Oxidative stress in neurodegeneration: cause or consequence?

Due to the risks that water contamination implies for human health and environmental protection, monitoring the quality of water is a major concern of the present era. Therefore, in recent years several efforts have been dedicated to the development of fast, sensitive, and selective sensors for the detection of heavy metal ions. In particular, fluorescent sensors have gained in popularity due to their interesting features, such as high specificity, sensitivity, and reversibility. Thus, this review is devoted to the recent advances in fluorescent sensors for the monitoring of these contaminants, and special focus is placed on those devices based on fluorescent aptasensors, quantum dots, and organic dyes.

https://www.mdpi.com/1424-8220/19/3/599/pdf

Fluorescent Sensors for the Detection of Heavy Metal Ions in Aqueous Media.

In this work, a new phenazine-based derivative ( L-1 ) which based on 2,3-diamino-phenazine and 5-(4-chlorphenyl)-2-furaldehyde was designed to act efficiently in a chemodosimeter approach for the rapid and selective detection of silver ion in aqueous solution over a wide pH range. The addition of Ag + to an aqueous solution of L-1 induced a change in the solution color from yellow to shallow orange and fluorescent quenching, indicating that L-1 could act as an excellent ON−OFF-type fluorescent chemosensor for Ag + . With a detection limit of 3.25 × 10 −7  M, the chemosensor shows great potential to monitor Ag + in environmental analysis systems. Furthermore, this sensor can serve as a recyclable component in sensing materials. These properties make L-1 act as an accurate Ag + controlled ON−OFF−ON fluorescence switch and implication (IMP) function logic gate. In addition, the actual usage of sensor L-1 was further demonstrated by test kits and silica gel plates. Notably, the stoichiometry of the complexes between the sensor and Ag + is indicative of a 2:1 ratio which was determined by a Job's plot yielded from fluorescence titrations. And the mode of interaction between Ag + ions and L-1 has been supported by 1 H NMR spectroscopy and mass spectrometry studies.

A colorimetric and reversible fluorescent chemosensor for Ag+ in aqueous solution and its application in IMPLICATION logic gate

Sulfur-based fluorescent probes for HOCl: Mechanisms, design, and applications

Two fluorescein-based fluorescent chemosensors L1 and L2 have been synthesized successfully by simultaneously introducing two functional groups as metal ion bonding sites on the 4,5-positions of fluorescein via a one-pot Mannich-type reaction The chemosensors exhibit high selectivity and sensitivity for Ag+ ions due to the high thiophility and selenophility of silver ions The detection mechanism is based on the Ag+-induced ring opening process of the spironolactone of the fluorescein fluorophore The stoichiometry of the complex between the sensor and Ag+ is indicative of a 1 : 2 ratio which was determined by a Job's plot yielded from fluorescence titrations

Preparation of fluorescein-based chemosensors and their sensing behaviors toward silver ions

A ratiometric fluorescent probe for hypochlorous acid and its biological applications

Because of their high extinction coefficients, high quantum yields, and reasonable water solubility, xanthene dyes have played crucial roles in the field of molecular imaging as fluorescent tracers. In this work, a novel hydroxyl regioisomeric rhodol 1 has been designed and synthesized. Both absorption and fluorescence data in water revealed that the rhodol isomer 1 can generate stable optical signals in the pH range 4–10. The maximum absorbance wavelength (ca. 540 nm) of 1 meets perfectly the discrete excitation of the laser at 539 nm, and the emission maximum wavelength (ca. 590 nm) is largely red shifted compared to that of the rhodol fluorophore (ca. 540 nm). Meanwhile, the dye could be easily designed to form chemodosimeters or probes by modification of the carboxyl group or the hydroxyl group. The hydrazide derivative and the silyl ether derivative of the dye in aqueous media exhibited excellent selectivity and sensitivity toward Hg2+ and F−, respectively. Thus, the excellent optical properties and chemical properties of this dye allow it to be designed as a fluorescent tracer for biological applications.

Design and synthesis of a rhodol isomer and its derivatives with high selectivity and sensitivity for sensing Hg2+ and F− in aqueous media

The invention discloses a preparation method of a pH-stable xanthene dye fluorescent probe. Compared with seminaphtho fluorescein and seminaphthorhodamine type fluorescent dyes, the seminaphthorhodamine type xanthene fluorescent probe material has stable pH fluorescence opening effects in a water phase under different pH conditions due to limitation of a self conjugated system structure, and the xanthene fluorescent dye can be used for preparing a xanthene dye hydrazine derivative for detecting mercury ions. The pH-stable xanthene dye fluorescent probe disclosed by the invention has the advantages of good pH stability and light stability, relatively good water solubility and good cell membrane permeability. Moreover, the hydroxyl position of the xanthene dye and the carboxyl position of the spiro lactone can be easily modified to generate biology-related tracers; the derivative with the hydroxyl position modified by hydrazine has remarkable selective recognition performance for mercury, and can be used as a mercury detecting fluorescent probe very well.

Preparation method and application of pH-stable xanthene dye fluorescent probe

A novel homodimer of the styryldehydropyridocolinium dye (TPTP) has been synthesized and characterized. Free TPTP exhibited low fluorescence quantum yield and large Stokes shift (over 160 nm) in water. However, it showed a significant fluorescence turn-on effect upon intercalation into DNA base pairs. Meanwhile, the fluorescence intensity of the intercalated structures formed by TPTP and DNA decreased quickly upon addition of deoxyribonuclease I, indicating that the dye can be used to monitor deoxyribonuclease I activity and DNA hydrolysis. Electrophoresis analysis revealed that the dye had intercalative binding to DNA and can potentially be used for DNA staining in electrophoresis. Thus, the innate nature of large Stokes shift and excellent fluorescence turn on effect upon interaction with DNA endue the dye with a wide range of applications.

Huirong Yao

Papers

Preparation of fluorescein-based chemosensors and their sensing behaviors toward silver ions

A ratiometric fluorescent probe for hypochlorous acid and its biological applications

Design and synthesis of a rhodol isomer and its derivatives with high selectivity and sensitivity for sensing Hg2+ and F− in aqueous media

Preparation method and application of pH-stable xanthene dye fluorescent probe

A Novel Styryldehydropyridocolinium Homodimer: Synthesis and Fluorescence Properties Upon Interaction with DNA