Cathodic electrochemiluminescence of L012 and its application in antioxidant detection.

Cathodic electrochemiluminescence (ECL) of a luminol (or its analogues)-dissolved oxygen (O2) system is an ideal alternative to ECL of the traditional luminol-hydrogen peroxide (H2O2) system, which can efficiently avoid the self-decomposition of H2O2 at room temperature. However, the mechanism for the generation of cathodic ECL by the luminol (or its analogues)-O2 system is still ambiguous. Herein, we report the study of cathodic ECL generation by the L012-O2 system at a glassy carbon electrode (GCE). The types of reactive oxygen species (ROS) involved generated during ECL reactions were verified. A possible reaction mechanism for the system was proposed and the rate constants of related reactions were estimated. Furthermore, several intermediates of L012 involved in the proposed pathways were validated by electrochemistry-coupled mass spectrometry. Finally, the cathodic ECL system was successfully used for measuring the antioxidant capacity of commercial juice with Trolox as a standard.

Recent Progress in Photoelectrochemical Sensing of Pesticides in Food and Environmental Samples: Photoactive Materials and Signaling Mechanisms.

Pesticides have become an integral part of modern agricultural practices, but their widespread use poses a significant threat to human health. As such, there is a pressing need to develop effective methods for detecting pesticides in food and environmental samples. Traditional chromatography methods and common rapid detection methods cannot satisfy accuracy, portability, long storage time, and solution stability at the same time. In recent years, photoelectrochemical (PEC) sensing technology has gained attention as a promising approach for detecting various pesticides due to its salient advantages, including high sensitivity, low cost, simple operation, fast response, and easy miniaturization, thus becoming a competitive candidate for real-time and on-site monitoring of pesticide levels. This review provides an overview of the recent advancements in PEC methods for pesticide detection and their applications in ensuring food and environmental safety, with a focus on the categories of photoactive materials, from single semiconductor to semiconductor-semiconductor heterojunction, and signaling mechanisms of PEC sensing platforms, including oxidation of pesticides, steric hindrance, generation/decrease in sacrificial agents, and introduction/release of photoactive materials. Additionally, this review will offer insights into future prospects and confrontations, thereby contributing novel perspectives to this evolving domain.

Multi-emitter metal-organic frameworks as ratiometric luminescent sensors for food contamination and spoilage detection.

Food contamination and spoilage is a worldwide concern considering its adverse effect on public health and food security. Real time monitoring food quality can reduce the risk of foodborne disease to consumers. Particularly, the emergence of multi-emitter luminescent metal-organic frameworks (LMOFs) as ratiometric sensory materials has provided the possibility for food quality and safety detection with high sensitivity and selectivity taking advantage of specific host-guest interactions, pre-concentrating and molecule-sieving effects of MOFs. Furthermore, the excellent sensing performance of multi-emitter MOF-based ratiometric sensors including self-calibration, multi-dimensional recognition and visual signal readout is able to meet the increasing rigor requirement of food safety evaluation. Multi-emitter MOF-based ratiometric sensors have become the focus of food safety detection. This review focuses on design strategies for different multiple emission sources assembly to construct multi-emitter MOFs materials based on at least two emitting centers. The design strategies for creating multi-emitter MOFs can be mainly classified into three categories: (1) multiple emission building blocks assembly in a single MOF phase; (2) single non-luminescent MOF or LMOF phase as a matrix for chromophore guest(s); (3) heterostructured hybrids of LMOF with other luminescent materials. In addition, the sensing signal output modes of multi-emitter MOF-based ratiometric sensors have critically discussed. Next, we highlight the recent progress for the development of multi-emitter MOF as ratiometric sensors in food contamination and spoilage detection. Their future improvement and advancing direction potential for their practical application is finally discussed.

Advanced gut-on-chips for assessing carotenoid absorption, metabolism, and transport.

Bioengineered strategies enable gut chips to faithfully replicate essential features of intestinal microsystems, encompassing geometric properties, peristalsis, intraluminal fluid flow, oxygen gradients, and the microbiome. This emerging technique serves as a powerful tool for nutrition studies by emulating the absorption and distribution processes in a manner highly relevant to human physiology. It offers unprecedented accessibility for investigating the mechanisms governing nutrition metabolism. While the application of gut-on-chip models in disease modeling and drug screening has been extensively explored, their potential in dietary nutrition research remains relatively unexplored. This comprehensive review provides an overview of the different approaches employed in constructing gut-on-chip platforms using diverse cell sources and niche mimics. Furthermore, it explores the applications and prospects of gut-on-chips in nutrition-related investigations, with a specific focus on carotenoid transport, absorption, and metabolism. Lastly, this review discusses the future development trajectory of this groundbreaking technology paradigm, highlighting its broad applicability in the field of food technology. By harnessing the capabilities of these state-of-the-art techniques within gut chip platforms, researchers can establish a robust scientific foundation for unraveling the intricate mechanisms that govern the behavior and functional properties of carotenoids.

Recent advances on natural colorants-based intelligent colorimetric food freshness indicators: fabrication, multifunctional applications and optimization strategies.

With the increasing concerns of food safety and public health, tremendous efforts have been concentrated on the development of effective, reliable, nondestructive methods to evaluate the freshness level of different kinds of food. Natural colorants-based intelligent colorimetric indicators which are typically constructed with natural colorants and polymer matrices has been regarded as an innovative approach to notify the customers and retailers of the food quality during the storage and transportation procedure in real-time. This review briefly elucidates the mechanism of natural colorants used for intelligent colorimetric indicators and fabrication methodologies of natural colorants-based food freshness indicators. Subsequently, their multifunctional applications in intelligent food packaging systems like antioxidant packaging, antimicrobial packaging, biodegradable packaging, UV-blocking packaging and inkless packaging are well introduced. This paper also summarizes several optimizing strategies for the practical application of this advanced technology from different perspectives. Strategies like adopting a hydrophobic matrix, constructing double-layer film and encapsulation have been developed to improve the stability of the indicators. Co-pigmentation, metal ion complexation, pigment-mixing and using substrates with high surface area are proved to be effective to enhance the sensitivity of the indicators. Approaches include multi-index evaluation, machine learning and smartphone-assisted evaluation have been proven to improve the accuracy of the intelligent food freshness indicators. Finally, future research opportunities and challenges are proposed. Based on the fundamental understanding of natural colorants-based intelligent colorimetric food freshness indicators, and the latest research and findings from literature, this review article will help to develop better, lower cost and more reliable food freshness evaluation technique for modern food industry.

Advances of microfluidic intestine-on-a-chip for analyzing anti-inflammation of food.

Microfluidic intestine-on-a-chip enables novel means of emulating human intestinal pathophysiology in vitro, which can potentially reduce animal testing and substitute simple 2D culture system. Though a great deal of work has been done in the development of microfluidic platforms for intestinal disease modeling and drug screening, potential investigation of the effect of bioactive food compounds on intestinal inflammation remains largely unexplored. In this review, different biomaterials and chip designs have been explored in the fabrication of intestine-on-a-chip. Other key parameters must be carefully controlled and selected, including shear stress, cell type and cell co-culture spatial configuration, etc. Appropriate techniques to quantify the barrier integrity including trans-epithelial electric resistance, specific tight junction markers and permeability measurements should be standardized and compared with in vivo data. Integration of the gut microbiome and the provision of intestinal-specific environment are the key parameters to realize the in vivo intestinal model simulation and accelerate the screening efficiency of bioactive food compounds.

Formation and biological effects of protein corona for food-related nanoparticles.

The rapid development of nanoscience and nanoengineering provides new perspectives on the composition of food materials, and has great potential for food biology research and applications. The use of nanoparticle additives and the discovery of endogenous nanoparticles in food make it important to elucidate in vivo safety of nanomaterials. Nanoparticles will spontaneously adsorb proteins during transporting in blood and a protein corona can be formed on the nanoparticle surface inside the human body. Protein corona affects the physicochemical properties of nanoparticles and the structure and function of proteins, which in turn affects a series of biological reactions. This article reviewed basic information about protein corona of food-related nanoparticles, elucidated the influence of protein corona on nanoparticles properties and protein structure and function, and discussed the effect of protein corona on nanoparticles in vivo. The effects of protein corona on nanoparticles transport, cellular uptake, cytotoxicity, and immune response were reviewed, and the reasons for these effects were also discussed. Finally, future research perspectives for food protein corona were proposed. Protein corona gives food nanoparticles a new identity, which makes proteins bound to nanoparticles undergo structural transformations that affect their recognition by receptors in vivo. It can have positive or negative impacts on cellular uptake and toxicity of nanoparticles and even trigger immune responses. Understanding the effects of protein corona have potential in evaluating the fate of the food-related nanoparticles, providing physicochemical and biological information about the interaction between proteins and foodborne nanoparticles. The review article will help to evaluate the safety of protein coronas formed on nanoparticles in food, and may provide fundamental information for understanding and controlling nanotoxicity.

Effect of pre-frying on distribution of protons and physicochemical qualities of mackerel.

BACKGROUND: In this work, low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging were used to investigate the changes in protons (from water and oil) distribution of mackerel during the frying process. The relationship between proton migration and some physicochemical indexes was established by partial least squares regression (PLSR). The changing mechanism of the quality characteristics and physicochemical properties of fish meat under different frying conditions was analysed by LF-NMR combined with PLSR, which provided theoretical support for the development of canned mackerel food. RESULTS: LF-NMR results showed that three kinds of T2 protons assigned to protein-water interaction (T21 ), multilayer bound water (T22 ), oil and free water (T23 ), respectively. As the frying temperature increased, protons from the T22 peak significantly decreased, while protons from the T23 peak remarkably increased. The microstructure of fried mackerel was destroyed; cooking loss, oil content, a* value, b* value, hardness and chewiness increased; and the protein content and L* value decreased. Furthermore, PLSR analysis revealed that significant correlation was observed between the cooking loss, TPA parameter (chewiness), colour parameter (L*) and LF-NMR parameters. CONCLUSION: Different frying temperatures and times had a strong effect on the physicochemical properties of mackerel. Good prediction models could be established by proton migration using the LF-NMR technique and PLSR for fried mackerel. Quality control of fried fish could be realized by monitoring the change in LF-NMR data. © 2021 Society of Chemical Industry.

Smart Bimodal Imaging of Hypochlorous Acid In Vivo Using a Heterobimetallic Ruthenium(II)-Gadolinium(III) Complex Probe.

A unique heterobimetallic Ru(II)-Gd(III) complex, Ru-AN-Gd, is reported to serve as an effective probe for bimodal phosphorescence-magnetic resonance (MR) imaging of hypochlorous acid (HClO) in vitro and in vivo. The probe was designed by incorporating a MR contrast agent, Gd-DOTA, into a HClO-responsive bipyridine-Ru(II) complex derivative. The specific reaction between Ru-AN-Gd and HClO triggers the cleavage of an ether bond in the probe molecule, resulting in phosphorescence turn-on and MR turn-off responses to HClO. The integration of MR and phosphorescence detection modes allows the probe to be employed for detecting HClO in a quite wide concentration range (0.6-2000 µM) and for imaging HClO at various resolutions ranging from the subcellular level to the whole body without a depth limit. Its applicability was demonstrated by phosphorescence imaging of lysosomal HClO in live cells, visualization of HClO generation in a mouse arthritis model, and bimodal phosphorescence-MR imaging of HClO in drug-induced acute liver and kidney injury of a mouse. The research achievements suggested the potential of Ru-AN-Gd for diagnosis and treatment monitoring of HClO-related disease.

Biocompatible fluorescent carbon dots derived from roast duck for in vitro cellular and in vivo C. elegans bio-imaging.

Biocompatible fluorescent carbon dots (CDs) were prepared via a simple and green route using duck breasts as a natural carbon source. The CDs from duck breasts were well dispersed, and their mean particle size decreased from 2.59 to 1.95 nm when the roasting temperature increased from 200 to 300 °C. Abundant functional groups such as OH, COOH, and NH2 were observed on the surface of the CDs, providing the CDs with good water solubility. These CDs emitted strong fluorescence under ultraviolet light irradiation and exhibited superior photostability. The absolute fluorescence quantum yield of CDs rose from 10.53% to 38.05% when the relative nitrogen content of CDs increased from 7.18% to 12.73%. The CDs showed low toxicity to PC12 cells for prolonged exposure. Therefore, the duck CDs were successfully developed as fluorescent probes for in vitro PC12 cells and in vivo Caenorhabditis elegans imaging. These results indicated that the CDs derived from roast duck were biocompatible and can potentially be used as probes in bio-imaging.

Fluorescent carbon dots derived from urine and their application for bio-imaging.

This study aims to obtain water-soluble fluorescent carbon dots (C-dots) from low-value metabolites through a simple, economical, one-step synthetic route. The urine C-dots (UCDs) and hydrothermally treated urine C-dots (HUCDs) were obtained, respectively, using straightforward Sephadex filtration method from human adults and hydrothermal reaction method. The UCDs and HUCDs emit fluorescence upon being excited with ultraviolet light with a quantum yield of 4.8% and 17.8%, respectively. TEM analysis revealed that UCDs and HUCDs had an average size of 2.5 nm and 5.5 nm, respectively. X-ray photoelectron spectroscopy (XPS) analysis showed the UCDs and HUCDs were mainly composed of carbon, oxygen and nitrogen. Fourier-transform infrared (FTIR) spectroscopy demonstrated the presence of functional groups, such as amino, hydroxyl, carboxylate and carbonyl groups onto the C-dots. The UCDs and HUCDs can be directly used for in vivo and in vitro imaging in Hela cells, Caenorhabditis elegans, onion epidermal cells and bean sprouts. The cytotoxicity study revealed that the UCDs and HUCDs were not toxic to normal rat kidney (NKR) cells with good biocompatibility. The results revealed that the C-dots derived from urine have good biocompatibility, strong fluorescence and may have potential to be a safe fluorescent probe for bio-imaging.

Characterization of moisture migration of beef during refrigeration storage by low-field NMR and its relationship to beef quality.

BACKGROUND: In this study, low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) were used to investigated the moisture migration of beef during refrigeration storage, and its relationships to some physicochemical quality indicators were analyzed using partial least squares regression. RESULTS: Three water components ascribed to bound water, immobilized water and free water in beef matrix were revealed by LF-NMR relaxation results. The transverse relaxation time and peak area of immobilized water declined as storage proceeded, as a result of disruption to the microstructure revealed by scanning electron microscope images. MRI images found obvious water migration of beef during refrigeration storage, and scanning electron microscopy images revealed that the integrity of the muscle fiber bundle was destroyed. In addition, increased storage time also led to increases in pH, total volatile basic nitrogen, TBARS (thiobarbituric acid reactive substances) value, weight loss, cooking loss and b* value, and to decreases in water holding capacity (WHC), L* and a* values, and textural properties. CONCLUSION: The strong correlations between water migration and the physicochemical quality changes suggested the possibility of LF-NMR as a rapid and non-invasive method to evaluate beef quality. © 2019 Society of Chemical Industry.

Highly fluorescent carbon dots for visible sensing of doxorubicin release based on efficient nanosurface energy transfer.

OBJECTIVES: To prepare fluorescent carbon dots for loading cationic anticancer drug through donor-quenched nanosurface energy transfer in visible sensing of drug release. RESULTS: Highly fluorescent carbon dots (CDs) were prepared by a facile hydrothermal approach from citric acid and o-phenylenediamine. The obtained CDs showed a high quantum yield of 46 % and exhibited good cytocompatibility even at 1 mg/ml. The cationic anticancer drug doxorubicin (DOX) can be loaded onto the negatively charged CDs through electrostatic interactions. Additionally, the fluorescent CDs feature reversible donor-quenched mode nanosurface energy transfer. When loading the energy receptor DOX, the donor CDs' fluorescence was switched "off", while it turned "on" again after DOX release from the surface through endocytic uptake. CONCLUSIONS: Most DOX molecules were released from the CDs after 6 h incubation and entered cell nuclear region after 8 h, suggesting the drug delivery system may have potential for visible sensing in drug release.

Influence of microemulsion-mucin interaction on the fate of microemulsions diffusing through pig gastric mucin solutions.

Mucus layer, a selective diffusion barrier, has an important effect on the fate of drug delivery systems in the gastrointestinal tract. To study the fate of microemulsions in the mucus layer, four microemulsion formulations with different particle sizes and lipid compositions were prepared. The microemulsion-mucin interaction was demonstrated by the fluorescence resonance energy transfer (FRET) method. Moreover, the microemulsions were observed aggregated into micron-sized emulsions by laser confocal microscopy. We concluded the microemulsion-mucin interaction not only led to microemulsions closely adhered to mucins but also destroyed the structure of microemulsions. At last, the diffusion of blank microemulsions and microemulsion-carried drugs (resveratrol and hymecromone) through mucin solutions was determined by the fluorescence recovery after photobleaching (FRAP) method and the Franz diffusion cell method. The results demonstrated the diffusion of microemulsions was significantly hindered by mucin solutions. The particle size of microemulsions had a negligible effect on the diffusion coefficients. However, the type of lipid played an important role, which could form hydrophobic interactions with mucins. Interestingly, microemulsion-carried drugs with different core/shell locations seemed to suffer different fates in the mucin solutions. The drug incorporated in the oil core of microemulsions, resveratrol, was transported through the mucus layer by the carriers, while the drug incorporated in the surfactant shell of microemulsions, hymecromone, was separated from the carriers and diffused toward the epithelium in the form of free molecules.

Ultrasmall Chitosan-Genipin Nanocarriers Fabricated from Reverse Microemulsion Process for Tumor Photothermal Therapy in Mice.

Nanocarriers play an important role in improving the photo- and thermal-stability of photosensitizers to gain better pharmacokinetics behavior in tumor photothermal therapy. Herein, PEGylated chitosan (CG-PEG; PEG: polyethylene glycol) nanoparticles with ultrasmall size (∼5 nm) were prepared through a water-in-oil reverse microemulsion method using genipin as a cross-linker. Particle size and zeta-potential can be tuned by varying the molar ratio between chitosan amino groups and genipin. CG-PEG-ICG (ICG: indocyanine green) nanoparticles were fabricated by adding ICG to CG-PEG aqueous solution through a self-assembly method via electrostatic interaction. The resultant CG-PEG-ICG nanoparticles exhibited improved photo- and thermal-stability, good biocompatibility, and low toxicity. When irradiated with a laser, the cells incubated with CG-PEG-ICG nanoparticles showed very low cell viability (15%), indicating the CG-PEG-ICG nanoparticles possess high in vitro photothermal toxicity. Moreover, the CG-PEG nanocarriers can significantly alter the biodistribution and prolong the retention time of ICG in the mice body after intravenous injection. In vivo photothermal study of tumors injected with CG-PEG-ICG nanoparticles containing ICG at a concentration greater than 100 µg·mL(-1) (100 µL) induced irreversible tissue damage. The growth of U87 tumors was dramatically inhibited by CG-PEG-ICG nanoparticles, demonstrating that the CG-PEG nanoparticles may act as potential ICG nanocarriers for effective in vivo tumor photothermal therapy.

Synthesis and evaluation of a targeted nanoglobular dual-modal imaging agent for MR imaging and image-guided surgery of prostate cancer.

PURPOSE: To synthesize and evaluate a peptide targeted nanoglobular dual modal imaging agent specific to a cancer biomarker in tumor stroma for MRI and fluorescence visualization of prostate tumor in image-guided surgery. METHODS: A peptide (CGLIIQKNEC, CLT1) targeted generation 2 nanoglobular (polylysine dendrimer with a silsesquioxane core) dual modal imaging agent, CLT1-G2-(Gd-DOTA-MA)-Cy5, was synthesized by stepwise conjugation of Gd-DOTA-MA, Cy5 and peptide to the dendrimer. Contrast enhanced MR imaging of the targeted dual imaging agent was evaluated on a Bruker 7T animal scanner with male athymic nude mice bearing orthotopic PC3-GFP prostate tumor. Fluorescence tumor imaging of the agent was carried out on a Maestro fluorescence imaging system. RESULTS: The targeted agent CLT1-G2-(Gd-DOTA-MA)-Cy5 produced greater contrast enhancement in the tumor tissue than the control agent KAREC-G2-(Gd-DOTA-MA)-Cy5 at a dose of 30 µmol-Gd/kg in the MR images of the tumor bearing mice. Signal-to-noise ratio (SNR) of CLT1-G2-(Gd-DOTA-MA)-Cy5 in the tumor tissue was approximately 2 fold of that of the control agent in the first 15 min post-injection. The targeted agent also resulted in bright fluorescence signals in the tumor tissue. CONCLUSION: The CLT1 peptide targeted nanoglobular dual-imaging agent CLT1-G2-(Gd-DOTA-MA)-Cy5 has a potential for MRI and fluorescence visualization of prostate tumor.

Effect of lipolysis on drug release from self-microemulsifying drug delivery systems (SMEDDS) with different core/shell drug location.

The objective of this study is to investigate the effect of lipolysis on the release of poorly water-soluble drug from SMEDDS in the perspective of drug core/shell location. For this purpose, four SMEDDS formulations with various core/shell properties were developed based on long-chain lipid or medium-chain lipid as well as different surfactant/oil ratios. Poorly water-soluble drugs, hymecromone and resveratrol, were significantly solubilized in all SMEDDS formulations and the diluted microemulsions. Fluorescence spectra analysis indicated that hymecromone was mainly located in the shell of microemulsions, while resveratrol was located in the core. The effect of lipolysis on the release rates of drugs with different core/shell locations were investigated by a modified in vitro drug release model. For the drug located in the shell, hymecromone, the release profiles were not affected during the lipolysis process and no significant differences were observed among four formulations. For the drug located in the core, resveratrol, the release rates were increased to various degrees depending on the extent of digestion. In conclusion, the drug core/shell location plays an important role for determining the effect of lipolysis on drug release from SMEDDS formulation.

ROS-responsive carboxymethyl chitosan nanoparticles loaded with astaxanthin for alleviating oxidative damage in intestinal cells.

The controlled release of antioxidant substances at the intestinal oxidative damage site is crucial for alleviating intestine-related diseases. Herein, the novel ROS-responsive carrier was synthesized through simple amidation reaction between carboxymethyl chitosan (CMC) and methionine (Met), a natural organic compound containing ROS-responsive linkages (thioether). Initially, astaxanthin (AXT) nanoparticles (AXT2@CMT) with excellent stability and drug loading capacity (39.68 ± 0.23 µg/mL) were prepared by optimizing various reaction conditions. In the simulated high-concentration ROS environment of the intestine, CMT achieved a transition from hydrophobic groups (thioether) into hydrophilic groups (sulfone), which was conducive to the controlled release of AXT. In vitro cell experiments revealed that AXT2@CMT could effectively alleviate the oxidative damage in intestinal epithelioid cell line No. 6 (IEC-6 cell) caused by H2O2. This study achieved a straightforward preparation of ROS-responsive nanocarrier through food ingredients, offering a theoretical foundation for the controlled release of AXT at the intestinal oxidative damage site.

Green synthesis of Zn2+ nanocarriers from Auricularia auricula fermentation broth with excellent antioxidant activity.

Nanoparticles (NPs) possessing nanoscale dimensions and remarkable antioxidant activity were synthesized via a green hydrothermal method utilizing Auricularia auricula fermentation broth, referred to as AFNPs. The functional groups on the surface of the AFNPs significantly contributed to the formation of AFNPs-Zn2+. The AFNPs-Zn2+ appeared a zinc retention rate of 40.80 % after gastrointestinal digestion. When compared to typical zinc supplements, AFNPs-Zn2+ did not exhibit visible cytotoxicity or hemolysis. Furthermore, AFNPs-Zn2+ demonstrated the ability to mitigate cell damage resulting from zinc deficiency. In vivo experiments showed that AFNPs-Zn2+ were mainly observed in the stomach, intestine, kidney, and testis after oral administration. In vivo distribution experiments indicated predominant presence of AFNPs-Zn2+ in the stomach, intestine, kidney, and testis following oral administration. This study highlights the potential for Auricularia auricula NPs to serve as the efficient, stable, and safe nanocarriers for Zn2+.