Search

A rapid and convenient strategy to monitor the productivity of biomanufacturing is essential for the research in optimizing relevant bioprocesses. In this work, we have developed a fluorescein‐derived probe (FL‐DT) that reacts rapidly with thiol groups via 1,4‐Michael addition reaction of the sulfhydryl to unsaturated ketone and releases fluorescence. FL‐DT specifically forms fluorescent adduct with two adjacent thiols in a protein of interest (POI), making the probe a reliable tool for protein quantification. The production of xylanase fused with a short di‐Cys tag was then successfully monitored and quantified with FL‐DT in Escherichia coli system under different protein expression conditions, providing useful information for optimizing the bioprocess. Our work provides a convenient and efficient strategy for POI labeling and monitoring bioproduction. [ABSTRACT FROM AUTHOR]

Albuminuria is a crucial urine biomarker of human unhealthy events such as kidney diseases, cardiovascular diseases, and diabetes. However, the accurate diagnosis of albuminuria poses a significant challenge owing to the severe interference from urine fluorescence and urine drugs. Here, we report a novel flavone-based fluorescent probe, DMC, by incorporating the FA1-targeting methylquinazoline group into a flavone skeleton with the extend π-conjugation. DMC exhibited a rapid response time, high sensitivity, and selectivity towards human serum albumin (HSA) in urine. Moreover, the red-shifted fluorescence and the FA1-targeted HSA-binding of DMC efficiently mitigated the interference from both urine fluorescence and urine drug metabolites. Furthermore, the establishment of a portable testing system highlighted the potential for point-of-care testing, offering a user-friendly and accurate approach to diagnose A2-level and A3-level albuminuria. We expect that the success of this DMC-based diagnostic platform in real urine samples can signify a significant advancement in early clinical diagnosis of albuminuria and its associated diseases. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A new fluorescence turn-on probe for determining fructose is synthesized. • This fructose sensor exhibits new binding modes. • The binding of probe to fructose occurs quickly. • This strategy is successfully used for analysis of fructose in food. • NBD-PQ-B/PEO fiber film realizes on-site detection of fructose conveniently. High fructose intake is an important cause of metabolic disease. Due to the increasing prevalence of metabolic diseases worldwide, the development of an accurate and efficient tool for monitoring fructose in food is urgently needed to control the intake of fructose. Herein, a new fluorescent probe NBD-PQ-B with 7-nitrobenz-2-oxa-1, 3-diazole (NBD) as the fluorophore, piperazine (PQ) as the bridging group and phenylboronic acid (B) as the recognition receptor, was synthesized to detect fructose. The fluorescence of NBD-PQ-B increased linearly at 550 nm at an excitation wavelength of 497 nm with increasing fructose concentration from 0.1 to 20 mM. The limit of detection (LOD) of fructose was 40 μM. The pKa values of NBD-PQ-B and its fructose complexes were 4.1 and 10.0, respectively. In addition, NBD-PQ-B bound to fructose in a few seconds. The present technique was applied to determine the fructose content in beverages, honey, and watermelon with satisfactory results. Finally, the system could not only be applied in an aqueous solution with a spectrophotometer, but also be fabricated as a NBD-PQ-B/polyvinyl oxide (PEO) film by electrospinning for on-site food analysis simply with the assistance of a smartphone. [ABSTRACT FROM AUTHOR]

Two novel fluorescent chemosensors based on the benzothiazole derivative were designed, synthesized, and used as a selective hydrazine sensor in a DMSO and HEPES buffer mixture (10 mM, pH 7.4)(9:1, v/v). The probes displayed high sensitivity and selectivity of hydrazine after adding more than 18 types of analyte. The application of the probes in detecting N 2 H 4 in living cells and in the gas state was also investigated. The single crystal X-ray study of the fluorescent sensor both before and after treatment with N 2 H 4 confirmed the proposed mechanism based on excited state intramolecular proton transfer (ESIPT). [ABSTRACT FROM AUTHOR]

In the present study, a mitochondria-targeted fluorescent probe FL based on fluorescein derivative for hypochlorite sensing was designed and synthesized. The probe FL showed highly selective to HOCl among various reactive oxygen/nitrogen species. With the increasing amount of HOCl from 0 to 50 μM, a linear correlation between the fluorescence intensity of FL at 530 nm and the concentration of HOCl was found. The detection limit is calculated to be 0.068 μM. Furthermore, the probe demonstrated a perfect mitochondria targetable ability and it was successfully applied to image mitochondrial HOCl in living HeLa cells. The success of subcellular imaging indicated that the mitochondria-targetable probe FL might be further used to investigate biological functions and pathological roles of HOCl at organelle levels. [ABSTRACT FROM AUTHOR]

Highly sensitive and selective fluorescent probes 1 and 2 for detection of palladium ions (Pd 2+ ) were synthesized based on excited-state intramolecular proton transfer process (ESIPT) using 2-(2′-hydroxy-)benzothiazole moiety. Different metal ions were used to optimize their sensitivity and selectivity but best results were obtained with Pd 2+ . Probe 1 produced green fluorescence with Stokes shift of about 163 nm upon addition of Pd 2+ , whereas probe 2 displayed red fluorescence with a large Stokes shift of about 217 nm under similar conditions. The detection limits of 1 and 2 to Pd 2+ were found to be 285 nM and 14.6 nM, respectively. Mechanistic aspects of probes 1 and 2 were discussed to account for the optical changes leading to the strong ESIPT fluorescence in very short duration. Furthermore, the portable test strips were also prepared by direct deposition of the probe molecules onto the filter paper to detect the lowest possible ppm levels of Pd 2+ . [ABSTRACT FROM AUTHOR]

In this work, we developed three fluorescent probes ( F-1 , F-2 , and F-3 ) based on fluorescein, mono-formylated fluorescein, and bis-formylated fluorescein for hydrogen sulfide (H 2 S) detection. The probe F-3 , which bears two aldehyde groups, exhibited the fastest response. This fast response is attributed to the ortho effect of the aldehyde group, which enables fast nucleophilic addition of H 2 S to an aldehyde group and subsequent intramolecular thiolysis of dinitrophenyl ether. In addition, the aldehyde groups on F-3 react with biothiols (e.g., cysteine, homocysteine) to form thiazolidine diastereomers, which suppress the fluorescence of fluorescein. The introduction of two aldehyde groups also resulted in high selectivity of F-3 towards H 2 S. Furthermore, good linearity was observed between F-3 fluorescence intensity at 510 nm and H 2 S concentration in the range of 0–10 µM. F-3 exhibited a detection limit as low as 0.024 μM. Confocal laser scanning micrographs of HeLa cells incubated with F-3 confirmed that F-3 is cell-permeable and can successfully detect H 2 S in living cells. [ABSTRACT FROM AUTHOR]

Developing ultraviolet (UV) sensors that can visualize UV light in the environment for productive life has been widely practiced. A challenging problem that arises in this domain is the quantitative analysis of UV light. In this study, we identified a novel naphthalimide derivative, NDGF , which can undergo decomposition to various degrees when irradiated by UV light with different intensities, so as to produce corresponding fluorescence intensities. Moreover, NDGF was prepared as a UV-responsive film NDGF-PEO which also has outstanding competence in the quantification of UV intensity. The surprising thing is that this novel UV-responsive decomposition mechanism of NDGF has been demonstrated and has great potential to open new doors for the development of naphthalimide-based photocages and novel UV quantitative sensors. [Display omitted] • A photocage-type probe NDGF for the detection of UV intensity was prepared. • The novel photolyzed sensing mechanism of NDGF was proved. • NDGF-PEO can reliably quantify UV intensity as a portable fiber film sensor. • NDGF-PEO can respond well to solar UV intensity during one day. [ABSTRACT FROM AUTHOR]

Biological thiols are crucial in biological processes. Therefore, a probe capable of targeting and imaging biothiols in living cells, as well as rapidly labelling the thiols in proteins, is desirable and imperative. Herein, we designed and synthesized FRB-T containing α , β -unsaturated ketones to recognize thiols for detecting biothiols and selectively labelling the sulfhydryl-containing proteins. The probe initially exhibited weak fluorescence and then performed 1, 4-Michael addition reaction between its α , β -unsaturated ketone and thiols, along with the spiro ring-opening, leading to remarkable fluorescence enhancement and colour changes. The specificity of FRB-T towards thiols was high, and its detection limits were 70 nM for cysteine (Cys) and 1.51 μg/mL for ovalbumin (OVA). Furthermore, FRB-T has also been successfully applied to biothiols imaging in Hela cells, and rapid labelling of the sulfhydryl-containing proteins without washing step. [Display omitted] • A biothiol-specific probe with strong fluorescence enhancement and colorimetric response. • The probe owns low LOD of 70 nM and 1.51 μg/mL for Cys and OVA respectively. • A new type of reagent for labelling sulfhydryl-containing proteins without washing. [ABSTRACT FROM AUTHOR]

In this paper, highly sensitive and selective fluorescent probe 1 for GSH is designed and synthesized based on modulation of the excited-state intramolecular proton transfer (ESIPT) process of 2-(2′-hydroxy-3′-ethoxyphenyl)benzothiazole. Upon introducing GSH in neutral solution containing CTAB micelles, dinitrophenyl, the protecting group of the probe, is removed via the nucleophilic substitution, thereby retrieving the ESIPT process of 2-(2′-hydroxy-3′-ethoxyphenyl)benzothiazole, which results in a fluorescence enhancement at 485 nm. Additionally, the fluorescence intensity of the probe is linearly proportional to GSH concentration ranging from 0 to 100 μM and the obtained detection limit is as low as 0.81 μM. The enhanced selectivity toward GSH over Cys and Hcy is also attributed to one more carboxyl group in GSH. Importantly, the probe is successfully utilized for monitoring GSH in living HeLa cells. [ABSTRACT FROM AUTHOR]

A new fluorescein-based probe is found to be sensitive and selective for the detection of hypochlorite anion in aqueous buffer solution. The probe displays high water solubility, pH-independent fluorescence, and biocompatibility. A possible detection mechanism is that HOCl oxidizes the C N bond into aldehyde, resulting in bright emission. Results show that the probe has a 7.3 nM detection limit to hypochlorite anion. In addition, the probe is successfully utilized for monitoring endogenously produced hypochlorite in living macrophage cells upon stimulation. [ABSTRACT FROM AUTHOR]

A new fluorescein-based fluorescent probe for the detection of Au 3+ has been developed. This probe was derived from 4′,5′-fluoresceindicarboxaldehyde and exhibited highly selective and sensitive response toward gold(III) ions in aqueous solution. There is a good linear relationship between the fluorescence intensity at 523 nm and the concentrations of Au 3+ ranging from 0 μM to 60 μM, which makes it effective for the detection of Au 3+ . The limit of detection (LOD) was evaluated to be 0.07 μM based on S/N = 3. The fluorescence enhancement was attributed to the irreversible C N bond hydrolysis that occurred to this probe in the presence of Au 3+ , generating the fluorescent 4′,5′-fluoresceindicarboxaldehyde. Furthermore, the imaging experiments indicated that this probe is cell-permeable and can be used to detect Au 3+ within living cell. [ABSTRACT FROM AUTHOR]

A perylene-based probe was developed for uridine diphosphate (UDP) sensing and cell imaging. The probe presented about 4-fold fluorescence enhancement in the presence or absence of 100 equiv UDP. The selectivity toward UDP over other phosphor-containing anions was observed. The selective UDP sensing was speculated to be related to the binding affinities of Zn 2+ ions in sensor with the uridine and phosphate moieties of UDP. Furthermore, this probe was also applied to image of UDP in living cells. [ABSTRACT FROM AUTHOR]

• Hydrogel microsphere sensor is fabricated by self-assembly method using microfluidic chip. • The sensor exhibits high sensitivity for Al3+ and Hg2+ with a detection limit of 70 nM and 120 nM, respectively. • The hydrogel microsphere sensor are reusable. • The hydrogel microsphere sensor has been successfully applied to the detection of real samples. Traditional fluorescent sensors for simultaneous detection of metal ions require the use of specially designed fluorescent probes. In this manuscript, we have employed a new strategy for the design of a sensor for simultaneous detection of metal ions that is based on a fluorescent probe encapsulated hydrogel matrix. An investigation designed to assess this strategy led to the development of a novel dual fluorescent encapsulated hydrogel microsphere sensor for sensitive and simultaneous detection of Al3+ and Hg2+. The hyperbranched poly (poly (ethylene glycol) diacrylate) (HB-PEGDA) and thiolated sodium alginate (SA-SH) composite hydrogel microspheres used to construct the sensor, which contain two fluorescent probes encapsulated in a highly dense manner, were prepared by using a self-assembly method in conjunction with a microfluidic device. The functionalized hydrogel microspheres were shown to exhibit high selectivity for Al3+ and Hg2+ among various metal ions with a detection limit of 70 nM and 120 nM, respectively. In addition, the hydrogel microspheres can be readily separated from test samples and utilized for repeated use by removing Al3+ and Hg2+ by addition of a solution containing EDTA and KI. Compared with previously devised sensors, the new HB-PEGDA/SA-SH composite hydrogel microspheres containing two encapsulated fluorescent probes are readily prepared and effective for simultaneous detection of two different metal ions. [ABSTRACT FROM AUTHOR]

• A novel method based on an indicator of copper reaction for tracing Cys oxidation process was developed. • The fluorescence alteration mechanism during Cu2+-catalyzed oxidation of cysteine was analyzed. • The different fluorescence alteration trajectories can be applied to discriminate Cys, GSH and Hcy. Using cyanine dye-coupling 2-pyridylmethyl chelating unit as fluorescent probe, we successfully developed an indicator of copper clock reaction to monitor the process of cysteine (Cys) oxidation. During the monitoring assay, the fluorescent changes reflected three sequential reaction and binding behaviors including oxidation of Cys, oxidation of Cu(I) and binding between Cu(II) and the oxidation product cystine (Cys-Cys). Because the different kinetic trajectories were obtained when used Cys, GSH and Hcy as the substrates, respectively, a new strategy for distinguishing Cys from GSH and Hcy was further developed using the cyanine dye-coupling Cu(II) complex. [ABSTRACT FROM AUTHOR]