Surfactant Aggregates Encapsulating and Modulating: An Effective Way to Generate Selective and Discriminative Fluorescent Sensors

The heterogeneous structure and dynamic balancing nature of surfactant aggregates make them attractive in developing fluorescent sensors. They can provide a number of advantages, e.g., enhanced fluorescence stability and quantum yield, detection capability in aqueous solutions, and easy operation. Thus, various strategies have been used to construct surfactant aggregate-based fluorescent sensors. Surfactant aggregates play various roles in different strategies and realize multiple sensing behaviors. Many new functions have been discovered for surfactant aggregates in constructing fluorescent sensors. In this feature article, we briefly summarize the development of surfactant aggregate-based fluorescent sensors and their applications in three different types of sensing: selective sensing, multiple analyte sensing, and cross-reactive sensing. For each type of sensing, the design strategies and the roles of surfactant aggregates are particularly introduced. An understanding of these aspects will help to expand the applications of surfactant assemblies in the sensing field.

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

Mercury (Hg) is one of the major toxic heavy metals, harmful to the environment and human health. Thus, it is significantly important to find an easy and quick method to detect Hg²⁺. In this study, we designed and synthesized a simple fluorescent probe with excellent properties, such as high sensitivity and selectivity, rapid response, and outstanding water solubility. When Hg²⁺ (5 μM) was added to the probe solution, it exhibited a very large fluorescent enhancement (about 350-fold stronger than the free probe) with the help of hydrogen peroxide (H₂O₂). Probe HCDC could quantitatively detect Hg²⁺ in the range of 0–10 μM using the fluorescence spectroscopy method and the detection limit was measured to be about 0.3 nM (based on a 3σ/slope). Analytical application was also studied, and the probe HCDC exhibited excellent response to Hg²⁺ with the addition of H₂O₂ in real water samples. So, our proposed probe HCDC provided a practical and promising method for determining Hg²⁺ in the environment.

A novel water-soluble, highly selective and sensitive rapid-response fluorescent probe was developed to monitor mercury ions in real water samples.

Zinc(II) Ion Sensing in Aqueous Micellar Solution Using Modified Bipyridine-Based "Turn-On" Fluorescent Probes and its Application in Bioimaging

The bipyridine-based constructs 4-(pyridine-2-yl)-3H-pyrrolo[2,3-c]quinoline (PPQ) and [6-(3H-pyrrolo[2,3-c]quinolin-4-yl)pyridin-2-yl]methanol (PPQ-OH) and their assemblies with surfactants are evaluated as turn-on fluorescent sensors for Zn²⁺ ions in aqueous solution. This study strives to overcome the problem of low water solubility of the hydrophobic PPQ and PPQ-OH by using micelles. Whereas the ligands show selective sensing behavior for Zn²⁺ over important biological cations including Na⁺ , K⁺ , Ca²⁺ , Mg²⁺ in anionic sodium dodecyl sulfate and non-ionic Tween 80 micelles, no Zn²⁺ sensing is observed in cationic cetyltrimethylammonium bromide micelles. Unlike in DMF, Cd²⁺ interference is observed in aqueous conditions, which can be avoided either by performing the study at pH≥9 or by carrying out a time-resolved fluorescence study. Analysis of the Job plot data, the fluorescence lifetimes, and experiments on varying micellar shape and pH, confirms that the coordination volume of the resulting octahedral metal complex and formation of a five-membered chelate ring are critical factors for Cd²⁺ interference. The described sensing systems are capable of detecting Zn²⁺ ions at the micromolar level. Additionally, it is shown that PPQ and PPQ-OH can be used to detect Zn²⁺ in HeLa cells under physiological conditions in bioimaging studies.

Triphenylphosphine-assisted highly sensitive fluorescent chemosensor for ratiometric detection of palladium in solution and living cells

A triphenylphosphine-assisted highly sensitive fluorescent chemosensor for ratiometric detection of palladium in solution and living cells was developed.

A facile naphthalene-based fluorescent chemodosimeter for mercury ions in aqueous solution

A facile naphthalene-based fluorescence “turn-on” chemodosimeter for rapid, selective and sensitive detection of Hg²⁺ by mercury-promoted hydrolysis of the vinylether group has been reported.

Functionalizable red emitting calcium sensor bearing a 1,4-triazole chelating moiety

Herein we developed a functionalizable OFF–ON red emitting fluorescent calcium probe based on a new chelating system formed by CuAAC click chemistry (Huisgen cycloaddition).

A highly sensitive hemicyanine-based fluorescent chemodosimeter for mercury ions in aqueous solution and living cells

A novel hemicyanine-based fluorescence turn-on chemodosimeter for Hg²⁺ by mercury triggered hydrolysis of vinyl ether group has been reported.