【作者】 黄晓；

【导师】 苏彬；

【作者基本信息】 浙江大学 ， 化学， 2017， 硕士

【摘要】 液/液界面（ITIES）作为模拟生物膜最简单的模型,为研究和理解生物界面或生物膜上的物质传递和交换提供了一种便利的手段。与传统的固体电极/溶液相比,ITIES电化学不仅可以研究电子转移反应,还可以研究离子转移反应和偶联反应,比如氧还原反应和析氢反应。ITIES电化学广泛应用于非氧化还原活性离子的检测,包括无机离子、有机离子和生物分子等。近年来,微型化的液/液界面（micro-/nano-ITIES）越来越引起科学家的研究兴趣,这是因为micro-/nano-ITIES具有以下显著优点：（1）降低溶液的电势降,增大电化学信号；（2）加快传质速率,提高检测灵敏度；（3）小尺寸界面增强界面稳定性；（4）两电极检测体系简化装置。迄今为止,科学家提出了多种方法构建微纳液/液界面,主要包括微纳米玻璃管、多孔膜（沸石膜、γ-氧化铝膜、PET膜、硅膜等）和金属颗粒沉积等。而目前微型化液/液界面的研究热点聚焦于：（1）发展新型策略构建微型化液/液界面；（2）拓展液/液界面电化学的分析应用领域。本论文共分为四个部分,主要包括以下的内容：第一章介绍了ITIES的发展历史和有关基础理论（包括离子转移反应和稳态电流）,着重介绍了构建nano-ITIES的策略及其表征方法,归纳总结了常用的电化学检测方法和nicro-/nano-ITIES的应用（包括离子传感、动力学研究和扫描电化学显微镜成像等）。第二章构建了具有高度有序、垂直孔道的二氧化硅纳米薄膜修饰的纳米级别液/液界面（SNM/nano-ITIES）,其中由Stober溶液生长法制备得到的SNM具有超小均一孔径（2-3nm）、超薄厚度（～70-80nm）和极高的孔隙率(4.0×10⁴pores μm^-2)。本章采用小尺寸四乙基铵阳离子（TEA⁺）,运用电化学方法（循环伏安法和差分脉冲伏安法）对体系进行电化学表征,结果表明分析物浓度和电化学信号强度具有良好的线性关系,并且从电化学曲线中可计算得到相关热力学常数（扩散常数、标准转移电位、分配系数等）。此外,利用小尺寸甲基橙阴离子（MO^-）研究了体系的电荷选择性,即对阴离子的排斥作用；利用两种不同电性的卟啉离子(H₂TMPyP⁴⁺和FeTPPS^4-)研究了体系的尺寸选择性,即对大尺寸离子的排阻作用。第三章研究了抗高血压药物酒石酸美托洛尔阳离子（MTP）在SNM/nano-ITIES体系中的离子转移伏安行为,可得到MTP的标准转移电位、表面扩散系数和分配系数等热力学参数,线性范围宽（1 μM-1 mM）,检测限低达0.5μM。此外,选取了七种不同的干扰物质（即D-葡萄糖、尿素、抗坏血酸、甘氨酸、MgCl₂、Na₂SO₄和牛血清蛋白（BSA））作为代表,研究它们对MTP检测的可能影响。除BSA以外,其余六种对转移信号的影响基本可以忽略；BSA的加入缩短了电位窗并降低了稳态电流。本章还研究了MTP在三种复杂样品（即尿液、血清和全血）中的电化学信号,尽管灵敏度有所下降,但稳态电流和MTP浓度之间仍存在良好的线性关系。采用标准加入法,成功地测定了Betaloc牌酒石酸美托洛尔药片中MTP的含量,和理论浓度十分相近。最后,本章还验证了SNM/nano-ITIES体系具有优良的稳定性和重复性。第四章总结本论文工作,并展望了SNM/nano-ITIES体系的发展前景和不足之处。更多还原

【Abstract】 Electrochemistry at the liquid/liquid interface, or so-called the interface between two immiscible electrolyte solutions （ITIES）, provides a facile biomimetic approach to study and understand mass transport and exchange at the biological interfaces and membranes. In comparison with the conventional electrochemistry method, namely, that at the solid/liquid interface, not only the electron transfer reaction but also ion transfer reaction as well as the coupled reactions （e.g., the oxygen reduction and hydrogen evolution reactions） can be addressed. It has been widely applied in the nonredox electrochemical detection of various ions, ranging from inorganic and organic ions to biochemical substances, in particular when their oxidation/reduction is difficult.For decades, miniaturization of the ITIES （micro-/nano-ITIES） have attracted increasing research interests. Miniaturization of the ITIES can effectively lower large iR drop bring by the organic liquids, improve detection sensitivity and limit of detection due to enhanced mass transfer and rapid interfacial processes and stabilize the liquid/liquid interface by miniaturizing its area. In addition, the electrochemical measurements can be performed in a two-electrode format using the conventional potentiostat. Till now, many approaches have been developed to create nano-ITIES, under the support of glass nanopipet, nanoporous materials with extremely high pore density （such as nanoporous silica films, track etched polymer, the solid-state silicon nitride nanopore membranes and silicate/zeolite membranes） and metal particles. With the development of nanotechnology and bioscience, the studies of ITIES focus on developing novel strategies to fabricate miniaturized ITIES and extending their applications in various fields. This thesis has been divided into four parts:The first chapter briefly introduced the development of ITIES and relevant basic theory （ion transfer reaction and steady-state current）; then emphatically introduced the strategies to fabricate nano-ITIES and its characterization. Electrochemical detection methods and applications of micro-/nano-ITIES were also included.The second chapter demonstrated a novel and facile method to build nano-ITIES array with the support of ultrathin freestanding silica nanochannel membrane （SNM）.The array consists of a high density (4.0 × 10⁴ pores μm^-2) of individual nano-ITIES of 2-3 nm and behaves as a microinterface characteristic of diffusion geometry with two back-to-back inlaid microdisc interfaces. Thus, ion transfer across the nano-ITIES array yielded symmetric steady-state current waves. Furthermore, because of the ultrasmall size of each independent nano-ITIES, an apparent size-selective ion transfer was observed. In addition, since the SNM surface is negatively charged, the transfer of anions encountered strong electrostatic repulsion from the nanochannel walls, with the magnitude of ion transfer current apparently dependent on the ionic strength of aqueous solutions.In the third chapter, SNM/nano-ITIES has been developed for investigation of the ion-transfer voltammetric behavior of metoprolol （MTP）, an antihypertensive drug, and for its detection in complex samples. Important thermodynamic parameters, such as the partition coefficient and apparent diffusion coefficient of MTP, were obtained. Seven different interfering substances, namely glucose, urea, ascorbic acid, glycine, MgCl₂, Na₂SO₄ and BSA, were chosen as models of interferents in biological samples to study their influence on the ion-transfer current signal of MTP. The results confirmed that the steady-state current waves barely changed in the presence of these interferents except BSA. The presence of BSA shortened the potential window and decreased the ion-transfer current magnitude. Moreover, the determination of MTP in complex samples （i.e. urine, serum and blood） and pharmaceutical forms were conducted without sample pretreatment. A wide linear dynamic range and a low limit of detection were achieved. SNM/nano-ITIES was proved to be stable and repeatable.The last chapter summarized the work presented in this thesis. Attempts were made to propose the future research trend of SNM/nano-ITIES.更多还原