二苯丙氨酸二肽组装体电化学生物传感应用

二苯丙氨酸二肽因其结构简单,可自组装形成生物相容性良好、形状各异的微纳结构,已成为构筑生物功能材料的重要基元之一。本课题组近年来围绕二苯丙氨酸二肽组装体的功能化及其在电化学生物传感领域的应用开展了系列工作。基于此,本文总结了这些短肽组装功能材料在电化学酶传感、免疫传感、microRNA传感、细胞传感和电致化学发光领域的应用进展,展望了今后可能的发展方向。     

自组装膜在生物矿化中的应用

文章综述了自组装膜在生物矿化中的应用研究进展。介绍了有机硅烷类、有机硫化物类、脂肪羧酸类和醇胺类等自组装膜体系。概述了自组装膜在碳酸钙、草酸钙和羟基磷灰石研究中的现状,并对其今后的发展趋势进行了展望。     

自组装技术及其在生物传感器中的应用研究

构造高度有序性和重复性的生物分子薄膜是提高生物传感器检测性能的关键,自组装膜以其原位自发形成、热力学稳定、制作方便简单、对基底材料形状要求低、可人为地通过合成来设计分子结构和进行分子剪裁等特点,应用于构筑电化学酶传感器,引起了广泛的关注。分析了自组装膜形成的原理,介绍了自组装技术在电极表面固定酶的方法,综述了自组装技术在生物传感器中的应用,展望了自组装技术应用的发展趋势。     

硫醇自组装膜的电化学研究进展

综述了在金电极上硫醇自组装膜的电化学表征方法，性质和应用，介绍了自组装膜上的电子传递机理，并进行了简要的展望。     

有序介孔TiO2溶剂挥发自组装法的合成研究

以三嵌段聚醚P123（PEO20-PPO70-PEO20,M=5875）为模板剂,用溶剂挥发自组装法（EISA法）制备了介孔二氧化钛粉体。采用高温焙烧的方法除去模板剂,对合成的样品TiO2粉体进行了XRD、N2等温吸附-脱附等实验表征,研究了焙烧温度对样品比表面、孔径、孔容的影响。     

溶剂调控苯丙氨酸衍生物自组装结构的研究

本文利用四氢呋喃与水的不同比例来对苯丙氨酸衍生物自组装聚集体进行调控,通过扫描电子显微镜(SEM)、紫外和荧光对其自组装结果进行表征。研究了苯丙氨酸衍生物自组装过程中的溶剂效应。实现了通过改变溶剂对苯丙氨酸衍生物自组装的调控。     

含膦酸酯的L-苯丙氨酸二肽衍生物合成与抗肿瘤作用

为了寻找抗肿瘤活性化合物，设计合成了9个含膦酸酯结构的L-苯丙氨酸二肽衍生物，经1H NMR 、13C NMR 和MS对合成的产物进行了结构确认。采用溴化噻唑蓝四氮唑 (MTT) 法对目标化合物进行了体外抗肿瘤活性测试。结果表明：部分目标物对所测肿瘤细胞有增殖抑制作用，呈现潜在的抗肿瘤活性。尤以Ⅲi最为突出，对人肺癌细胞(A549)和人食管癌细胞(EC-109)均有显著抑制作用，IC50分别为6.8±0.9 μ mol/L、7.0±1.2 μ mol/L，与对照药cisplatin接近。     

冷等离子体诱导生物分子自组装制备生物材料研究进展

生物材料在污水处理、气体检测、储能、光催化等领域展现出良好的应用前景。但传统生物材料制备方法复杂,且使用高毒性有机溶剂。实现简单、绿色的生物材料制备是目前亟需解决的问题。室温下冷等离子体诱导生物分子自组装制备生物材料,不需有机溶剂,不需高温焙烧、H₂还原、化学还原和光致还原,实现了生物材料制备过程的简单化、绿色化。通过冷等离子体诱导生物分子自组装已制备出厚度为(1.03±0.14)nm的生物膜以及含有尺寸小于10 nm、分散性极好的金属纳米颗粒的金属/生物复合材料。但相关研究刚起步,许多科学问题仍然未知,特别是冷等离子体诱导生物分子自组装机理需进一步研究。这些科学问题一旦得到完美诠释,必定会实现生物材料的可控、宏量制备。     

含膦酸酯的L-苯丙氨酸二肽衍生物的合成及其抗肿瘤作用

为了寻找抗肿瘤活性化合物,以芳香醛和亚磷酸二乙酯为原料,在三乙胺作用下,制备中间体Ⅰ;以L-苯丙氨酸甲酯盐酸盐和Boc-氨基酸为原料,经缩合、酯水解制备中间体Ⅱ;然后,中间体Ⅰ与中间体Ⅱ经1-乙基-(3-二甲基氨基丙基)碳酰二亚胺盐酸盐/1-羟基苯并三唑缩合,脱保护,制备了9个含膦酸酯结构的L-苯丙氨酸二肽衍生物,经~1HNMR、~(13)CNMR和MS对合成产物结构进行了确证。采用溴化噻唑蓝四氮唑(MTT)法对目标化合物进行了体外抗肿瘤活性测试。结果表明,部分目标物对所测肿瘤细胞有增殖抑制作用,呈现潜在的抗肿瘤活性。尤以O,O'-二乙基[α-(4-氟苯基)-α-(L-脯氨酰-L-苯丙氨酰氧基)]甲基膦酸酯(Ⅲi)最为突出,对人肺癌细胞(A-549)和人食管癌细胞(EC-109)均有显著抑制作用,对应的半抑制浓度(IC_(50))分别为(6.8±0.9)、(7.0±1.2)μmol/L,与对照药顺铂接近。     

苯丙氨酸的电化学储锂性能

为了研究苯丙氨酸的电化学储锂活性,首先借助傅立叶红外光谱(FTIR)和扫描电镜(SEM)对苯丙氨酸的微观结构及形貌进行了表征,然后将其用作锂离子电池负极活性材料,并通过恒流充/放电、循环伏安(CV)和交流阻抗(AC)技术研究了其电化学脱/嵌锂性能.结果表明:苯丙氨酸负极材料在0.1C循环充/放电50次后,可逆放电比容量为55.2 mAh·g-1;同时表现了良好的倍率性能,表明有机苯丙氨酸作为锂离子电池负极活性材料的良好可行性.     

Cisplatin electrochemical biosensor

Platinum complexes play an important role in the chemotherapy of various tumour diseases. The aim of this paper was to investigate if a metallothionein (MT) modified hanging mercury drop electrode can be applied as a cisplatin electrochemical biosensor. The modification of the mercury electrode surface by MT and the determination of cisplatin were performed by adsorptive transfer stripping technique and differential pulse voltammetry. The detection limit (3 S/N) of cisplatin ([Pt^II(NH₃)₂Cl₂]⁰) calculated from the decrease of CdT peak was about 2.5 pmol in 5 μl (0.5 μM) at the interaction time of 400 s. Moreover, we tested the influence of human blood serum as a complex biological matrix on the way of determination of cisplatin. On the basis of the obtained results we estimated that we are able to determine tens of picomoles of cisplatin (5 μl drop) in the presence of human blood serum.     

Hybrid electrochemical biosensor for organophosphorus pesticides quantification

An electrochemical biosensor for organophosphorus (OP) pesticides trace level concentrations determination was developed and characterized. It integrates a hybrid biorecognition element consisting of immobilized Arthrobacter globiformis and free acetylcholinesterase (ACh) with a Clark type oxygen probe transducer. The bacteria convert the ACh-generated choline to betaine with oxygen consumption measured as a Clark probe current change. This change representing the sensor response correlates to the concentration of the OP pesticides inhibiting the Ach-catalyzed acetylcholine hydrolysis to choline. The conditions for maximal sensor response to choline were optimized according to the methodology of design of experiments. The analytical performances of the enzyme substrate determination in a wide concentration range (0.1-20 μmol dm⁻³ of acetylcholine) and different ACh activities were established. It was demonstrated that the biosensor ensures reproducible, accurate and reliable chlorophos quantification reaching a limit of detection (LOD) of 1 nmol dm⁻³ and a sensitivity of 0.0252 μA/p(mol dm⁻³) under optimal experimental conditions. The biosensor response time is 200 s and the storage stability is t_L50 = 49 days for the bacterial membrane at ambient temperature. The device is reusable, the bacterial membrane being not affected by OP. The biosensor was applied to chlorophos determination in contaminated milk.     

A new electrochemical biosensor for hydrogen peroxide using HRP/AgNPs/cysteamine/p-ABSA/GCE self-assembly modified electrode

An electrochemical hydrogen peroxide biosensor was designed by immobilizing horseradish peroxidase (HRP) on Ag nanoparticles/cysteamine/p-aminobenzene sulfonic acid/glassy carbon (GC) electrode. Ag nanoparticles can act as tiny conduction centers on electrodes that adsorb redox enzymes, facilitating the transfer of electrons with no requiring any loss of biological activity. The forerunner film was first electropolymerized on the glassy carbon electrode with p-aminobenzene sulfonic acid (p-ABSA) by cyclic voltammetry. The cysteamine (CA) was bound on the surface of the film by electrostatic force, then Ag nanoparticles were immobilized on the cysteamine monolayer, and lastly HRP was adsorbed onto the surfaces of the Ag nanoparticles. A dramatic decrease in the overvoltage of H₂O₂ was observed with improved sensitivity, which makes the modified electrodes of great promise for oxidase-based amperometric biosensors. The biosensor responded to H₂O₂ in the linear range from 1.2×10⁶ mol/L to 9.8×10³ mol/L with a detection limit of 1.1×10⁸ mol/L. Moreover, the obtained biosensor exhibited good accuracy and high sensitivity.     

Temperature-induced reversible self-assembly of diphenylalanine peptide and the structural transition from organogel to crystalline nanowires

Controlling the self-assembly of diphenylalanine peptide (FF) into various nanoarchitectures has received great amounts of attention in recent years. Here, we report the temperature-induced reversible self-assembly of diphenylalanine peptide to microtubes, nanowires, or organogel in different solvents. We also find that the organogel in isopropanol transforms into crystalline flakes or nanowires when the temperature increases. The reversible self-assembly in polar solvents may be mainly controlled by electronic and aromatic interactions between the FF molecules themselves, which is associated with the dissociation equilibrium and significantly influenced by temperature. We found that the organogel in the isopropanol solvent made a unique transition to crystalline structures, a process that is driven by temperature and may be kinetically controlled. During the heating-cooling process, FF preferentially self-assembles to metastable nanofibers and organogel. They further transform to thermodynamically stable crystal structures via molecular rearrangement after introducing an external energy, such as the increasing temperature used in this study. The strategy demonstrated in this study provides an efficient way to controllably fabricate smart, temperature-responsive peptide nanomaterials and enriches the understanding of the growth mechanism of diphenylalanine peptide nanostructures.     

A whole cell electrochemical biosensor for water genotoxicity bio-detection

This work presents a novel micro-fluidic whole cell biosensor for water toxicity analysis. The biosensor presented here is based on bacterial cells that are genetically “tailored” to generate a sequence of biochemical reactions that eventually generate an electrical signal in the presence of genotoxicants. The bacterial assay was affected by toxicant contaminated water for an induction time that ranged between 30 min and 120 min. Enzymatic substrate (pAPP) was added to the assay generating the electrochemical active material (pAP) only when toxicants are sensed by the bacteria. The bacteria were integrated onto a micro-chip that was manufactured by MEMS technology and comprises various micro-chambers with volume ranging between 2.5 nl and 157 nl with electrode radius between 37.5 μm and 300 μm. We describe the biochip operation, its electrochemical response to calibration solutions as well as to the whole cell assays. The potential use of the whole cell biochip for toxicity detection of two different genotoxicants, nalidixic acid (NA) and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), is demonstrated. We demonstrate minimal toxicant detection of 10 μg/ml for NA using 30 min for induction and 0.31 μM for IQ using 120 min for induction, both 3 min after the addition of the substrate material.     

Improved electrochemical nucleic acid biosensor based on polyaniline-polyvinyl sulphonate

DNA biosensor based on polyaniline (PANI)-polyvinyl sulphonate (PVS) has been fabricated using electrochemical entrapment technique for detection of organophosphorus pesticides (chlorpyrifos and malathion). These double stranded calf thymus DNA (dsCT-DNA) entrapped PANI-PVS/indium-tin-oxide (ITO) bioelectrodes have been characterized using square wave voltammetry (SWV), Fourier transform infra-red spectroscopy (FT-IR), scanning electron microscopy (SEM) and electrochemical impedance techniques, respectively. These dsCT-DNA entrapped PANI-PVS/ITO bioelectrodes have been found to have response time of 30 s, stability of about 6 months and detection limit for chlorpyrifos and malathion as 0.5 ppb and 0.01 ppm, respectively.     

Stability of diphenylalanine peptide nanotubes in solution

Over the last couple of years, self-organizing nanotubes based on the dipeptide diphenylalanine have received much attention, mainly as possible building blocks for the next generation of biosensors and as drug delivery systems. One of the main reasons for this large interest is that these peptide nanotubes are believed to be very stable both thermally and chemically. Previously, the chemical and thermal stability of self-organizing structures has been investigated after the evaporation of the solvent. However, it was recently discovered that the stability of the structures differed significantly when the tubes were in solution. It has been shown that, in solution, the peptide nanotubes can easily be dissolved in several solvents including water. It is therefore of critical importance that the stability of the nanotubes in solution and not after solvent evaporation be investigated prior to applications in which the nanotube will be submerged in liquid. The present article reports results demonstrating the instability and suggests a possible approach to a stabilization procedure, which drastically improves the stability of the formed structures. The results presented herein provide new information regarding the stability of self-organizing diphenylalanine nanotubes in solution.     

Nucleic acid biosensor for DNA hybridization detection using rutin-Cu as an electrochemical indicator

The complex of rutin-Cu (C₈₁H₈₆Cu₂O₄₈, abbreviated by Cu₂R₃, R = rutin) was synthesized and characterized by elemental analysis and IR spectra. Cyclic voltammetry (CV) and fluorescence spectroscopy were used to investigate the interaction of Cu₂R₃ with salmon sperm DNA. It was revealed that Cu₂R₃ could interact with double-stranded DNA (dsDNA) by a major intercalation role. Using Cu₂R₃ as a novel electroactive indicator, an electrochemical DNA biosensor for the detection of specific DNA fragment was developed and its selectivity for the recognition with different target DNA was assessed by differential pulse voltammetry (DPV). The target DNA related to coliform virus gene could be quantified ranged from 1.62 × 10⁻⁸ mol L⁻¹ to 8.10 × 10⁻⁷ mol L⁻¹ with a good linearity (r = 0.9989) and a detection limit of 2.3 × 10⁻⁹ mol L⁻¹ (3σ, n = 7) was achieved by the constructed electrochemical DNA biosensor.     

A highly selective electrochemical biosensor for Hg using hemin as a redox indicator

A highly selective electrochemical biosensor for the detection of Hg²⁺ in aqueous solution has been developed. This sensor is based on the strong and specific binding of Hg²⁺ by two DNA thymine bases (T–Hg²⁺–T). The hemin worked as a redox indicator to generate a readable electrochemical signal. Short oligonucleotide strands containing 5 thymine (T₅) were used as probe. Thiolated T₅ strands were self-assembled through Au–S bonding on gold electrode. In the presence of Hg²⁺, the specific coordination between Hg²⁺ and thymine bases resulted in more stable and porous arrangement of oligonucleotide strands, so hemin could be adsorbed on the surface of gold electrode and produced an electrochemical signal, which was monitored by differential pulse voltammetry (DPV). The DPV showed a linear correlation between the signal and the concentration of Hg²⁺ over the range 0–2 μM (R² = 0.9983) with a detection limit of 50 nM. The length of probe DNA had no significant impact on the sensor performance. This electrochemical biosensor could be widely used for selective detection of Hg²⁺.