offer an effective platform for sensing and catalysis. As extraordinary zero‐dimensional materials, carbon‐based quantum dots (CQDs) have been attracting tremendous attention due to their excellent properties such as good chemical stability, environmental friendliness, nontoxicity and abundant resources. Compared with the traditional methods for the preparation of CQDs, electrochemical (EC) methods offer advantages of simple instrumentation, mild reaction conditions, low cost and mass production. In return, CQDs could provide cost‐effective, environmentally friendly, biocompatible, stable and easily‐functionalizable probes, modifiers and catalysts for EC sensing. However, no specific review has been presented to systematically summarize both aspects until now. In this review, the EC preparation methods of CQDs are critically discussed focusing on CQDs. We further emphasize the applications of CQDs in EC sensors, electrocatalysis, biofuel cells and EC flexible devices. This review will further the experimental and theoretical understanding of the challenges and future prospective in this field, open new directions on exploring new advanced CQDs in EC to meet the high demands in diverse applications.     

Two new NiII and ZnII metal–organic frameworks of glutarate and 1,4‐bis[(2‐methyl‐1H‐imidazol‐1‐yl)methyl]benzene ligands: syntheses,structures and luminescence sensing properties

Two new metal–organic frameworks (MOFs), namely, three‐dimensional poly[diaquabis{μ₂‐1,4‐bis[(2‐methyl‐1H‐imidazol‐1‐yl)methyl]benzene}bis(μ₂‐glutarato)dinickel(II)] monohydrate], {[Ni₂(C₅H₆O₄)₂(C₁₆H₁₈N₄)₂(H₂O)₂]·H₂O}_n or {[Ni₂(Glu)₂(1,4‐mbix)₂(H₂O)₂]·H₂O}_n, ( I ), and two‐dimensional poly[[{μ₂‐1,4‐bis[(2‐methyl‐1H‐imidazol‐1‐yl)methyl]benzene}(μ₂‐glutarato)zinc(II)] tetrahydrate], {[Zn(C₅H₆O₄)(C₁₆H₁₈N₄)]·4H₂O}_n or {[Zn(Glu)(1,4‐mbix)]·4H₂O}_n ( II ), have been synthesized hydrothermally using glutarate (Glu^2?) mixed with 1,4‐bis[(2‐methyl‐1H‐imidazol‐1‐yl)methyl]benzene (1,4‐mbix), and characterized by single‐crystal X‐ray diffraction, IR and UV–Vis spectroscopy, powder X‐ray diffraction, and thermogravimetric and photoluminescence analyses. Ni^II MOF ( I ) shows a 4‐connected 3D framework with point symbol 6⁶, but is not a typical dia network. Zn^II MOF ( II ) displays a two‐dimensional 4⁴‐ sql network with one‐dimensional water chains penetrating the grids along the c direction. The solid‐state photoluminescence analysis of ( II ) was performed at room temperature and the MOF exhibits highly selective sensing toward Fe³⁺ and Cr₂O₇^2? ions in aqueous solution.     

A Computational Study of CIONO2H+: Structure and Vibrations

Two protonated forms of chlorine nitrate, HClONO⁺ ₂ and ClONO₂H⁺, are treated ab initio by the Hartree-Fock and the second order Møller-Plesset perturbation approach with the standard 6–31G* basis set. Both minimum energy structures are planar (C ₃ symmetry) and their structural, energy, and vibrational parameters are reported. The computations conclude that the proton attacks the chlorine nitrate at its central, not end, oxygen atom. The protonation causes a considerable elongation of the central ON bond which becomes most probable place of cleavage. The dissociation should yield the neutral HOCl and NO⁺ ₂. These quantum-chemical findings well agree with the previous experimental indications.

     

5-(Perfluorooctylthio)acetamidofluorescein (5-FOAF) as a convenient tag for inspecting the surface coverage of fluorinated coatings

Fluorinated compounds are commonly used for anti-stick coating but it is difficult to inspect the coverage of the coating without expensive instruments. Herein, we demonstrated that the 5-(perfluorooctylthio)acetamidofluorescein (5-FOAF) probe can be synthesized in one step and used as a testing reagent to inspect the fluorinated coating on silica- or metal-based surfaces. 5-FOAF is composed of a perfluoroalkyl domain, which has high specific affinity towards fluorinated compounds, and a fluorophore domain, which exhibits fluorescence emission visible by naked eyes. Thus, 5-FOAF will retain on the surface coated with fluorinated compounds but not on the un-coated surface and the emitted fluorescence from the retained tags serves as a semi-quantitative measure of the fluorine coverage across the surface. For this study, silica-based or metal-based surfaces were activated by silane chemistry and then coated with fluorinated compounds. The coating procedure was judiciously optimized to achieve a homogeneous coating. 5-FOAF probe was synthesized in-house and shown to retain on the fluorinated surface 2-5 times stronger than the bare surface. Moreover, by studying the retention on a non-fluoro hydrophobic substrate made of polydimethylsiloxane, the affinity of 5-FOAF with the fluorinated coating was confirmed to be specific and distinguishable from nonspecific hydrophobic interaction. In conclusion, we synthesized a novel chemical, 5-FOAF, and demonstrated its usefulness as a simple testing reagent for fluorinated coatings.