Synthesis and assembly of ultrathin film of Ni(OH)2 nanoparticles at gas/liquid interface, its high electrocatalytical oxidation toward bio-thiols and selective determination of cysteine

Three asymmetric BODIPY derivatives as fluorescent probes for highly selective and sensitive detection of cysteine in living cells

Biothiols are widely involved in various important physiological activities and play a significant role in maintaining redox homeostasis in living organisms. Herein, we designed and synthesized three new asymmetric fluorescent probes (BDP-S-Ph, BDP-S-ENE and BDP-S-R) to discriminate Cys from Hcy/GSH. These probes reacted with Cys to form meso-amino-BODIPYs via SNAr substitution-rearrangement, thereby inducing a fluorescence turn-on effect. Moreover, they could selectively and sensitively detect Cys in solution with low detection limits (50 nM, 28 nM and 87 nM, respectively). Through comparing the response rates of the three probes to Cys, we concluded that the increase of conformational restrictions led to a decrease in probe reactivity. Besides, the sensing mechanism was demonstrated by mass spectrometry. Furthermore, cell experiments indicated that the probes were able to image exogenous and endogenous Cys through green or red channels in living cells.

BODIPY-based Fluorescent Probe for the Detection of Cysteine in Living Cells

Cysteine (Cys), as one of the important amino acids, plays a vital role in various physiological and pathological processes. Hence, it is meaningful to develop a convenient and sensitive detection method. Herein, a novel BODIPY-based fluorescent probe (BDP-DM) was developed, which had a higher selectivity for Cys than other amino acids, including homocysteine (Hcy) and glutathione (GSH). Ultimately, we concluded that the BDP-DM probe could be used to successfully detected intracellular Cys in living HeLa cells.

Microliter Sample Insulin Detection Using a Screen-Printed Electrode Modified by Nickel Hydroxide

The monitoring of insulin, which is the only hormone that helps regulate blood glucose levels in the body, plays a key role in the diagnosis and treatment of diabetes. However, most techniques today involve complicated electrode fabrication and testing processes, which are time-consuming and costly, and require a relatively large volume of sample. To overcome these drawbacks, we present here a low-cost insulin detection method based on a screen-printed electrode (SPE) modified by nickel hydroxide (Ni(OH)₂). This novel method only requires 300 μL of insulin sample, and the time it takes for electrode preparation is about 12 times shorter than traditional electrode fabrication methods such as coating and sol-gel methods. The electrochemical behaviors of the Ni(OH)₂-coated SPE (NSPE) sensing area in insulin aqueous solutions are studied using cyclic voltammetry, amperometric i-t curves, and electrochemical impedance spectroscopy. The results demonstrate that the NSPE sensing surface has excellent detection properties, such as a high sensitivity of 15.3 μA·μM^-1 and a low detection limit of 138 nM. It takes a short time (∼10 min) to prepare the NSPE sensing surface, and only two drops (∼300 μL) of insulin samples are required in the detection process. Moreover, the selectivity of this method for insulin detection is verified by detecting mixtures of insulin and ascorbic acid or bovine hemoglobin. Finally, we discuss the potential clinical applications of this method by detecting various concentrations of insulin in human serum.

Carbon quantum dot-AgOH colloid fluorescent probe for selective detection of biothiols based on the inner filter effect

Here, we present a selective and sensitive fluorescent probe for the detection and distinction of biothiols, such as glutathione (GSH) and cysteine (Cys). The adsorbance of Cys onto the surface of AgOH colloid could result in enhanced absorbance from 250 to 400 nm in the UV-vis absorption spectrum, while the addition of GSH could dissolve the AgOH colloid resulting in no change in the UV-vis absorption spectrum. Utilizing these different phenomena, two fluorescent probes were established based on the inner filter effect (IFE). The first probe, the "CDs-AgOH colloid" fluorescent probe, was used to quantitatively analyze Cys over a linear concentration range from 33 to 317 μM and a detection limit of 7.2 μM. The second probe, the "CDs-AgOH colloid-Cys" fluorescent probe, was used to quantitatively analyze GSH, with a detection limit down to 3.6 μM, and a linear range of detection of approximately 16.7 to 100 μM. The fluorescent probes were successfully applied for the detection of GSH in a fetal bovine serum (FBS) sample. Based on these results, IFE is considered to be an effective way to distinguish GSH and Cys.

Design and Synthesis of a Fluorescent Probe with a Large Stokes Shift for Detecting Thiophenols and Its Application in Water Samples and Living Cells

A turn-on florescent probe (probe-KCP) was developed for highly selective detection of thiophenols based on a donor-excited photo-induced electron transfer mechanism. Herein, the synthesis of the probe, a chalcone derivative, through a simple straightforward combination of a carbazole-chalcone fluorophore with a 2,4-dinitrophenyl functional group. In a kinetic study of the probe-KCP for thiophenols, the probe displayed a short response time (~30 min) and significant fluorescence enhancement. In selection and competition experiments, the probe-KCP exhibited excellent selectivity for thiophenols over glutathione (GSH), cysteine (Cys), sodium hydrosulfide (NaSH), and ethanethiol (C₂H₅SH) in addition to common anions and metal ions. Using the designed probe, we successfully monitored and quantified thiophenols, which are highly toxic. This turn-on fluorescence probe features a remarkably large Stokes shift (130 nm) and a short response time (30 min), and it is highly selective and sensitive (~160-fold) in the detection of thiophenols, with marked fluorescence in the presence of thiophenols. probe-KCP responds to thiophenols with a good range of linearity (0–15 μM) and a detection limit of 28 nM (R² = 0.9946) over other tested species mentioned including aliphatic thiols, thiophenol analogues, common anions, and metal ions. The potential applications of this carbazole-chalcone fluorescent probe was successfully used to determine of thiophenols in real water samples and living cells with good performance and low cytotoxicity. Therefore, this probe has great potential application in environment and biological samples.

A series of BODIPY-based probes for the detection of cysteine and homocysteine in living cells

Biothiols, such as glutathione (GSH), homocysteine (Hcy) and cysteine (Cys), are important biomarkers and play crucial roles in many physiological processes. Thus, the detection of biothiols is highly important for early diagnosis of diseases and evaluation of disease progression. Herein, new types of BODIPY-based fluorescent probes (probe 1, probe 2 and probe 3) capable of cysteine (Cys)/homocysteine (Hcy) sensing with high selectivity over other amino acids were developed. In addition, we further studied the influence of different electronegativity substituents on these probes to sensing Cys/Hcy. Ultimately, we concluded that the electron withdrawing group on probe 1 can accelerate the probe response to Cys/Hcy, and probe 1 was successfully applied for selective imaging Cys/Hcy in living cells.

A selective colorimetric sensing strategy for cysteine based on an indicator-displacement mechanism

Rapid determination of cysteine in aqueous solution is important for the diagnosis and treatment of some diseases.

A NIR fluorescent chemodosimeter for imaging endogenous hydrogen polysulfides via the CSE enzymatic pathway

Sodium polysulfides (Na₂S_n, n > 1) as important raw materials in the chemical industry can afford hydrogen polysulfides (H₂S_n, n > 1) under physiological conditions.

A new colorimetric and fluorescent probe with a large stokes shift for rapid and specific detection of biothiols and its application in living cells

A new colorimetric and fluorescent probe with a large stokes shift for rapid and specific detection of biothiols, and its application in living cells.

A Two-Photon Fluorescent Probe for Lysosomal Thiols in Live Cells and Tissues

Lysosome-specific fluorescent probes are exclusive to elucidate the functions of lysosomal thiols. Moreover, two-photon microscopy offers advantages of less phototoxicity, better three dimensional spatial localization, deeper penetration depth and lower self-absorption. However, such fluorescent probes for thiols are still rare. In this work, an efficient two-photon fluorophore 1,8-naphthalimide-based probe conjugating a 2,4-dinitrobenzenesulfonyl chloride and morpholine was designed and synthesized, which exhibited high selectivity and sensitivity towards lysosomal thiols by turn-on fluorescence method quantitatively and was successfully applied to the imaging of thiols in live cells and tissues by two-photon microscopy.

Preparation of Au@Ag nanoparticles at a gas/liquid interface and their application for sensitive detection of hydrogen peroxide

Preparation of Au@Ag NPs at a gas/liquid interface by a seed-mediated growth procedure and their application for sensitive detection of hydrogen peroxide.

Electrocatalysis and electroanalysis of nickel, its oxides, hydroxides and oxyhydroxides toward small molecules

The electrocatalysis toward small molecules, especially small organic compounds, is of importance in a variety of areas. Nickel based materials such as nickel, its oxides, hydroxides as well as oxyhydroxides exhibit excellent electrocatalysis performances toward many small molecules, which are widely used for fuel cells, energy storage, organic synthesis, wastewater treatment, and electrochemical sensors for pharmaceutical, medical, food or environmental analysis. Their electrocatalytic mechanisms are proposed from three aspects such as Ni(OH)2/NiOOH mediated electrolysis, direct electrocatalysis of Ni(OH)2 or NiOOH. Under exposure to air or aqueous solution, two distinct layers form on the Ni surface with a Ni hydroxide layer at the air-oxide interface and an oxide layer between the metal substrate and the outer hydroxide layer. The transformation from nickel or its oxides to hydroxides or oxyhydroxides could be further speeded up in the strong alkaline solution under the cyclic scanning at relatively high positive potential. The redox transition between Ni(OH)2 and NiOOH is also contributed to the electrocatalytic oxidation of Ni and its oxides toward small molecules in alkaline media. In addition, nickel based materials or nanomaterials, their preparations and applications are also overviewed here.