Fe-MOF/AuNP-based ratiometric electrochemical immunosensor for the detection of deoxynivalenol in grain products.

A ratiometric assay was designed to improve the sensitivity and reliability of electrochemical immunosensors for deoxynivalenol (DON) detection. The indicator signal caused by the Fe-based metal-organic framework nanocomposites loaded with gold nanoparticles and the internal reference signal from the [Fe(CN)6]3-/4- in the electrolyte came together at the immunosensor. When immunoreactivity occurred, the indicator signals decreased as the concentration of DON increased, while the internal reference signals increased slightly. The ratio of the indicator signal to the internal reference signal was available for reproducible and sensitive monitoring of DON. The prepared immunosensor showed excellent performance in the range from 0.5 to 5000 pg mL-1, and the detection limit was 0.0166 pg mL-1. The immunosensor achieved satisfactory detection toward DON in spiked and actual samples and has a promising application in the control of DON in grain products.

Co-metabolism of Na+/K+ ion regulated physiological enhancement on selenium-accumulation in Saccharomyces yeasts.

BACKGROUND: Selenium is an important nutritional supplement that mainly exists naturally in soil as inorganic selenium. Saccharomyces cerevisiae cells are excellent medium for converting inorganic selenium in nature into organic selenium. RESULTS: Under the co-stimulation of sodium selenite (Na2SeO3) and potassium selenite (K2SeO3), the activity of selenophosphate synthetase (SPS) was improved up to about five folds more than conventional Na2SeO3 group with the total selenite salts content of 30 mg/L. Transcriptome analysis first revealed that due to the sharing pathway between sodium ion (Na+) and potassium ion (K+), the K+ largely regulates the metabolisms of amino acid and glutathione under the accumulation of selenite salt. Furthermore, K+ could improve the tolerance performance and selenium-biotransformation yields of Saccharomyces cerevisiae cells under Na2SeO3 salt stimulation. CONCLUSION: The important role of K+ in regulating the intracellular selenium accumulation especially in terms of amino acid metabolism and glutathione, suggested a new direction for the development of selenium-enrichment supplements with Saccharomyces cerevisiae cell factory. © 2024 Society of Chemical Industry.

Advances on removal of organophosphorus pesticides with electrochemical technology.

Widespread use of organophosphorus pesticides (OPs), especially superfluous and unreasonable use, had brought huge harm to the environment and food chain. It is because only a small part of the pesticides sprayed reached the target, and the rest slid across the soil, causing pollution of groundwater and surface water resources. These pesticides accumulate in the environment, causing environmental pollution. Therefore, in recent years, the control and degradation of OPs have become a public spotlight and research hotspot. Due to its unique advantages such as versatility, environmental compatibility, controllability, and cost-effectiveness compatibility, electrochemical technology has become one of the most promising methods for degradation of OPs. The fundamental knowledge about electrochemical degradation on OPs was introduced in this review. Then, a comprehensive overview of four main types of practical electrochemical technologies to degrade pesticides were presented and evaluated. The knowledge contained herein should conduce to better understand the degradation of pesticides by electrochemical technology, and better exploit the degradation of pesticides in the environment and food. Overall, the objective of this review is to provide comprehensive guidance for rational design and application of electrochemical technology in the degradation of OPs for the safety of the environment and food chain in the future.

Routine analysis of pesticides in foodstuffs: Emerging ambient ionization mass spectrometry as an alternative strategy to be on your radar.

Pesticides residues in foodstuffs are longstanding of great concern to consumers and governments, thus reliable evaluation techniques for these residues are necessary to ensure food safety. Emerging ambient ionization mass spectrometry (AIMS), a transformative technology in the field of analytical chemistry, is becoming a promising and solid evaluation technology due to its advantages of direct, real-time and in-situ ionization on samples without complex pretreatments. To provide useful guidance on the evaluation techniques in the field of food safety, we offered a comprehensive review on the AIMS technology and introduced their novel applications for the analysis of residual pesticides in foodstuffs under different testing scenarios (i.e., quantitative, screening, imaging, high-throughput detection and rapid on-site analysis). Meanwhile, the creative combination of AIMS with high-resolution mass analyzer (e.g., orbitrap and time-of-flight) was fundamentally mentioned based on recent studies about the detection and evaluation of multi-residual pesticides between 2015 and 2021. Finally, the technical challenges and prospects associated with AIMS operation in food industry were discussed.

Sensitive and reproducible gold nanostar@metal-organic framework-based SERS membranes for the online monitoring of the freshness of shrimps.

Given the prevalence of food safety, online monitoring of food quality is essential. Surface-enhanced Raman scattering (SERS) has excellent sensitivity and molecular fingerprinting capabilities in analytical fields, but its accuracy in food safety monitoring is severely constrained, particularly for gaseous molecules. To further develop the SERS technique in food sensing, in this work, a slippery liquid-infused porous surface (SLIPS) platform was developed for the real-time monitoring of the change in gaseous molecules in shrimp spoilage processes. In order to monitor the change in pH and gaseous biogenic amine molecules (BAs), 4-mercaptopyridine (4-Mpy) and 4-mercaptobenzaldehyde (4-MBA)-functionalized ZIF-8-encapsulated gold nanostars (AuNS@ZIF-8) were utilized as response probes, respectively. Due to the superior gaseous molecule trapping ability of ZIF-8 and the excellent enrichment effect of SLIPS substrates, the use of 4-Mpy and 4-MBA-functionalized AuNS@ZIF-8-SLIPS substrates exhibited excellent online SERS sensing performance for pH and gaseous putrescine molecules. The detection ranges for pH and gaseous BAs were 4.0-9.0 and 10-7-10-3 (v/v) with RSDs of 4.1% and 4.2%, respectively. Furthermore, the SERS monitoring platform was used to monitor shrimp spoilage at 25 °C and 4 °C in real time. Hence, the AuNS@ZIF-8-SLIPS membrane strategy can serve as a promising alternative to ensure accurate, real-time, and non-destructive monitoring of gaseous molecules for food freshness.

Surface-enhanced Raman scattering based determination on sulfamethazine using molecularly imprinted polymers decorated with silver nanoparticles.

Molecularly imprinted polymers (MIPs) were combined with surface-enhanced Raman scattering (SERS) and AgNPs were prepared by in situ reduction within the MIP for selective and sensitive detection of sulfamethazine (SMZ). The MIP@AgNPs composites were characterized in detail by several analytical techniques, showing the generation of polymers and the formation of AgNPs hot spots. The specific affinity and rapid adsorption equilibrium rates of MIP@AgNPs composites were verified by static and kinetic adsorption studies. The MIP@AgNPs with high selectivity and excellent sensitivity were used as SERS substrates to detect SMZ. A good linear correlation (R2 = 0.996) in rang of 10-10-10-6 mol L-1 was observed between the Raman signal (1596 cm-1) and the concentration of SMZ. The limit of detection (LOD) was as low as 8.10 × 10-11 mol L-1 with relative standard deviations (RSD) of 6.32%. The good stability and reproducibility are also fully reflected in the SERS detection based on MIP@AgNPs. The method was successfully applied to the analysis of lake water samples, with recoveries in the range 85.1% to 102.5%. In summary, SERS detection based on MIP@AgNPs can be developed for a wider and broader range of practical applications. Schematic illustration of MIP@AgNPs sensor for the SERS detection of sulfamethazine.

Characterizing the Internal Structure of Chinese Steamed Bread during Storage for Quality Evaluation Using X-ray Computer Tomography.

Chinese steamed bread (CSB) is a traditional food of the Chinese nation, and the preservation of its quality and freshness during storage is very important for its industrial production. Therefore, it is necessary to study the storage characteristics of CSB. Non-destructive CT technology was utilized to characterize and visualize the microstructure of CSB during storage, and also to further study of quality changes. Two-dimensional and three-dimensional images of CSBs were obtained through X-ray scanning and 3D reconstruction. Morphological parameters of the microstructure of CSBs were acquired based on CT image using image processing methods. Additionally, commonly used physicochemical indexes (hardness, flexibility, moisture content) for the quality evaluation of CSBs were analyzed. Moreover, a correlation analysis was conducted based on the three-dimensional morphological parameters and physicochemical indexes of CSBs. The results showed that three-dimensional morphological parameters of CSBs were negatively correlated with moisture content (Pearson correlation coefficient range-0.86~-0.97) and positively correlated with hardness (Pearson correlation coefficient range-0.87~0.99). The results indicate the inspiring capability of CT in the storage quality evaluation of CSB, providing a potential analytical method for the detection of quality and freshness in the industrial production of CSB.

Progress on aptamer-based SERS sensors for food safety and quality assessment: methodology, current applications and future trends.

It is well known that food safety has aroused extensive attentions from governments to researchers and to food industries. As a versatile technology based on molecular interactions, aptamer sensors which could specifically identify a wide range of food contaminants have been extensively studied in recent years. Surface-enhanced Raman spectroscopy integrated aptamer combines the advantages of both technologies, not only in the ability to specifically identify a wide range of food contaminants, but also in the ultra-high sensitivity, simplicity, portable and speed. To provide beneficial insights into the evaluation techniques in the field of food safety, we offer a comprehensive review on the design strategies for aptamer-SERS sensors in different scenarios, including non-nucleic acid amplification methods ("on/off" mode, sandwich mode, competition model and catalytic model) and nucleic acid amplification methods (hybridization chain reaction, rolling circle amplification, catalytic hairpin assembly). Meanwhile, a special attention is paid to the application of aptamer-SERS sensors in biological (foodborne pathogenic, bacteria and mycotoxins) and chemical contamination (drug residues, metal ions, and food additives) of food matrix. Finally, the challenges and prospects of developing reliable aptamer-SERS sensors for food safety were discussed, which are expected to offer a strong guidance for further development and extended applications.

Flexible surface-enhanced Raman scatting substrates: recent advances in their principles, design strategies, diversified material selections and applications.

Surface-enhanced Raman scattering (SERS) is widely used as a powerful analytical technology in cutting-edge areas such as food safety, biology, chemistry, and medical diagnosis, providing ultra-fast, ultra-sensitive, nondestructive characterization and achieving ultra-high detection sensitivity even down to the single-molecule level. Development of Raman spectroscopy is strongly dependent on high-performance SERS substrates, which have long evolved from the early days of rough metal electrodes to periodic nanopatterned arrays building on solid supporting substrates. For rigid SERS substrates, however, their applications are restricted by sophisticated pretreatments for detecting solid samples with non-planar surfaces. It is therefore essential to reassert the principles in constructing flexible SERS substrates. Herein, we comprehensively review the state-of-the-art in understanding, preparing and using flexible SERS. The basic mechanisms behind the flexible SERS are briefly outlined, typical design strategies are highlighted and diversified selection of materials in preparing flexible SERS substrates are reviewed. Then the recent achievements of various interdisciplinary applications based on flexible SERS substrates are summarized. Finally, the challenges and perspectives for future evolution of flexible SERS and their applications are demonstrated. We propose new research directions focused on stimulating the real potential of SERS as an advanced analytical technique for commercialization.

An Overview on Recent Progress of the Hydrogels: From Material Resources, Properties, to Functional Applications.

Hydrogels, as the most typical elastomer materials with three-dimensional (3D) network structures, have attracted wide attention owing to their outstanding features in fields of sensitive stimulus response, low surface friction coefficient, good flexibility, and bio-compatibility. Because of numerous fresh polymer materials (or polymerization monomers), hydrogels with various structure diversities and excellent properties are emerging, and the development of hydrogels is very vigorous over the past decade. This review focuses on state-of-the-art advances, systematically reviews the recent progress on construction of novel hydrogels utilized several kinds of typical polymerization monomers, and explores the main chemical and physical cross-linking methods to develop the diversity of hydrogels. Following the aspects mentioned above, the classification and emerging applications of hydrogels, such as pH response, ionic response, electrical response, thermal response, biomolecular response, and gas response, are extensively summarized. Finally, this review is done with the promises and challenges for the future evolution of hydrogels and their biological applications.

Current Progress on Antibiotic Sensing Based on Ratiometric Fluorescent Sensors.

Antibiotics, which can be used as veterinary drugs, are widely used in the prevention and treatment of infectious diseases for animals. However, overuse of antibiotics had caused serious problems on food contamination and human harm. For control such public issues, several of techniques have been in recent years. Ratiometric fluorescent (RF) technique, as one of the most promising strategies for quantitatively evaluated analytes, had been extensively developed for the readily measurements on the two different fluorescent emission intensities. In this review, the construction strategies for recent RF sensors will be mainly focused on. Meanwhile, the recent advances and new tendencies for detection of antibiotics based on RF technique shall be introduced. Finally, outlooks on the opportunities and challenges for quantitative fluorescence sensing on antibiotics will be summarized.

Sensitive Techniques for POCT Sensing on the Residues of Pesticides and Veterinary Drugs in Food.

For the immense requirement on agriculture and animal husbandry, application of pesticides and veterinary drugs had become a normal state in the farming and ranching areas. However, to intently pursue the yields, large quantities of residues of pesticides and veterinary drugs have caused serious harm to both the environment and the food industry. To control and solve such an issue, a variety of novel techniques were developed in recent years. In this review, the development and features about point-of-care-testing (POCT) detection on the residues of pesticides and veterinary drugs, such as, electrochemistry (EC), enzyme-linked immunosorbent assay (ELISA) and nano-techniques, were systematically introduced. For each topic, we first interpreted the strategies and detailed account of such technical contributions on detection and assessment of the residues. Finally, the advantages and perspectives about mentioned techniques for ultrasensitive assessment and sensing on pesticides and veterinary drugs were summarized.

Ultrasensitive fluorometric determination of iron(iii) and inositol hexaphosphate in cancerous and bacterial cells by using carbon dots with bright yellow fluorescence.

An ON-OFF-ON dual-function fluorescent nanoprobe is described for the trace detection of ferric ions and inositol hexaphosphate (IP6) in living cells. It is based on the use of yellow-fluorescent nitrogen-doped carbon dots (YN-CDs). Highly fluorescent YN-CDs were synthesized by a hydrothermal process. They have an absolute quantum yield of 2.15% and excitation/emission peaks at 420/575 nm. Fluorescence is quenched by Fe3+via photo-induced electron transfer. The quenchometric assay has a 34 nM detection limit for Fe(iii). On addition of IP6 which has a high affinity for Fe3+ due to the formation of Fe-O-P bonds, fluorescence becomes gradually restored. The resulting ON-OFF-ON assays for Fe(iii) and IP6 are reliable and sensitive. IP6 can be detected at concentrations as low as 2 nM. The nanoprobe was then applied to the determination of Fe3+ and IP6 in living cells in a food matrix. Furthermore, YN-CDs exhibited excellent biocompatibility. Hence, the probe can be applied as a fluorescent ink for bioimaging, both in vitro (cancer cells and bacteria) and in vivo (nematodes and mice).

Extraction, Purification, Structural Characteristics, Biological Activities and Pharmacological Applications of Acemannan, a Polysaccharide from Aloe vera: A Review.

: Aloe vera is a medicinal plant species of the genus Aloe with a long history of usage around the world. Acemannan, considered one of the main bioactive polysaccharides of Aloe vera, possesses immunoregulation, anti-cancer, anti-oxidation, wound healing and bone proliferation promotion, neuroprotection, and intestinal health promotion activities, among others. In this review, recent advancements in the extraction, purification, structural characteristics and biological activities of acemannan from Aloe vera were summarized. Among these advancements, the structural characteristics of purified polysaccharides were reviewed in detail. Meanwhile, the biological activities of acemannan from Aloe vera determined by in vivo, in vitro and clinical experiments are summarized, and possible mechanisms of these bioactivities were discussed. Moreover, the latest research progress on the use of acemannan in dentistry and wound healing was also summarized in details. The structure-activity relationships of acemannan and its medical applications were discussed. Finally, new perspectives for future research work on acemannan were proposed. In conclusion, this review summarizes the extraction, purification, structural characteristics, biological activities and pharmacological applications of acemannan, and provides information for the industrial production and possible applications in dentistry and wound healing in the future.

Study on the wall-breaking method of carotenoids producing yeast Sporidiobolus pararoseus and the antioxidant effect of four carotenoids on SK-HEP-1 cells.

The cell wall of carotenoids producing yeast Sporidiobolus pararoseus was broken through five different methods: acid-heating method, dimethyl sulfoxide (DMSO) method, enzymatic method, high-pressure homogenization (HPH) method, and cell autolysis method. HPH method not only brought the optimum breaking effect (wall-breaking extent of 72.3%) and the highest carotenoid extraction rate (67.2%), but also had the advantages of short-time, simple process, safe, and pollution-free. After optimization, the wall-breaking extent and the carotenoid extraction rate were enhanced to 78.3% and 82.5%, respectively. And the optimum conditions of HPH were obtained as homogenization pressure 80 MPa, bacterial liquid concentration 8% and homogenization for three times. Moreover, cell experiments demonstrated that all of the four carotenoids (ß-carotene, γ-carotene, torulene, and torularhodin) purified from intracellular products of S. pararoseus. had the effect of resistance to oxidative damage from hydrogen peroxide on SK-HEP-1 cells, and torulene showed the most notable effect among them.

Comet-like Heterodimers "Gold Nanoflower @Graphene Quantum Dots" Probe with FRET "Off" to DNA Circuit Signal "On" for Sensing and Imaging MicroRNA In Vitro and In Vivo.

Cardiovascular diseases have recently become the number one cause of death worldwide and the risk of getting cardiovascular diseases is doubled as the age increases. MicroRNA-34a (miRNA-34a) as an important potential sensor of aging and cellular senescence could be used in early diagnostics. Herein, a new ultrasensitive platform on the basis of the fluorescence resonance energy transfer (FRET) "off" to DNA circuit signal "on" principle was established, termed comet-like heterodimers gold nanoflower (AuNF) @ graphene quantum dots (GQDs) probe. We discussed that the distance of 4 nm between AuNF and GQDs would increase fluorescence quenching efficiency, and light up sensitivity after the probe combined with a target miRNA initiating DNA circuit strategy. The target miRNA-34a can be quantified down to 0.1 fM, which is about 2 orders of magnitude lower than the existing sensing protocols. Furthermore, we constructed the aging myocardial cell and animal model, and the nanoprobe presented low cytotoxicity and satisfied signal imaging in vitro and in vivo. Significantly, this platform herein is envisioned to provide a reliable guidance for early diagnosing cardiovascular diseases and proposing therapeutic protocols.

Ultrasensitive "FRET-SEF" Probe for Sensing and Imaging MicroRNAs in Living Cells Based on Gold Nanoconjugates.

MicroRNAs (miRNAs), a kind of single-stranded small RNA molecule, play significant roles in the physiological and pathological processes of human beings. Currently, miRNAs have been demonstrated as important biomarkers critically related to many diseases and life nature, including several cancers and cell senescence. It is valuable to establish sensitive assays for monitoring the levels of intracellular up-regulated/down-regulated miRNA expression, which would contribute to the early prediction of the tumor risk and cardiovascular disease. Here, an oriented gold nanocross (AuNC)-decorated gold nanorod (AuNR) probe with "OFF-enhanced ON" fluorescence switching was developed based on fluorescence resonance energy transfer and surface enhanced fluorescence (FRET-SEF) principle. The nanoprobe was used to specifically detect miRNA in vitro, which gave two linear responses represented by the equation F = 1830.32 log C + 6349.27, R2 = 0.9901, and F = 244.41 log C + 1916.10, R2 = 0.9984, respectively, along with a detection limit of 0.5 aM and 0.03 fM, respectively. Furthermore, our nanoprobe was used to dynamically monitor the expression of intracellular up-regulated miRNA-34a from the HepG2 and H9C2 cells stimulated by AFB1 and TGF-ß1, and the experimental results showed that the new probe not only could be used to quantitively evaluate miRNA oncogene in vitro, but also enabled tracking and imaging of miRNAs in living cells.

Printing Functional Protein Nanodots on Soft Elastomers: From Transfer Mechanism to Cell Mechanosensing.

Living cells sense the physical and chemical nature of their micro/nano environment with exquisite sensitivity. In this context, there is a growing need to functionalize soft materials with micro/nanoscale biochemical patterns for applications in mechanobiology. This, however, is still an engineering challenge. Here a new method is proposed, where submicronic protein-patterns are first formed on glass and are then printed on to an elastomer. The degree of transfer is shown to be governed mainly by hydrophobic interactions and to be influenced by grafting an appropriate fluorophore onto the core protein of interest. The transfer mechanism is probed by measuring the forces of adhesion/cohesion using atomic force microscopy. The transfer of functional arrays of dots with size down to about 400 nm, on elastomers with stiffness ranging from 3 kPa to 7 MPa, is demonstrated. Pilot studies on adhesion of T lymphocytes on such soft patterned substrates are reported.

Using fluorescence immunochromatographic test strips based on quantum dots for the rapid and sensitive determination of microcystin-LR.

A novel immunosensor for the detection of microcystin-LR (MC-LR) was constructed with use of immunochromatographic test strips (ICTS). Quantum dots were chosen to be the fluorescent labels for the immune sensor in ICTS because of their excellent optical and electronic properties with a relatively narrow emission spectrum. The detection sensitivity of the ICTS was related to the concentration of the fluorescent probe and the amount of the MC-LR standards. Under optimal conditions, with MC-LR as the target, the ICTS sensor had a linear range from 0.25 to 5 µg/L, with a correlation coefficient of 0.9901 and a detection limit of 0.1 µg/L. Furthermore, the repeatability of the ICTS was good, and the coefficient of variation was 10%. The ICTS immunosensor allows the reliable detection of MC-LR in water, and has potential in simple, sensitive detection applications. Graphical Abstract A novel method was developed to detect MC-LR using QDs based immunochromatographic test strip.

Size-Tunable Organic Nanodot Arrays: A Versatile Platform for Manipulating and Imaging Cells.

Arrays of protein nanodots with dot-size tuned independently of spacing (e.g., ∼100 to 600 nm diameter for 900 nm spacing) are fabricated. The mechanism of size control is demonstrated, by numerical simulations, to arise from shadow effects during deposition of a sacrificial metal mask. We functionalize the nanodots with antibodies and embed them in a polymer-cushion or in lipid-bilayers or transfer them to soft elastomers. Their ability to influence cell architecture and local membrane organization is demonstrated in T-lymphocytes, using reflection interference contrast and total internal reflection fluorescence microscopy.