Construction of a dual-excitation ratiometric fluorescent probe for determining peroxynitrite levels in living cells and zebrafish.

Peroxynitrite (ONOO-) is a highly reactive oxygen species that plays a critical role in many physiological and pathological processes of cell function. This study aimed to propose a ratiometric fluorescent probe BDHCA derived from coumarin for determining the ONOO- level. ONOO- could specifically induce oxidative cleavage of the conjugated C = C double bond in probe BDHCA, providing a fluorescent ratiometric output. The response of probe BDHCA to ONOO- was selective, fast, and highly sensitive, with a detection limit of 50.3 nM. Biological imaging experiments suggested that probe BDHCA could be used to image ONOO- in living RAW264.7 cells and zebrafish.

A dihydro-benzo[4,5]imidazo[1,2-c]quinazoline-based probe with aggregation-induced ratiometric emission for the ratiometric fluorescent detection of peroxynitrite in living cells and zebrafish.

As a significant kind of reactive oxygen species (ROS), peroxynitrite (ONOO-) plays an indispensable role in many physiological and pathological processes. This study aimed to synthesize a novel dihydro-benzo[4,5]imidazo[1,2-c]quinazoline-based probe 1 for detecting ONOO-. In 99.5% H2O solution, probe 1 displayed a distinct aggregation-induced ratiometric emission (AIRE), and would selectively respond toward ONOO-via a ratiometric fluorescent signal, along with a short response time (<30 s) and ultra-sensitivity (LOD = 17.6 nM). Moreover, the probe was applied for monitoring the concentration fluctuations of ONOO- in HeLa cells and zebrafish.

Multibranched flower-like ZnO anchored on pectin/cellulose nanofiber aerogel skeleton for enhanced comprehensive antibacterial capabilities.

In this study, F-ZnO NPs were used as antibacterial agents, mussel bionic dopamine exerted its adhesive action to immobilize F-ZnO NPs on the pectin/CNF aerogel skeleton. Fruit and vegetable antimicrobial mats with safety, long duration of action and high efficiency were prepared and its potential application has been investigated. The results showed that a dopamine layer was deposited on the surface of the CNF, which promoted the tight adhesion of the F-ZnO NPs to the aerogel skeleton. The F-ZnO@D-CNF aerogel exhibited a slow release of zinc ions, with the first two days being 0.40 ± 0.16 and 1.01 ± 0.13 mg/mL. The aerogel was light, can stand on the petals without collapsing, has regular and uniform pore structure, good tensile/compressive properties and high antibacterial/anti-fungal properties. Strawberries packaged with F-ZnO@D-CNF aerogel exhibited an extended shelf life of 5 days. Additionally, the strawberries maintained a soluble solid content of 6.9 ± 0.82 % and a Vc content of 44.67 ± 3.51 mg/100 g. The weight loss, color and firmness were also notably superior to the other four groups. The final concentration of zinc ions in strawberries was 3.71 ± 0.28 µg/g, which is far below the recommended dietary intake.

A zeolitic imidazolate framework-90-based probe for fluorescent detection of mitochondrial hypochlorite in living cells and zebrafish.

An inorganic-organic hybrid probe MP-ZIF-90 was synthesized via a simple condensation reaction based on the free CHO groups of zeolitic imidazolate framework-90 (ZIF-90) and 4-methyl-1-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl)pyridinium bromide (MP). This probe exhibited intense green emission, which was selectively quenched by the addition of ClO- anions. The response of probe MP-ZIF-90 toward ClO- was rapid (within 20 s) and sensitive, with a limit of detection (LOD) of 0.612 µM. Importantly, the utilization of the probe in the fluorescence imaging of ClO- anions in the mitochondria of living cells and zebrafish was demonstrated.

A coumarin-pyrazole-based probe for the fluorescence detection of phosgene with high selectivity and sensitivity.

The high toxicity of phosgene poses potential threats to public health and safety. In this work, a novel fluorescent probe was designed to detect phosgene using hydroxyl and pyrazole moieties as the recognition sites. The response to phosgene with probe 1 was fast (less than 30 s), highly selective and sensitive with the limit of detection being 4.78 nM in solution. Furthermore, probe 1 was employed to conveniently fabricate paper test strips for efficiently detecting phosgene gas. The limit of detection was obtained as 0.014 ppm by using a smartphone RGB app, revealing that probe 1 has good prospects for sensitively detecting phosgene gas.

A p-toluenesulfonamide-modified benzo[h]chromene hydrazone: Fluorescent turn-on detection of hypochlorite and its application to imaging the endoplasmic reticula of living cells and zebrafishes.

Hypochlorite (ClO-) is a ROS that plays a crucial role in the immune system in the body. As the largest organelle in the cell, the endoplasmic reticulum (ER) manages various life activities. Thus, a simple hydrazone-based probe was designed, which provided a fast turn-on fluorescent response toward ClO-. With a terminal p-toluenesulfonamide group as the endoplasmic reticulum (ER)-specific site, probe 1 was mainly accumulated at ER of living cells, and could be used for imaging endogenous and exogenous HClO in cells and zebrafishes.

A dual-emission fluorescence probe for the detection of viscosity and hydrazine in environmental and biological samples.

The microenvironments of biological systems are associated with the pathology of organisms. This study, aimed to construct a hemicyanine-based probe (1), which can respond to mitochondrial viscosity and hydrazine (N2H4), for imaging application in living cells and zebrafish. The probe showed no fluorescence due to the intramolecular rotation in the solution; however, it exhibited a strong emission at 730 nm when the molecules were restricted to a high-viscosity environment. The addition of N2H4 caused an elimination reaction of the N-substituted group in the pyridinium part and further broke the CC bond to produce a highly fluorescent hydrazone. Also, the probe could selectively and quantitatively detect N2H4 via the fluorescence enhancement at 510 nm in a concentration range of 0 µM-140µM, with the limit of detection being 0.0485 µM. This probe may be used to study diseases related to N2H4 and viscosity changes in biological systems. Furthermore, the analysis methods based on probe 1 for N2H4 detection in soil, water, and air samples were successfully established.

A novel AIRE-based fluorescent ratiometric probe with endoplasmic reticulum-targeting ability for detection of hypochlorite and bioimaging.

Hypochlorite (ClO-) plays an important role in the human immune defense system, but high concentrations of ClO- in the endoplasmic reticulum (ER) damage cellular proteins, causing ER stress, cell death, and various diseases. Herein, we developed a simple hydrazone probe (1) featuring aggregation-induced ratiometric emission, which would quickly (within 20 s) and sensitively (detection limit of 15.4 µM) respond to ClO- in an almost pure aqueous solution via a fluorescent ratiometric output. Furthermore, the probe was employed to track the level of ClO- in the ER of HeLa cells and zebrafish.

Functionalized cellulose nanocrystal embedded into citrus pectin coating improves its barrier, antioxidant properties and potential application in food.

Due to the hydrophilic of the pectin material, the coating has poor barrier properties and a negative preservation effect on fresh fruits. In this study, citrus pectin coating with improved barrier and antioxidant properties was prepared by embedding with functional cellulose nanocrystals (CNC). It was assessed that cellulose nanocrystals grafted with p-coumaric acid (CNC-P) were uniformly dispersed in the pectin matrix to improve coating barrier properties. The addition of 8 % CNC-P to the pectin coating led to a decrease in water vapor and oxygen permeability from the coating by 12.6 % and 22.3 %, respectively. Additionally, the grafted p-coumaric acid (PA) introduced antioxidant properties to the cellulose nanocrystals. The fresh-cut fruits preservation assay showed that the coating containing CNC-P exerted a stronger inhibition effect of the browning process within 8 h than other coatings. This study suggests that pectin coating embedded with CNC-P has the potential to be used in food packaging.

Effects of enhanced hygiene measures on severe diarrhea and anastomotic leak after colorectal cancer surgery: the experience of a tertiary referral hospital in China.

Background: The 2019 novel coronavirus (COVID-19) global pandemic has greatly changed the mode of hospital admissions. This study summarized and analyzed the incidence of severe diarrhea and anastomotic leakage during different periods for colorectal cancer surgery. Methods: From January 2017 to September 2020, 2,619 colorectal operations were performed in Peking Union Medical College Hospital. In contrast with previous years, enhanced hand hygiene training, more frequent ventilation of the wards, and separate bed treatments for patients were implemented in 2020. Data on incidence of severe diarrhea and anastomotic leakage were retrieved and collected. Results: The number of cases of severe diarrhea after colorectal surgery was 32 (4.60%), 24 (3.33%), 32 (3.83%), and 11 (2.99%) in 2017, 2018, 2019, and 2020 respectively, while the incidence of anastomotic leakage was 3.30% (23/696), 3.75% (27/720), 2.87% (24/835), and 2.17% (8/368), respectively. There was no significant difference in the incidence of postoperative severe diarrhea or anastomotic leakage across the various years. Conclusions: The number of colorectal surgeries in 2020 was significantly decreased due to the COVID-19 pandemic. Among the different years, no difference was observed regarding the incidence of postoperative flora disorder or anastomosis leakage. Enhanced hygiene measures during the COVID-19 epidemic partially contributed to the decrease of severe diarrhea and anastomotic leakage.

A dual-ratiometric mitochondria-targeted fluorescent probe to detect hydrazine in soil samples and biological imaging.

Hydrazine (N2H4) is carcinogenic, extremely toxic, and induces serious environmental contamination and physiological dysfunction; however, it is widely used as an industrial material. Hence, the development of a simple and effective analytical method to detect N2H4 detection in both environmental and biological sectors is warranted. In this work, an intramolecular charge transfer (ICT)-based fluorescent probe 1, namely (Z)- 1-(4-acetoxybenzyl)- 4-(1-cyano-2-(7-(diethylamino)- 2-oxo-2 H-chromen-3-yl)vinyl)pyridin-1-ium, was designed for dual-excitation (420 and 600 nm, excitation separations >160 nm), near infrared (NIR)-emissive, and ratiometric fluorescent detection of N2H4. The sensing behavior of probe 1 for N2H4 detection was shown to be available over a wide pH range, and detection limits of 68 nM and 569 nM were achieved at excitation wavelengths of 420 and 600 nm, respectively. In addition, probe 1 was successfully used to image mitochondrial N2H4 in living cells and zebrafish. Furthermore, the probe was also capable of determining hydrazine signals in test strips and environmental soil.

Europium (III) complex-based fluorescent probe for instantaneous, selective, and sensitive detection of phosgene.

Phosgene (carbonyl chloride, COCl2) is a widely used colorless gas in organic synthesis. However, its high toxicity sets a severe potential damage of public safety. As the fluorescence method has the advantages of simple operation and real-time detection of phosgene, it is extremely important to develop a fluorescent phosgene probe for public health and safety. This study aimed to present a simple Eu3+ complex (1) with 2-hydroxyl-1H-benzimidazole moiety as a novel phosgene probe. Probe 1 exhibited characteristic emission of Eu3+ in CH3CN solution, which was specifically quenched after encountering phosgene. The change in the solution color from light red to dark could be easily distinguished with the naked eye under a 365 nm ultraviolet lamp. Finally, the test paper with probe 1 was fabricated for effortless, selective, and visual detection of phosgene gas.

A simple colorimetric and fluorometric probe for rapid detection of CN- with large emission shift.

In this work, a novel probe R was synthesized via Knoevenagel reaction between 3H-benzo[f]chromium-2-formaldehyde and ethyl cyanoacetate for selective detection of CN- in both colorimetric and fluorescent signal channels. The recognition of CN- was through the nucleophilic reaction of CN- to C = C of probe R, which destroys π-conjugation and blocks the ICT effect of the probe, resulting in colorimetric and fluorometric responses. Probe R showed great sensitivity toward CN-, with large fluorescent emission (595 nm) and low detection limit (0.70 µM). Moreover, probe R can detect exogenous CN- in living cells.

Site-specific sulfur-for-metal replacement in a silver nanocluster.

A new Ag36 nanocluster with a closed electronic structure and eight valence electrons is reported, which has a similar structure to that of an open-shell Ag34 nanocluster with three valence electrons, except that in the shell two (Ag-PPh3)+ cations replace two S2- anions specifically. The fine structural modulation leads to various levels of activity for singlet oxygen photogeneration due to the distinct optical gaps of the nanoclusters.

Simultaneous detection of lysosomal SO2 and viscosity using a hemicyanine-based fluorescent probe.

The changes in sulfur dioxide and viscosity of lysosomes are significant indicators in physiological processes and the cell microenvironment. This study aimed to synthesize a hemicyanine-based probe for simultaneous detection of SO2 and viscosity. The probe could not only rationally detect sulfur dioxide in a semi-aqueous solution with high sensitivity (limit of detection = 0.78 µM) and fast response (within 30 s) but also monitor viscosity via fluorescence emission enhancement at 580 nm. Further, the dual-response probe was successfully used to image SO2 and viscosity in the lysosomes of living cells.

Multidimensional (0D-3D) nanofillers: Fascinating materials in the field of bio-based food active packaging.

Nanoscience paves the new way for the development of bio-based food packaging. Recently, research on bio-nanocomposite packaging has gained momentum, driven by consumers' pursuits of food quality and the reduction of resource waste. This is mainly attributable to its excellent biogradability, non-toxicity, consumer friendliness and its potential for functional properties that contribute to extending the shelf life of foods. Bio-nanocomposite packaging materials can be prepared by incorporating nano-sized additives into biopolymeric matrices. The review investigates how dimensional qualities of nanofillers affect functional properties, rather than just the biopolymer matrix as a whole. The features of various nanofillers were first introduced in this review. As a result, the functional variations amongst nanofillers of different dimensions were emphasized. After that, some concrete applications, the main obstacles and solutions were discussed in detail. Finally, a clear perspective and prospect for the future manufacturing and research directions of biological nanocomposites prepared for active packaging were presented.

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.

Intelligent packaging films incorporated with anthocyanins-loaded ovalbumin-carboxymethyl cellulose nanocomplexes for food freshness monitoring.

An intelligent colorimetric film was prepared to monitor mushrooms freshness by incorporating anthocyanin-loaded ovalbumin-carboxymethyl cellulose nanocomplexes (OVA-CMC-ACNs) into corn starch/polyvinyl alcohol matrix. The results showed that ACNs could be loaded into OVA-CMC nanocomplexes with larger particle size and more uniform size distribution. The structure, physical properties, colorimetric response and practical application of films were studied. Compared with SP/ACNs film incorporation of free anthocyanins, SP/OVA-CMC-ACNs film had denser structure, higher mechanical and water barrier properties, and better thermal stability, which were related to the hydrogen bond among film components by FT-IR. The SP/OVA-CMC-ACNs film showed obvious colorimetric response in CO2 gas and pH buffer. The successful applications of intelligent film for the freshness monitoring of mushrooms. The intelligent film could monitor the freshness of mushrooms during the storage by visual color change from purple to pink. These results indicated that prepared SP/OVA-CMC-ACNs film have great application potential in intelligent food packaging.

A quinoline-based probe for the ratiometric fluorescent detection of sulfite in lysosomes of living cells.

A lysosome-targeting ratiometric fluorescent probe was synthesized for detecting sulfite based on sulfite-triggered nucleophilic addition reaction. Due to the specific reaction, the fluorescence intensity ratio (I530/I390) of the probe in an almost aqueous solution (0.5% DMSO) changed significantly after the addition of HSO3-, corresponding to the change in the fluorescence color of the solution from green to blue. The recognition was conducted using high-resolution mass spectrometry, proton nuclear magnetic resonance, and density functional theory calculations. The fluorescent probe could be utilized to quantitatively monitor HSO3- in lysosomes of living C6 glioma cells and real-water samples.

A ratiometric fluorescent probe for hydrogen sulfide in neat aqueous solution and its application in lysosome-targetable cell imaging.

Hydrogen sulfide (H2S) has been recently regarded as one of the most important gasotransmitters in the metabolic system, while abnormal H2S concentration is associated with various diseases. Although numerous fluorescent probes have been developed for the detection of cellular H2S, only a few of them can monitor lysosomal H2S with ratiometric fluorescent output. Here, we developed a water-soluble probe 1 toward H2S by introducing 2,4-dinitrophenyl ether into a novel merocyanine-based dye. As expected, H2S induced an obvious red-shift of the probe from 520 nm to 580 nm in neat aqueous solution, and this fluorescent ratiometric response is highly selective and sensitive (with the detection limit of 0.81 nM), rapid (within 10 s), and effective in a wide pH range (2.0-10.0). In particular, the probe was successfully applied for tracing H2S in the lysosomes of living cells and in zebrafish.