生物条形码检测技术及其研究进展

生物条形码检测技术是利用磁场作用收集"金纳米颗粒-被检物-磁性微球"复合物,再释放其中的条形码链,然后可选用多种方法对条形码链进行下一步检测。生物条形码检测技术在蛋白质及核酸的检测方面显示出极高的灵敏度,在不依赖酶反应的情况下,检测蛋白质可以达到10-18mol水平,同时在核酸检测方面也能达到PCR反应的灵敏度。该技术是一种新型的诊断技术,在临床诊断方面有着广泛的应用前景。     

纳米金生物条形码技术检测痕量二噁英类化合物

建立一种基于纳米金生物条形码技术的二噁英快速筛检方法.利用二噁英诱 导激活的芳香烃受体复合物,特异识别以纳米金为报告基团的二噁英反应探针,该 探针被释放后进行条形码放大,通过纳米金银染技术增强识别信号,并记录其吸光度值,从 而可以简单灵敏地快速筛检二噁英类化合物.在一定的反应时间和浓度范围内（10^-14～10^-10mol/L）,溶液的吸光度值与2,3,7,8 四氯二苯并二噁英（2,3,7,8-tetrachlorodibenzo-p-dioxin,TCDD）浓度之间呈正相关 ,方法检测限为0.01 pmol/L,变异系数为5%～8%.用纳米金生物条形码（Nano Barcod e,nanoparticle based bio barcode）方法和现有的生物分析方法（CALUX,chemical activated luciferase gene expression）分别测定TCDD标准品,并绘制剂量效应曲线.结 果表明,本方法灵敏度高,线性范围宽,重复性好.本研究纳米金生物条形码方法的检测灵 敏度高于CALUX将近5倍(EC₅₀分别为 4×10^-12 mol/L 和 2×10^{- 11} mol /L),检测限较CALUX降低了10倍（检测限分别为1×10^-14 mol/L 和1×10 ^-13 mol/L）,变异系数分别为5%～8%和15%～30%.     

利用生物条形码技术对蓝舌病毒VP7蛋白进行微量检测

目的：建立高灵敏检测蓝舌病毒VP7蛋白的生物条形码检测方法。方法：制备VP7蛋白的多抗及特异DNA链标记的金纳米颗粒探针（NP）和VP7蛋白单抗标记的磁性微球探针（MMP）,形成MMP-VP7蛋白-NP三明治复合物后,再利用去杂交将NP探针上标记的DNA链释放出来,通过PCR或芯片检测方法鉴定释放的DNA链,确定VP7蛋白的存在。结果：建立了蓝舌病毒VP7蛋白的生物条形码检测体系,检测灵敏度可达10fg/mL,为常规ELISA检测的106倍。结论：为发展高灵敏度的蓝舌病毒生物条形码检测试剂盒鉴定了基础。     

纳米生物条形码技术在分子诊断中的应用

纳米生物条形码技术是一种新型的分子诊断技术,在核酸和蛋白质检测领域已经分别达到和超过现今的检测灵敏度.该技术采用纳米颗粒修饰的核酸或抗体对靶分子进行识别,并利用磁场将其分离,操作简单,不依赖酶反应,具有广泛的应用前景.该技术在病毒DNA、癌症的指标蛋白质等方面的应用已有文献报道,并有望成为一种常规的分子诊断工具.     

纳米级金微粒在DNA生物传感器研究中的应用

纳米金颗粒具有独特的物理、化学性质和良好的生物兼容性,已广泛应用于生命科学研究中的示踪技术.将该技术与DNA传感器相结合,可显著提高生物传感器的灵敏度,缩短检测时间和提高检测通量,已成为近年来的研究重点.     

基于纳米金修饰的核酸适体生物传感器用于环孢素浓度的体外测定

利用环孢素(CsA)的两条高亲和力核酸适体生物传感器用于环孢素浓度的体外测定,在柠檬酸三钠为还原剂条件下,以氯金酸为原料,制备纳米金(Au)溶液,并对其进行表征,将aptamer-Ⅰ经酰胺化反应共价结合到磁性纳米颗粒表面,以纳米金(Au)修饰aptamer-Ⅱ,以固定在磁性纳米颗粒表面的aptamer-Ⅰ与环孢素孵育,再与Au-aptamer-Ⅱ作用,形成磁性纳米颗粒/环孢素/纳米金三明治夹心结构,磁分离技术分离三明治复合物,210 nm处检测分离前后紫外吸收强度的变化,对环孢素进行定量检测。结果紫外检测结果显示,制备的纳米金溶胶在520 nm处呈现典型的吸收峰,JEM-4 000EX电镜结果显示,纳米金溶胶颗粒粒径分布均匀、形貌、分散度较好,粒径大小在30 nm左右,此法对环孢素的响应范围是50~1 500 ng/m L,其线性回归方程为Y=4×10~(-3)X+5.769×10~(-1),R=0.997 3。此法可在1~2 h内完成检测,有望用于血液环孢素浓度的测定。     

纳米金-聚乙烯亚胺基因载体的制备

目的:基因方法治疗癌症近年来取得了很大的突破,因此基因载体的构建显得尤为重要.其中纳米基因载体合成简单,成本低廉,并能够包裹、浓缩、保护核苷酸使其免受核酸酶降解,因此纳米材料广泛地应用于基因输送.我们拟开展聚乙烯亚胺-纳米金基因载体的制备及其表征.方法:采用层层包裹技术制备基因载体,首先通过柠檬酸钠还原法制备纳米金颗粒后,应用11-巯基十一烷酸对金颗粒进行修饰,使其表面带有羧基,然后进一步将带有氨基的低分子量聚乙烯亚胺与羧基进行连接.应用动态光散射(DLS),紫外可见光谱(UV)和透射电子显微镜(TEM)对构建的纳米基因载体进行表征.结果:成功制备了聚乙烯亚胺-纳米金基因载体,检测表明每一步制备出的产物纳米尺寸在20-30nm之间,液体均匀稳定,分散系数(PDI)在0.2以下,Zeta电位测定表明,每步的产物电荷变化与外层包裹的反应物有关.尽管金颗粒外层包裹聚乙烯亚胺,但是总体上纳米载体尺寸没有发生太大的变化,TEM检测表明每一步形成了均匀的、单分散的、球状的纳米颗粒.结论:我们通过层层包裹技术成功制备了聚乙烯亚胺-纳米金基因载体,在进一步开展的生物活性的检测中,希望通过纳米载体的携带作用,将基因转染进靶细胞,从而检测相关基因对靶细胞的沉默作用,提高基因药物的应用,为开发新型基因药物提供基础.     

牛血清蛋白与纳米金颗粒相互作用的研究

为了研究纳米颗粒与蛋白质的相互作用原理,我们选取纳米金颗粒及牛血清蛋白为材料,通过牛血清蛋白与纳米金颗粒的物理吸附作用,结合蛋白酶K酶切、SDS洗脱以及SDS-聚丙烯酰胺凝胶电泳检测的方法,我们了解到,纳米颗粒与蛋白质的结合主要是由蛋白质中的某一段特定的序列结合在纳米颗粒的表面所导致的,该结果的发现不仅对纳米颗粒在生物体内广泛的应用奠定了理论基础,对功能性纳米颗粒在生物体内功能的发挥也是至关重要的。     

微生物介导的金纳米颗粒合成

金纳米颗粒凭借其独特的光学和电化学特性,广泛应用于信息存储、化学传感、医学成像、药物传输以及生物标记等领域。近年来,生物法合成金纳米颗粒因其环境友好、绿色低毒等特点引起研究者的广泛关注。研究表明,多种微生物包括细菌、放线菌、真菌和病毒等均具有合成金纳米颗粒的能力。本文综述了微生物介导合成金纳米颗粒的特性、机制及应用,并对未来发展趋势进行了展望。     

基于纳米颗粒光学特性的癌症检测

这篇综述总结了一些基于纳米颗粒光学特性来检测癌症生物标志物和癌细胞的方法。利用纳米颗粒的癌症诊断技术正在逐渐替代传统技术。尽管仍存在一些缺点,但与传统方法相比,基于纳米颗粒的传感器在生物标记检测或癌细胞检测应用中还是有很多优势。这项先进的技术在即时癌症诊断中将非常有用,并且成本低廉,非常有希望成为人性化检测平台的一部分。     

Fluorescent bio-barcode DNA assay for the detection of Salmonella enterica serovar Enteritidis

Salmonella enterica serovar Enteritidis is one of the most frequently reported causes of foodborne illness. It is a major threat to the food safety chain and public health. A highly amplified bio-barcode DNA assay for the rapid detection of the insertion element (Iel) gene of Salmonella Enteritidis is reported in this paper. The biosensor transducer is composed of two nanoparticles: gold nanoparticles (Au-NPs) and magnetic nanoparticles (MNPs). The Au-NPs are coated with the target-specific DNA probe which can recognize the target gene, and fluorescein-labeled barcode DNA in a 1:100 probe-to-barcode ratio. The MNPs are coated with the 2nd target-specific DNA probe. After mixing the nanoparticles with the 1st target DNA, the sandwich structure (MNPs-2nd DNA probe/Target DNA/1st DNA probe-Au-NPs-barcode DNA) is formed. A magnetic field is applied to separate the sandwich from the unreacted materials. Then the bio-barcode DNA is released from the Au-NPs. Because the Au-NPs have a large number of barcode DNA per DNA probe binding event, there is substantial amplification. The released barcode DNA is measured by fluorescence. Using this technique, the detection limit of this bio-barcode DNA assay is as low as 2.15 x 10(-16)mol (or 1 ng/mL).     

Ultrasensitive electrical detection of protein using nanogap electrodes and nanoparticle-based DNA amplification

The present study describes an ultrasensitive protein biochip that employs nanogap electrodes and self-assembled nanoparticles to electrically detect protein. A bio-barcode DNA technique amplifies the concentration of target antigen at least 100-fold. This technique requires the establishment of conjugate magnetic nanoparticles (MNPs) and gold nanoparticles (AuNPs) through binding between monoclonal antibodies (2B2), the target antigen, and polyclonal antibodies (GP). Both GP and capture ssDNA (single-strand DNA) bonds to bio-barcode ssDNA are immobilized on the surface of AuNPs. A denature process releases the bio-barcode ssDNAs into the solution, and a hybridization process establishes multilayer AuNPs over the gap surface between electrodes. Electric current through double-layer self-assembled AuNPs is much greater than that through self-assembled monolayer AuNPs. This significant increase in electric current provides evidence that the solution contains the target antigen. Results show that the protein biochip attains a sensitivity of up to 1 pg/μL.     

The bio-barcode assay for the detection of protein and nucleic acid targets using DTT-induced ligand exchange

The recently developed bio-barcode assay for the detection of nucleic acid and protein targets without PCR has been shown to be extraordinarily sensitive, showing high sensitivity for both nucleic acid and protein targets. Two types of particles are used in the assay: (i) a magnetic microparticle with recognition elements for the target of interest; and (ii) a gold nanoparticle (Au-NP) with a second recognition agent (which can form a sandwich around the target in conjunction with the magnetic particle) and hundreds of thiolated single-strand oligonucleotide barcodes. After reaction with the analyte, a magnetic field is used to localize and collect the sandwich structures, and a DTT solution at elevated temperature is used to release the barcode strands. The barcode strands can be identified on a microarray via scanometric detection or in situ if the barcodes carry with them a detectable marker. The recent modification to the original bio-barcode assay method, utilizing DTT, has streamlined and simplified probe preparation and greatly enhanced the quantitative capabilities of the assay. Here we report the detailed methods for performing the ligand exchange bio-barcode assay for both nucleic acid and protein detection. In total, reagent synthesis, probe preparation and detection require 4 d.     

Detection of proteins using a colorimetric bio-barcode assay

The colorimetric bio-barcode assay is a red-to-blue color change-based protein detection method with ultrahigh sensitivity. This assay is based on both the bio-barcode amplification method that allows for detecting miniscule amount of targets with attomolar sensitivity and gold nanoparticle-based colorimetric DNA detection method that allows for a simple and straightforward detection of biomolecules of interest (here we detect interleukin-2, an important biomarker (cytokine) for many immunodeficiency-related diseases and cancers). The protocol is composed of the following steps: (i) conjugation of target capture molecules and barcode DNA strands onto silica microparticles, (ii) target capture with probes, (iii) separation and release of barcode DNA strands from the separated probes, (iv) detection of released barcode DNA using DNA-modified gold nanoparticle probes and (v) red-to-blue color change analysis with a graphic software. Actual target detection and quantification steps with premade probes take approximately 3 h (whole protocol including probe preparations takes approximately 3 days).     

Aptamer-based bio-barcode assay for the detection of cytochrome-c released from apoptotic cells

The recently developed bio-barcode (BBC) assay using polymerase chain reaction (PCR) to generate signals has been shown to be an extraordinarily sensitive method to detect protein targets. The BBC assay involves a magnetic microparticle (with antibody to capture the target of interest) and gold nanoparticle (with recognition antibody and thiolated single-stranded barcode DNAs) to form a sandwich around the target. The concentration of target is determined by the amount of barcode DNA released from the nanoparticles. Here we describe a modification using aptamers to substitute the gold nanoparticles for the BBC assay. In this study, we isolated a 76-mer monoclonal aptamer against cytochrome-c (cyto-c) and this single-stranded DNA in defined 3D structure for cyto-c was used in the BBC assay for both recognition and readout reporting. After magnetic separation, the aptamer was amplified by PCR and this aptamer-based barcode (ABC) assay was sensitive enough to detect the cyto-c in culture medium released from the apoptotic cells after drug treatment at the picomolar level. When compared to the conventional cyto-c detection by Western blot analysis, our ABC assay is sensitive, and time for the detection and quantification with ready-made probes was only 3 h.     

基于纳米金的比色分析法在核酸检测中的应用

随着纳米技术的发展,运用纳米粒子检测核酸成为研究的热点.在众多检测方法中,基于纳米金的比色分析法操作较为简便,只需普通光学仪器甚至肉眼即可观察结果,从而表现出广阔的市场及临床应用前景.基于纳米金的比色分析法有多种,不同检测原理的方法在灵敏度和实用性上存在差异.根据纳米金是否经寡核苷酸探针修饰可将其分为基于功能化纳米金的比色分析法和基于未功能化纳米金的比色分析法,前者又分为利用纳米金颜色变化的聚集反应体系以及利用纳米金特殊氧化-还原能力的银染增强体系.     

Detection of single-nucleotide polymorphisms using gold nanoparticles and single-strand-specific nucleases

The current study reports an assay approach that can detect single-nucleotide polymorphisms (SNPs) and identify the position of the point mutation through a single-strand-specific nuclease reaction and a gold nanoparticle assembly. The assay can be implemented via three steps: a single-strand-specific nuclease reaction that allows the enzyme to truncate the mutant DNA; a purification step that uses capture probe-gold nanoparticles and centrifugation; and a hybridization reaction that induces detector probe-gold nanoparticles, capture probe-gold nanoparticles, and the target DNA to form large DNA-linked three-dimensional aggregates of gold nanoparticles. At high temperature (63 degrees C in the current case), the purple color of the perfect match solution would not change to red, whereas a mismatched solution becomes red as the assembled gold nanoparticles separate. Using melting analysis, the position of the point mutation could be identified. This assay provides a convenient colorimetric detection that enables point mutation identification without the need for expensive mass spectrometry. To our knowledge, this is the first report concerning SNP detection based on a single-strand-specific nuclease reaction and a gold nanoparticle assembly.     

Improving Pb2+ detection using DNAzyme-based fluorescence sensors by pairing fluorescence donors with gold nanoparticles

For previously reported fluorescence Pb(2+) sensors, DNAzymes have lead to a significant increase in Pb(2+) detecting sensitivity and specificity. However, these sensors suffer from incomplete fluorescence quenching and require additional steps for annealing DNAzymes and substrates as well as for removing the uncoupled substrates. In this study, we successfully overcome these issues by immobilizing the substrate nucleic acids on gold nanoparticles through thiol linkages. The immobilization of the substrate molecules to the gold nanoparticles lead to almost-complete fluorescence quenching and fast Pb(2+) detection, without altering the Pb(2+) specificity of the DNAzymes. After optimizing the concentration of DNAzymes, reaction time and pH, we could detect Pb(2+) as low as 5 nM within 20 min without the preliminary and the post treatments. Considering the multi-color-fluorescence quenching capability of gold nanoparticles and the to-be-developed functional nucleic acids for other metal ions, this study could extend the application of DNAzymes to the detection of multiple heavy metal ions.     

超快脉冲控制PCR（upPCR）技术及应用

在精准医疗、个性化医疗的大背景下,分子诊断在病原体检测、肿瘤诊断、优生优育、环境保护、食品安全等领域的应用越来越广泛,并逐渐向操作简单、快速准确、低成本、适用于基层及家庭使用的分子即时检测（point-of-care testing,POCT）方向发展。超快脉冲控制PCR（ultra-fast pulse-controlled PCR,upPCR）是实时荧光定量PCR（qPCR）技术的延伸和升级,该技术利用能量脉冲控制扩增反应中的金属加热元件（主要是纳米金）,在几百微秒内完成溶液局部微环境的快速升温,实现模板DNA的解链变性,停止加热后反应微环境可被周围溶液快速冷却到聚合酶的延伸温度,实现引物退火和模板DNA的扩增,单个变性-扩增循环仅有1.5~5 s,远快于传统PCR（约90 s/循环）,从而能够极大地加快扩增反应速度。upPCR技术在保留了传统qPCR高灵敏度、高特异性和多重检测等优势的基础上,增加了超快速（低于15 min）、设备简单等新优势,非常适合用于基层检测等分子POCT场景。本文主要对upPCR技术的原理、设备、核心原料及在分子诊断中的应用进行综述,并对该技术存在的优缺点,以及未来的技术发展和应用趋势进行了讨论。     

纳米材料在生物医学检测中的应用

纳米技术的兴起,对生物医学领域的变革产生了深远的影响。纳米材料是纳米技术发展的重要基础,它具有许多传统材料所不具备的独特的理化性质,因此在生物医学、传感器等重要技术领域有着广泛的应用前景。对几类常见的纳米材料包括纳米金、量子点、磁性纳米粒子、碳纳米管和硅纳米线在蛋白质、DNA、金属离子以及生物相关分子检测方面的应用进行综述。