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The multifunction integrated optical chip (MIOC) is one of the most critical parts of the interferometric fiber optic gyroscope (IFOG), and research on the halfwave voltage of the MIOC is meaningful for a high-precision IFOG. In this paper, the correlation between the frequency and halfwave voltage, which affects the interference light intensity of IFOG, is presented theoretically. A widespread measurement method for frequency dependence of the halfwave voltage, based on lock-in amplification and sinusoidal modulation, is proposed. Further, the measurement result and the oscillation of interference light intensity in the Sagnac interferometer are presented, which are in great agreement with the theory. This paper proposes the frequency dependence of the halfwave voltage and provides a new error research direction for the improvement of the MIOC in a high-precision IFOG.

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High-throughput and low-cost detection of mycotoxins in complex matrices is becoming increasingly urgent but it is still challenging to perform ultrasensitive analyses. Here we report a green and practical cytometric microbead magnetic suspension array (CBMSA) strategy for rapid and economical detection of aflatoxin B1 (AFB1) in multiple batches of lotus seed samples. The protocol included (1) fabrication of suspension array chips by immobilizing biotin-modified bovine serum albumin-AFB1 (antigen) onto the surface of streptavidin-coated magnetic microbeads in a multiwell array, (2) indirect immunocompetition of antigen and target of AFB1 in lotus seed samples with the specific antibodies, (3) rapid magnetic separation regardless of complex pretreatment steps, and (4) ultrasensitive fluorescence detection of fluorescein isothiocyanate-labeled goat anti-mouse immunoglobulin G (FITC-IgG) probes. After systematic optimization of some crucial parameters, the developed CBMSA assay allowed for ultrasensitive detection of AFB1 with limit of detection as low as 7.8125 pg·kg-1. For high-throughput analysis, the CBMSA technique was capable of on-site co-instantaneous detection of 50-100 samples in one operation within 30 s, only needing a small amount (50 µL) of solution, which is much cheaper, greener, and more user-friendly than conventional techniques. Moreover, CBMSA with magnetic separation is free of multiple centrifugation and cleanup steps to avoid unpredictable loss of targets. Since various capture and fluorescent probes can be randomly constructed and bound onto the surface of magnetic microbeads to establish an ultrasensitive detection system, the CBMSA technique is very promising for more trace analytes in complex matrices and for broad point-of-need applications, such as drug screening and real-time high-throughput analysis.

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Immunoaffinity columns (IACs) are most popularly used for mycotoxin clean-up in complex matrices prior to chromatographic analysis. But, their high cost has limited their wide application and the regeneration of IACs for multiple instances of reuse is important. This study aimed to investigate the feasibility of regeneration and reuse of IACs for purification of ochratoxin A (OTA) in spiked raw malt and dried ginger samples followed by high performance liquid chromatography-fluorescence detection. After each use, the IACs were filled with phosphate buffer saline (PBS) as the preservation solution and stored at 8 °C overnight for regeneration and reuse until the recovery rate was <70%. The results showed that matrix type, preparation procedure, and pH value of sample extraction exhibited major effects on the reuse of IACs for OTA clean-up. While, after modifying the sample preparation procedure using water as the diluent and the solution at a pH of 7 to 8, the IACs could be used eight and three times for the spiked raw malt and dried ginger samples with OTA after regeneration. Regarding the traditional procedure recommended in Chinese Pharmacopoeia (2015 edition), the IACs could be used for three and two times for the spiked raw malt and dried ginger samples with OTA, respectively. Therefore, the corresponding experimental cost could be reduced to one-eighth and one-third of the original cost. This is the first study on the regeneration and reuse of IACs for OTA clean-up in complex Chinese herbal medicines, providing a green and economical tool for a large number of samples analysis with low cost.

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The high acidity and complex components of Hibiscus sabdariffa have provided major challenges for sensitive determination of trace aflatoxins. In this study, sample pretreatment of H. sabdariffa was systematically developed for sensitive high performance liquid chromatography-fluorescence detection (HPLC-FLD) after ultrasonication-assisted extraction, immunoaffinity column (IAC) clean-up and on-line post-column photochemical derivatization (PCD). Aflatoxins B1, B2, G1, G2 were extracted from samples by using methanol/water (70:30, v/v) with the addition of NaCl. The solutions were diluted 1:8 with 0.1 M phosphate buffer (pH 8.0) to negate the issues of high acidity and matrix interferences. The established method was validated with satisfactory linearity (R > 0.999), sensitivity (limits of detection (LODs) and limits of quantitation (LOQs) of 0.15-0.65 and 0.53-2.18 µg/kg, respectively), precision (RSD <11%), stability (RSD of 0.2-3.6%), and accuracy (recovery rates of 86.0-102.3%), which all met the stipulated analytical requirements. Analysis of 28 H. sabdariffa samples indicated that one sample incubated with Aspergillus flavus was positive with aflatoxin B1 (AFB1) at 3.11 µg/kg. The strategy developed in this study also has the potential to reliably extract and sensitively detect more mycotoxins in other complex acidic matrices, such as traditional Chinese medicines, foodstuffs, etc.

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OBJECTIVES: This study aimed to explore the transfer rates of aflatoxins from several contaminated herbal medicines by fungi to their decoctions. METHODS: Five types of commonly used herbal medicines including Lilii Bulbus, Hordei Fructus Germinatus, Nelumbinis Semen, Polygalae Radix and Bombyx Batryticatus were selected as the examples. Raw herbal medicine samples were treated by ultrasonication-assisted extraction with 70% methanol and immunoaffinity column clean-up, and the decoctions were prepared following the commonly used boiling method with water for 2 h. Then, the optimized high-performance liquid chromatography with fluorescence detection (HPLC-FLD) method was validated for the quantitative analysis of four aflatoxins (AFG2 , AFG1 , AFB2 and AFB1 ) after postcolumn photochemical derivatization, which was proved to be reliable and sensitive. KEY FINDINGS: Aflatoxins were detected to be transferred from the herbal medicines to decoctions with significantly different transfer rates in the five types of herbal medicines. Quietly high transfer rates of 7.26-115.36% for AFG2 , 4.37-26.37% for AFB1 and 9.64-47.68% for AFB2 were obtained. AFB1 as the most toxic aflatoxin expressed the lowest transfer rate, but still exhibited high amount in the samples. CONCLUSIONS: Therefore, the monitoring of aflatoxins in herbal medicines and their decoctions is in great urgency to ensure the security of consumers taking decoctions.

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Owing to the intrinsic factors and some extrinsic environmental conditions, many foods, agricultural products and Chinese materia medicas (CMMs), if not handled properly in the processes of growth, harvesting, processing and storage, can be easily contaminated by all kinds of molds to produce mycotoxins of serious toxicity, which will not only affect the quality, safety and effectiveness of CMMs, but also result in potential threatens to human and animal's health and life. Therefore, in recent decades, it has become the focus on how to prevent and control the foods, agricultural products and CMMs from being moldy and producing toxicity for scientific preservation. Many Chinese herbal medicines (CHMs) especially those with high content of volatile oils with strong antifungal activities have been applied for the scientific preservation of foods, agricultural products and CMMs. Based on these situations, natural anti-mildew agents have been further developed and made into some useful dosage forms, such as tablets, aerosol, liposomes and inclusion, which will not only greatly expand the application scope of CHMs to make the use of anti-mildew agents more convenient, but also achieve the sustained or controlled release of the antifungal effect for scientific preservation of foods, agricultural products and CMMs.

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Ochratoxin A (OTA) is a toxic secondary metabolite mainly produced by Aspergillus and Penicillium species, with strong renal toxicity, teratogenic, carcinogenic, mutagenic effect. Studies have shown that OTA is not only widely contaminated in food and feed crops, but also has been widely contaminated in Chinese herbal medicines such as spices, licorice and so on. In view of OTA's universality and harmfulness, this paper summarizes the flow visualization test strip, microsphere, electrochemical sensor, surface enhanced Raman spectroscopy technology in OTA rapid detection, which provides reference for the research and application of high throughout detection instrument miniaturization in order to achieve OTA quick detection and simple operation.

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Ginger has got increasing worldwide interests due to its extensive biological activities, along with high medical and edible values. But fungal contamination and mycotoxin residues have brought challenges to its quality and safety. In the present study, the relationship of content of mycotoxins accumulation and bioactive components variation in ginger after infection by toxigenic fungi were investigated for the first time to elucidate the influence of fungal contamination on the inherent quality of ginger. After being infected by Aspergillus flavus and Aspergillus carbonarius for different periods, the produced mycotoxins was determined by an immunoaffinity column clean-up based ultra-fast liquid chromatography coupled with tandem mass spectrometry, and the main bioactive components in ginger were analyzed by ultra performance liquid chromatography-photodiode array detection. The results showed that consecutive incubation of ginger with A. flavus and A. carbonarius within 20 days resulted in the production and accumulation of aflatoxins (especially AFB1) and ochratoxin A, as well as the constant content reduction of four bioactive components, which were confirmed through the scanning electron microscope images. Significantly negative correlation was expressed between the mycotoxins accumulation and bioactive components variation in ginger, which might influence the quality and safety of it. Furthermore, a new compound was detected after inoculation for 6 days, which was found in our study for the first time.

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Accurate and sensitive quantification of a specific class of mycotoxins at trace levels in complex matrices with greener approaches is of significant importance. In this study, a green and economical protocol of magnetic microspheres-based cytometric bead array (CBA) assay on indirect competitive principle was developed for sensitive and rapid detection of ochratoxin A (OTA) in malts with a small number of standard and sample solutions. The protocol included the competition of OTA in malt samples and that covalently coupled on the surface of microspheres with its monoclonal antibodies, the separation and aggregation of the magnetic microspheres, and the fluorescence detection of fluorescein isothiocyanate labeled goat anti-mouse immunoglobulin G probes. The magnetic microspheres-based CBA assay allowed for ultralow limit of detection (0.025µgkg-1) for OTA and showed higher sensitivity compared with the common polystyrene beads-based CBA method. This is the first report on the magnetic microspheres-based CBA assay by using a simple and easy-to-operate magnetic separator for highly sensitive and rapid detection of OTA in complex malt samples. By consuming less solvent, time and cost, as well as fewer standard and samples, the developed green protocol expressed high potential for one-site real-time detection of trace components in complex matrices.

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For seeking novel antibacterial agents with high efficacy and low toxicity to deal with drug resistance, the effects of Salvia miltiorrhizae from various sources on Escherichia coli were evaluated by microcalorimetry coupled with chemometrics. Firstly, the heat-flow power-time curves of E. coli growth affected by different S. miltiorrhizae samples were recorded. Then, some crucial quantitative thermo-kinetic parameters including growth rate constant, heat-flow power and heat output, etc. were obtained from theses curves and were further investigated by some powerful chemometric techniques including similarity analysis, multivariate analysis of variance, hierarchical clustering analysis and principle component analysis. By analyzing the principle parameters, growth rate constant of the second exponential phase (k 2) and the heat-flow output powers of the second highest peak (P 2), together with the derived parameter inhibitory ratio (I,  %), it could be quickly concluded that the tested S. miltiorrhizae samples from different sources in China exhibited strong antibacterial effects on E. coli and the samples from Beijing city exhibited the strongest anti-E. coli effects, which might be used as novel and underlying antibacterial candidates for the resistance of E. coli to the existing drugs in practice. This study provides a useful tool and helpful idea to accurately and rapidly evaluate the antibacterial effects of some complex matrices, offering some references for exploring new antibacterial agents.

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Chinese medicinal materials (CMMs) are easily to be contaminated by all kinds of molds to produce various mycotoxins due to their internal factors and the external environmental conditions during the growth, harvesting, processing, and especially storage processes. This will not only affect the quality of CMMs, resulting in enormous financial loss, but also influence the safety and effectiveness of CMMs, posing potential threats to human health. With the increase in awareness of "traditional Chinese medicine health" idea, more and more attention has been paid on how to prevent and control these CMMs from being mouldy to guarantee their safety. Some physical and chemical techniques have been restricted for protecting CMMs due to their own disadvantages. As a green, safe and economic strategy for the preservation of CMMs, "couplet medicine" technique based on the principle of "protecting CMM with another CMM" has been developed: two kinds of CMMs are stored together and fight against each other to prevent mildew metamorphism, exhibiting no obvious changes in color, smell and quality. Nowadays, certain application results have been obtained for the "antagonistic storage" method based on the above mode and principle. In this paper, we would review and discuss the mechanism, practical application and the problems of "couplet medicine" technique, and provide scientific evidences for developing safe and effective tools to protect CMMs from being mouldy.

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