基于上转换荧光标记和磁分离技术的沙门氏菌DNA检测新方法

利用水热法制备NaYF4:Yb3+Er3+荧光纳米颗粒,表面氨基化修饰后与探针核酸单链共价偶联,形成荧光标记显示探针。再将氨基化的Fe3O4磁性纳米颗粒与捕获核酸单链进行共价偶联,制备磁分离捕获探针。基于DNA杂交互补反应,加入体系中的目标DNA链分别与两端互补的荧光显示探针和磁分离捕获探针形成三明治夹心结构,通过外加磁场收集分离。加入的目标DNA链浓度越大,体系荧光强度越大。结果表明,复合结构的荧光强度与目标DNA链浓度成正比,在0.01~10 pmol/L范围内呈现良好的线性关系,最低检测限达3 fmol/L。     

猪肉成分胶体金检测试纸条的制备研究

利用互补核酸序列的相互作用原理,研发了一种用于鉴别猪肉成分的胶体金试纸条及检测方法。首先采用柠檬酸三钠法合成粒径30 nm左右的胶体金粒子,进一步将猪特异性DNA的某条单链片段与胶体金粒子共价偶联(探针A),其互补片段固定在硝酸纤维素膜上作为检测探针(探针B),通过探针结合导致胶体金粒子的聚集显色实现猪肉成分的检测。结果表明,探针A与胶体金偶联的最佳用量为60μL(0.1 mmol/L),探针B喷涂的最佳浓度是7.5 nmol/L,试纸条的检出限为10%。     

金纳米粒子-DNA折纸组装体的构建及对17β-雌二醇的检测

目的 为实现DNA折纸上金纳米粒子的高效组装和雌二醇的可视化检测,本研究将正丁醇法和“一步退火”法结合用于金纳米粒子快速修饰和在DNA折纸上高效组装,并将DNA折纸与适配体和金纳米粒子结合用AFM可视化检测雌二醇。方法 巯基修饰的DNA与金纳米粒子混合物与正丁醇接触,快速除去水分, 通过Au-S键共价结合形成致密的球形核酸。引入一种自下而上可编程DNA自组装的方法-DNA折纸术(DNA Origami), 利用其精确的定位功能, 将DNA折纸单链和球形核酸混合, 一步退火形成DNA折纸-金纳米粒子组装体结构。进一步将DNA折纸与适配体结合, 金纳米粒子作为信号探针, 利用原子力显微镜(Atomic Force Microscope, AFM) 进行17β-雌二醇(E2)的可视化检测。结果 通过加盐实验和电位表征, 表明正丁醇法能够在几秒内完成金纳米粒子的表面功能化, 节省了实验时间; 通过AFM表征, 表明“一步退火”可以实现金纳米粒子在DNA折纸上的高效组装, 并且“一步退火”的组装效果远远好于“二步退火”。生物传感器可以通过AFM直观地检测50 ng/mL的E2。结论 在本研究中,利用正丁醇法合成的球形核酸经过一步退火实现了在DNA折纸上的高效组装,其次,提出了基于DNA折纸可视化检测E2的纳米生物传感新方法。     

适配体增强金纳米粒子类过氧化物酶活性快速检测鸡蛋中的恩诺沙星

目的 利用核酸适配体增强金纳米粒子类过氧化物酶(peroxidase,POD)活性,建立了一种快速检测鸡蛋中恩诺沙星的方法。方法 金纳米粒子具有类POD活性,能催化H₂O₂氧化3,3’-5,5’四甲基联苯胺(3,3’-5,5’tetramethylbenzidine, TMB)反应,加入核酸适配体后,适配体通过Au-N键吸附于金纳米粒子表面,使催化活性增强;进一步加入靶标物恩诺沙星后,核酸适配体与靶标物特异性结合而脱离金纳米粒子表面,使催化活性减弱。基于此建立了恩诺沙星比色检测方法,优化了反应条件,并将其用于鸡蛋样品检测中。结果 在核酸适配体浓度为10 nmol/L, TMB浓度为0.3 mmol/L,显色反应时间为20 min时,反应体系的吸光度变化随恩诺沙星浓度在5～150μmol/L范围内具有良好的线性关系,检出限为1.98μmol/L。该方法具有良好的选择性和抗干扰能力,将此法用于鸡蛋中的恩诺沙星的检测,加标回收率为92.67%～109.04%。结论 该方法简便快速,为鸡蛋中恩诺沙星检测提供了一种新的尝试方法。     

基于核酸适配体杂交链式反应比色法检测鼠伤寒沙门氏菌

该研究探讨了基于核酸适配体特异性识别机制和杂交链式反应（hybridization chain reaction,HCR）扩增策略,以金纳米粒子（gold nanoparticles,AuNPs）颜色变化为比色信号,设计了一种无标记、无酶、灵敏的鼠伤寒沙门氏菌（Salmonella typhimurium,S. typhimurium）比色检测法。根据鼠伤寒沙门氏菌核酸适配体设计引发链和两个发夹探针,核酸适配体捕获鼠伤寒沙门氏菌,触发引发链打开发夹探针,发生杂交链式反应,在实现目标菌信号放大同时,利用反应前发夹探针粘性末端以及反应后形成的杂交长链对金纳米粒子结合差异性,产生比色信号,实现鼠伤寒沙门氏菌的快速检测。通过对杂交链式反应时间、发夹探针与金纳米粒子结合时间以及发夹探针浓度等实验参数进行优化,提高实验灵敏度。在最优实验条件下,鼠伤寒沙门氏菌浓度对数值与紫外吸光比值（A630/525）在103~107 CFU/mL范围内呈现良好的线性关系,检测限为6.3×101 CFU/mL,在牛奶样品中加标回收率为90.05%~109.97%。本比色法操作方便,无需要化学修饰以及复杂仪器且实验结果可视,为鼠伤寒沙门氏菌监测提供一种新的方法。     

基于核酸适配体-金纳米粒子比色传感器快速检测食品中赭曲霉毒素A

本研究以核酸适配体为识别元件实现对赭曲霉毒素A(OTA)的高选择性识别,以及采用金纳米粒子做为比色探针,建立了适用于OTA快速检测的比色适配体传感器。研究结果表明,该比色传感器对OTA具有较高的灵敏度和特异性,操作简单快速,能用于实际食品样品中OTA的快速筛查检测;该比色传感器在520nm和650nm下吸光度的比值(A520/A650)与OTA浓度在0.05~5μM的范围内呈线性相关,检测限为0.02μM。     

基于纳米金复合探针的沙门氏菌快速定量检测

鉴于现有沙门氏菌检测方法的缺陷,研发一种快速、简便、低成本、高灵敏的沙门氏菌新型快速定量检测技术。通过水相合成法制备碲化镉量子点,用显示DNA将一个金纳米粒子连接上百个量子点制备显示探针进行信号放大;采用水热-溶剂热方法制备氨基化Fe_3O_4磁性纳米粒子,并利用亲和素与生物素特异性结合的原理,连接捕获DNA制备捕获探针,测定沙门氏菌DNA荧光强度。结果显示:在10~1 000fmol/L范围内,沙门氏菌的DNA浓度与荧光强度呈良好的线性关系,回归方程为I_F=0.198[DNA]+55.00,R~2=0.997,检出限为8fmol/L。在检测被沙门氏菌污染的牛奶样品中,也显示了优良的准确性,最低检出限为4fmol/L。     

金纳米棒比色探针法测定维生素C的初步研究

目的采用金纳米棒作为探针,构建一套灵敏简单的用于检测维生素C的比色方法。方法采用壳聚糖-三聚磷酸钠复合物作为还原剂和稳定剂制备金纳米棒;采用紫外-可见光分光光度计和透射电子显微镜对其进行表征;根据金汞齐的形成原理,通过金纳米棒的长短径比值下降所造成的溶液颜色的明显变化,快速检测体系中不同浓度的维生素C。结果当检测体系中出现维生素C时,颜色由蓝色变为橙色;在维生素C浓度为1~100μmol/L和250—2000μmol/L范围内时,其浓度与体系吸光度比值(A_(530)/A_(640))呈现明显的线性关系,相关系数分别为0.9894和0.9843,检出限为0.067μmol/L。结论该体系下制备的金纳米比色探针可以实时快速检测维生素C的含量。     

基于纳米金标记-适配体识别的伏马菌素B_1检测新方法

基于核酸适配体识别和纳米金变色效应构建了伏马菌素B1(FB1)的可视化检测新方法。实验以纳米金为载体,首先在纳米金表面组装巯基化的适配体互补短链DNA1/FB1-适配体复合物;当加入目标物时,适配体链与目标物结合,与互补短链DNA1发生解离;此时再加入纳米金标记的与适配体互补短链1互补的短链DNA2,二者杂交可导致纳米金粒子的聚集而使溶液颜色发生变化,进而实现目标物的可视化检测。通过条件优化,有效避免了由于盐浓度过高使纳米金发生聚集所产生的误差。同时在纳米金与短链DNA孵化时加入表面活性剂十二烷基硫酸钠(SDS),使NaCl浓度达到了500 mmol/L而纳米金颜色仍不发生改变,打破了以往熟化NaCl浓度100 mmol/L就使纳米金颜色发生变化的界限,使附着在纳米金上的DNA量扩大了3倍。方法检测线性范围为125～1 500 ng/L,检测限为125 ng/L。该方法已成功应用于啤酒中FB1的检测。     

基于纳米金显色的非标记核酸适配体可视化检测重金属镉的方法研究

目的建立以特异性非标记核酸适配体为识别探针的重金属镉可视化检测方法。方法根据适配体与镉的高亲和力结合特性,利用纳米金溶液在盐诱导下凝聚后引起的颜色变化反应,通过分光光度计检测溶液的吸光度来检测镉离子浓度。通过优化适配体DNA浓度、盐离子浓度和纳米金溶液体积,确定最佳反应条件,建立样品溶液中镉离子浓度与吸光度的线性关系。结果该方法的线性范围和检测限分别是0.14~10 ng/m L和0.14 ng/m L,可以满足痕量检测要求。通过对灌溉水样的加标回收实验证明,检测体系具有很好的实用性和复杂基体适应性。结论利用核酸适配体和纳米金显色实现了镉的痕量可视化检测,该方法是一种简单、快速、灵敏的检测方法,在现场快速检测和高通量分析中都具有很好的应用前景。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the