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Food packaging with efficient antibacterial ability is highly desirable and challenging in facing the crisis of microbial contamination. However, most present packaging is based on metal-based antibacterial agents and requires a time-consuming antibacterial process. Here, the unique packaging (CC/BB films) featuring aggregation-induced emission behavior and photodynamic inactivation activity is prepared by dispersing self-assembled berberine-baicalin nanoparticles (BB NPs) into a mixed matrix of sodium carboxymethylcellulose-carrageenan (CC). The superiority of this design is that this packaging film can utilize sunlight to generate reactive oxygen species, thus eradicating more than 99% of E. coli and S. aureus within 60 min. Also, this film can release BB NPs to inactivate bacteria under all weather conditions. Surprisingly, the CC/BB nanocomposite film presented excellent mechanical performances (29.80 MPa and 38.65%), hydrophobicity (117.8°), and thermostability. The nanocomposite film is validated to be biocompatible and effective in protecting chicken samples, so this work will provide novel insights to explore safe and efficient antibacterial food packaging.

Considering the importance of rapid and effective detection of nitrite in food samples, herein, we report a multistep heterophase synthetic strategy for constructing crystalline-amorphous zinc/cobalt iron porous nanosheets (C-A Zn/Co-Fe PNSs) on carbon cloth. Notably, the C-A Zn/Co-Fe PNSs@CC electrochemical interface consists of interlaced carbon fibers with many uniformly distributed hybrid nanosheets containing crystalline-amorphous interfacial sites. This particular hybrid structure permits local enrichment of nitrite for enhanced nitrite capture efficiency, laying a solid foundation for the ultrasensitive detection of nitrite. In proof-of-concept experiments, we verified that C-A Zn/Co-Fe PNSs@CC could be used to analyze nitrite with good sensitivity and reproducibility. It is worth mentioning that an ultra-low LOD of 0.44 μM was obtained for the detection of nitrite. The designed electrochemical sensor worked well in complex samples such as sausages and tap water under optimal parameters.

Imidacloprid (IDP) residue in modern agricultural production seriously endangers human health and environmental safety. The establishment of a rapid and efficient method for the detection of IDP residue can effectively prevent its harm to human health. Herein, we demonstrate the carbon cloth (CC) prepared by a high-temperature annealing strategy possesses enhanced electrochemical performance, which could be directly used in electrochemical IDP sensing. Annealed carbon cloth (ACC) is endowed with higher defects, rougher surfaces, more functional groups, more hydrophilic surface, and increased ion-accessible surface area. Furthermore, the ACC electrode shows superior electrocatalytic reduction activity towards IDP, possessing a wide linear range of 5-100 μM, a low detection limit of 0.04 μM, and high sensitivity of 35.58 μA mM

Functional food components have attracted extensive attention for their nutritional and physiological properties. However, the instability and low bioavailability seriously limited their applications in the food and pharmaceutical industries. Herein, we successfully constructed a multifunctional three-phase nano-delivery system of polysaccharide-polyphenol-protein, namely chitosan-tannin-lysozyme nanoparticles (CS-TA-L NPs). Employing chitosan as the wall material, tannin and lysozyme were incorporated into the chitosan matrix by ion crosslinking and ultrasonic assisted methods, forming the nanoparticles with core-shell structures. Consequently, this simple, feasible and green nano-delivery system protected the biological activities of tannin and lysozyme, improved the stability of CS-TA-L NPs, and endowed chitosan nanoparticles with antioxidant and antibacterial properties, which provided a theoretical basis for constructing the multifunctional nano-delivery systems.

Excessive residues of nitrofurantoin (NFT) can cause serious contamination of water bodies and food, and potential harm to ecosystems and food safety. Given that, rapid and efficient detection of NFT in real samples is of particular importance. MoS

Considering excess nitrites are detrimental to the human body and environment, designing a rapid, sensitive, and real-time quantitative determination for nitrite is of great significance for environmental preservation and public health. In this paper, Co

Antimonene quantum dots (AMQDs) are attracting considerable attention due to their fascinating physicochemical properties. However, research on their semiconductor characteristics, especially the photoluminescence performance, is still in a preliminary stage and the experimental verification is scarcely reported, significantly restricting their further applications. Herein, the photoluminescence property of AMQDs is experimentally verified. The AMQDs are prepared by probe sonication-assisted liquid-phase exfoliation and show robust blue fluorescence, and the photoluminescence is hardly affected by pH. In view of the derivatization reaction of tetracyclines (TET) at different pHs, AMQDs are developed as a pH-mediated dual-channel ratiometric fluorescent probe for TET detection. Under acidic conditions, the AMQDs' probe exhibits unique recognition behavior due to the inherent fluorescence of TET and the solvent-enhancing effect, that is, the fluorescence changes from blue to red. Under alkaline conditions, this fluorescent probe realizes the transition from blue to yellow-green because of the decomposition of TET. The limits of detection are 27 × 10-9 and 74 × 10-9 m, respectively. The high sensitivity and remarkable fluorescence changes make AMQDs ideal probes for TET sensing. Additionally, this is the first report on the photoluminescence property of AMQDs. It is believed that this work will open a new avenue for AMQDs in optical sensing fields.

Covalent organic frameworks (COFs) have attracted tremendous interest due to their promising applications, including electrocatalysis originating from their unique structural features. However, it remains a challenge to prepare COFs for p-nitrophenol (PNP) and o-nitrophenol (ONP) electrocatalysis because it is quite difficult to manipulate their dimension, composition, and morphology with abundant active sites. Here, a facile ambient temperature synthesis of unique Fe3O4-based magnetic COFs nanosphere (Fe3O4@AT-COFs) with different surface morphologic structure is reported, which exhibits higher surface area, good water dispersity, long-term stability, excellent electrical conductivity and pre-concentration effect. The prepared Fe3O4@AT-COF-based electrochemical sensor is then directly employed for the simultaneous detection of PNP and ONP with a wide linear detection range of 10–3000 μM and low detection limits (LOD) of 0.2361 μM and 0.6568 μM, respectively. Meanwhile, the Fe3O4@AT-COF can be also well-applied in lake and tap water for monitoring PNP and ONP with outstanding sensitivity and reliability, which is expect to be a high-efficient electrocatalyst with great promise for signal amplification of electrochemical sensing.

A new ratiometric platform was developed for sensing Hg

Plastic pollution and food spoilage have drawn public attention, which may cause a great threat to the global environment and human health. Therefore, natural antimicrobial packaging has a pivotal share in solving these problems. In this study, biodegradable and antibacterial packaging films were successfully prepared via incorporating self-assembled berberine-cinnamic acid nanoparticles (BC NPs) into the film matrixes. With the addition of BC NPs, the UV-shielding property, hydrophobicity, and thermal stability of packaging were apparently improved. Meanwhile, the films also held considerable mechanical property and good biocompatibility, where the migrations of films in two food simulants were all far less than the permitted limits. Furthermore, nanocomposite films (NFs) exhibited strong antibacterial ability against both E. coli and S. aureus. By measuring the fluorescence spectrum and ROS production of films, we certificated NFs were AIE-active, and the antimicrobial activity of NFs was significantly enhanced under white light. Finally, the packaging test further indicated NFs could inhibit microbial growth of chicken samples well. The sustainable NFs will be ideal candidate materials to replace plastics and extend the shelf life of food products.

Considering excess nitrites are detrimental to the human body and environment, designing a rapid, sensitive, and real-time quantitative determination for nitrite is of great significance for environmental preservation and public health. In this paper, Co3O4 nanoflowers coupled with ultrafine MoO3 nanoparticles (MoO3/Co3O4) are obtained via a hybrid electrochemical deposition strategy (HED). The as-designed MoO3/Co3O4/CC integrating electrode exhibits superior electrocatalytic properties towards nitrite oxidation, owing to the synergistic effect between MoO3 and Co3O4 caused by the heterostructure of MoO3/Co3O4. The electrode achieved a low response time of 2 s, an excellent sensitivity of 1704.1 μA mM−1 cm−2, and a low limit of detection of 0.075 μM (S/N = 3). Furthermore, the electrode displays promise for nitrite detection in complex food such as water and sausages samples. Our study will provide a significant strategy for the application of bimetallic heterostructure to explore the design of sensing interfaces.

Excessive intake and emission of nitrite will cause serious harm to the ecosystem and human health. Herein, the AuNPs/Co(OH)2 nanocomposites with a unique three-dimensional (3D) hierarchical structure are designed and synthesized for the detection of nitrite. Wheatear-like cobalt hydroxide (Co(OH)2) is synthesized on carbon cloth (CC) by hydrothermal method. Flower bud-like gold nanoparticles (AuNPs) are electrodeposited on Co(OH)2. By integrating the common advantages of AuNPs and Co(OH)2 such as enlarged specific surface area, significantly increased active sites, high conductivity, and 3D hierarchical structure, the proposed AuNPs/Co(OH)2/CC electrode shows excellent nitrite sensing properties, with the linear range of 0.625–3387.5 μM, the limit of detection (LOD) of 0.1 μM, and high sensitivity of 2475.5 μA mM−1 cm−2. Moreover, the sensor can measure nitrite content in sausages with high recoveries, indicating its feasibility in practical application. This work guides the reasonable design of 3D hierarchical nanomaterials and the construction of high-performance sensing interfaces.

Graphene based metal nanocomposites are widely used in electrochemical glucose sensors for their prominent synergistic effects. Many reviews have been reported to summarize and compare the two types of synthetic technologies that post immobilization and in situ growth for preparing these nanocomposites. However, these comparisons and evaluations are almost based on the nanomaterials comprised of different components. Based on rationally selecting β-cyclodextrins as the common functional reagents, we have innovatively synthesized two novel graphene based metal nanocomposites composed of the identical ingredients through the developed post immobilization method and new one-step electrodeposition in situ growth approach respectively. After optimized the key parameters to ensure the optimal synthesis conditions were provided, we have further performanced the systematically comparative study on properties of the two nanocomposites from many aspects, so as to scientifically evaluate the two synthesis technologies. Glucose sensors based on the two resultant nanocomposites have been fabricated successfully, both of them showed high response ability. Sensitivity of the sensor modified by the nanocomposite synthesized through in situ growth was improved 3–8 times, demonstrated this strategy is more effective. Our work would provide guidelines to synthesize graphene based metal nanocomposites which has potential applications in electroanalysis.

Large uptakes of nitrite have been proven to be detrimental to human health, therefore, the development of high-performance nitrite sensors is highly emergent. Herein, a carbon selenide nanofilms modified carbon fiber cloth (CSe2 NF/CC) electrode was obtained via in-situ synthesis to detect nitrite. The electrode integrates the collective merits of macroporous CC and pleated carbon selenide nanofilms, possessing a low overpotential of 0.83 V, a high electrochemical active surface area (EASA) of 5.39 cm2, great electrical conductivity, and fast charge transport as well as ion diffusion. The proposed electrode achieved a low limit of detection of 0.04 μmol L−1 (S/N = 3), a high sensitivity of 2048.56 μA mmol L−1 cm−2, excellent selectivity, and long-term stability. Additionally, the CSe2 NF/CC was successfully used for nitrite detection in different food samples such as pickled vegetables and sausage samples.

The valorization, resource generation and the functional characteristic exploration of domestic waste still face enormous challenges. Kiwi peels, a common kind of fruit waste, contain a large amount of phenolic substances, including polyphenols, flavonoids, etc., which can be explored and reused in food and biomedical fields. By ultrasonic assisted extraction technology, we obtained conversional fluorescence kiwi peel phenolic extracts (PE) which possessed gradient magenta fluorescence relying on the content of ethanol in the solution, as well as strong antioxidant activity. Besides, metal ions sensing assay revealed that PE can specifically sense Hg2+ and Cu2+ (LOD: 1.16 and 0.17 μM, respectively) accompanied with a fluorescence conversion from magenta fluorescence to blue. Moreover, employing the prepared PE as fluorescent probes, imaging of HeLa cells can be easily achieved with satisfactory resolution. Additionally, PE was incorporated into the gelatin matrix, successfully fabricating a green, edible degradable film with excellent antioxidant activity.

In this work, to prevent the spoilage of food by microbial contamination, copper sulfide nanoparticles (CuS NPs) with photothermal effect were successfully synthesized by a one-step hydrothermal method and uniformly dispersed in natural carrageenan (Carr) to obtain Carr/CuS films. Photothermal-induced antibacterial testing confirmed that the Carr/CuS film has a broad-spectrum antibacterial activity against Escherichia coli (99.2%) and Staphylococcus aureus (99.9%). Antibacterial test on beef also proved that near-infrared (NIR) irradiation significantly improved the antibacterial ability of the Carr/CuS film against bacteria on the food sample. In addition, compared with the Carr film, the Carr/CuS film with high transparency showed enhanced mechanical properties and thermal stability. The introduction of this NIR-induced strategy is expected to open a new way for broadening the application of antibacterial packaging.

Various pesticides employed in modern agriculture result in large amounts of pesticide residues in agricultural production, greatly threatening human health. Herein, we report a facile approach to fabricate a reduced graphene oxide/cyclodextrin modified glassy carbon electrode (rGO/CD/GCE) for the sensitive electrochemical sensing of imidacloprid (IDP). Three different modified electrodes using CDs (α-, β-, γ-CD) were fabricated, and their electrochemical performance was further studied. The results demonstrate that α-CD possesses the best signal amplification for IDP. Compared with wet-chemical synthesis of rGO/CDs (W-rGO/CDs), the electrochemical synthesis of rGO/CDs (E-rGO/CDs) produced sensors that showed better performance for IDP sensing. Taking advantage of prepared E-rGO/α-CD nanocomposite, the fabricated sensor offered a low detection limit (0.02 μM) with a wider linear range (0.5–40 μM) and long-term stability. The new sensor was successfully applied for the detection of IDP in brown rice, providing a new technique for efficient and convenient monitoring of pesticide residues in food.

In this paper, a self-supported electrode for nitrite detection was obtained by loading ferrous selenide nanorods on carbon cloth (FeSe NR/CC) via in situ synthesis. The morphology and chemical composition of the FeSe NR/CC were characterized using scanning electron microscope (SEM), X-ray diffractogram (XRD), and X-ray photoelectron spectroscopy (XPS). Owing to the synergistic effect between FeSe nanorods and carbon cloth, the rich redox active sites, and the lower transferring resistance, the binder-free and self-supported sensor based on FeSe NR/CC exhibits a wide linear relationship from 0.625 μM to 6775.5 μM, a fast-current response of 3 s, and a high sensitivity of 1107.7 μA mM−1 cm−2. The detection limit of the FeSe NR/CC was evaluated as 0.07 μM and the developed sensor displays excellent selectivity, stability, and reproducibility. Additionally, the as-prepared sensor has been successfully applied to detect nitrite in pickled vegetable samples, proving its feasibility for practical applications. Therefore, the self-supported and binder-free electrode proposed in this study could be used as a highly efficient and cost-effective electrochemical nitrite sensing device to achieve rapid quantitative detection of nitrite in food samples.

Silicon-doped carbon quantum dots (Si-CQDs) were employed to fabricate a ratiometric fluorometric probe that shows high selectivity for hydroquinone (HQ). The Si-CQDs were prepared through hydrothermal treatment of N-[3-(trimethoxysilyl)propyl]-ethylenediamine. If HQ is oxidized in a solution of the Si-CQDs, 1,4-benzoquinone will be formed which quenches the blue fluorescence (with excitation/emission peaks at 360/435 nm) of the Si-CQDs. Simultaneously, intense green fluorescence (with a emission peak at 513 nm) appears, probably due to the formation of n-π clathrates or of a quinone imine between 1,4-benzoquinone and amino groups on the surface of the Si-CQDs. The ratio of the green and blue fluorescence can be applied to the determination of HQ with a 0.077 μM detection limit. The analytical range extends from 1 to 40 μM. Graphical abstract Schematic of a silicon-doped carbon quantum dot-based ratiometric fluorescence probe with blue and green emission for the visual and fluorometric determination of hydroquinone.

Because of the indiscriminate use of antibiotics and threats of the drug resistance, bacterial wound infection remains one of the most difficult medical issues. Therefore, it is of great significance to develop novel antibacterial platforms. In this work, we successfully prepared gallic acid functional silver nanoparticles (GA-Ag NPs) by a one-pot method and then embedded them into the network structure of a biocompatible polysaccharide to obtain a novel hydrogel (GA-Ag NP hydrogel) with outstanding bactericidal effect. In this system, the embedded GA-Ag NPs not only act as an antibacterial agent sustainably released from the matrix of the hydrogel to realize sterilization, but also act as a photothermal agent that effectively and controllably converts 808 nm near-infrared ray light into heat to kill bacteria. In vitro testing verified the outstanding broad-spectrum sterilization property of the GA-Ag NP hydrogel against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). In vivo wound healing experiments confirmed the practical potential of this hydrogel in combating bacterial infections and accelerating wound healing. Hemolysis and cytotoxicity experiments showed that it has good biocompatibility. The development of this novel antibacterial hydrogel opens a new way to strengthen the antimicrobial arsenal for fighting bacterial infections.

Novel 3D porous Ni/Cu(OH)2 nanospheres (Ni/Cu(OH)2 NS) were directly grown on a Ni foam (NF) via a facile one-step potentiostatic deposition synthesis route. The resultant Ni/Cu(OH)2 NS possessed an abundance of catalytic which gave them excellent catalytic properties for the electrochemical detection of glucose in alkaline conditions. Using these NS in a promising and integrated non-enzymatic glucose sensor, a high sensitivity of 8722 μA mM−1 cm−2, a low detection limit of 1.27 μM, and a linear detection range from 10 to 1490 μM were obtained at the Ni/Cu(OH)2 NS/NF anode. Additionally, the proposed sensor exhibited excellent anti-interference capability, good reproducibility, and long duration stability. It was successfully applied to glucose detection in human blood serum, showing excellent effectiveness.

A simple and novel immunochromatographic assay (ICA) was developed for specific and sensitive determination of ochratoxin A (OTA) employing microorganism (MO) as reducers and carriers. In this work, microorganism loaded gold nanoparticles (MO@AuNPs) composites were synthesized by reacting Yeast/Lactobacillus (LAB) with HAuCl4 via biosorption and subsequent bioreduction. The synthesis conditions (pH and reaction time) and main parameters (morphology, diameter and functional groups) of MO@AuNPs were investigated. Owing to the large sizes (about 2 μm) and high adsorption abilities of MO@AuNPs, the few antibodies were labeled, resulting a lower detection limit for ICA. After optimization, the linear detection of OTA using MO@AuNPs-based immunoassay ranged from 0.1 to 1.6 ng/mL, and the visual limit of detection (vLOD) was 0.1 ng/mL, which was nearly 8-fold lower than traditional AuNPs-ICA. Meanwhile, the proposed strategy also possessed high specificity for OTA against other mycotoxins. The applicability of the platform was successfully assessed through the detection of OTA in rice, corn, ginger and green bean samples. The results indicated that these creative sensing elements are promising alternatives and bring an innovative inspiration for biological detections.