RSPO2 as Wnt signaling enabler: Important roles in cancer development and therapeutic opportunities

R-spondins are secretory proteins localized in the endoplasmic reticulum and Golgi bodies and are processed through the secretory pathway. Among the R-spondin family, RSPO2 has emanated as a novel regulator of Wnt signaling, which has now been acknowledged in numerous in vitro and in vivo studies. Cancer is an abnormal growth of cells that proliferates and spreads uncontrollably due to the accumulation of genetic and epigenetic factors that constitutively activate Wnt signaling in various types of cancer. Colorectal cancer (CRC) begins when cells in the colon and rectum follow an indefinite pattern of division due to aberrant Wnt activation as one of the key hallmarks. Decades-long progress in research on R-spondins has demonstrated their oncogenic function in distinct cancer types, particularly CRC. As a critical regulator of the Wnt pathway, it modulates several phenotypes of cells, such as cell proliferation, invasion, migration, and cancer stem cell properties. Recently, RSPO mutations, gene rearrangements, fusions, copy number alterations, and altered gene expression have also been identified in a variety of cancers, including CRC. In this review, we addressed the recent updates regarding the recurrently altered R-spondins with special emphasis on the RSPO2 gene and its involvement in potentiating Wnt signaling in CRC. In addition to the compelling physiological and biological roles in cellular fate and regulation, we propose that RSPO2 would be valuable as a potential biomarker for prognostic, diagnostic, and therapeutic use in CRC.

Recent progress and future directions of the research on nanoplastic-induced neurotoxicity

Many types of plastic products, including polystyrene, have long been used in commercial and industrial applications. Microplastics and nanoplastics, plastic particles derived from these plastic products, are emerging as environmental pollutants that can pose health risks to a wide variety of living organisms, including humans. However, it is not well understood how microplastics and nanoplastics affect cellular functions and induce stress responses. Humans can be exposed to polystyrene-microplastics and polystyrene-nanoplastics through ingestion, inhalation, or skin contact. Most ingested plastics are excreted from the body, but inhaled plastics may accumulate in the lungs and can even reach the brain via the nose-to-brain route. Small-sized polystyrene-nanoplastics can enter cells by endocytosis, accumulate in the cytoplasm, and cause various cellular stresses, such as inflammation with increased pro-inflammatory cytokine production, oxidative stress with generation of reactive oxygen species, and mitochondrial dysfunction. They induce autophagy activation and autophagosome formation, but autophagic flux may be impaired due to lysosomal dysfunction. Unless permanently exposed to polystyrene-nanoplastics, they can be removed from cells by exocytosis and subsequently restore cellular function. However, neurons are very susceptible to this type of stress, thus even acute exposure can lead to neurodegeneration without recovery. This review focuses specifically on recent advances in research on polystyrene-nanoplastic-induced cytotoxicity and neurotoxicity. Furthermore, in this review, based on mechanistic studies of polystyrene-nanoplastics at the cellular level other than neurons, future directions for overcoming the negative effects of polystyrene-nanoplastics on neurons were suggested.

Food liposomes: Structures, components, preparations, and applications

This review explores liposomes, focusing on their structure, components, the characteristics influencing their stability and applicability in foods, and preparation methods. The role of phospholipids and liposome modulators in preparing liposomes of desired structure and size is emphasized. The potential of liposomes to enhance food value through liposomal encapsulation and delivery of functional substances is reviewed. Conventional and advanced liposome preparation methods are reviewed, underscoring their impact on the marketability of liposomes. The review highlights the need for research into lecithin properties and modulators that enhance liposome stability. The need to develop cost-effective and rapid liposome preparation methods is identified as a key factor in improving the marketability of food liposomes and promoting their use in foods.

Dual techniques for trace copper determination: DES/Dithizone based liquid phase microextraction-flame atomic absorption spectrophotometry and digital image based colorimetric probe

In this study, a sample preparation procedure was developed to preconcentrate copper ions from aqueous samples for determination by flame atomic absorption spectrometry (FAAS) and digital image based colorimetry (DIC) systems. This was achieved by complexing copper ions with dithizone (Cu-DZ) and extracting the complex from aqueous solution in a single step. For the DES/DZ-FAAS system, a low detection limit of 2.3 ng mL-1 was recorded over a broad and linear working range. For the DIC system, the linear relationship between the change in red color intensity of the red-green-blue (RGB) color scale and the concentration of copper in the Cu-DZ complex was utilized for the validation of the method. The DIC system also recorded a broad and linear working range with a satisfactory detection limit of 14.7 ng mL-1. Spike recovery experiments performed with eucalyptus tea extracts yielded high recovery results in the range of 91-107%.

Rational construction of reliable fluorescent probes for rapid detection and imaging evaluation of hazardous thiophenol in real-food and biosystems

Thiophenol (PhSH), a highly reactive aromatic thiol, plays an essential role as a common industrial raw material in food, pesticides, pharmaceuticals, and cosmetics. In this work, we designed and constructed two fluorescent probes CM-PhSH and CM-Ratio-PhSH by a rational strategy. Specifically, coumarin fluorophores with excellent optical properties were modified, and olefinic unsaturated bonds served as reaction sites for the detection of PhSH. Based on this, the introduction of the nitro group at specific positions of the CM-PhSH changed the fluorescence emission of the CM-Ratio-PhSH, eventually obtaining a novel ratiometric fluorescent probe CM-Ratio-PhSH for PhSH detection. Surprisingly, these two probes exhibited advantages such as high specificity and low limit of detection (LOD) for CM-PhSH 32.3 nM and CM-Ratio-PhSH 40.2 nM, respectively. Furthermore, subsequent experiments demonstrated CM-PhSH and CM-Ratio-PhSH could be successfully used for highly selective and rapid detection of PhSH in aqueous solutions, live cells, and complex food samples.

Aggregation-induced enhancement of pyrene-based metal-organic framework as a new electrochemiluminescence emitter for ultrasensitive detection of sulfadimethoxine

In this study, a signal-on electrochemiluminescence (ECL) aptasensor for ultrasensitive detection of sulfadimethoxine (SDM) was constructed based on a competitive aptamer strategy. Specifically, cerium-metal-organic framework (Ce-MOF) with large specific surface area and excellent electrical conductivity was combined with gold nanoparticles (AuNPs) to form a substrate, followed by the immobilisation of double-stranded DNA (dsDNA) via AuN bonds. In the presence of SDM, the aptamer tended to form an aptamer-SDM complex, which caused dsDNA to dissociate. After release of the aptamer, the capture probe (CP) combined with the tracer label to enhance the ECL signal. As expected, the prepared sensor displayed an ideal linear response range from 10.0 fg mL-1 to 100 ng mL-1 with a limit of detection (LOD) of 1.28 fg mL-1 and successfully detected SDM in milk and quality control samples.

A colorimetric assay for H2O2 and glucose based on the morphology transformation of Au/Ag nanocages to nanoboxes

Herein, we introduced a sensitive colorimetric platform for hydrogen peroxide (H2O2) assay based on gold/silver (Au/Ag) nanocages with porous structure. In the presence of H2O2, the morphology of hollow Au/Ag nanocages was converted to closed nanoboxes, altering their localized surface plasmon resonance (LSPR) peak position and the solution color from light blue to deep blue. The morphology transformation and LSPR peak position of Au/Ag nanocages were proportional to H2O2 concentration at the range of 0.1 to 50 µM. The limit of detection (LOD) was obtained to be 0.02 µM, and the relative standard deviation (RSD, for 0.2, 2.0, and 20 µM) was 2.7, 2.3, and 2.9%, respectively. Moreover, a smartphone-based colorimetric sensor was developed for H2O2 assay at the concentration range of 0.25-4.0 µM, with LOD of 0.2 µM and RSD of 3.2, 2.5, and 2.9% (for 0.5, 1.0, and 3.0 µM, respectively). We exploited the established sensor for glucose assay by measuring the generated H2O2 from the enzymatic reaction between glucose and glucose oxidase. There was a linear relationship between LSPR peak wavelength variations and the amount of glucose from 1.0 to 50 µM, with LOD of 0.4 µM and RSD of 3.2, 3.1, and 3.8% (for 2.0, 10, and 30 µM, respectively). The sensor was successfully applied to determine H2O2 and glucose in food and human serum samples, respectively.

Visualized test of environmental water pollution and meat freshness: Design of Au NCs-CDs-test paper/PVA film for ratiometric fluorescent sensing of sulfide

Hydrogen sulfide (H2S) is an environmental pollutant, and also the major released gas during the decay of meat products. To protect the ecological environment and human health, the establishment of a swift, convenient, and accurate detection method for H2S becomes essential. However, existing methods are still suffering from complex synthesis, high toxicity, poor visualization, and high detection limit. Herein, Au NCs-CDs nanocomposite-based test paper and polyvinyl alcohol (PVA) film are combined with a smartphone for sensitive and specific sulfide visualized monitoring. After the addition of sulfide, the fluorescence color changes from orange to green, achieving a quantitative linearity towards sulfide from 5 nM to 30 μM, with a low detection limit of 4.20 nM. The proposed method shows practicability in natural water samples. Furthermore, distinct fluorescence color variation is shown towards H2S originating from spoiled meat, showing the potential application prospect of Au NCs-CDs-PVA film as a meat freshness detector.

MnO2 in-situ coated upconversion nanosystem for turn-on fluorescence detection of hypoxanthine in aquatic products

Hypoxanthine concentration is a potential indicator to evaluate the freshness in the early post-mortem of several aquatic products. Based on MnO2 in-situ coated upconversion nanoparticles (UCNPs) and xanthine oxidase (XOD), a novel sensor was conducted for the efficient, sensitive determination of hypoxanthine. In this strategy, upconversion fluorescence quenched by MnO2 would be restored by H2O2 and uric acid (UA), two products from the XOD-catalyzed reactions of hypoxanthine. Through pretreatment with short-time heating and alkylation by N-ethylmaleimide (NEM) to avoid potential interference from reducing substances in the food matrix, this method exhibited satisfactory selectivity. The fluorescence intensity of green emission Igreen was positively proportional to hypoxanthine concentration at a wide range of 0.5-50 mg/L with a detection limit of 0.14 mg/L. Moreover, this convenient method was employed to quantify the hypoxanthine in fish, shrimp, and shellfish samples, showing excellent potential for the application in quality control of aquatic products.

Smartphone-based electrochemical sensor for cost-effective, rapid and on site detection of chlorogenic acid in herbs using biomass-derived hierarchically porous carbon synthesized by a soft-hard dual template method

To achieve excellent germplasm resource screening and ensure the quality control of herbal tea raw material, it is important to establish a cost-effective, rapid, and on site quantitative detection method for their bioactive constituents. We developed a smartphone-operated sensor for electrochemical detection of chlorogenic acid (CGA) using hierarchically porous carbon (DSiFPC), synthesized through a soft-hard dual template strategy with tannin acid as a carbon source, silica colloid as a hard template, and Pluronic F127 as a soft template. The DSiFPC modified glassy carbon electrode sensor showed excellent electrocatalytic ability towards CGA, with a wide linear range of 0.03-1 μM and a low limit of detection of 6.2 nM. It was successfully applied for detecting CGA in dried flowers of Lonicera japonica. Furthermore, a portable sensor utilizing a DSiFPC modified screen-printed electrode was employed for on site detection of CGA in fresh Eucommia ulmoides leaves, yielding satisfactory recoveries.

Deep eutectic solvents based in situ isolation technique for extractive deterpenation of essential oils

Essential oils, intricate blends of volatile compounds obtained from a variety of sources, play a crucial role in numerous industries. To elevate product quality, deterpenation becomes an indispensable step. This study proposes an in situ isolation technique based on deep eutectic solvents (DESs) for the deterpenation of essential oil. Salient features of relevant compounds were obtained using conductor-like screening model for real solvents (COSMO-RS) and density functional theory (DFT) methods to predict deterpenation performance. Tetrabutylammonium chloride (TBAC) was chosen based on the results of theoretical analysis and experiment to extract hydroxy-terpenoids. COSMO-RS was employed to evaluate the extraction performance at different molar ratios, and then combined with experimental analysis to determine the optimal conditions. The σ-profiles of organic solvents and their interactions with terpene revealed n-hexane to be the best solvent for purifying DES. TBAC and terpenoids were obtained through the re-extraction procedure, with a recovery of 81.8-84.4%.

MOF-based nanocomposites as transduction matrices for optical and electrochemical sensing

Metal Organic Frameworks (MOFs), a class of crystalline microporous materials have been into research limelight lately due to their commendable physio-chemical properties and easy fabrication methods. They have enormous surface area which can be a working ground for innumerable molecule adhesions and site for potential sensor matrices. Their biocompatibility makes them valuable for in vitro detection systems but a compromised conductivity requires a lot of surface engineering of these molecules for their usage in electrochemical biosensors. However, they are not just restricted to a single type of transduction system rather can also be modified to achieve feat as optical (colorimetry, luminescence) and electro-luminescent biosensors. This review emphasizes on recent advancements in the area of MOF-based biosensors with focus on various MOF synthesis methods and their general properties along with selective attention to electrochemical, optical and opto-electrochemical hybrid biosensors. It also summarizes MOF-based biosensors for monitoring free radicals, metal ions, small molecules, macromolecules and cells in a wide range of real matrices. Extensive tables have been included for understanding recent trends in the field of MOF-composite probe fabrication. The article sums up the future scope of these materials in the field of biosensors and enlightens the reader with recent trends for future research scope.

Monolithic 3D structural-substrate SERS sensing platform for ultrasensitive and highly-specific analysis of trace bisphenol A

Constructing advanced substrates with excellent features is promising for sensitive surface-enhanced Raman spectroscopy (SERS) detection. Here a novel capillary monolithic 3D structural-substrate SERS platform with Au@cDNA@Ag@Cyanine 3-aptamer nanoparticles (Au@cDNA@Ag@Cy3-Apt NPs) was fabricated for rapid, highly specific profiling of ultra-trace Bisphenol A (BPA). The proposed SERS platform combined both in-capillary SERS and aptamer-affinity recognition strategies, in which the superior SERS properties of Au-Ag NPs, aptamer selectivity, and the advantages of capillary monolith were integrated. A 3D hierarchically porous network was constructed in the monolithic column, which was endowed with rich hotspots for SERS, rapid sample permeation, and better analysis efficiency than most plane-shaped SERS modes. By varying the amount of Ag+ precursor, the Ag-shell thickness on SERS was finely tuned to guarantee Cy3 label in proximity to the plasmonic surface. Based on the biorecognition of aptamer, the selective identification of BPA occurred and exhibited a significant change in SERS intensity without obvious interference. As a result, the monolithic SERS platform featured facile operation, excellent specificity, and rapid analysis (10 min, much less than the solution-based or planar substrate SERS modes). Ultra-high sensitivity and robust reproducibility for BPA analysis was achieved with a low limit of detection (LOD) at 9.12 × 10-4 ng/L. The feasibility of this SERS platform for monitoring BPA in water and milk samples was also validated. This work lights a new access to capillary monolithic SERS-sensing platform for ultrasensitive and specific analysis of BPA.

A novel Cu-MOFs nanosheet/BiVO4 nanorod-based ECL sensor for colorectal cancer diagnosis

Although luminescence metal organic framework (MOFs) has displayed the significant advantages, the limitations in the electrochemical performance (e.g. rapid charge recombination rates and inadequate charge transport) limited the sensing application of MOFs. Herein, a novel Cu-MOFs/BiVO4 nanorod-based electrogenerated chemiluminescence (ECL) sensor has been developed. Firstly, Cu-MOFs with strong luminescence were synthesized via the three-layer approach as ECL emitter. Furthermore, BiVO4 nanorods was modified on the electrode as the actuator to improve the electrochemical activity of Cu-MOFs in the ECL process. As an n-type semiconductor, BiVO4 formed a complementary structure with p-type semiconductor Cu-MOF. Therefore, electrons in the conduction band of BiVO4 transferred to that of Cu-MOF. As a result, more electrons reacted with coreactant on the surface of Cu-MOF, which effectively enhanced the ECL performance of 2D Cu-MOFs nanosheets. As a result, the quantitation of KRAS gene was realized in the linear range of 0.1 pM-1 nM with a detection limit of 0.02 fM. Moreover, the detection of KRAS gene in actual colorectal cancer samples was also carried out with good recovery, which offered a broad application possibility for ECL research and clinical analysis.

Artificial Intelligence in ADME Property Prediction

Absorption, distribution, metabolism, excretion (ADME) are key properties of a small molecule that govern pharmacokinetic profiles and impact its efficacy and safety. Computational methods such as machine learning and artificial intelligence have gained significant interest in both academic and industrial settings to predict pharmacokinetic properties of small molecules. These methods are applied in drug discovery to optimize chemical libraries, prioritize hits from biological screens, and optimize ADME properties of lead molecules. In the recent years, the drug discovery community witnessed the use of a range of neural network architectures such as deep neural networks, recurrent neural networks, graph neural networks, and transformer neural networks, which marked a paradigm shift in computer-aided drug design and development. This chapter discusses recent developments with an emphasis on their application to predict ADME properties.

Antiviral Drug Target Identification and Ligand Discovery

This chapter intends to provide a general overview of web-based resources available for antiviral drug discovery studies. First, we explain how the structure for a potential viral protein target can be obtained and then highlight some of the main considerations in preparing for the application of receptor-based molecular docking techniques. Thereafter, we discuss the resources to search for potential drug candidates (ligands) against this target protein receptor, how to screen them, and preparing their analogue library. We make specific reference to free, online, open-source tools and resources which can be applied for antiviral drug discovery studies.

Dual-ligand hydrogen-bonded organic framework: Tailored for mono-phosphopeptides and glycopeptides analysis

Hydrogen-bonded organic frameworks (HOFs) have emerged as a promising class of materials for applications of separation and enrichment. Utilizing multiple-ligands to construct HOFs is a promising avenue towards the development of structurally stable and functionally diverse frameworks, offering opportunities to create customized binding sites for selective recognition of biomolecules. In recent years, due to the crucial role that protein post-translational modifications (PTMs) play in maintaining protein function and regulating signaling pathways, and the growing recognition of the extensive cross-talk that can occur between PTMs, simultaneous analysis of different types of PTMs represents a requirement of a new generation of enrichment materials. Here, for the first attempt, we report a dual-ligand HOF constructed from borate anion and guanidinium cation for the simultaneous identification of glycopeptides and phosphopeptides, especially mono-phosphopeptides. According to theoretical calculations, the HOF functional sites display a synergistic "matching" effect with mono-phosphopeptides, resulting in a stronger enrichment effect for mono-phosphopeptides as compared to multi-phosphopeptides. Also, due to its high hydrophilicity and boronate affinity, this material can efficiently capture glycoproteins. HOF is set to become an active research direction in the development of highly efficient simultaneous protein enrichment materials, and offers a new approach for comprehensive PTMs analysis.

A benzothiazole-salt-based fluorescent probe for precise monitoring the changes of pH and viscosity

This work presented a novel ratiometric fluorescent probe (NBO) based on benzothiazole dye, which could monitor the pH fluctuations with high sensitivity via the intramolecular charge transfer (ICT) process. NBO was developed with a good linear response in the pH range of 5.75-7.00 (pKa = 6.5) and a reversible structural change in acidic and alkaline environments. Besides, NBO also has the potential to detect the viscosity changes. Meanwhile, NBO has been successfully applied to the pH monitoring of a variety of water samples in natural environment and human serum. With the treatment of different solutions at pH 2.0 - pH 9.0, the test strips showed significant color changes under both 365 nm UV lamp and room light. When the test strips were applied to white wine, pH could be detected quickly and easily by the naked eyes. Therefore, a novel probe that can be used to detect pH in environment, human serum and food has been successfully developed.

Antifouling modification for high-performance isolation of circulating tumor cells

Circulating tumor cells (CTCs), which shed from solid tumor tissue into blood circulatory system, have attracted wide attention as a biomarker in the early diagnosis and prognosis of cancer. Given their potential significance in clinics, many platforms have been developed to separate CTCs. However, the high-performance isolation of CTCs remains significant challenges including achieving the sensitivity and specificity necessary due to their extreme rarity and severe biofouling in blood, such as billions of background cells and various proteins. With the advancement of CTCs detection technologies in recent years, the highly efficient and highly specific detection platforms for CTCs have gradually been developed, resulting in improving CTC capture efficiency, purity and sensitivity. In this review, we systematically describe the current strategies with surface modifications by utilizing the antifouling property of polymer, peptide, protein and cell membrane for high-performance enrichment of CTCs. To wrap up, we discuss the substantial challenges facing by current technologies and the potential directions for future research and development.

A surfactant-based quasi-hydrophobic deep eutectic solvent for dispersive liquid-liquid microextraction of gliflozins from environmental water samples using UHPLC/fluorescence detection

Despite the anticipated exceptional properties of deep eutectic solvents (DES) in microextraction techniques, their self-aggregation behaviour has only been sporadically studied in the previous literature. In the presented study, a novel surfactant-based quasi-hydrophobic deep eutectic solvent (DES) is synthesized and utilized in dispersive liquid-liquid microextraction (DLLME) of three gliflozins in environmental water samples as a proof-of-concept examples. The synthesized DES is composed of benzalkonium chloride (BZKCl) as a hydrogen bond acceptor and octanol (Oct) as a hydrogen bond donor. A full optimization of the extraction conditions was carried out including molar ratio and composition of DES, volume of DES, volume of water samples, extraction time and type of diluting solvent. Moreover, the extraction mechanism was thoroughly investigated, and it was established that the extraction of the target analytes is attributed to the analytes' incorporation into the micelles' cores that facilitates mass transfer from the aqueous layer into DES layer. Furthermore, micelles formed by surfactant-based DES will provide adequate dispersion of extractant phase within water samples, which consequently improves the extraction efficiency. Micelles formation was confirmed by transmission electron microscopy (TEM). Furthermore, 1H NMR spectra verifies that the synthesized DES keeps its integrity even after extraction, which excludes any decomposition of DES after DLLME procedure. The extraction recovery is in an excellent agreement with the hydrophobicity of the investigated drugs, being the highest for the most hydrophobic one. The extracted analytes were separated by UHPLC coupled with fluorescence detection. Under the optimized experimental conditions, the method exhibits excellent linearity and a high detection sensitivity with a limit of detection of 0.5, 2.0 and 0.1 ng mL-1 for EMP (empagliflozin), DAP (dapagliflozin) and CAN (canagliflozin), respectively. The greenness of the developed microextraction approach was assessed by different greenness metrics such as Complex GAPI and AGREE tools. The developed method shows excellent greenness of synthetic procedure for preparation of DES, the environmentally benign nature of DLLME procedure as well as the greenness of the developed UHPLC approach.

Fabrication of a re-useable ionic liquid-based colorimetric organo nanosensor for detection of nerve agents' stimulants

Nerve agents are highly poisonous organophosphorus chemicals, and the possibility of being used in terrorist attacks seriously threatens public safety. Thus, developing quick and straightforward detection techniques for these dangerous substances is paramount for the scientific communities. In this contribution, we have fabricated a sensitive and easily applicable ionic liquids (ILs) based colorimetric sensor for detecting various nerve agents' stimulants in solution and gas phases, respectively, based on methyl orange (MO)-based IL ([P66614]+[MO]-) derived from MO dye and trihexyltetradecylphosphonium chloride (P66614Cl) by a simple ion exchange mechanism. The developed [P66614]+[MO]- and water-suspended [P66614]+[MO]- nanoparticles are found to be very much sensitive to detecting various nerve agents' stimulants having detection limits in the μM range in any medium and could be identified based on the response times which is found to be superior to many chemosensors available in the literature. The naked eye observed a distinct color change from yellow to fuchsia in the presence of nerve agents' stimulants, which shows better sensitivity than the free organic indicator. Furthermore, a facile test strip with [P66614]+[MO]- and water-suspended [P66614]+[MO]- NPs has been fabricated that can achieve visual detection of various nerve agents' stimulants within the stockpiles of other analogous harmful analytes. Also, a dip-stick experiment has been performed to detect harmful toxic analytes vapor. The effectiveness of [P66614]+[MO]- and water-suspended [P66614]+[MO]- NPs in identifying and quantifying various nerve agents' stimulants demonstrated its potential for usage as a signal tool for real sample analysis.

Fluorescence determination of the total amount of tetracyclines by a flavonol-based supramolecular sensor

Tetracyclines (TCs) are a group of broad-spectrum antibiotics against multiplying microorganisms yet with several adverse effects on humans. Since all types of TCs have the similar chemical skeleton and mechanism of action, quantification of total amount of TCs in the environment was of particular importance. To date, dozens of fluorescent probes have been reported for TCs detection, but only very few of them enabled detection of total TCs. In this study, we report a novel supramolecular sensor constructed by human serum albumin as the recognition moiety and a flavonol fluorophore as the indicator. Under the 370 nm UV excitation, this sensor exhibits the rapid response (5 s), acceptable sensitivity (limit of detection ∼ 0.58 μM), long dynamic detection range (0-20 μM), prominent specificity, and excellent anti-interference properties for analysis of total TCs. The mechanism was carefully validated using 1H NMR, fluorescence titration experiments, molecular docking, and mass spectrometry. We expect this work can inspire more sensor design for TCs quantification.

Diketopyrrolopyrrole-based fluorescent probe for visualizing over-expressed carboxylesterase in fever via ratiometric imaging

Fever is the result of inflammation and the innate self-defense response of organisms, can cause abnormal changes in the activity of many enzymes in organisms, including the important carboxylesterase (CE). Monitoring the activity changes of CE in vivo during a fever will help to understand heat-related pathological mechanisms. In this paper, we designed diketopyrrolopyrrole-based ratiometric fluorescent probes DPP-FBC-P and DPP-FBO-P containing alkyl chain and diethylene glycol monomethyl ether chain respective for detection of CE. Both probes could realized fast response to CE and displayed good selectivity and high sensitivity. Compared with DPP-FBO-P, DPP-FBC-P had better biocompatibility, larger signal to noise ratio (225-fold vs 125-fold) and lower detection limit (1.6 × 10-5 U/mL vs 4.2 × 10-5 U/mL). Moreover, the probe DPP-FBC-P had been successfully applied to image the endogenous CE in HepG2 cells and solid tumors, and also visualized the over expressed CE in fever cells. Most importantly, the changes of CE level in the liver of fever mice model induced by LPS were monitored with the assistance of DPP-FBC-Pvia dual channel ratio imaging for the first time. In addition, fluorescence color signal in solution was captured by smart phone, and the linear relationship between RGB ratio (G/R) and CE concentration was established. This work will provide a potential approach for investigating the physiological and pathological processes of heat related diseases.

Detection mechanism and the outlook of metal-organic frameworks for the detection of hazardous substances in milk

Milk has a high nutritional value. However, milk is easily contaminated in the production, processing, and storage processes, which harms consumers' health. Therefore, the harmful substances' detection in milk is important. Metal-organic frameworks (MOFs) have proven high potential in food safety detection due to their unique porous structure, large effective surface area, large porosity, and structural tunability. This article systematically describes the detection mechanism of fluorescence, electrochemical, colorimetric, and enzyme-linked immunosorbent assay based on MOFs. The progress of the application of MOFs in the detection of antibiotics, harmful microorganisms and their toxins, harmful ions, and other harmful substances in milk in recent years is reviewed. The structural tunability of MOFs enables them to be functionalized, giving the ability to be applied to different detection methods or substances. Therefore, MOFs can be used as an advantageous sensing material for detecting harmful substances in the complex environment of milk.