One-pot green synthesis of ZIF-8/IgG composite for the precise orientation and protection of antibody and its application in purification and detection of aflatoxins in peanut oil.

This study presents a novel approach toward the one-pot green synthesis of ZIF-8/IgG composite, focusing on its precise orientation and protection of the anti-aflatoxins antibody. The antibody orientation is achieved through the specific binding of IgG to the Fc region of the antibody, while the antibody protection is accomplished by the structural change restriction of ZIF-8 framework to the antibody. Consequently, the antibody exhibits enhanced target capability and significantly improved tolerance to organic solvents. The ZIF-8/IgG/anti-AFT was employed for the purification and detection of AFTs by coupling with UPLC. Under optimized conditions, the recoveries of spiked AFTs in peanut oils are between 86.1% and 106.4%, with relative standard deviations (RSDs) ranging from 0.8% to 8.8%. The linearity range is 0.5-20.0 ng for AFB1 and AFG1, 0.125-5.0 ng for AFB2 and AFG2, the limit of detection is 0.1 ng for AFB1 and AFG1, 0.03 ng for AFB2 and AFG2.

A Magnetic Beads-Based Sandwich Chemiluminescence Enzyme Immunoassay for the Rapid and Automatic Detection of Lactoferrin in Milk.

Lactoferrin (LF), an iron-binding glycoprotein with immunological properties and a high nutritional value, has emerged as a prominent research focus in the field of food nutrition. Lactoferrin is widely distributed in raw milk and milk that has undergone low-temperature heat treatment during pasteurization, making its rapid and accurate detection crucial for ensuring the quality control of dairy products. An enzyme-linked immunosorbent assay-based analytical protocol has often been referred to for the detection of LF in real samples. Signal amplification was accomplished using the streptavidin-biotin system. Here, an automated magnetic beads-based sandwich chemiluminescence enzyme immunoassay (MBs-sCLEIA) system was developed for the quantification of lactoferrin in pasteurized milk. The MBs-sCLEIA system consists of an automated chemiluminescence-based analyzer and a lactoferrin MBs-sCLEIA assay kit. Notably, our proposed method eliminates the need for pretreatment procedures and enables the direct addition of milk samples, allowing for the automatic quantitative detection of lactoferrin within a rapid 17 min timeframe for up to eight samples simultaneously. The MBs-sCLEIA was linear over the range of 7.24-800 ng/mL and displayed a limit of detection (LOD) of 2.85 ng/mL. As its good recovery and CV values indicate, the method exhibited high precision and accuracy. Furthermore, it was verified that it was selective towards five additional common milk proteins. A good correlation was observed between the results from the MBs-sCLEIA and heparin affinity column-HPLC (r2 = 0.99042), which proves to be a useful and practicable way of conducting an accurate analysis of lactoferrin in dairy products.

Automatic Pretreatment of Dispersive Liquid Liquid Microextraction Based on Immunomagnetic Beads Coupled with UPLC-FLD for the Determination of Zearalenone in Corn Oils.

Sample pretreatment is a vital step in the detection of mycotoxins, and traditional pretreatment methods are time-consuming, labor-intensive and generate much organic waste liquid. In this work, an automatic, high-throughput and environmentally friendly pretreatment method is proposed. Immunomagnetic beads technology and dispersive liquid-liquid microextraction technology are combined, and the zearalenone in corn oils is directly purified and concentrated under the solubilization effects of surfactant. The proposed pretreatment method allows for the batch pretreatment of samples without pre-extraction using organic reagents, and almost no organic waste liquid is produced. Coupled with UPLC-FLD, an effective and accurate quantitative detection method for zearalenone is established. The recovery of spiked zearalenone in corn oils at different concentrations ranges from 85.7 to 89.0%, and the relative standard deviation is below 2.9%. The proposed pretreatment method overcomes the shortcomings of traditional pretreatment methods and has broad application prospects.

Development and Validation of an Automated Magneto-Controlled Pretreatment for Chromatography-Free Detection of Aflatoxin B1 in Cereals and Oils through Atomic Absorption Spectroscopy.

A chromatography-free detection of aflatoxin B1 (AFB1) in cereals and oils through atomic absorption spectroscopy (AAS) has been developed using quantum dots and immunomagnetic beads. A magneto-controlled pretreatment platform for automatic purification, labeling, and digestion was constructed, and AFB1 detection through AAS was enabled. Under optimal conditions, this immunoassay exhibited high sensitivity for AFB1 detection, with limits of detection as low as 0.04 µg/kg and a linear dynamic range of 2.5-240 µg/kg. The recoveries for four different food matrices ranged from 92.6% to 108.7%, with intra- and inter-day standard deviations of 0.7-6.3% and 0.6-6.9%, respectively. The method was successfully applied to the detection of AFB1 in husked rice, maize, and polished rice samples, and the detection results were not significantly different from those of liquid chromatography-tandem mass spectrometry. The proposed method realized the detection of mycotoxins through AAS for the first time. It provides a new route for AFB1 detection, expands the application scope of AAS, and provides a reference for the simultaneous determination of multiple poisonous compounds (such as mycotoxins and heavy metals).

An Automatic Immunoaffinity Pretreatment of Deoxynivalenol Coupled with UPLC-UV Analysis.

An immunoaffinity magnetic beads (IMBs) based automatic pretreatment method was developed for the quantitative analysis of deoxynivalenol (DON) by ultra-performance liquid chromatography and ultraviolet detector (UPLC-UV). First, N-hydroxysuccinimide-terminated magnetic beads (NHS-MBs) with good magnetic responsivity and dispersibility were synthesized and characterized by optical microscopy, scanning electron microscopy (SEM), and laser diffraction-based particle size analyzer. Then, the amino groups of anti-DON monoclonal antibody (mAb) and the NHS groups of NHS-MBs were linked by covalent bonds to prepare IMB, without any activation reagent. The essential factors affecting the binding and elution of DON were meticulously tuned. Under optimal conditions, DON could be extracted from a real sample and eluted from IMB by water, enabling environmentally friendly and green analysis. Hence, there was no need for dilution or evaporation prior to UPLC-UV analysis. DON in 20 samples could be purified and concentrated within 30 min by the mycotoxin automated purification instrument (MAPI), allowing for automated, green, high-throughput and simple clean-up. Recoveries at four distinct spiking levels in corn and wheat ranged from 92.0% to 109.5% with good relative standard deviations (RSD, 2.1-7.0%). Comparing the test results of IAC and IMB in commercial samples demonstrated the reliability and superiority of IMB for quantitatively analyzing massive samples.

Copper Oxide Nanoparticle-Based Immunosensor for Zearalenone Analysis by Combining Automated Sample Pre-Processing and High-Throughput Terminal Detection.

A rapid and high-throughput fluorescence detection method for zearalenone (ZEN) based on a CuO nanoparticle (NP)-assisted signal amplification immunosensor was developed using an automated sample pretreatment and signal conversion system. CuO NPs with high stability and biocompatibility were used as carriers to immobilize anti-ZEN antibodies. The obtained CuO NP-anti-ZEN can maintain the ability to recognize target toxins and act as both a signal source and carrier to achieve signal conversion using automated equipment. In this process, target toxin detection is indirectly transformed to Cu2+ detection because of the large number of Cu2+ ions released from CuO NPs under acidic conditions. Finally, a simple and high-throughput fluorescence assay based on a fluorescent tripeptide molecule was employed to detect Cu2+, using a multifunctional microporous plate detector. A good linear relationship was observed between the fluorescence signal and the logarithm of ZEN concentration in the range of 16.0-1600.0 µg/kg. Additionally, excellent accuracy with a high recovery yield of 99.2-104.9% was obtained, which was concordant with the results obtained from LC-MS/MS of naturally contaminated samples. The CuO NP-based assay is a powerful and efficient screening tool for ZEN detection and can easily be modified to detect other mycotoxins.

Development and validation of a rapid and efficient method for simultaneous determination of mycotoxins in coix seed using one-step extraction and UHPLC-HRMS.

Coix seed is an important food and traditional Chinese medicine in China and other Asian countries. Notably, coix seed is currently being used as a traditional medicine for the treatment of COVID-19 in China. However, coix seeds are generally contaminated by mycotoxins, and this risk cannot be ignored. In this paper, we developed a method that involves direct extraction and UHPLC-HRMS analysis for the simultaneous detection of 24 mycotoxins in coix seeds. UHPLC-HRMS instrument and data acquisition parameters, and the sample pretreatment were optimised. One-step extraction showed several advantages compared to the three commercial solid-phase extraction clean-up methods, including ease of use, reduced time of sample preparation, low cost, good recovery, and acceptable matrix effect. The method validation results indicate that all mycotoxins have good linearity and sensitivity. Recoveries were between 74.2-101.1%, and RSD ranged from 0.1-5.8%. The LOQs for 24 mycotoxins were in the range of 0.5-100 µg/kg. To survey the contamination levels of these mycotoxins in commercial coix seeds, more than 70 samples were collected from Chinese markets and were analysed using the newly developed method. Zearalenone (positive ratio: 98.7%, range:1.1-1562 µg/kg), deoxynivalenol (positive ratio: 87%, range: 8.4-382.5 µg/kg), nivalenol (positive ratio: 85.7%, range: 26.8-828.2 µg/kg), fumonisin B1 (positive ratio: 84.4%, range:2.5-314.5 µg/kg), fumonisin B2 (positive ratio: 75.3%, range:1.6-72.8 µg/kg), fumonisin B3 (positive ratio: 48%, range:1.0-203.6 µg/kg), aflatoxin B1 (positive ratio: 29.9%, range: 0.39-14.7 µg/kg), sterigmatocystin (positive ratio: 29.9%, range: 1.4-51.6 µg/kg), and tenuazonic acid (positive ratio: 19.5%, range 36.1-105.7 µg/kg) were the most frequent mycotoxin contaminants. These results highlight the importance of routine monitoring and control of mycotoxins in coix seeds.

Reliable and disposable quantum dot-based electrochemical immunosensor for aflatoxin B1 simplified analysis with automated magneto-controlled pretreatment system.

An integrated aflatoxin B1 (AFB1) detection platform with quantum dot (QD)-based electrochemical immunosensor and an automated magneto-controlled pretreatment system was successfully developed. The automated pretreatment system adopts the immunoaffinity magnetic beads (IMB) as the capture probe of AFB1 and QD-labeled AFB1 complete antigen (AFB1-BSA-QDs) as the signal probe. AFB1-BSA-QDs can be easily converted into corresponding metallic cations through acidic treatment, which can be detected electrochemically via anode stripping voltammetry (ASV). Moreover, a disposable screen-printed electrode (SPE) without requiring any further modification is used in the novel electrochemical immunosensor' making routine testing feasible. Under optimal conditions, the detectable concentration range of AFB1 was 0.08-800 µg/kg. The metal ion signal associated linearly with the logarithm of AFB1 concentration within the range of 5-240 µg/kg, with a detection limit of 0.05 µg/kg. The spiked recoveries of three different concentrations in four different matrixes ranged from 83.9 to 118.0%, and inter-day relative standard deviations were below 10%. Furthermore, the methodology was validated by analyzing naturally contaminated samples, and results of the novel immunosensor were in good agreement with those of LC-MS/MS, demonstrating the potentiality of the developed method for the monitor of AFB1 in cereals and oils.

An Automated and High-Throughput Immunoaffinity Magnetic Bead-Based Sample Clean-Up Platform for the Determination of Aflatoxins in Grains and Oils Using UPLC-FLD.

Sample clean-up remains the most time-consuming and error-prone step in the whole analytical procedure for aflatoxins (AFTs) analysis. Herein, an automated and high-throughput sample clean-up platform was developed with a disposable, cost-effective immunoaffinity magnetic bead-based kit. Under optimized conditions, the automated method takes less than 30 min to simultaneously purify 20 samples without requiring any centrifugation or filtering steps. When coupled to ultra-high performance liquid chromatography with fluorescence detection, this new analysis method displays excellent accuracy and precision as well as outstanding efficiency. Furthermore, an interlaboratory study was performed in six laboratories to validate the novel protocol. Mean recovery, repeatability, reproducibility, and Horwitz ratio values were within 91.9%-107.4%, 2.5%-7.4%, 2.7%-10.6%, and 0.26%-0.90, respectively. Results demonstrate that the developed sample clean-up platform is a reliable alternative to most widely adopted clean-up procedures for AFTs in cereals and oils.

Rational Construction of Highly Tunable Donor-Acceptor Materials Based on a Crystalline Host-Guest Platform.

Organic donor-acceptor systems have attracted much attention due to their various potential applications. However, the rational construction and modulation of highly ordered donor-acceptor systems could be a challenge due to the complicated self-assembly process of donor and acceptor species. Considering the well-defined arrangement of species at the molecule level, a crystalline host-guest system could be an ideal platform for the rational construction of donor-acceptor systems. Herein, it is shown how the rational construction of highly tunable donor-acceptor materials can be achieved based on a crystalline host-guest platform. Within the well-established metal-organic framework NKU-111 as the crystalline host enabled by the relatively stable coordination-directed assembly, the introduction and arrangement of guest molecules in the crystals allow the rational construction of the NKU-111⊃guest donor-acceptor system. The donor-acceptor interaction in the systems can be readily modulated with different guest molecules, which can be justified by the well-demonstrated guest-dependent characteristics. Accordingly, the NKU-111⊃guest reveals highly tunable donor-acceptor properties such as charge-transfer-based emissions and electrical conductivity. This work indicates the potential of crystalline host-guest systems as an ideal platform for systematic investigations of donor-acceptor materials.

Janus PEGylated gold nanoparticles: a robust colorimetric probe for sensing nitrite ions in complex samples.

We presented a Janus PEGylated AuNP probe where PEGs and recognition ligands (e.g., 4-aminobenzenethiol, 4-ABT) were asymmetrically functionalized on an AuNP. With this design, the probes showed high colloidal stability, signal robustness, specificity, and sufficient sensitivity in the determination of NO2- in various complex samples.

Plasmonic ELISA based on the controlled growth of silver nanoparticles.

Herein, we demonstrate a plasmonic ELISA based on the alkaline phosphatase (ALP)-mediated growth of silver nanoparticles (AgNPs) for the sensitive, rapid, and naked-eye detection of cancer biomarkers in clinical serum samples. This approach was used to measure the low-abundance alpha fetal protein (AFP) in clinical sera, which demonstrates its great capability in the differentiation of cancers and evaluation of therapeutic responses. Impressively, the readout of the plasmonic assay depends on the rapid formation of Ag colloidal solutions with various degrees of yellow color, which can be distinguished by the naked eye, without the need for sophisticated platforms. The limit of detection of the plasmonic ELISA for alpha fetal protein (AFP) can be as low as 0.23 ng mL-1, which is approximately 10 folds lower than that of conventional ELISA. This plasmonic ELISA opens a new avenue for the early detection of cancers and monitoring of cancer reoccurrence especially in resource-poor regions where convenient diagnostic tools are highly desirable.

Targeted structure modulation of "pillar-layered" metal-organic frameworks for CO2 capture.

Two new zinc MOFs with similar "pillar-layered" framework structures based on 1,1'-biphenyl-2,2',6,6'-tetracarboxylic acid (H4bpta) and two different bipyridine pillar ligands, namely {[Zn4(bpta)2(4-pna)2(H2O)2]·4DMF·3H2O}n (1) and {[Zn2(bpta)(bpy-ea)(H2O)]·2DMF·H2O}n (2) (4-pna = N-(4-pyridyl)isonicotinamide and bpy-ea = 1,2-bis(4-pyridyl)ethane), have been synthesized and investigated with their CO2 adsorption properties. By analysis of the structure properties and the CO2 adsorption performances of these two MOFs, it was found that the introduction of polar acylamide groups via 4-pna resulted in 1 with enhanced CO2 capacity and CO2/CH4 selectivity at low pressure. In contrast, the framework of 2 shows flexible properties originating from the flexibility of the ethanediylidene group in the bpy-ea ligand, which benefits the sieve effect of pores to give higher CO2/CH4 selectivity at a relatively high pressure range.

Fluorous metal-organic frameworks with enhanced stability and high H2/CO2 storage capacities.

A new class of metal-organic frameworks (MOFs) has been synthesized by ligand-functionalization strategy. Systematic studies of their adsorption properties were performed at low and high pressure. Importantly, when fluorine was introduced into the framework via the functionalization, both the framework stabilities and adsorption capacities towards H2/CO2 were enhanced significantly. This consequence can be well interpreted by theoretical studies of these MOFs structures. In addition, one of these MOFs TKL-107 was used to fabricate mixed matrix membranes, which exhibit great potential for the application of CO2 separation.