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.     

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.     

卤键在化学传感和分子识别中的应用

卤键是一种新的分子间非共价作用力,它存在于卤素原子(路易斯酸)和具有孤电子对的原子或π-电子体系(路易斯碱)之间,在超分子化学、材料科学、生物识别和药物设计等领域已经显示出独特的优势。本文主要从卤键的特征和在化学传感和分子识别中的应用以及发展前景等几方面进行了介绍,期望引起人们对卤键的更多关注。     

星载太阳紫外光谱监视器的地面辐射定标

星载太阳紫外光谱监视器是一种小型化、高精度紫外-真空紫外光谱辐射计,它有两种工作模式,即探测太阳紫外光谱辐照度的太阳模式和探测大气的太阳后向散射紫外光谱辐亮度的大气模式。对应这两种工作模式分别建立了紫外-真空紫外光谱辐照度和紫外光谱辐亮度定标装置。光谱辐照度标准灯直接辐照仪器的漫反射板进行仪器的光谱辐照度响应度定标,光谱辐照度标准灯辐照标准漫反射板形成朗伯面光源进行仪器的光谱辐亮度响应度定标。误差分析表明:160~250 nm光谱辐照度绝对定标误差为6.5%,250~400 nm为4.3%;250~400 nm光谱辐亮度绝对定标误差为5.9%。星载太阳紫外光谱监视器获得的地外太阳紫外光谱辐照度与大气的太阳后向散射光谱辐亮度数据,同国际上的观测结果相比一致性达±10%。     

熊猫型保偏光纤光栅温度和压力传感特性的实验研究

对熊猫型保偏光纤光栅的传感特性进行了深入的实验研究,采用温箱和压力罐分别进行了温度和压力传感特性的实验研究.实验结果表明:在0～2.5 MPa的压强范围内,熊猫型保偏光纤光栅两个偏振方向上的压力敏感系数分别为0.004 88 nm/MPa和0.003 52 nm/MPa;在15～50 ℃的温度范围内,两个偏振方向上的温度敏感系数为0.01018 nm/℃和0.008 8 nm/℃.该光纤光栅两偏振态对温度和压力的不同敏感特性可用于解决光纤光栅的交叉敏感问题.     

内陆水体叶绿素a含量定量检测的研究

以武汉东湖为实验基地,通过对其水体的多次检测,获得了从2006年6月到9月4个月的东湖水体透射光谱,并与蒸馏水透射光谱进行比较,对东湖水富营养化程度进行了定性分析.采用一种新的测量方法得到叶绿素a浓度与677 nm和703 nm处相对强度的差值和比值有很好的线性相关性,建立了东湖水体叶绿素a含量的准确定量检测模型,为实现对东湖水实时、快速、准确监测提供了基础,为高精度遥感水质分析提供了参考.