Advances in immunoassay-based strategies for mycotoxin detection in food: From single-mode immunosensors to dual-mode immunosensors

Mycotoxin contamination in foods and other goods has become a broad issue owing to serious toxicity, tremendous threat to public safety, and terrible loss of resources. Herein, it is necessary to develop simple, sensitive, inexpensive, and rapid platforms for the detection of mycotoxins. Currently, the limitation of instrumental and chemical methods cannot be massively applied in practice. Immunoassays are considered one of the best candidates for toxin detection due to their simplicity, rapidness, and cost-effectiveness. Especially, the field of dual-mode immunosensors and corresponding assays is rapidly developing as an advanced and intersected technology. So, this review summarized the types and detection principles of single-mode immunosensors including optical and electrical immunosensors in recent years, then focused on developing dual-mode immunosensors including integrated immunosensors and combined immunosensors to detect mycotoxins, as well as the combination of dual-mode immunosensors with a portable device for point-of-care test. The remaining challenges were discussed with the aim of stimulating future development of dual-mode immunosensors to accelerate the transformation of scientific laboratory technologies into easy-to-operate and rapid detection platforms.     

免疫传感器在食品真菌毒素检测中的应用

真菌毒素污染是造成粮食和食品安全问题的重要因素之一。传统的分析检测技术如色谱分析法、免疫化学法等用于真菌毒素检测中具有耗时长、样品前处理繁琐等特点。本文介绍了采用生物免疫传感器快速检测真菌毒素的方法,主要综述了它们在各类粮食、食品等基质中真菌毒素检测的应用现状,并简要分析了该技术存在的不足,对其应用前景做出了展望。     

基于免标记电化学免疫传感的蔬菜中农药残留检测研究

本文利用层层自组装技术构建了一种用于农药残留高灵敏检测的免标记电化学免疫传感器。该免疫传感器首先通过在天然聚合物海藻酸钠修饰的玻碳电极上利用电化学方法原位聚合金纳米粒子,然后借助金纳米粒子与蛋白质抗体之间的较强吸附作用进一步原位组装农药抗体,从而成功构建了免标记电化学免疫传感器。实验中以呋喃丹农药为模型,呋喃丹分子通过特异性的免疫反应在抗体功能化电极表面生成免疫复合物,该复合物阻碍了电化学探针在电极表面的电子传递,从而减小了免疫传感器的电流响应,利用电流响应的变化与农药分子浓度的关系可以实现呋喃丹农药的快速、高灵敏检测。在优化的实验条件下,该传感器对呋喃丹农药的线性检测范围为1~105μg/L,检测限为1μg/L。同时,该免疫传感器还实现了多种蔬菜样品中呋喃丹农药残留的高灵敏检测。     

基于G-四链体/硫黄素T无标记荧光适配体传感器快速检测氟苯尼考

硫黄素T(ThT)通过非共价相互作用与G-四链体结合,形成G-四链体/ThT复合物,呈现出较强荧光强度,而游离ThT荧光十分微弱。当存在氟苯尼考(FF)时,具有G-四链体结构的适配体(Apt)对靶标的高亲和力,使得Apt/FF复合物形成并释放ThT,荧光强度降低。基于这一特点,本研究设计一种灵敏快速的现场检测体系,用于检测氟苯尼考,即基于G-四链体/硫黄素T的无标记荧光适配体传感器。该适配体传感器的检测范围为0.0128~200 ng/mL,实际检出限0.0128 ng/mL,检测总时长10 min。同时,对实际加标样品(牛奶和鸡蛋)进行回收率计算,加标回收率在91.2%~117.1%之间。所建立的无标记荧光适配体传感器具有高特异性、成本低、耗时短等优点,可用于实际样品的现场检测。     

非标记蛋白组学法鉴别牛肉丸中肉类掺假的方法研究

以猪、牛、鸡、鸭等4种肉类的肌肉组织为研究对象,采用纳升级液相色谱-四极杆静电场轨道阱高分辨质谱鉴别肉蛋白,基于数据依赖型采集模式和多元统计分析对不同的肉蛋白进行相对定量,探讨非标记蛋白组学法在肉丸掺假鉴定中的应用。结果显示:液相色谱的洗脱条件影响肽段分离效果和蛋白鉴定数,从猪、牛、鸡、鸭4种原料肉中共分别鉴定出归属于2 715,889,659,1 143种蛋白质的80 554,33 350,40 969,32 923条特异性肽段。通过序列搜索(BLAST)和UniProt数据库比对分析,分别鉴别出猪、牛、鸡、鸭肉源特征肽段12,15,19,16条,主要来源于肌红蛋白、肌球蛋白、清蛋白、载脂蛋白和血红蛋白等。在数据依赖型采集模式下,4种肉类来源的32条特征肽信号强度高,重现性好,可用于肉类种属鉴别和肉蛋白的相对定量。不同蛋白提取剂显著影响牛肉丸中蛋白质的含量以及特征肽段的信号强度(P<0.05),而色谱分离梯度对特征肽的鉴别及信号强度影响不大。非标记定量蛋白组学测定结果表明:从不同价位的牛肉丸中鉴别到的主要蛋白含量差异显著(P<0.05)。采用二维正交偏最小二乘判别分析,可很好地区分纯牛肉和掺假的牛肉丸,有69.2%的牛肉丸样品中含有猪肉或鸡肉,而鸭肉未检出。     

冬枣果实发育过程中非标记定量蛋白质组学分析

考察冬枣不同成熟阶段的蛋白质组,分析差异表达蛋白质及功能,为研究冬枣成熟发育机制提供理论依据.采集开花后第55(幼果期)、76(果实膨大期)、96(果实白熟期)、116天(果实脆熟期)的沾化冬枣样品,利用非标记定量蛋白质组学技术对4个阶段冬枣样品蛋白质组进行分析,各阶段样品与前一阶段相比,得到差异表达蛋白质,并进行基因...     

Label-free gold nanoclusters as quenchable fluorescent probes for sensing olaquindox assisted by glucose oxidase-triggered Fenton reaction

Glucose oxidase (GOx) catalyses oxidation of glucose accompanied with the generation of hydrogen peroxide. With the addition of Fe²⁺, hydroxyl radical produced by Fenton reaction between hydrogen peroxide and Fe²⁺ may quench the fluorescence of gold nanoclusters. In this work, a fluorescent enzyme-linked immunosorbent assay with gold nanoclusters was designed with a straightforward signal output, in which the fluorescence of gold nanoclusters was quenched by GOx-triggered Fenton reaction. Olaquindox was selected as a target analyte. Gold nanoclusters capped with bovine serum albumin and GOx-linked olaquindox conjugates were successfully prepared. Olaquindox in samples directly competed with the GOx-linked olaquindox conjugates for binding immobilized antibody. Consequently, the fluorescence signal increased with the amount of olaquindox. Under optimal conditions, the fluorescent enzyme-linked immunosorbent assay exhibited a favorable performance to detect olaquindox in swine feeds, demonstrating a good linear range from 1.0 µg kg^?1 to 150 µg kg^?1 with a reliable correlation coefficient (R² = 0.9918); the limit of detection was 0.68 µg kg^?1. Average recoveries in spiked samples were 85.3% to 113.5%. The proposed strategy is a promising approach for the detection of olaquindox and other harmful small molecules.     

Coliphage as pressure surrogates for enteric viruses in foods

In this study the potential of using selected bacteriophages as pressure surrogates for hepatitis A virus (HAV) and Aichi virus (AiV) was investigated. The coliphages included, T₄, MS2, Qβ, λ imm 434, λ cI 857 and λ cI 857A. T₄ displayed similar pressure responses as HAV and was chosen for further study. The most pressure-resistant phage, MS2, was selected as a possible surrogate to estimate AiV inactivation by high pressure processing (HPP). HAV, AiV and their selected bacteriophage surrogates were treated at a range of pressures and times in three different media. All four were treated in phosphate-buffered saline (PBS), artificial seawater (ASW) or oyster slurry (OS) at 250, 400 or 500 MPa for 1, 5 or 10 min at 20 °C. While T₄ had similar pressure resistance to HAV under conditions of high (500 MPa) and lower pressure (250 MPa), inactivation trends were very different following treatment at 400 MPa and when the viruses were suspended in OS. MS2 showed similar resistance as AiV but at ambient treatment temperatures only. The highest levels of inactivation of MS2 were achieved at 60 °C and 500 MPa. AiV was eliminated at 60 °C for 5 min at ambient pressure, but > 3 log survived exposure to 60 °C at 500 MPa. This degree of protection by pressure may be important in determining the mechanisms of pressure and heat resistances in other viruses.Industrial relevanceGreater knowledge of the responses of viruses and their surrogates to high pressure will aid in the validation of new high pressure-processed food that may be at risk to contamination from HAV or other enteric viruses.     

Innovative nonthermal technologies for inactivation of emerging foodborne viruses

Various foodborne viruses have been associated with human health during the last decade, causing gastroenteritis and a huge economic burden worldwide. Furthermore, the emergence of new variants of infectious viruses is growing continuously. Inactivation of foodborne viruses in the food industry is a formidable task because although viruses cannot grow in foods, they can survive in the food matrix during food processing and storage environments. Conventional inactivation methods pose various drawbacks, necessitating more effective and environmentally friendly techniques for controlling foodborne viruses during food production and processing. Various inactivation approaches for controlling foodborne viruses have been attempted in the food industry. However, some traditionally used techniques, such as disinfectant-based or heat treatment, are not always efficient. Nonthermal techniques are considered a new platform for effective and safe treatment to inactivate foodborne viruses. This review focuses on foodborne viruses commonly associated with human gastroenteritis, including newly emerged viruses, such as sapovirus and Aichi virus. It also investigates the use of chemical and nonthermal physical treatments as effective technologies to inactivate foodborne viruses.     

稀土铽离子介导的非标记适配体传感器评估食品中的重金属银污染

作为最具毒性的重金属之一,银在食品和环境中的污染对人体健康会造成严重危害。该研究基于稀土铽离子（Tb3+）能够结合单链DNA发出特征荧光的原理,利用Ag+能与胞嘧啶（C）结合形成C-Ag+-C结构以组成双链DNA的特性,构建了一种特异性识别Ag+的非标记核酸适配体荧光传感器。该传感器通过Tb3+对单双链DNA结构变化灵敏的特征荧光响应,能够实现对Ag+的高灵敏和快速的定量检测。该方法对Ag+的检测限为391.50 nmol/L,满足国家对于饮用水中Ag+限量检测的要求（0.05 mg/L,即 463.50 nmol/L）。该方法的回收率测定结果在93.02%~102.72%范围内,其相对标准差范围为1.27%~7.14%,证明了它的应用有效性;相较于其他的分子检测方法,该方法具有无需进行化学标记以降低成本,且操作简便,检测响应速度快等优点,为临场快速检测重金属银污染提供了一种可能的途径。     

非标记液质联用法测定市售鸡肉和猪肉的蛋白组

采用非标记液质联用法对市售鸡肉和猪肉样品进行蛋白组测定,比较两种肉在新鲜和熬煮后的小肽种类、量的相对变化。结果显示新鲜鸡肉的蛋白主要是大于100kD的蛋白,pI值范围为6～11;而鸡肉汤中蛋白主要是10～150kD,pI值范围为4～9;新鲜猪肉的蛋白主要是大于100kD的蛋白,pI值范围为6～11,与鸡肉相似;而猪肉汤中蛋白主要是10～100kD,pI值范围为3～9。显示了不同肉材质在相似加工中,其蛋白组的变化会有所不同,根据这些不同,提示由蛋白组测试提取出的指标可为肉质量的评价提供新的评价方式。     

发展葡萄无毒化栽培控制病毒病危害

病毒病是影响葡萄生长发育、产量和品质的重要因素,栽培无病毒苗木是控制葡萄病毒病危害的根本措施。本文简要论述了世界葡萄病毒病研究与无毒化栽培概况、我国葡萄病毒病发生状况、葡萄病毒病的危害、无病毒苗木的优越性、我国发展葡萄无毒化栽培所具备的条件以及发展葡萄无毒化栽培存在的问题。     

不同养殖模式大黄鱼非标记定量差异蛋白组学分析

通过非标记定量蛋白质组学技术研究不同养殖模式大黄鱼的蛋白质差异。选取普通网箱养殖大黄鱼和深水网箱养殖大黄鱼,提取肌肉总蛋白,通过高效液相色谱-质谱联用技术进行鉴定、分析。质谱数据使用MaxQuant软件将峰信号转化为肽段/蛋白的表达矩阵数据,然后使用Perseus软件可视化展示数据。不同养殖模式大黄鱼蛋白质进行Student’s t检验,筛选出差异表达蛋白后并对其进行基因功能分类、代谢通路富集和蛋白质相互作用网络分析,以P<0.05为差异有统计学意义。通过数据库比对获得6 077条多肽,分别对应于1 232个蛋白,其中130个蛋白在大黄鱼间存在显著差异表达,76个上调蛋白,54个下调蛋白,其中上调倍数最高的属于TCP伴侣蛋白,下调倍数最高的属于α-1(I)链状胶原蛋白。生物信息学分析发现,不同养殖模式大黄鱼蛋白质的差异主要在于热休克蛋白、伴侣蛋白、球蛋白及胶原蛋白等,而不同养殖模式中环境温度可能是导致大黄鱼蛋白质显著差异表达的主要因素。     

Efficacy of cold atmospheric plasma for inactivation of viruses on raspberries

In this study, the effectiveness of cold atmospheric plasma (CAP) in inactivating murine norovirus (MNV/human norovirus surrogate) and hepatitis A virus (HAV) on aerosol-inoculated dark red Willamette raspberries was explored. Pulsed positive corona discharge system fed by synthetic air was used for the production of CAP. Raspberries were treated for 1, 3, 5, 7, and 10 min at 25 W. Application of CAP enabled a 4 log₁₀ infectivity reduction in <5 min for MNV and approximately 10 min for HAV (from starting level of 6.91 and 7.84 log₁₀ PFU/mL, respectively). Viral genome copies reduction of 3.18 log₁₀ for MNV and 4.32 for HAV were found from starting level of 5.76 and 6.47 log₁₀ gc/μL, respectively. CAP treatment did not result in significant degradation of fruit color, an important quality attribute. The study demonstrated CAP as an efficient post-harvest decontamination method to reduce viral load in raspberries without significantly affecting its quality parameters.Industrial relevanceDue to the fast-processing paces required in the raspberry industry, it is difficult to assure the complete microbiological safety of this fruit. Cold atmospheric plasma is a practical, environmentally-friendly, non-thermal tool for the effective reduction of microbial pathogens. The model developed in this study demonstrated that CAP treatment of fresh raspberries not only inactivated hazardous enteric viruses in a short time (10 min) but also unaffected fruit color stability. The simplicity of described CAP design and low-cost inputs (air and electricity) enable the commercial application of inexpensive plasma chambers for continuous surface decontamination of large volumes of raspberries without bringing processing to a standstill.     

Research Watch: Filtering viruses

Drinking Water.     

Ribosomal frameshifting in yeast viruses

Proper maintenance of translational reading frame by ribosomes is essential for cell growth and viability. In the last 10 years it has been shown that a number of viruses induce ribosomes to shift reading frame in order to regulate the expression of gene products having enzymatic functions. Studies on ribosomal frameshifting in viruses of yeast have been particularly enlightening. The roles of viral mRNA sequences and secondary structures have been elucidated and a picture of how these interact with host chromosomal gene products is beginning to emerge. The efficiency of ribosomal frameshifting is important for viral particle assembly, and has identified ribosomal frameshifting as a potential target for antiviral agents. The availability of mutants of host chromosomal gene products involved in maintaining the efficiency of ribosomal frameshifting bodes well for the use of yeast in future studies of ribosomal frameshifting.