化学发光免疫法检测食品中恩诺沙星残留的研究

建立了基于多克隆抗体的化学发光免疫检测技术,用于测定动物源性食品中恩诺沙星残留含量。反应条件优化结果为:抗体包被最佳稀释倍数为64000倍,最佳酶标抗原稀释倍数为256000倍。结果显示:该方法的回归曲线方程为y=-13.898x+110.38(R2=0.9893),检测线性范围为3~810pg/mL,IC50为69.63pg/mL,IC10为1.41pg/mL;鸡肉、鱼肉、虾肉、蜂蜜、牛奶空白组织样品中恩诺沙星的最低检测限分别为3.76、4.59、2.85、2.65、4.20pg/mL,最低定量限分别为6.13、7.35、3.57、3.73和6.48pg/mL,回收率在88.28%~102.6%,板内和板间的平均变异系数分别为2.61%和4.71%。表明本研究建立的化学发光免疫检测方法满足动物源性食品恩诺沙星残留的检测要求。     

基于单克隆抗体的双酚A半抗原直接包被的酶联免疫吸附法的建立

传统的人工抗原包被酶联免疫吸附法(ELISA)依赖疏水相互作用将人工抗原与酶标板结合,会影响半抗原的呈现与识别,且多采用多克隆抗体为检测抗体,这些均会导致检测灵敏度下降和标准化难度增大。该研究选择双酚酸(BVA)作为双酚A(BPA)的半抗原与蛋白质偶联制备人工抗原免疫BALB/c小鼠,获得一株可分泌BPA单克隆抗体(MAb)的杂交瘤细胞株。利用3-氨丙基三乙氧基硅烷硅化处理酶标板,将BVA直接包被在酶标板上,建立了一种基于MAb的半抗原直接包被的BPA间接竞争ELISA法。该检测方法最低检测限IC10为0.29 ng/mL,半数抑制率IC50为5.4 ng/mL,水样中加标回收率为94.04%~102.31%。与人工抗原包被BPA ELISA检测方法(IC10:0.5 ng/mL,IC50:16.65 ng/mL,水样中加标回收率为89.72%~105.25%)相比,检测灵敏度显著性提高。     

谷物中赭曲霉毒素A化学发光酶免疫分析法的建立

建立了间接竞争化学发光酶免疫法检测赭曲霉毒素A(ochratoxin A,OTA),该方法IC50为112 pg/mL,检出限是2.47 pg/mL,平均批内和批间变异系数分别为7.03%和14.7%。在大米和小麦样本中添加浓度1.5～6μg/kg的OTA标品,平均回收率在66.97%～97.96%之间,与其他常见真菌毒素未见交叉反应。将该方法应用于30份谷物样本(包括20份大米样本和10份小麦样本)中OTA的检测,检测结果与商品化ELISA试剂盒的相关系数R2=0.942 4。该方法简单、灵敏、快速、准确适用于谷物中OTA的检测。     

重金属镉特异性抗体的制备及icELISA检测方法的建立

为检测食品中的重金属镉残留问题,本研究建立了基于重金属镉抗体的酶联免疫分析方法。利用异硫氰酸苄基乙二胺四乙酸(Isothiocyanobenzyl-EDTA,ITCBE)螯合Cd~(2+)并偶联牛血清白蛋白(BSA)和卵清白蛋白(OVA),合成了针对Cd~(2+)的免疫原Cd-ITCBE-BSA和包被原Cd-ITCBE-OVA,通过紫外扫描鉴定说明偶联成功;以Cd-ITCBE-BSA免疫Balb/c小鼠,制备出Cd~(2+)抗血清并对其免疫学特性进行鉴定,进一步说明了抗原合成成功,在此基础上进行了条件优化并建立了针对镉的icELISA检测方法。方法的检测限(IC10)为0.18 ng/mL,IC50为1.15 ng/mL,线性检测范围(IC20～IC80)为0.24～5.54 ng/mL。除了与Hg~(2+)有2.16%的交叉反应率,该方法对Pb~(2+)、Fe~(3+)、Cu~(2+)和Cr3+交叉反应率均小于0.3%,板内变异系数和板间变异系数都低于10%。此抗体特异性强灵敏度高,建立的icELISA方法可应用于食品中重金属镉的快速检测。     

呋喃西林代谢物多克隆抗体制备及酶联免疫吸附分析方法

为了建立检测呋喃西林代谢物(SEM)的酶联免疫吸附分析方法(ELISA),将所设计合成的系列半抗原与牛血清白蛋白(BSA)偶联制备免疫原并免疫新西兰大白兔,筛选获得源于新颖半抗原H3的具有高亲和力、高特异性抗SEM多克隆抗体。同时,基于设计合成的系列同/异源包被抗原,考察了不同结构包被原对ELISA灵敏度的影响,发现H4-OVA作为异源包被原建立SEM的ELISA检测方法可获得最佳的检测效果,结果显示:ELISA方法的半抑制浓度(IC50)为12.37ng/mL;定量检测线性范围(IC20～IC80)为0.439～110.78ng/mL;检测限(IC10)达0.07ng/mL,达到了国内外相关检测限量要求,可应用于实际食品样品检测。     

半抗原直接包被的四环素酶联免疫吸附分析法的建立

为建立更优的四环素（tetracycline,TC）酶联免疫吸附分析法（enzyme?linked immunosorbent assay,ELISA）,将TC 与蛋白质偶联制备人工完全抗原免疫BALB/c 小鼠,获得抗TC 的单克隆抗体（monoclonal antibody,MAb）。采用酸性高锰酸钾羧化酶标板,将TC 直接包被在酶标板上,并对ELISA 反应体系条件进行优化,构建一种半抗原直接包被的TC ELISA 检测方法。所制备的MAb 特异性良好,交叉反应率低。所构建的检测方法最低检测限IC10 值为0.306 ng/mL,半数抑制率IC50值为9.26 ng/mL,牛奶和水中加标回收率分别为96.46%～101.89%、96.84%～102.50%。与人工完全抗原包被的检测方法相比（IC10值：0.624 ng/mL,IC50值：28.24 ng/mL,牛奶和水中加标回收率分别为93.86%～105.12%、94.04%～105.56%）,检测灵敏度有明显提高,并可用于实际样品中TC 含量的检测,具备良好的应用前景。     

脱氧雪腐镰刀菌烯醇(DON)直接竞争ELISA方法的建立

利用前期制备得到的DON酶标抗原(辣根过氧化物酶标记)以及抗DON抗体,建立检测食品中DON含量的直接竞争ELISA方法。该方法的检测范围1～100ng/mL,灵敏度达0.56ng/mL,半数抑制浓度IC50为10ng/mL;与DON类似物T-2毒素的交叉反应率为12%;玉米淀粉样品回收率在80.2%～91.1%之间,平均批间变异<15%,平均批内变异<3%。     

化学发光酶联免疫法检测苏丹红Ⅰ

为检测食品中苏丹红Ⅰ残留,建立间接竞争化学发光酶联免疫分析（chemi luminescent enzymeimmunoassay,CLEIA）法。通过优化包被抗原中本抗原与载体物质的量比、包被抗原质量浓度、抗体稀释比例,建立竞争抑制曲线。线性范围为0.156～5 ng/mL,最低检测限为0.078 9 ng/mL,IC50为0.679 ng/mL。CLEIA回收率为75.08%～112.18%,变异系数为8.89%～15.61%;通过与酶联免疫吸附（enzyme-linked immunosorbent assay,ELISA）法进行比较,在相同抗原抗体质量浓度条件下,CLEIA法测定的IC50较ELISA方法降低30%,具有较高的灵敏度。     

一种新型玉米赤霉烯酮的定量检测方法

采用间接竞争法原理和液相芯片技术平台,选用玉米赤霉烯酮单克隆抗体(Monoclonal Anti-ZEN)对玉米赤霉烯酮(ZEN)定量检测方法进行探索。将ZEN-BSA与36﹟微球偶联,同时加入待检的游离的ZEN小分子和其标记有生物素的ZEN单克隆抗体,偶联抗原和目标抗原竞争结合生物素标记抗体,通过报告分子SA-PE在532 nm波长的激光下,即可检测出报告分子发出的荧光强度,荧光强度与待检ZEN的量成反比。该研究优化了液相反应体系中ZEN单克隆抗浓度、确定了ZEN单抗临界饱和浓度以及抗原抗体最佳孵育时间,其中ZEN单抗临界饱和浓度为2.0μg/mL,偶联抗原和抗体最佳孵育时间为3h。研究所建立的ZEN液相芯片定量检测方法,以国际通用的IC50作为衡量标准,其检测灵敏度为0.005 4μg/mL,线性范围为0.000 8～0.04μg/mL。应用该方法对脱脂牛奶和全脂牛奶进行加标回收检测,平均回收率均大于75%。该方法简化了样品的纯化和分离步骤,经过实际样品的检测,证明方法灵敏、稳定、快速、简便,适用于大量样本的检测。     

单增李斯特菌与志贺氏菌多重PCR检测技术的建立

目的:为食品、卫生行业提供一种简便、灵敏、快速,并且特异性强的单增李斯特菌(Listeria Monocyto-genes)与志贺氏菌(Shigella)多重PCR检测方法.方法:根据单增李斯特茵转录调节子基因prfA、志贺氏茵侵袭性质粒抗原H基因ipaH筛选出引物;优化多重PCR的引物浓度、退火温度及Mg2+等条件,分析单-PCR及多重PCR的特异性、灵敏度;结合24 h增茵培养.确定多重PCR检测人工污染脱脂灭茵乳的检出限.结果:多重PCR扩增出了预计的PCR产物,即单增李斯特茵(274bp)和志贺氏茵(421bp).该方法的灵敏度:78 pg单增李斯特茵基因组DNA、7.5pg志贺氏茼基因组DNA.多重PCR检测人工污染脱脂灭菌乳,单增李斯特茵与志贺氏茵的灵敏度分别为2cfu/25mL和1.6cfu/25mL.结论:该方法在食品、卫生行业具有很好的应用和开发前景.     

Natural co-occurrence of fumonisins, deoxynivalenol, zearalenone and aflatoxins in field trial corn in Argentina

Corn samples collected from the main production area in Argentina in 1995 were surveyed for the natural occurrence of Fusarium mycotoxins and aflatoxins. Fumonisins B₁, B₂ and B₃ and zearalenone were found in all samples. A positive relationship was found between fumonisins B₁, B₂ and B₃, B₁ and B₃, and B₂ and B . Deoxynivalenol and aflatoxins were not de3 tected. Mycological survey has also revealed the predominance of Fusarium moniliforme . This is the first report on the simultaneous occurrence of fumonisins and zearalenone in corn from the main production area in Argentina.     

基于异源包被的 曲安奈德竞争酶联免疫检测方法

为监控曲安奈德的滥用情况,本研究建立了曲安奈德竞争酶联免疫检测方法。将曲安奈德(Triamcinolone acetonide,TCA)半抗原通过活泼酯法与钥孔戚血蓝蛋白(keyhole limpet hemocyanin,KLH)偶联获得曲安奈德完整抗原TCA-KLH;通过免疫小鼠、细胞融合及筛选获得一株能够稳定分泌抗曲安奈德的单克隆抗体细胞株,制备并纯化了腹水抗体。将TCA和地塞米松(Dexamethasone,DEX)半抗原通过活泼酯法分别与牛血清白蛋白(bovine serum albumin,BSA)偶联作为包被原,建立曲安奈德同源及异源的间接竞争酶联免疫分析方法(indirect competitive enzyme linked immunosorbent assay,ic-ELISA)。在同源包被情况下,曲安奈德灵敏度为5.4 ng/mL,而DEX异源包下灵敏度为0.53 ng/mL。未观察该方法到对哈西奈德、布地奈德、安西奈德以外的其他糖皮质激素的交叉反应。在添加回收实验中,使用20%甲醇水溶液提取动物组织的添加回收率在75%~95%之间。该方法能有效应用于动物组织中曲安奈德的快速筛查。     

Determination of zearalenone in corn flour and a cheese snack product using high-performance liquid chromatography with fluorescence detection

The presence of the mycotoxin zearalenone in corn flour and a cheese snack derived from this was determined. Thirty-eight samples (corn flour and cheese snacks) of different brands were analysed for zearalenone using high-performance liquid chromatography with fluorescence detection. Zearalenone was detected in corn flour and cheese snack samples with average content of 0.377 ppm (maximum, 0.889 ppm) and 0.832 ppm (maximum, 1.471 ppm) respectively. The recovery from spiked corn flour and cheese snack samples ranged from 70-87%. The method had a limit of detection of 0.01 µg ml^-1. The linearity of method was determined (y = 5.88 x + 0.25, r² = 0.9999), and optimum assay range was 0.05-30 µg ml^-1. The occurrence of zearalenone in the maize product confirms the need to assess the exposure of the Iranian population to this mycotoxin.     

Survey for aflatoxins, ochratoxin A, zearalenone and fumonisins in maize imported into the United Kingdom

This survey examined 140 samples of raw maize as received at ports or at major maize mills in the UK and 12 after initial cleaning. Samples were examined for aflatoxins B₁, B₂, G₁ and G₂, ochratoxin A, zearalenone and fumonisins B₁, B₂ and B₃ using fully validated analytical HPL C methods with detection limits of 0.1 mu g/kg for each aflatoxin and ochratoxin A, 4 mu g/ kg for zearalenone and 10 mu g/kg for each fumonisin. 95.0% and 92.1% of samples met the new EC statutory maximum permissible level for total aflatoxins and aflatoxin B₁ respectively. The maximum concentration of ochratoxin A found was 1.5 mu g/kg. Zearalenone and fumonisins were detected in almost every sample with 41.7% of maize containing more than 100 mu g/kg of zearalenone and 48% of samples containing more than 1000 mu g/kg total fumonisins. Initial cleaning of raw maize reduced aflatoxin concentrations by about 40% and total fumonisins by 32%.     

Mycotoxins in infant cereal foods from the Canadian retail market

Three hundred and sixty-three samples of cereal-based infant foods were collected from the Canadian retail marketplace over 3 years. The samples included oat-, barley-, soy-, and rice-based infant cereals, mixed-grain infant cereals, teething biscuits, creamed corn, and soy-based formulas. Samples were analysed for targeted mycotoxins (deoxynivalenol, nivalenol, HT-2 toxin, zearalenone, ochratoxin A, fumonisins B₁ and B₂, and five ergot alkaloids). Soy-based cereals (which usually contain corn) exhibited the highest incidences of deoxynivalenol (100%), zearalenone (46%) and fumonisins (75%). Overall, deoxynivalenol was the most frequently detected mycotoxin -- it was detected in 63% of samples analysed. Survey results demonstrated the regular occurrence of multiple mycotoxins in cereal-based infant foods.     

Fumonisin levels in commercial corn products in Buenos Aires, Argentina

Fumonisins B₁ (FB₁) and B₂ (FB₂) were determined in 35 samples of corn flour and corn grits destined for human consumption and purchased directly from Buenos Aires food shops and supermarkets from October 1996 to January 1997 and during the month of January 1998. During the first period of sample collecting, 16 out of 19 samples were found to be contaminated. Considering all 19 samples, contamination levels were between not detected and 1860 ng/g FB₁, and from not detected to 768 ng/g FB₂. During the second period all 16 samples were found to be contaminated with levels ranging from 75 to 4987 ng/g FB₁, and from not detected to 1818 ng/g FB₂. The levels of FB₁ and FB₂ in the samples collected during January 1998 were significantly higher than the samples collected during the period from October 1996 to January 1997. No significant difference was found in terms of fumonisin levels between the branded and unbranded samples.     

基于还原氧化石墨烯的电化学适配体传感器对黄曲霉毒素M1的检测

本实验基于还原氧化石墨烯（RGO）构建了一种用于黄曲霉毒素M₁（AFM₁）检测的电化学适配体传感器。采用红枣汁还原氧化石墨烯（GO）制备RGO,RGO通过滴涂法修饰在玻碳电极（GCE）表面,利用电沉积法将纳米金修饰在RGO/GCE上,AFM₁的适配体（Apt）通过Au-S键固定在AuNPs/RGO/GCE电极表面用于靶标AFM₁的捕获。当AFM₁存在时,AFM₁与适配体特异性结合形成AFM₁-Apt复合物,该复合物阻碍了电子的传递,导致电化学信号减弱。对RGO的制备条件进行优化,利用差示脉冲伏安法（DPV）监测电极表面的电化学信号,并对不同类型的毒素（黄曲霉毒素B₁、黄曲霉毒素B₂、赭曲霉毒素A和伏马毒素B₁）、不同浓度的AFM₁（1×10?7~5×10?4 ng/mL）以及羊乳样品进行检测以确定电化学适配体传感器的特异性、灵敏性和实用性。结果表明,GO:红枣汁=2:1（V:V）,pH=11时所制备的RGO的导电能力最强。传感器的电信号与AFM₁浓度的对数呈线性关系,检测范围为1×10?7~5×10?4 ng/mL,检测限为3.3×10?5 pg/mL,同时所建立的方法仅对AFM₁的检测有响应,而对干扰毒素无响应,说明电化学适配体传感器的特异性良好。使用建立的AFM₁电化学适配体传感器对羊奶中的AFM₁含量进行测定,发现所构建的传感器具有很高的灵敏性和良好的选择性,有望应用于食品工业中真菌毒素的快速、准确检测当中。     

Occurrence of aflatoxins in layer feed and corn samples in Konya province, Turkey

The natural occurrence ofaflatoxin was investigated in layer feed and corn samples brought to Konya Veterinary Control and Research Institute Laboratory between 15 April and 15 December 2002. Seventy-eight samples (52 feeds, 26 corn samples) were analysed for total aflatoxin (B₁ + B₂ + G₁ + G₂) by an ELISA screening method. Aflatoxin contamination was determined in 37 feed samples (71.1%) and 15 corn samples (57.7%), with a range of1.5-133 μg kg^-1. However, a majority ofthe aflatoxin contamination was less than 5 μg kg^-1 (50% within the positive samples). Two feed samples and two corn samples exceeded the maximum tolerated levels in feed (20 μg kg^-1) and feedstuffs (50 μg kg^-1) for total flatoxin.     

Survey of aflatoxins in beer sold in Canada

Between March 1998 and March 2002, 304 samples of domestic (Canadian) and imported beers from 36 countries were picked up for the determination of aflatoxins B₁, B₂, G₁ and G₂. Twelve samples were positive with aflatoxins greater than the limit of quantitation (LOQ) (aflatoxin B₁, 4.4 ng l^-1; aflatoxin B₂, 3.4 ng l^-1; aflatoxin G₁, 11.2 ng l^-1; and aflatoxin G₂, 6.2 ng l^-1). Five samples from Mexico, two samples from Spain and one from Portugal contained aflatoxin B₁. Four samples from India contained aflatoxins B₁ and B₂. The remaining samples contained less than the LOQ for aflatoxins B₁, B₂, G₁ and G₂. The analytical method for this survey was based on that of Scott and Lawrence (Scott PM, Lawrence GA. 1997. Determination of aflatoxins in beer. Journal of AOAC International 80:1229-1234.). Aflatoxins B₁, B₂, G₁ and G₂ were determined at parts per trillion (ng l^-1) levels in beer by immunoaffinity column cleanup followed by derivatization with trifluoroacetic acid and reversed-phase liquid chromatography with fluorescence detection.     

低温等离子体对黄曲霉毒素B1的降解效能

目的:确定低温等离子体降解黄曲霉毒素B₁（Aflatoxin B₁，AFB₁）最佳工艺条件，并探究其在农产品中应用的可行性。方法:选取低温等离子体不同激发条件（峰值电压、工作频率、作用时间），研究其对溶液中AFB₁的降解效果。通过Center Composite Design（CCD）法进行响应面试验，获取最优降解组合及各因素交互作用机制，并考察此条件下玉米中AFB₁降解效果。结果:当AFB₁浓度为1000 μg/L时，其降解率随峰值电压及作用时间（除90~120 s）的增加，工作频率的下降而极显著升高（P<0.01）。响应面优化后最佳工艺条件为峰值电压160 kV、工作频率50 Hz、作用时间165 s，此时AFB₁降解率为99.62%。此外，将优化后的降解条件在受AFB₁污染的玉米（23.18±0.06 μg/kg）中进行应用，发现180 s处理时间下，其降解率可达39.29%。结论:通过CCD法确定了低温等离子体技术降解AFB₁最优工艺，证实了其在玉米中的降解效果。表明低温等离子体技术在降低谷物黄曲霉毒素污染方面具有巨大潜力。