A dual-reaction sites fluorescent probe for accurate detection of benzoyl peroxide in food

Benzoyl peroxide (BPO) is widely used as a whitening agent in flour, but excessive intake of BPO will severely endanger human health. To quickly and accurately detect BPO on-site, we have rationally designed a novel fluorescent probe PTPY-BE with dual-reaction sites. PTPY-BE underwent a specific cascade reaction with BPO to achieve high-contrast fluorescence turn-on response along with significant achromic reaction. The probe has high sensitivity, excellent selectivity, strong anti-interference ability and low detection limit (LOD = 0.83 mg·kg-1) for BPO. Furthermore, a portable detection platform was fabricated, which offers the portability and color visualization of traditional test strips and the color recognition of a smart device, enabling on-site visualization and quantitative detection of BPO. This platform has been successfully used to determine BPO in real food samples with good recoveries (93.59% - 107.13%). Therefore, this platform possessed great prospect and potential application for the determination of BPO in food.

Highly selective fluorescent probe for detecting mercury ions in water

Mercury ion (Hg²⁺) is a well-known toxic heavy metal. It has become one of the most significant environmental pollutants in the world because of its serious physiological toxicity, persistence, easy migration, and high bioconcentration. Thus, the development of methods for monitoring Hg²⁺ is indispensable. Herein, we have designed and synthesized a new fluorescent probe, TPH, for the detection of Hg²⁺ in the water environment. The TPH probe could quantitatively detect Hg²⁺ between 0 and 5 μM (LOD = 16 nM), with a linear range of 0-2.5 μM. In addition, the TPH probe was used to monitor Hg²⁺ in water samples successfully. Thus, this probe is suitable for monitoring Hg²⁺ in the actual water environment.

BODIPY-Hg2+ Complex: A Fluorescence "Turn-ON" Sensor for Cysteine Detection

A BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) based pioneering sensing material (HLPy) having 2-amino pyridine as receptor was synthesized and used for the selective detection of Hg2+ ions. The synthesized HLPy features a high affinity towards Hg2+ (ka = 2.04 × 105 M-1), accompanied by effective quenching of fluorescence in DMF:H2O (1:9 v/v, 10 mM HEPES buffer, pH 7.4) with 54 nM limit of detection (LOD). The emission titration experiments (Job's plot) in the presence of varying mole-fraction of Hg2+ ions reveals the formation of non-fluorescent 2:1 coordination complex [Hg(LPy)2]. The resulting non-fluorescent [Hg(LPy)2] was thoroughly characterized using various spectroscopic techniques and analyses. Interestingly, the non-fluorescent complex [Hg(LPy)2] is able to specifically respond towards Cys over other biothiols and amino acids through a reversible de-complexation mechanism. As a result, the remarkable recovery of the fluorescence can be observed. The limit of detection (LOD) for Cys detection is estimated to be 29 nM in DMF:H2O (1:9 v/v, 10 mM HEPES buffer, pH 8.0). The reversibility and reusability of [Hg(LPy)2] were achieved by the sequential addition of Cys and Hg2+ ions up to five cycles. Moreover, the removal of Hg2+ ions up to 89% from aqueous samples using HLPy was successfully demonstrated.

Recent Developments in Fluorescent Materials for Heavy Metal Ions Analysis From the Perspective of Forensic Chemistry

Forensic chemistry deals with the analysis of various types of physical evidences related to crime, corresponding to the detection of target substances or elements in complex matrices. There is a vital need for highly selective, rapid, and sensitive biosensing technologies in heavy metal ions analysis especially those from living persons, autopsy, food, water, soil, and other identified substances at very preliminary stages. Fluorescent materials-based method for heavy metal ions detection is one of the most important analytical methods, resulting in the ability to measure analytes in complex matrices with unsurpassed selectivity and sensitivity. In this mini review, different fluorescent materials-based analytical methods aiming at several heavy metal ions detection are exclusively reviewed through a comprehensive literature survey. In addition, current challenges to achieve integrated evidence analysis process are briefly discussed to provide an outlook for heavy metal ions detection based on fluorescent analytical methods in the forensic chemistry field.

Rhodols - synthesis, photophysical properties and applications as fluorescent probes

The formal replacement of one dialkylamino group in rhodamines with a hydroxyl group transforms them into rhodols. This apparently minor difference is not as small as one may think; rhodamines belong to the cyanine family whereas rhodols belong to merocyanines. Discovered in the late 19th century, rhodols have only very recently begun to gain momentum in the field of advanced fluorescence imaging. This is in part due to the increased understanding of their photophysical properties, and new methods of synthesis. Rationalization of how the nature and arrangement of polar substituents around the core affect the photophysical properties of rhodols is now possible. The emergence of so-called π-expanded and heteroatom-modified rhodols has also allowed their fluorescence to be bathochromically shifted into regions applicable for biological imaging. This review serves to outline applicable synthetic strategies for the synthesis of rhodols, and to highlight important structure-property relationships. In the first part of this Review, various synthetic methods leading to rhodols are presented, followed by structural considerations and an overview of photophysical properties. The second part of this review is entirely devoted to the applications of rhodols as fluorescent reporters in biological imaging.

Sensitivity limits of biosensors used for the detection of metals in drinking water

Even when present in very low concentrations, certain metal ions can have significant health impacts depending on their concentration when present in drinking water. In an effort to detect and identify trace amounts of such metals, environmental monitoring has created a demand for new and improved methods that have ever-increasing sensitivities and selectivity. This paper reviews the sensitivities of over 100 recently published biosensors using various analytical techniques such as fluorescence, voltammetry, inductively coupled plasma techniques, spectrophotometry and visual colorimetric detection that display selectivity for copper, cadmium, lead, mercury and/or aluminium in aqueous solutions.