Search

As effective methods to accurately and rapidly detect protamine remains a major challenge, here we present a fluorescent protein chromophore‐based probe (IDL‐FP) utilizing twisted‐intramolecular charge transfer (TICT) to detect protamine. The introduction of an electron‐donor group 4‐dimethylaminobenzaldehyde extends the emission wavelength of IDL‐FP to the red region. The deprotection of t‐butyloxy carbonyl groups can then generate an electronegative carboxyl group, which promotes the binding to protamine via electrostatic attraction. Thus, IDL‐FP is sensitive and specific towards protamine and can serve as a highly selective detector for protamine with a detection limit as low as 8.87 ng/mL. As IDL‐FP exhibited good stability in physiological pH environment, we successfully apply IDL‐FP to detect spiked‐in protamine in human serum. In summary, probe IDL‐FP is a promising tool for the quantitative determination of protamine. [ABSTRACT FROM AUTHOR]

Abstract: A facile and effective synthesis for a wide variety of 4-arylidene-5-imidazolinone derivatives was developed. 4-Arylidene-5-oxazolinones were prepared by Erlenmeyer azlactone synthesis from N-acylglycines and arylaldehydes. The ring-opening reactions of the 4-arylidene-5-oxazolinones with primary amines afforded 2-acylamino-3-arylacrylamides in excellent yields. A new dehydrative cyclization of the 2-acylamino-3-arylacrylamides in pyridine under reflux furnished the corresponding 4-arylidene-5-imidazolinones in good yields. [Copyright &y& Elsevier]

Many incurable or unmanageable human protein conformational diseases are associated with the misfolding or aggregation of the aberrantly processed or mutant proteins. In this work, we report an aggregation-induced emission (AIE) derivative of fluorescent protein chromophore used to detect the insoluble protein aggregates in live cells. Based on the 4-hydroxybenzylidene-imidazolinone (HBI), we designed and synthesized a series of AIEgens that span a wide range of viscosity coefficients (χ), thus mimicking the viscous microenvironment of a wide variety of amorphous protein aggregates. The mechanism of these AIEgens were systematically investigated using a combination of photophysical studies, computational analyses and structure-function studies. With the aid of the AggTag method, the optimized probe was used to realize the imaging of the aggregated proteome under the control of the proteostasis network. Besides, we also described the formation and decomposition of protein aggregates under the control of small molecule proteostasis regulators. Briefly, we developed a series of AIEgens that explore varying viscosity sensitivities to visualize protein aggregation in live cells as well as study other biological processes that associated with local viscosity changes. • Low HOMO-LUMO energy gap and tight packing inside the crystal helps to improve the viscosity sensitivity of AIEgens. • AggTag method is a facile and effective way to realize the imaging of protein aggregates. • P1-Halo can visualize the insoluble aggregates in live cells. [ABSTRACT FROM AUTHOR]

The green fluorescent protein (GFP) chromophore has been widely applied as a biological marker or viscosity sensor. However, modulation of GFP chromophore for photodynamic therapy (PDT) has rarely been reported. Inspired by this, through the unique phenothiazine-anchored strategy, a near-infrared emission photosensitizer Lys-PtzFP was designed and synthesized to achieve this process. The maximum absorption wavelength of Lys-PtzFP was 460 nm and the corresponding molar extinction coefficient was 6.60 × 104 M−1 cm−1 in MeOH. The maximum emission wavelengths of Lys-PtzFP was at 725 nm. The photosensitizer Lys-PtzFP showed a high singlet oxygen quantum yield (Φ Δ = 0.42) and low fluorescence quantum yield (φ F = 0.002) in MeOH. Besides, Lys-PtzFP possessed high specificity for lysosomes with negligible dark cytotoxicity (MTT assay >94.6%), good photostability and low half-maximal inhibitory concentration (IC 50) of 0.93 μM. Finally, the intracellular photodynamic therapy experiments revealed that Lys-PtzFP can produce singlet oxygen in lysosomes and induce apoptosis under irradiation. In conclusion, Lys-PtzFP could be a promising photosensitizer for PDT and two-photon imaging applications. This type of photosensitizer can inspire the development of new photosensitizers for further explore highly efficient PDT. • Heavy atom-free photosensitizer, Φ Δ = 0.42, IC 50 = 0.93 μM. • Phenothiazine-GFP chromophore with near-Infrared emission of 725 nm. • Two-photon fluorescent imaging. [ABSTRACT FROM AUTHOR]

An aggregation-induced emission (AIE) fluorescent protein chromophore-based probe (CBZ-FP) for detection of human carboxylesterases (CESs) was designed and synthesized. CBZ-FP exhibited good cell permeability with a large stokes shift (116 nm) and can be applied to reveal the actual activities of CES1 in living cells associated with pesticides detoxification process. CBZ-FP can also serve as a fluorescence indicator of pesticide exposure in the way of hydrolyzing the carboxylic acid ester group in CBZ-FP. Therefore, CBZ-FP has high selectivity for CESs and can detect real-time activity of CES1 in biological samples. Molecular docking study was used to explore the binding of CESs and CBZ-FP. Finding that only one specific activity site of CESs can bind with probe. In view of the fact that, the biotransformation of drugs and poisons containing ester groups can carry out normally depending on CESs, Carboxylesterase probes are expected to contribute to the characterization of relevant disease. [Display omitted] • An aggregation-induced emission (AIE) fluorescent protein chromophore-based probe (CBZ-FP) for detection of human carboxylesterase 1 (CES1) as well as pesticide residue carbaryl was designed and synthesized. • CES1 and carbaryl can be quantitatively determined by CBZ-FP, which is believed due to hydrolyzing the carboxylic acid ester group in CBZ-FP by CES1. • CBZ-FP further exhibits good cell permeability as well as good tolerance towards wide pH variations, and can be applied to monitor the real activities of CES1 in living cells. • Molecular docking study shows that only one specific activity site of CES1 can bind with probe before and after hydrolysis. [ABSTRACT FROM AUTHOR]

Herein, a lysosomal targeting LysFP@ZIF-8 metal-organic framework (MOF) was fabricated using fluorescent protein chromophore-based probe (LysFP) for selectively detection of carboxylesterase 1 (CES1) in living cells. Unlike the regular small molecule fluorescent probes, LysFP@ZIF-8 showed wide range pH tolerabiligy, high selectivity and sensitivity to CES1 in bio-samples, and was successfully applied to achieve the visual monitoring of CES1 activity in living cells. Low detection limit and high fluorescence quantum yield was calculated as 79 ng/mL and 0.76 for LysFP@ZIF-8, respectively. Furthermore, LysFP@ZIF-8 can also serve as a fluorescence indicator of organophosphates pesticide exposure in the way of hydrolyzing the carboxylic acid ester group in LysFP. This type of probe can inspire the development of fluorescent tools for further explore many pathological processes. ga1 • A LysFP@ZIF-8 metal-organic framework (MOF) was fabricated for selectively detection of carboxylesterase 1 (CES1). • LysFP@ZIF-8 with lysosome labeling ability and can be used for monitoring CES1 activities in living cells. • LysFP@ZIF-8 was successfully applied to the quantitative detection of endogenous and exogenous carboxylesterase 1. • LysFP@ZIF-8 has been successfully used as an effective tool in pesticide residue detection. [ABSTRACT FROM AUTHOR]

Designing fluorescent probe for detecting carboxylesterase 1 is remains challenging. Herein, a red emission human carboxylesterase 1 (CES1) probe (CAE-FP) was synthesized based on fluorescent protein chromophore. Probe CAE-FP can specific detect human CES1 with high selectively. The fluorescence quantum yield was calucated as 0.19. The carboxylic acid ester in CAE-FP could be easily hydrolyzed by CES1 under physiological conditions, and this process could induce the obvious fluorescence signal in red emission region. The detection limit of CES1 was calculated as 84.5 ng/mL. Due to the biological detoxification mechanism of carboxylesterase and the obvious inhibitory effect of pesticides on its activity, CAE-FP was applied to detect carbamate pesticide and have achieved good application results. Since fluorescent protein chromophore has excellent biocompatibility, probe CAE-FP with good cell membrane permeable and was successfully applied to monitor the real activities of CES1 in living cells. In summary, this is one of the few reported fluorescent probes that can specific detect the real-time activity of CES1 in biological samples. Besides, we first applied the fluorescent protein chromophore to construct the specific target enzyme probe. This work would contribute to further investigate CES1-associated physiological and pathological processe. Image 1 • A red emission carboxylesterase 1 (CES1) probe (CAE-FP) was developed based on fluorescent protein chromophore. • CAE-FP could selectively detect CES1 from other hydrolytic esterases with fluorescence enhancement phenomenon. • CAE-FP exhibits a good linear relationship with the concentrations of CES1 and carbaryl, from which CAE-FP could quantitatively detect CES1 and carbaryl. • CAE-FP could monitor the real-time activities of CES1 in biological samples. [ABSTRACT FROM AUTHOR]

Hypochlorous acid (HOCl/ClO−), a reactive oxygen species (ROS), plays an indispensable role in the human immune system. In this article, a novel red-emission phenothiazine fluorescent protein chromophore RFP-Ptz was developed for the detection of HOCl in cells. In the presence of HOCl, the fluorescence signal 610 nm rose gradually and reached its plateau with 15-fold enhancement; the fluorescence quantum yield increased from 0.01 to 0.12. The electrophilic substitution of Cl+ towards phenolic hydroxyl group made the probe exhibited a high selective fluorescence response with a limit of detection (LOD) of 6.76 × 10−7 M over other analyte species and ROS. This recognition mechanism of oxygen‒chlorine bond (O–Cl) formation has confirmed by HRMS. Finally, the RFP-Ptz can be used to response HOCl with low cytotoxicity and good biocompatibility (MTT cytotoxicity assay > 89.5%). The biocompatible RFP-Ptz was successfully applied to the fluorescence imaging of HOCl-related in SGC-7901 cells. The chemical modulation of GFP on detecting HOCl based on an unusual sensing mechanism of oxygen‒chlorine bond (O–Cl) formation, and its imaging applications in SGC-7901 cells. Image 1 • A red-emission fluorescent protein chromophore RFP-Ptz was developed. • RFP-Ptz can detect HOCl in living cells. • Unusual mechanism of oxygen‒chlorine bond formation was confirmed. • RFP-Ptz exhibit low cytotoxicity and good biocompatibility. [ABSTRACT FROM AUTHOR]