A metal-organic framework and quantum dot-based ratiometric fluorescent probe for the detection of formaldehyde in food.

A green and sensitive ratio fluorescence strategy was proposed for the detection of formaldehyde (FA) in food based on a kind of metal-organic frameworks (MOFs), MIL-53(Fe)-NO, and nitrogen-doped TiC MXene quantum dots (N-TiC MQDs) with a blue fluorescence at 450 nm. As a type of MOFs with oxidase-like activity, MIL-53(Fe)-NO can catalyze o-phenylenediamine (OPD) into yellow fluorescent product 2,3-diaminophenazine (DAP) with a fluorescent emission at 560 nm. DAP has the ability to suppress the blue light of N-TiC MQDs due to inner filter effect (IFE).

[Opening experiments: synthesis, purification, and characterization of polyethyleneimine-modified carbon dots].

Open experiments are an effective means of cultivating top-notch innovative talents. Based on student interests, research hotspots and our laboratory conditions, an experimental scheme was designed. In this experiment, polyethyleneimine modified carbon dots (PEI-CDs) were prepared via a one-step hydrothermal method using citric acid (CA) as the carbon source and PEI as the surface passivator.

Self-Assembled DNA Nanospheres Driven by Carbon Dots for MicroRNAs Imaging in Tumor via Logic Circuit.

DNA nanostructures with diverse biological functions have made significant advancements in biomedical applications. However, a universal strategy for the efficient production of DNA nanostructures is still lacking. In this work, a facile and mild method is presented for self-assembling polyethylenimine-modified carbon dots (PEI-CDs) and DNA into nanospheres called CANs at room temperature.

DNA Robots for CRISPR/Cas12a Activity Management and Universal Platforms for Biosensing.

The CRISPR/Cas12a system is a revolutionary genome editing technique that is widely employed in biosensing and molecular diagnostics. However, there are few reports on precisely managing the -cleavage activity of Cas12a by simple modification since the traditional methods to manage Cas12a often require difficult and rigorous regulation of core components. Hence, we developed a novel CRISPR/Cas12a regulatory mechanism, named NA obots for nzyme ctivity anagement (DREAM), by introducing two simple DNA robots, apurinic/apyrimidinic site (AP site) or nick on target activator.

CRISPR/Cas12a-based fluorescence aptasensor integrated with two-dimensional cobalt oxyhydroxide nanosheets for IFN-γ detection.

Cytokine storm (CS) is a risky immune overreaction accompanied by significant elevations of pro-inflammatory cytokines including interferon-γ (IFN-γ), interleukin and tumor necrosis factor. Sensitive detection of cytokine is conducive to studying CS progress and diagnosing infectious diseases. In this study, we developed a tandem system combining aptamer, strand displacement amplification (SDA), CRISPR/Cas12a, and cobalt oxyhydroxide nanosheets (termed Apt-SCN tandem system) as a signal-amplified platform for IFN-γ detection.

A dual-emission ratiometric fluorescence strategy with enzyme-based inhibition for organophosphorus pesticides determination.

A fast, eco-friendly and accurate ratiometric fluorescent strategy is presented for the determination of organophosphorus pesticides (OPs) using intrinsic dual-emission silica nanoparticles modified with Rhodamine 6G (SiNPs-Rho6G). SiNPs-Rho6G had intrinsic dual-emission at 410 and 550 nm. The substrate acetylcholine was catalyzed by acetylcholinesterase (AChE) to produce thiocholine (TCh).

Fluorometric Assay of Tyrosinase and Atrazine Based on the Use of Carbon Dots and the Inhibition of Tyrosinase Activity.

Sensitive and convenient strategy of tyrosinase (TYR) and its inhibitor atrazine is in pressing demand for essential research as well as pragmatic application. In this work, an exquisite label-free fluorometric assay with high sensitivity, convenience and efficiency was described for detecting TYR and the herbicide atrazine on the basis of fluorescent nitrogen-doped carbon dots (CDs). The CDs were prepared via one-pot hydrothermal reaction starting from citric acid and diethylenetriamine.

Novel dual-emission sulfur quantum dot sensing platform for quantitative monitoring of pesticide 2,4-dichlorophenoxyacetic acid.

In this work, a novel environment-friendly dual-emission Rhodamine B modified sulfur quantum dots (RhB-SQDs) sensing platform was established to economically monitor organochlorine pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) through regulating the activity of alkaline phosphatase (ALP). This dual emission RhB-SQDs exhibited excellent fluorescence and high photostability with emission wavelengths of 455 nm and 580 nm. ALP catalyzed the hydrolysis of the substrate p-nitrophenyl phosphate to p-nitrophenol, which quenched RhB-SQDs fluorescence at 455 nm due to the internal filtration effect, but had no effect the fluorescence intensity of RhB-SQDs at 580 nm.

Spherical Hydrogel Sensor Based on PB@Fe-COF@Au Nanoparticles with Triplet Peroxidase-like Activity and Multiple Capture Sites for Effective Detection of Organophosphorus Pesticides.

The residues of organophosphorus pesticides (OPs) have drawn worldwide increasing attention because of their potential fatal effects on human health and ecological systems. It is of great significance to develop an efficient and portable method for in-field detection of OPs. Herein, a novel core-shell nanocomposite of prussian blue@Fe-covalent organic framework@Au (PB@Fe-COF@Au) was constructed.

Programmable CRISPR-Cas12a and self-recruiting crRNA assisted dual biosensing platform for simultaneous detection of lung cancer biomarkers hOGG1 and FEN1.

Human 8-oxoguanine DNA glycosylase (hOGG1) and flap endonuclease 1 (FEN1) are recognized as potential biomarkers in lung cancer investigations. Developing analytical platforms of simultaneously targeting hOGG1 and FEN1 with high selectivity, sensitivity, especially programmability and universality is highly valuable for clinical research. Herein, we established a signal-amplified platform for simultaneously detecting hOGG1 and FEN1 on the basis of cleavage-induced ligation of DNA dumbbell probes, rolling circle transcription (RCT) and CRISPR-Cas12a.

Glucose and pH responsive fluorescence detection system based on simple synthesis of silicon-coated perovskite quantum dots.

Perovskite quantum dots (PQDs) are extremely unstable in ambient air due to their inherent structural instability, which limits the wide application of PQDs. In this work, silicon-coated CsPbBr PQDs (CsPbBr@SiO) was synthesized via a simple method. The SiO coating effectively isolated PQDs from water and oxygen in the environment, which were the main elements that destroyed the structure stability of PQDs.

Thermal Stress Induces Metabolic Responses in Juvenile Qingtian Paddy Field Carp .

Extreme fluctuations in water temperature lead to significant economic losses for the aquaculture industry. (locally called Qingtian paddy field carp), is a local variety commonly found in Zhejiang province, China. Unlike traditional aquaculture environments, the water temperature range between day and night in the rice field environment is much larger, and the high temperature in summer may exceed the growth threshold of fish because there is no manual intervention; therefore, the study of how the Qingtian paddy field carp (PF carp) adapts to high-temperature conditions can shed light how the species adapt to the rice field environment.

Metal-organic frameworks-assisted nonenzymatic cascade amplification multiplexed strategy for sensing acute myocardial infarction related microRNAs.

Amplification strategies for multiple microRNAs (miRNAs) detection are pivotal for acute myocardial infarction (AMI). Herein, we rationally developed a metal-organic frameworks-assisted nonenzymatic cascade amplification strategy for simultaneous quantification of three AMI-related miRNAs (miR-21, miR-499 and miR-133a). The fluorescence of the elaborately designed DNA molecular beacons with the respective modification of FAM, TAMRA and Cy5 in the terminal was quenched by a metal-organic framework named Fe-MIL-88.

A ratiometric lanthanide-free fluorescent probe based on two-dimensional metal-organic frameworks and carbon dots for the determination of anthrax biomarker.

A lanthanide-free fluorescent probe has been constructed for the first time based on two-dimensional metal-organic frameworks (2D MOFs) and carbon dots (CDs) for ratiometric determination of dipicolinic acid (DPA), the biomarker of Bacillus anthracis. The fluorescence intensity at 659 nm increased due to the release of organic ligands TCPP resulting from the selective interaction between DPA and Zn of 2D MOFs. CDs provided a reference signal at 445 nm which was almost unaffected, realizing self-calibration DPA sensing.

Dual-Emissive Fluorescent Sensor Based on Functionalized Quantum Dots for the Simultaneous Determination of Nitric Oxide and Hydrogen Sulfide.

A simple, direct fluorescent sensor was developed to simultaneously determine nitric oxide and hydrogen sulfide based on 4-(((3-aminonaphthalen-2-yl)amino)methyl)benzoic acid (DAN-1)-functionalized CdTe/CdS/ZnS quantum dots (QDs@DAN-1). In this sensor, DAN-1 could specifically recognize nitric oxide and yield highly fluorescent naphtho triazole (DAN-1-T). Meanwhile, the fluorescence intensity of the QDs could be quenched by hydrogen sulfide.

A novel profuse color card for convenient visual determination of iodide in human urine based on catalytic oxidation reaction.

In this work, we reported a novel and convenient profuse color card for naked eye determination of iodide (I) in urine using chromogenic substrate 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). I catalyzed the oxidation of ABTS by peroxyacetic acid causing ABTS to yield cyan product ABTS with a new absorption peak at 730 nm. The addition of rose-red dye rhodamine B (RhB) changes the overall color of the solution from pink to purple and finally to blue, which makes the solution multicolor and easy to distinguish.

Swietenine extracted from Swietenia relieves myocardial hypertrophy induced by isoprenaline in mice.

As a traditional plant medicine in tropical areas, Swietenia macrophylla seeds are usually applied for some chronic diseases, including hypertension, diabetes, and so on. Few studies have been carried out to identify the effective elements in seed extract and their indications. In this study, we first investigated the functions of the swietenine, an extract from S.

A nanoplatform based on metal-organic frameworks and coupled exonuclease reaction for the fluorimetric determination of T4 polynucleotide kinase activity and inhibition.

A nanoplatform based on metal-organic frameworks (MOFs) and lambda exonuclease (λ exo) for the fluorimetric determination of T4 polynucleotide kinase (T4 PNK) activity and inhibition is described. Fe-MIL-88 was selected as the nanomaterial because of its significant preferential binding ability to single-stranded DNA (ssDNA) over double-stranded DNA (dsDNA) and its quenching property. The synthesized Fe-MIL-88 was characterized by transmission electron microscope, scanning electron microscope, and X-ray photoelectron spectroscopy.

A redox modulated ratiometric fluorometric method based on the use of dual-color carbon dots for determination of the activity of enzymes participating in ascorbic acid-related reactions.

A turn-on ratiometric fluorescent assay is described for the determination of the activity of enzymes participating in ascorbic acid-forming reactions. Blue-emitting carbon dots (bCDs; with excitation/emission wavelength at 380/450 nm) serve as fluorescent indicator. Their fluorescence is reduced by Fe ions via an inner filter effect.

Ratiometric fluorescence monitoring of α-glucosidase activity based on oxidase-like property of MnO nanosheet and its application for inhibitor screening.

In recent years, α-glucosidase (α-Glu) inhibitor has been widely used in clinic for diabetic and HIV therapy. Although different systems have been constructed for sensitive and selective detection of α-Glu and screening its inhibitor, the method based on ratiometric fluorescence for α-glucosidase inhibitor screening remains poorly investigated. Herein, we constructed a new MnO nanosheet (NS)-based ratiometric fluorescent sensor for α-glucosidase activity assay and its inhibitor screening.

A ratiometric fluorescence probe based on carbon dots for discriminative and highly sensitive detection of acetylcholinesterase and butyrylcholinesterase in human whole blood.

A ratiometric fluorescence probe based on carbon dots (CDs) was developed for discriminative and highly sensitive detection of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activity in human whole blood. When o-phenylenediamine (OPD) was oxidized by Cu, the product 2,3-diaminophenazine (oxOPD) could effectively quench the fluorescence of CDs at 460 nm due to the inner filter effect and gave rise to a new emission peak at 570 nm. The AChE or BChE catalyzed hydrolysis reaction of acetylthiocholine or butyrylthiocholine to generate thiocholine, whose sulfhydryl group strongly captured Cu to inhibit the oxidization of OPD, thus effectively preserving the natural fluorescence emission of CDs.

Carbon dots coated with molecularly imprinted polymers: A facile bioprobe for fluorescent determination of caffeic acid.

A new and sensitive method for fluorescent determination of caffeic acid (CA) was proposed based on silane-functionazed carbon dots coated with molecularly imprinted polymers (CDs@MIPs). CDs@MIPs were prepared by using CA as the templates on the surface of silane-functionazed carbon dots(CDs) with a sol-gel process. The as-prepared CDs@MIPs were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and fluorescence spectroscopy.

One-Pot Synthesis of a Magnetic, Ratiometric Fluorescent Nanoprobe by Encapsulating FeO Magnetic Nanoparticles and Dual-Emissive Rhodamine B Modified Carbon Dots in Metal-Organic Framework for Enhanced HClO Sensing.

In this work, a new magnetic, ratiometric fluorescent nanoprobe has been designed and fabricated by encapsulating FeO magnetic nanoparticles (MNPs) and dual-emissive carbon dots into the cavities of metal-organic frameworks (MOFs). This one-pot method combined hybrid characteristics of MOFs with multiple properties of the encapsulated functional materials. The MOF-based nanoprobe possessed the advantages of MOFs (strong adsorption ability, accumulating the analytes), FeO MNPs (magnetic separation), and ratiometric sensors (eliminating the variabilities caused by the instability of the instruments and environment).

Aptamer based fluorometric β-lactoglobulin assay based on the use of magnetic nanoparticles and carbon dots.

The authors describe a fluorometric aptamer based assay for detecting β-lactoglobulin by using carbon dots (C-dots) as a signal indicator. The aptamer was immoblized on magnetite (FeO) nanoparticles (MNPs), and the C-dots served as a label for the complementary oligonucleotide (cDNA). The assay is based on the hybridization that takes place between aptamer and cDNA.