Electrophysiological Study of Single Gold Nanoparticle/α-Hemolysin Complex Formation: A Nanotool to Slow Down ssDNA Through the α-Hemolysin Nanopore
Electrophysiological Study of Single Gold Nanoparticle/α-Hemolysin Complex Formation: A Nanotool to Slow Down ssDNA Through the α-Hemolysin Nanopore
复制标题
DOI：
10.1002/smll.200801779
复制
发表时间：
2009-06-05
期刊：
影响因子：
13.3
通讯作者：
Stellacci, Francesco
中科院分区：
文献类型：
--
作者：
Astier, Yann;Uzun, Oktay;Stellacci, Francesco
Yann Astier，*Oktay Juun和Francesco Stellacci a-hemolysin(AHL)是一种七聚体蛋白质孔(图1)，其X射线结构已被解析。[1]AHL插入隔开两室水电解质的绝缘脂双层的能力使其成为测量在外加电位下通过孔的离子电流的有用系统。[2，3]当分析物与孔内的结合位置相互作用时，孔的导电性发生了显著的变化。在固定电位下，每个结合事件的当前阻断的范围和持续时间有助于揭示分析物的身份，而结合事件的频率则揭示分析物的浓度。AHL的化学和生物分子工程允许通过定制内部分析物结合位置来随机检测分子。[3]自从Bezrukov和Kasianowicz在H/D离子之间的区分方面的开创性工作以来，为基于纳米孔的分析物检测奠定了物理基础，描述了单链RNA和单链DNA的检测、量化和表征，并导致了使用AHL的“纳米矿力谱”。[4-8]短多核苷酸链中的单碱基错配、有毒金属离子、药物、对映体、TNT和核苷酸也被专门检测到。9-13不同化合物在孔内的共价连接也被报道用于研究偶氮苯的顺反异构化、共价键的多步形成或断裂以及DNA寡核苷酸的杂交。[14-20]聚乙二醇(PEG)和整个PAMAM树枝状大分子也被报道进入并共价连接在AHL内。[21-23]金属纳米颗粒是自组装单分子膜(SAM)在无机纳米晶体上的超分子组装。[24，25]它们为纳米矿石技术与分子和分子传感的接口提供了独特的机会，因为它们结合了无机核作为单电子、电荷和分子传感的性质磁性和刚性，而配体壳层的磁性和刚性决定了溶解性、伪酶行为和多价性。[26-31]据我们所知，我们首次描述了如何在a-溶血素(AHL)纳米孔中捕获单层保护的金纳米颗粒，并研究了其尺寸、电荷和表面性质。我们展示了单个3-巯基-1-丙磺酸钠(MPSA)包裹的金纳米晶在恒定电位下被捕获在AHL‘帽’中的独特的电导特征，以及它在倾斜电位下的离子校正。我们报道了跨膜电位幅值如何影响被捕获到孔内的纳米颗粒的大小，以及被捕获的纳米颗粒的大小与其停留时间(TOFF)之间的关系。我们发现，观察到的进入孔洞的最大纳米粒子产生了50%的孔洞电导区块。纳米颗粒和内孔表面之间的间距可以小到0.8 nm(考虑到
Yann Astier,* Oktay Uzun, and Francesco Stellacci a-Hemolysin (aHL) is a heptameric protein pore (Figure 1) for which the X-ray structure is resolved.[1] The ability of aHL to insert into an insulating lipid bilayer separating two chambers of aqueous electrolyte has made it a useful system to measure the ionic current that passes through the pore under an applied potential.[2, 3] When an analyte interacts with a binding site within the pore, a significant change in the pore conductivity is observed. At fixed potential, the extent and duration of the current block from each binding event help reveal the identity of the analyte, while the frequency of the binding events reveals the analyte concentration. Chemical and biomolecular engineering of aHL permit the stochastic sensing of molecules by tailoring internal analyte binding sites.[3] Since the pioneering work of Bezrukov and Kasianowicz on the discrimination between Hþ/Dþ ions, laying the physical basis for nanopore-based detection of analytes, detection, quantification, and characterization of ssRNA and ssDNA were described and led to ‘‘nanopore force spectroscopy’’using aHL.[4–8] Single-base mismatch in a short polynucleotide strand, toxic metal ions, drugs, enantiomers, TNT, and nucleotides have also been specifically detected.[2, 9–13] Covalent attachment of different compounds within the pore have also been reported for the study of cis-trans isomerization of azobenzene, the multistep formation or breaking of covalent bonds, and the hybridization of DNA oligonucleotides.[14–20] Poly (ethylene glycol)(PEG) and whole PAMAM dendrimers have also been reported to enter and covalently attach inside aHL.[21–23] Metal nanoparticles are supramolecular assemblies of a self-assembled monolayer (SAM) onto an inorganic nanocrystal.[24, 25] They offer unique opportunities for interfacing nanopore technologies with molecular and macromolecular sensing as they combine the properties of the inorganic core as single-electron charging, magnetism and rigidity, with those of the ligand shell for solubility, pseudo-enzymatic behavior, and multivalency.[26–31] To the best of our knowledge, for the first time we describe how it is possible to trap single-monolayer-protected gold nanoparticles in the a-hemolysin (aHL) nanopore, and study its size, charge, and surface properties. We show the unique conductance signature of a single sodium 3-mercapto-1-propanesulfonate (MPSA)-coated gold nanocrystal trapped inside the aHL ‘‘cap’’at constant potential, and its ionic correction at ramping potential. We report how the transmembrane potential amplitude conditions the size of the nanoparticle being trapped inside the pore, as well as the correlation between the size of the trapped nanoparticle and its dwell time (toff). We find that the largest nanoparticle observed to enter the pore yields a 50% block of the pore conductance. The space between the nanoparticle and the inner-pore surface can be as small as 0.8 nm (considering the