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The biocompatible MIL-88A metal-organic framework (MOF), synthesized from food-grade fumaric acid and ferric chloride, was introduced for the efficient one-step in situ encapsulation of capsaicinoids as a nanopreservative. The resulting MIL-88A@Caps nanoparticles can load 61.43 mg/g of capsaicinoids, surpassing conventional MOF-based encapsulation. The potent MIL-88A@Caps nanoformulations synergize the intrinsic antimicrobial properties of MIL-88A and capsaicinoids. At the same concentration (0.5 mg/mL), MIL-88A@Caps was highly effective against S. aureus and Salmonella , with inhibition rates of 94.90 ± 0.58% and 94.30 ± 1.24%, respectively, compared to MIL-88A (62.28 ± 5.04% and 70.46 ± 1.96%) and capsaicinoids (63.68 ± 1.25% and 49.53 ± 1.22%), respectively. Model precooked-chicken preservation experiments revealed that MIL-88A@Caps significantly delayed spoilage parameters compared to untreated samples, with more favorable viable counts (8.08 lgCFU/g), pH value (6.60 ± 0.02), TVB-N value (8.59 ± 0.21 mg/100 g), and color changes on day 9. Our findings yield a green nanopreservative for meat safety. [Display omitted] • MIL-88A serves as a food-grade nanocarrier for encapsulation of capsaicinoids. • Simple, green, and efficient synthsis of MIL-88A@capsaicinoids is achieved. • MIL-88A@Caps exerts snergistic antimicrobial activity against foodborne pathogens. • MIL-88A@Caps is a safe and effective nano-preservative for precooked chicken. [ABSTRACT FROM AUTHOR]

Microbiological safety of food is closely related to the activities of foodborne microorganisms, which is among the critical issues in the food industry that require careful screening. A series of analytical techniques have been employed for microbiological food safety detection but renders either analytical defects or practical limitations. With the sensitive and fingerprint sensing ability of surface-enhanced Raman scattering (SERS) technique and the easy operations of magnetic entities (MEs), SERS-based magnetic platforms (MagSERS) emerge as a potent candidate for the analysis of microbiological foodborne hazards. The current review focuses on the fundamentals and recent applications of MagSERS in microbiological safety of food. In this review, the design and fabrication of MagSERS are introduced, which comprises the functionalized MEs plus noble-metal SERS substrates, magnetic nanocomposites plus noble-metal SERS substrates, and magnetic SERS substrates, and the detection principles of MagSERS are illustrated in detail, including the combination of magnetic capture, separation, and enrichment of targets (via recognition elements functionalized MEs) with SERS substrates, as well as the magnetism-mediated hotspot engineering of SERS substrates. In addition, the current advances in MagSERS methods for detecting foodborne bacteria, biological toxins, and viruses are summarized and future perspectives for the food industry are also given. Key findings and conclusions : As demonstrated by the publications in the field, MagSERS that merges magnetic properties and SERS spectra can facilitate the detection of foodborne biohazards for their excellent target separation and enrichment (sampling), simplified assay procedures (assaying), optimized SERS effect and signal or signalling. As such, MagSERS platforms show a promising prospect in the construction of more simple, rapid, and sensitive biosensors for food safety. • Design, fabrication, and principles of diverse types of MagSERS are presented. • Current advances and future trends of MagSERS for food bioanalysis are proposed. • MagSERS is featured with simple sampling, rapid assaying, and sensitive signalling. • MagSERS can be used for assaying foodborne bacteria, biotoxins, and viruses. [ABSTRACT FROM AUTHOR]

Along with the intensification of global food supply, food security has become a fateful barrier throughout the global food trade and delivery. Reliable analytic techniques are in strong need to keep up with the continuous demand for food quality and safety monitoring. In this review, the current strategies for different fluorescence mechanisms of MOF-based sensors for food detection are classified and we highlight the construction strategy of MOFs to obtain high performance and multiple photonic function. In addition, recent applications of LMOFs in food safety analyzing as well as the typical sensing mechanisms are reviewed. Finally, we also outline the challenges in these fields and put forward the prospects for future development of LMOFs in food analysis. Fluorescent MOFs have been utilized as sensors to alleviate the food safety problems. The vast combination possibilities, synergistic effects, as well as controllable and ordered arrangements of multiple fluorescent units have distinguished MOFs from other analysis techniques and enabled them to be a promising platform for food quality and safety control. Reasonable crystal engineering principles offers MOFs with the structure–property correlations and varied fluorometric sensing properties, resulting in a rapidly increasing application in food safety. [Display omitted] • Novel analytic techniques facilitate better food safety control. • Luminescent MOFs have been well developed as sensors. • The flexible design enables MOFs capable of complicated food system. • The fluorescence mechanisms of LMOFs for food detection are classified. • The recent food applications and future trends of LMOFs are summarized. [ABSTRACT FROM AUTHOR]

• Discovery of oxidase-like activity and degradable property of γ-MnOOH nanowires. • Understanding of the degradation-activity correlation of γ-MnOOH nanozymes. • Designing a colorimetric platform for POC detection of OPs and AChE activity. • Low LODs, high selectivity, anti-interfere capacity, and workable in real samples. • This portable detection platform possessing great ecological sustainability. Despite the tremendous achievements of existing sensing techniques, sensitive and portable sensing of organophosphorus pesticides (OPs) in a non-polluting manner remains a challenging issue. This work proposed a facile colorimetric paper sensor using γ-MnOOH nanowires (NWs) as a degradable nanozyme and 3,3′,5,5′-tetramethylbenzidine (TMB) as a chromogenic indicator for rapid and sensitive screening of OPs and acetylcholinesterase (AChE) activity. The sensing mechanism was based on the easy disintegration of the oxidase-like γ-MnOOH NWs into invalid Mn2+ ions by the selective reaction with thiocholine (TCh) produced by AChE and acetylthiocholine iodide (ATCh), triggering a remarkable activity loss of MnOOH nanozymes towards TMB oxidation. The concentration of OPs, as an AChE inhibitor, was measured by the changes in absorbance at 652 nm or blue color of oxTMB products. Such detection platform in solution state achieved relatively low limits of detection (LODs) for AChE activity (0.007 mU mL−1), and for two typical OPs, i.e., omethoate (0.35 ng mL−1) and dichlorvos (0.14 ng mL−1), respectively. Further, the portable assembly of such AChE-nanozyme tandem reaction on test paper performed well, reaching LODs of 0.1 mU mL−1 for AChE, 10 ng mL−1 for omethoate, and 3 ng mL−1 for dichlorvos, respectively. Meanwhile, this sensing system showed great selectivity and anti-interfering capacity in both solution and solid states, and worked well in real serum and vegetable samples. The abovementioned results, along with evidence of its good ecological sustainability, demonstrated the superiority of this well-performing platform for application in the food, environmental, and medical fields. [ABSTRACT FROM AUTHOR]

Nanozyme technique with efficient modulating strategies is a promising tool for biocatalytic and biosensing applications, yet insights into target-responsive controllability of oxidase nanozymes remain largely unknown. In this contribution, we report a state-of-art oxidase-like and ssDNA-tunable nanozyme for biomolecular recognition. In detail, the spinel-type manganese cation substituted cobalt oxide (MnCo 2 O 4 ) submicrospheres can imitate oxidase for efficiently catalytic oxidation of colorimetric substrate, superior to current metal oxide-based oxidase nanozymes. More importantly, the nanozyme activity of spinel MnCo 2 O 4 can be reversibly inhibited by the attachment/detachment of aptamer strands on MnCo 2 O 4 surface via the aptamer-target binding event, enabling a new colorimetric access for detecting biomolecules. Taking highly toxic ochratoxin A (OTA) as model molecule, we can selectively determine OTA in maize samples with a limit of detection (3δ/ S ) of 0.08 ng/mL. The unique nanozyme property of spinel MnCo 2 O 4 , together with the principle of our approach, reveals the potential of ssDNA-tailorable oxidase nanozymes in biocatalytic and biosensing fields. [ABSTRACT FROM AUTHOR]

The growing concerns about microbial food safety and environmental contamination call for sustainable food active packaging materials and practices with high performance. This contribution proposed a biocatalytic spraying coating for fruit preservation using carboxymethyl cellulose nanofibers grafting enzyme-like metal-organic frameworks (CNF@Ce-MOF) with banana and mango as model fruits. The well-characterized biohybrid nanofibers were verified to simultaneously mimic good oxidase-like and apyrase-like activities, enabling effective enzyme-like sterilization against three typical foodborne pathogens, i.e. Escherichia coli O157: H7, Staphylococcus aureus , and methicillin-resistant Staphylococcus aureus , reaching killing rates as high as 90.46%. The biocidal •O 2 − generation and adenosine triphosphate depletion were the possible mechanisms causing the nonspecific bacteria death. Such antibacterial performance, as well as additional protective properties of CNF@Ce-MOF, facilitated the quality preservation during the 12-day storage of bananas and mangos by spray coating with the biomimetic CNF@Ce-MOF. It is expected that this work walks out the first step of nanozyme toward active packaging engineering for the fields of food, agriculture, and biomedicine. [Display omitted] • Biopolymeric nanozyme was created by biomineralizing in situ MOF on nanocellulose. • Dual enzyme biomimicry by CNF@MOF produced.•O 2 − species and depleted ATP • CNF@MOF possessed bacteriostatic activities, UV resistance and biocompatibility. • Pioneering research was conducted by introducing nanozyme into active packaging. • CNF@MOF coating improved quality and extended shelf life of banana and mango. [ABSTRACT FROM AUTHOR]

Efficient identification of pathogenic bacteria is greatly concerned with microbial food safety and foodborne diseases diagnosis. Surface-enhanced Raman scattering (SERS) tags are among the cutting-edge tools for bioanalysis, but facing troubles in either SERS sensitivity, durability, interfering signals, or universal recognition agents for target bacteria. This work proposed a multivariate scheme enabled by polyphenolic chemistry for the green synthesis, facile stabilization (functionalization), protective encapsulation, and bio-affinitive design of metal-phenolic networks (MPNs)-encapsulated silver SERS nanotags (AgNPs@4-mercaptobenzonitrile@MPNs). With remarkable SERS properties, shelf stability, and bacterial affinity, AgNPs@4-mercaptobenzonitrile@MPNs tags enabled rapid, reproducible, and interference-free SERS detection of two representative foodborne pathogens (i.e., E. coli O157: H7 and S. aureus) in the assistance of an aptamer-labelled magnetic probe, reaching good sensitivity and selectivity. Moreover, this SERS biosensor worked well in real food samples, manifesting the potential of polyphenolic chemistry in the customization of bio-affinitive SERS nanotags for food safety detection. [Display omitted] • Polyphenolic chemistry enabled from-synthesis-to-bioaffinity scheme of SERS tags. • Metal-phenolic networks acted as bioaffinity elements for bacterial recognition. • Polyphenolic SERS tags could be reliable detection probe for bacteria quantitation. • Polyphenolic SERS biosensor could detect foodborne bacteria down to 102 CFU/mL. • The SERS biosensor could work in milk and beef samples. [ABSTRACT FROM AUTHOR]

With the globalization of food supplies and worldwide concerns about foodborne illness, the food industry is confronting unprecedented safety challenges. Dyestuff chemistry, nanotechnology, and immunochromatography assay (ICA) have all been hot topics in recent decades, particularly in the respective professions. Regardless, the respective superiorities and weaknesses are difficult to integrate and overcome, hindering the widespread deployment in the food safety sector. In this review, the historical development and current mechanism design for various analysis patterns of dyestuff chemistry-encode signal tracers-based ICAs (dyestuff-based ICAs) for food safety monitoring are classified. And we highlight the construction strategy of dyestuff-encode signal tracers to obtain simpler steps, enhanced utilization efficiency, and brand-new function. Furthermore, the unique superiority and recent applications of dyestuff-based ICAs for food safety monitoring, as well as future-oriented innovation are reviewed. Finally, the challenges in this field were also spotlighted along with the outlook of profound developments for dyestuff-based ICAs in point-of-care (POC) settings. Dyestuff-based ICAs that combine multiple technologies emerge as POC tools for performing global food safety control owing to the rapidness, user-friendliness, and attraction on future-oriented innovation. Particularly with the maturation of traditional dyeing methods and the commercialization of related dyestuffs, dyestuff-based ICAs possess several merits, including cost-effectiveness, ease-of-labeling, and high performance while significantly shortening the distance from raw materials to ICA-based products. Following the advances in interdisciplinary innovations, dyestuff-based ICAs will undoubtedly reduce (or even eliminate) the inefficient back-and-forth between laboratories and tables, and spark a revolution in this field. Dyestuff chemistry-encoded signal tracers based immunochromatographic assays facilitates the POC deployment for food safety monitoring. [Display omitted] • Novel analytic techniques shortening the distance from raw materials to products. • Dyestuff-based ICAs offers excellent platform for food safety detection. • Simplified steps, enhanced efficiency, and brand-new sandwich pattern are created. • The mechanisms design of dyestuff-based ICAs for food detection are classified. • Strengths, barriers, recent food applications and future trends are summarized. [ABSTRACT FROM AUTHOR]

Food safety has attracted considerable attention in recent years. As a rapid, fingerprint-type recognition and nondestructive detection technique, surface-enhanced Raman scattering (SERS) has been among the promising techniques to meet the increasing needs for food safety analysis. Currently, emerging flexible SERS substrates as an alternative for colloidal and rigid SERS substrates have received great interest. Flexible SERS substrates possess the advantages of easy sampling by wrapping or swabbing on nonplanar surfaces, which facilitate the detection of contaminants from food surfaces and shed new lights on the nondestructive and sensitive detection of food analytes. In this review, the characteristics of different flexible materials such as cellulose, polymer film, cotton fabric, adhesive tape and bio-materials for constructing flexible SERS substrates are introduced, detection strategies including infiltration scheme, swab-sampling and in-situ detection are discussed, and recent applications of flexible SERS substrates in detecting trace pesticides in fruits and vegetables, chemical residues in animal farming including fungicides and antibiotics, illegal food additives and food-borne pathogens are highlighted. Flexible SERS substrates have been increasingly studied for detecting food contaminants. In preparing SERS substrates, different properties of the materials should be considered. For the detection strategies, compared with conventional infiltration scheme, swab-sampling is unique for flexible substrates and can collect target molecules directly from the surface, while in-situ detection is the most convenient, facile and nondestructive. Encouraging application results available show that flexible SERS substrates possess enormous potentials for food safety analysis and surveillance. • Flexible SERS substrates can provide rapid and nondestructive detection for foods. • Materials for constructing flexible SERS substrates are highlighted. • Different detection strategies using flexible SERS substrates are compared. • Recent applications of flexible SERS substrates in food safety are summarized. • Challenges and development of flexible SERS substrates are discussed. [ABSTRACT FROM AUTHOR]

• UiO-66(NH 2)@Au SERS platform with adsorbability and SERS-activity was synthesized. • New coccine and orange II were measured by SERS platform with satisfactory R2. • LOD was 0.4015 mg/L for new coccine and 0.0546 mg/L for orange II. • New coccine and orange II in food matrices were analyzed with acceptable recovery. Synthetic dyes have been widely applied to food processing, but abuse of colourants in food may pose risks to human health. To analyze new coccine (NC) and orange II (OII) in food, a versatile surface-enhanced Raman scattering (SERS) platform was proposed. A metal-organic framework (MOF, UiO-66(NH 2)) with octahedral crystal structure was synthesized and gold nanoparticles were grown on the MOF surface to fabricate UiO-66(NH 2)@Au versatile SERS platform. The UiO-66(NH 2)@Au displayed much better SERS performance than gold nanoparticles with high R2 of 0.9684 for NC and 0.9912 for OII and low LOD of 0.4015 mg/L for NC and 0.0546 mg/L for OII. The recoveries of NC and OII in Mirinda soft drink and paprika ranged from 82.92 to 109.63%. This study provided a sensitive and rapid method for determination of NC and OII through UiO-66(NH 2)@Au, and the proposed SERS platform revealed great potential for analyzing synthetic colourants in food samples. [ABSTRACT FROM AUTHOR]

Highlights • Gram staining and direct immunoassay were first adopted for S. Enteritidis detection. • The marking signal was derived from one-step bacteria staining with crystal violet. • The device exhibited excellent sensitivity, simplicity, selectivity and feasibility. • Results could be clearly distinguished by naked eyes even under a lower analyte level. Abstract Here, a facile, label-free and sensitive lateral flow strip (LFS) biosensor for foodborne pathogens was established relying on the innovative introduction of Gram staining and the direct immunoreaction. Target bacteria can be directly marked with crystal violet (CV) by one-step staining which is superior to traditional signal marking techniques in LFS assay, and the method's selectivity can be guaranteed by high-specificity monoclonal antibody. With Salmonella Enteritidis (S. Enteritidis) as a model target, this protocol can selectively detect 80 CFU mL−1 S. Enteritidis within 11 min in the optimized conditions. Moreover, with Listeria monocytogenes as another model target, the biosensor shows a high universality for detections of both gram-negative and gram-positive bacteria. The unexpected applicability of biological dye tracer in strip biosensor reveals that the biological dye can be a potential tool serving as a universal signal tracer for pathogenic microorganisms in food safety monitoring and early clinical diagnosis. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A chemical-staining (crystal violet) based lateral flow immunoassay (LFIA) is first proposed for small molecule detection. • The developed LFIA significantly simplify the assay behavior and conquer the intrinsic limitations of nanomaterials labels. • The LFIA were successfully applied in several food samples for furazolidone detection. Abstract The nanomaterials based lateral flow immunoassays (LFIAs) have been widely used for on-site detection of small molecules contaminants. Nevertheless, their practical applications are often constrained by the complicated materials synthesis and surface modification process of nanomaterials. Herein, inspired by chemical-staining, a crystal violet (CV) staining based LFIAs was innovatively developed for the first time to analyze small molecules contaminant with significantly simplified behaviour and surpassing repeatability. This nanomaterials-free technique overcomes the intrinsic limitations of nanomaterials, owing to the superior protein dye property of CV. To demonstrate the feasibility of the unique strategy, furazolidone (FZD) was used as a model analyte, results showed detection limits of as low as 7 and 1.53 ng mL−1 by visual observation and quantitative analysis, respectively. Finally, to validate its applicability in actual conditions, the platform is well applied in three kinds of food samples (shrimp, fish and pork). Furthermore, as the detection principle is based on the molecular recognition between antigen and antibody, our method may find general applications by staining other antibodies against other target analytes. [ABSTRACT FROM AUTHOR]

Immunochromatographic assays (ICAs) are most frequently used for on-site rapid screening of clenbuterol. To improve sensitivity, a novel probe with bacteria as signal carriers was developed. Bacteria can load a great deal of gold nanoparticles (AuNPs) on their surface, meaning much fewer antibodies are needed to produce clearly visible results, although low concentrations of antibody could also trigger fierce competition between free analyte and the immobilized antigen. Thus, a limited number of antibodies was key to significantly improved sensitivity. Analytical conditions, including bacterial species, coupling method, and concentration, were optimized. The visual detection limit (VDL) for clenbuterol was 0.1 ng/mL, a 20-fold improvement in sensitivity compared with traditional strips. This work has opened up a new route for signal amplification and improved performance of ICAs. Furthermore, inactivated bacteria could also be environment-friendly and robust signal carriers for other biosensors. [ABSTRACT FROM AUTHOR]

We presented a signal amplified lateral flow assay (LFA) based on magnetite nanoparticles (MNPs) labeled dual-probe and applied it in the high sensitive and rapid on-site detection of furazolidone metabolite of 3-amino-2-oxazolidinone (AOZ). The amplified signal benefited from high affinity between two probes of MNPs labeled murine monoclonal antibody (MNPs-MAb) and goat anti-mouse antibody (MNPs-GAMA) and was achieved by the generation of dual-probe network complex. This developed method could realize high sensitive detection of AOZ with a threshold value of 0.88 ng mL −1 and a detection limit of 0.044 ng mL −1 , the sensitivity was at least 10-fold improved than that of the traditional gold nanoparticle based LFA. This facile developed assay was successfully applied for rapid detection of AOZ in milk samples. The proposed method paves a new way for on-site screening of other hazardous substances in food and can be referred in all lateral flow assays. [ABSTRACT FROM AUTHOR]

In order to resolve the pollution and waste caused by urea-rich wastewater, designing superior and stable earth-abundant catalysts for urea oxidation reaction (UOR) have always been attractive and urgent but still challenging. Herein, we report on a facile surface-engineering strategy of building hierarchical nickel hydroxide nanosheet@nanowire array on Ni foam (Ni(OH) 2 NS@NW/Ni foam) as anode material toward superior urea electrolysis. This Ni(OH) 2 based-catalyst with peculiar nanosheet@nanowire configuration just requires a small potential of 0.34 V ( vs. SCE) to drive 10 mA cm −2 in 1.0 M KOH with 0.33 M urea, which outperforms the one with pure nanosheet array architecture and even the commercial Pt/C catalyst. Further, a two-electrode electrolysis system is built here with the cathode of cobalt phosphide nanowire array on Ni foam (Co 2 P NW/Ni foam) and anode of Ni(OH) 2 NS@NW/Ni foam for overall urea electrolysis, which needs a low voltage of 1.58 V to drive 5 mA cm −2 in 1.0 M KOH with 0.33 M urea. Note that, the current density presented in this work is based on the real surface area of Ni foam but not the geometric area, unless otherwise specified. [ABSTRACT FROM AUTHOR]

A signal amplified lateral flow immunoassay (LFIA) based on gold nanoparticles (GNPs) growth and accumulation for rapid detection of Salmonella Enteritidis ( S. Enteritidis) was developed. The signal was amplified on account of the high catalytic activity of GNPs toward the reaction between HAuCl 4 and NH 2 OH·HCl, which could produce new GNPs on the surface of the initial GNPs. The remarkable enhanced signal at the test and control lines can be clearly distinguished by naked eyes even under a lower analyte level. The lowest visible detection limit of the signal enhanced LFIA for S. Enteritidis was as low as 10 4 CFU/mL with excellent specificity, achieving a 100-fold improvement in sensitivity compared to the traditional GNP-based LFIA. Finally, for applicability demonstration the method was applied to milk for S. Enteritidis analysis. Except for incubation time, the process required only 6 h, which was obvious shorter than that of many reported methods. [ABSTRACT FROM AUTHOR]

• Multifunctional Fe 3 O 4 @Au nanoflowers have been successfully synthesized. • Au-4MBA@Ag nanospheres with stable and strong SERS signal was prepared as SERS tag. • High-performance SERS aptasensor was successfully developed by aptamer recognition. • The ultralow detection limit of AFB1 was estimated to be 0.40 pg·mL−1. Aflatoxin B1 (AFB1) as the most toxic mycotoxin in contaminated food can greatly threaten human health, and sensitive and selective detection of AFB1 is thus highly desired. An ultrasensitive surface-enhanced Raman spectroscopy (SERS) aptasensor was developed for AFB1 detection in peanut oil samples. SH-cDNA modified Fe 3 O 4 @Au nanoflowers acted as capture probes, SH-Apt modified Au@Ag nanospheres and commercial Cy3-Apt were used as reporter probes. Strong SERS signals of reporter probes were produced due to the recognition of AFB1 aptamer and its complementary strand (SH-cDNA). With the preferred binding of AFB1 aptamer to AFB1, reporter probes were released from capture probes, causing a linear decrease in SERS intensity. Therefore an ultralow detection limit of 0.40 pg·mL−1 in a wide linear range of 0.0001–100 ng·mL−1 was obtained and the sensibility of this SERS aptasensor was higher than that of the Cy3-Apt based SERS aptasensor. In addition, an excellent selectivity in interfering toxins and satisfactory recoveries of 96.6–115% in peanut oil samples were obtained, proving this aptasensor is a promising analytical tool in AFB1 detection. [ABSTRACT FROM AUTHOR]