Ultrasensitive fluorescent probe for visual biosensing of esterase activity in living cells and its imaging application

The potential of glycinin basic peptide derived from soybean as a promising candidate for the natural food additive and preservative: A review

Glycinin basic peptide (GBP) is the basic polypeptide of soybean glycinin that is isolated using cheap and readily available raw materials (soybean meals). GBP can bear high-temperature processing and has good functional properties, such as emulsification and adhesion properties et al. GBP exhibits broad-spectrum antimicrobial activities against Gram-positive and Gram-negative bacteria as well as fungi. Beyond that, GBP shows enormous application potential to improve the quality and extend the shelf life of food products. This review will systematically provide information on the purification, physicochemical and functional properties of GBP. Moreover, the antimicrobial activities and multi-target antimicrobial mechanism of GBP as well as the applications of GBP in different food products are also reviewed and discussed in detail. This review aims to offer valuable insights for the applications of GBP in the food industry as a promising natural food additive and preservative.

New Advances in the Exploration of Esterases with PET and Fluorescent Probes

Esterases are hydrolases that catalyze the hydrolysis of esters into the corresponding acids and alcohols. The development of fluorescent probes for detecting esterases is of great importance due to their wide spectrum of biological and industrial applications. These probes can provide a rapid and sensitive method for detecting the presence and activity of esterases in various samples, including biological fluids, food products, and environmental samples. Fluorescent probes can also be used for monitoring the effects of drugs and environmental toxins on esterase activity, as well as to study the functions and mechanisms of these enzymes in several biological systems. Additionally, fluorescent probes can be designed to selectively target specific types of esterases, such as those found in pathogenic bacteria or cancer cells. In this review, we summarize the recent fluorescent probes described for the visualization of cell viability and some applications for in vivo imaging. On the other hand, positron emission tomography (PET) is a nuclear-based molecular imaging modality of great value for studying the activity of enzymes in vivo. We provide some examples of PET probes for imaging acetylcholinesterases and butyrylcholinesterases in the brain, which are valuable tools for diagnosing dementia and monitoring the effects of anticholinergic drugs on the central nervous system.

A novel indene-chalcone-based fluorescence probe with lysosome-targeting for detection of endogenous carboxylesterases and bioimaging

An indene-chalcone-based fluorescence probe 1 was synthesized and characterized. Under physiological conditions (containing 5% DMSO), probe 1 showed satisfactory stability with a low background signal and recognized carboxylesterases (CEs) based on the catalytic hydrolysis of ester groups, releasing a significant green fluorescence. Probe 1 presents several features including a short response time (within 20 min), low detection limit (1.3 × 10^-4 U/mL) and large stokes shift (over 155 nm). Notably, commercial lysosomal dye co-staining experiments illustrated the lysosomal localization function of 1, with the probe also being used for cell and zebrafish imaging of endogenous CEs.

A dual-response fluorescent probe for discriminative sensing of hydrazine and bisulfite as well as intracellular imaging with different emission

Bisulfite and hydrazine are harmful to the environment safety and human health. Therefore, it is of great value to develop a smart fluorescent probe with high selectivity for detection of bisulfite and hydrazine. In our report, a dual-response fluorescent probe EDBI with high selectivity, rapid response, and low detection limit for discriminative determination HSO₃^- and N₂H₄ was exploited. The probe EDBI is capable of distinctive sensing HSO₃^- and N₂H₄ based on nucleophilic addition reactions by taking advantage of ratiometric fluorescence and fluorescence "on-off" mode, respectively. The dual-responses behaviors of probe EDBI toward HSO₃^- and N₂H₄ were attribute to different reaction sites, which it has been confirmed by HRMS. More importantly, cytotoxicity experiment authenticated that probe possesses low toxicity and good penetration. The probe EDBI with excellent performance, it was successfully employed to distinguishable sense HSO₃^- and N₂H₄ in living cells by diverse channel patterns. Therefore, this simple dual-response fluorescence probe is expected to be used for real-time monitoring bisulfite and hydrazine in biological samples.

The sensing mechanism of fluorescent probe for PhSH and the process of ESIPT

The detection mechanism of fluorescent probe FQ-DNP (DNP: 2,4-dinitropheno) for PhSH and the detailed ESIPT process of its product 2-(6-(diethylamino) quinolin-2-yl)-3-Hydroxy-4H-chromen-4-one (FQ-OH) have been revealed by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). For FQ-OH, the decreased bond length of H₆-N₇ and RDG analysis illustrate that the strength of hydrogen bond H₆-N₇ has been enlarged after photoexcitation, creating a good condition for ESIPT. To illustrate the ESIPT process in detail, the potential energy curves are performed and the transition state reaction energy is calculated. In the S₀ state, the FQ-OH could happen proton transfer (PT) to form keto, but the keto form is more unstable than enol form. After photoexcitation, in the S₁ state, FQ-OH could happen PT to produce stable keto form. Excited dynamic simulation shows that PT happens at 71.5 fs. The calculated absorption and emission spectra are in agreement with the experimental data, and the calculated Stokes shift is 160 nm. Frontier molecular orbitals (FMOs) and hole-electron analysis show that twisted intramolecular charge transfer (TICT) is responsible for the fluorescent quenching of FQ-DNP.