Spectroscopic Study of a Novel Binaphthyl Amine Fluorescent Probe for Chiral Recognition of D/L-Lysine

Lysine plays a crucial role in promoting development, enhancing immune function, and improving the function of central nervous system tissues. The two configurational isomers of amino acids have significantly different effects. Currently, methods for chiral recognition of lysine have been reported; however, previous detection methods have drawbacks such as expensive equipment and complicated detection processes. Fluorescence analysis, on the other hand, boasts high sensitivity, strong selectivity, and simple operation. In this study, we synthesized four novel Binaphthyl-Amine (BINAM)-based fluorescent probes capable of specifically identifying the L-configuration of lysine among the twenty amino acids that constitute human proteins. The enantiomeric fluorescence enhancement ratio (ef or ΔIL/ΔID) reached up to 15.29, demonstrating high enantioselectivity. In addition, we assessed the probe's recognition capabilities under varying pH levels, reaction times, and metal ion conditions, along with its limit of detection (LOD) and quantum yield. Our results suggest that this probe serves as a highly stable tool for the detection of chiral lysine.

Selective pyrophosphate detection via metal complexes

Pyrophosphate (PPi) anions are crucial in numerous biological and ecological processes involved in energy conversion, enzymatic reactions, and metabolic regulation along with adenosine. They are also significant biological markers for various processes related to diseases. Fluorescent PPi sensors would enable visual and/or biological detection in convenient settings. However, the current availability of commercial sensors has been limited to costly enzymes that are not compatible for imaging. Sensor development has also encountered challenges such as poor selectivity and stability, and limited practical applications. In this review, we analyze the situation of PPi sensing via commercial kits and focus on sensors that use metal complexes. We address their designs, sensing mechanisms, selectivities and detection limits. Finally, we discuss limitations and perspectives for PPi detection and imaging.

Azulene-based fluorescent chemosensor for adenosine diphosphate

AzuFluor® 435-DPA-Zn, an azulene fluorophore bearing two zinc(II)-dipicolylamine receptor motifs, exhibits fluorescence enhancement in the presence of adenosine diphosphate. Selectivity for ADP over ATP, AMP and PPi results from appropriate positioning of the receptor motifs, since an isomeric sensor cannot discriminate between ADP and ATP.

Turn-on detection of assorted phosphates by luminescent chemosensors

This review illustrates a variety of luminescent chemosensors for the selective detection of assorted phosphates via the “Turn-On” emission mechanism with focus on their design aspects, chemical structures and sensing mechanism.

A NIR Turn-on Fluorescent Sensor For Detection of Chloride Ions in vitro and in vivo

As the most abundant and significant anions in biosystem, chloride ions (Cl^-) participate in many important physiological processes. Thus, designing and synthesizing of a simple, sensitive, selective and long wavelength turn-on sensor for the detection and imaging of Cl^- in vitro and in vivo is very necessary. Herein, we have developed a simple porphyrin turn-on sensor 5, 10, 15, 20-Tetrakis (4-hydroxyphenyl) porphyrin (THPP) with near infrared emission wavelength (657 nm) for sensing chloride ions with remarkable sensitivity and selectivity. The detection of chloride ions was according to metal displacement assay (MDA) under physiological condition with a detection limit of 7.5 μM, and was applied to image Cl^- in vitro and in vivo successfully.

A novel platform self-assembled from squaraine-embedded Zn(ii) complexes for selective monitoring of ATP and its level fluctuation in mitotic cells

Using multiple interactions, a simple self-assembly based on a Zn(ii) coordination compound and squaraine () demonstrated a selective turn-on fluorescence response to ATP in the near infrared (NIR) region. More importantly, the self-assembly has been successfully applied to ATP imaging in the mitochondria of the gastric cancer cell line SGC-7901 and monitoring of level fluctuation of ATP during the mitotic period.

Fluorescence Sensing of Inorganic Phosphate and Pyrophosphate Using Small Molecular Sensors and Their Applications

The aim of this contribution is to provide an introduction and a brief summary of the principle of fluorescence molecular sensors specific to inorganic phosphate (Pi) and inorganic pyrophosphate (PPi) as well as their applications. In our introduction we describe the impact of both Pi and PPi in the living organism and in the environment, followed by a description of the principle of fluorescence molecular sensors and the sensing mechanism in solution. We then focus on exciting research which has emerged in recent years on the development of fluorescent sensors specific to Pi and PPi, categorized by chemical interactions between the sensor and the target molecule, such as hydrogen bonding, coordination chemistry, displacement assay, aggregation induced emission or quenching, and chemical reactions.

Hexaphenylbenzene-based fluorescent aggregates for detection of zinc and pyrophosphate ions in aqueous media: tunable self-assembly behaviour and construction of a logic device

The aggregates of HPB derivative 7 exhibited “on–on” response towards Zn²⁺ ions and this in situ prepared 7-Zn2+ ensemble was utilized as a “not quenched” probe for detection of PPi ions in aqueous media.

Synthesis of functionalized fluorescent gold nanoclusters for acid phosphatase sensing

A novel and convenient one-pot but two-step synthesis of fluorescent gold nanoclusters, incorporating glutathione (GSH) and 11-mercaptoundecanoic acid (MUA) as the functionalized ligands (i.e. AuNCs@GSH/MUA), is demonstrated. Herein, the mixing of HAuCl4 and GSH in aqueous solution results in the immediate formation of non-fluorescent GSH-Au(+) complexes, and then a class of ∼2.6 nm GSH-coated AuNCs (AuNCs@GSH) with mild orange-yellow fluorescence after several days. Interestingly, the intense orange-red emitting ∼1.7 nm AuNCs@GSH/MUA can be synthesized within seconds by introducing an alkaline aqueous solution of MUA into the GSH-Au(+) complexes or AuNC@GSH solution. Subsequently, a reliable AuNC@GSH/MUA-based real-time assay of acid phosphatase (ACP) is established for the first time, inspired by the selective coordination of Fe(3+) with surface ligands of AuNCs, the higher binding affinity between the pyrophosphate ion (PPi) and Fe(3+), and the hydrolysis of PPi into orthophosphate by ACP. Our fluorescent chemosensor can also be applied to assay ACP in a real biological sample and, furthermore, to screen the inhibitor of ACP. This report paves a new avenue for synthesizing AuNCs based on either the bottom-up reduction or top-down etching method, establishing real-time fluorescence assays for ACP by means of PPi as the substrate, and further exploring the sensing applications of fluorescent AuNCs.

Tetraphenylethene-pyridine salts as the first self-assembling chemosensor for pyrophosphate

We presented a novel approach for pyrophosphate (PPi) sensing. Two tetraphenylethene (TPE)-functionalised pyridine salts (TPM and TPH) were designed and synthesized. Both of them exhibited weak emission in the solution state that originates from intramolecular charge transfer (ICT) from TPE to the pyridine; the addition of PPi into the TPM aqueous solution would enhance the fluorescence intensity, which eliminates the emission quenching effect of the iodide ion by the formation of PPi-sensor nanoparticles. The detection limit of TPM was determined to be as low as 133 nM. Meanwhile, a thin solid film of TPM that could detect PPi rapidly was conveniently prepared.