Highly selective and sensitive fluorescent probe for the rapid detection of mercury ions

Sulfur-based fluorescent probes for biological analysis: A review

The widespread adoption of small-molecule fluorescence detection methodologies in scientific research and industrial contexts can be ascribed to their inherent merits, including elevated sensitivity, exceptional selectivity, real-time detection capabilities, and non-destructive characteristics. In recent years, there has been a growing focus on small-molecule fluorescent probes engineered with sulfur elements, aiming to detect a diverse array of biologically active species. This review presents a comprehensive survey of sulfur-based fluorescent probes published from 2017 to 2023. The diverse repertoire of recognition sites, including but not limited to N, N-dimethylthiocarbamyl, disulfides, thioether, sulfonyls and sulfoxides, thiourea, thioester, thioacetal and thioketal, sulfhydryl, phenothiazine, thioamide, and others, inherent in these sulfur-based probes markedly amplifies their capacity for detecting a broad spectrum of analytes, such as metal ions, reactive oxygen species, reactive sulfur species, reactive nitrogen species, proteins, and beyond. Owing to the individual disparities in the molecular structures of the probes, analogous recognition units may be employed to discern diverse substrates. Subsequent to this classification, the review provides a concise summary and introduction to the design and biological applications of these probe molecules. Lastly, drawing upon a synthesis of published works, the review engages in a discussion regarding the merits and drawbacks of these fluorescent probes, offering guidance for future endeavors.

Dual fluorescence response of calix[4]arene-1,8-naphthalimide derivatives towards Hg(II) /Cr(VI) and their antimicrobial studies of transparent biofilms with hyaluronic acid

In this study, 4-sulfo-1,8-naphthalimide calixarene of derivatives were prepared (3 and 4) then transparent biofilms of the Ag salts of these compounds were formed in the presence of hyaluronic acid (HA), and antimicrobial properties were investigated. In chemosensor studies, the sensing ability behavior of 3 and 4 towards some cations and anions was investigated by fluorescence spectroscopy. It was observed that the prepared chemosensors show selectivity towards Hg(II) and Cr(VI). Ligand-ion interaction occurs according to the photo-induced electron transfer (PET) mechanism. The stoichiometric ratio was calculated by using Stern-Volmer plot method and binding constant Ksv values were found as 5.2 × 107 M-1 and 5.5 × 107 M-1 for 3-Hg(II) and 4-Hg(II) complexes, respectively and 4.0 × 107 M-1 and 4.3 × 107 M-1 for 3-Cr(VI) and 4-Cr(VI) complexes. The detection limits of the complexes of 3-Hg(II) and 4-Hg(II) are 6.35 × 10-12and 6.81 × 10-12, while those of 3-Cr(VI) and 4-Cr(VI) are 1.41 × 10- 11and 8.37 × 10-12, respectively. As a result of the antimicrobial test performed with these compounds, it was observed that the most effective material was HA-3Ag, which showed a significant antibacterial effect against Sarcina lutea (S. lutea) at a minimum inhibitory concentration (MIC) value of 0.097 mg/mL.

A rhodamine NIR probe for naked eye detection of mercury ions and its application

Fluorescence imaging technology has developed rapidly with its advantages, and near-infrared probes are worthy of attention because of their less background interference, low light damage, and infinite potential. Rhodamine and its derivatives have the unique structure of lactam helices, which is an ideal platform for the construction of on-off fluorescent sensors. In this paper, a novel near-infrared fluorescent probe (RBLS) based on rhodamine derivatives was synthesized for the transient detection of mercury ions. The closed-on structure can realize reversible sensor recovery by adding S2-. The superior imaging capability in living cells and in vivo in zebrafish holds promise for biological applications. In addition, the naked eye test strips prepared with RBLS probes can be used to detect and screen Hg2+ in the environment and show good gradient change performance.

Recent Progress on Fluorescent Probes in Heavy Metal Determinations for Food Safety: A Review

One of the main challenges faced in food safety is the accumulation of toxic heavy metals from environmental sources, which can sequentially endanger human health when they are consumed. It is invaluable to establish a practical assay for the determination of heavy metals for food safety. Among the current detection methods, technology based on fluorescent probes, with the advantages of sensitivity, convenience, accuracy, cost, and reliability, has recently shown pluralistic applications in the food industry, which is significant to ensure food safety. Hence, this review systematically presents the recent progress on novel fluorescent probes in determining heavy metals for food safety over the past five years, according to fluorophores and newly emerging sensing cores, which could contribute to broadening the prospects of fluorescent materials and establishing more practical assays for heavy metal determinations.

A core-shell structure ratiometric fluorescent probe based on carbon dots and Tb3+ for the detection of anthrax biomarker

A novel core-shell structure ratiometric fluorescent probe was developed, which can selectively and sensitively detect 2,6-dipicolinic acid (DPA) as an anthrax biomarker. Carbon dots (CDs) was embedded into SiO₂ nanoparticles, which was acted as an internal reference signal. Tb³⁺ with green emission was connected to the carboxyl functionalized SiO₂, which was acted as a responsive signal. With the addition of DPA, the emission of CDs at 340 nm was unchanged, while the fluorescence of Tb³⁺ at 544 nm was enhanced by the antenna effect. In the concentration range of 0.1-2 μM, the fluorescence intensity ratio of I₅₄₄/I₃₄₀ showed a good linear relationship with the concentration of DPA, and the limit of detection (LOD) was 10.2 nM. In addition, the dual-emission probe showed an obvious fluorescence color change from colourless to green with increasing DPA under UV light, which enabled visual detection.

A fluorescence turn-on CDs-AgNPs composites for highly sensitive and selective detection of Hg2

In this paper, a simple and effective fluorescence turn-on approach for highly sensitive and selective monitoring Hg²⁺ ions was designed by using carbon dots (CDs) and silver nanoparticles (AgNPs). It reveals that the fluorescence of CDs solution can be quenched in the presence of AgNPs through inner filter effect (IFE) and the quenched CDs-AgNPs system is turned on after addition of Hg²⁺ ions, which is due to higher affinity of Hg²⁺ and AgNPs than that of CDs and AgNPs, thus resulting the disappearance of AgNPs from the CDs-AgNPs composites and leading to the fluorescence turn-on of CDs. The developed fluorescence turn-on approach exhibited high selectivity and sensitivity for detection of Hg²⁺. Under the optimum experimental conditions, good linearity was achieved over the range of 100-160 μM and the limit of detection (LOD) was estimated to be 2.22×10^-8 M for Hg²⁺. The recoveries of Hg²⁺ spiked in real samples ranged from 98.4% to 101.6%. Results of this study suggest that the fluorescence turn-on approach can be used to the detection of Hg²⁺ in real water samples.

A simple sensitive ratiometric fluorescent probe for the detection of mercury ions in living cells and zebrafish

Mercury, as a highly toxic heavy metal, can cause very serious harm to human health and even death in severe cases. Therefore, we synthesized a novel ratiometric fluorescent probe for detecting mercury ions, with mercaptoethanol as the recognition receptor. Probe CMER could determine mercury ions in 0-1.6 μM and the detection limit is 7.6 nM. Moreover, CMER manifested a fast response for Hg²⁺ (within 5 s) and simultaneously observed that the color changed from light yellow to orange by naked eye. In addition to these preeminent spectral properties, the probe also had satisfactory bioimaging results in RAW 264.7 macrophage cells and zebrafish.

Coumarin Thiourea-Based Fluorescent Turn-on Hg2+ Probe That Can Be Utilized in a Broad pH Range 1-11

A novel coumarin-thiourea conjugate was synthesized facilely. It served as a fluorescent turn-on chemosensor for selective detection of Hg²⁺ ion over other common competitive metal ions including Li⁺, Na⁺, K⁺, Ag⁺, Cu²⁺, Fe²⁺, Zn²⁺, Co²⁺, Ni²⁺, Mn²⁺, Sr²⁺, Ca²⁺, Mg²⁺, Al³⁺, Cr³⁺ and Fe³⁺ ions based on the Hg²⁺-promoted desulfurization and cyclization reactions. Addition of Hg²⁺ ion to the sensor solution in 2:8 EtOH/H₂O induced a hypsochromic shift of the UV-Vis absorption band from 360 nm to 340 nm accompanying distinct enhancement in the absorption intensity while addition of other metal ions failed to bring about substantial change in the absorption spectra. Addition of Hg²⁺ to the sensor solution also caused marked increase in the fluorescence emission intensity and most common competitive metal ions did not interfere with the selective sensing of Hg²⁺ ion by the sensor. The detection limit of Hg²⁺ ion by the probe was calculated to be 1.46 × 10^-7 M and the probe could be utilized for selective detection of Hg²⁺ ion by fluorescence turn-on mode over a broad pH range of 1-11.