Glucosamine Hydrochloride Functionalized Water‐Soluble Conjugated Polyfluorene: Synthesis,Characterization, and Interactions with DNA

Novel glucosamine hydrochloride functionalized water‐soluble conjugated polyfluorene was easily synthesized through Cu(I)‐catalyzed azide/alkyne “click” ligation and Suzuki coupling polymerization. The water‐solubility and biocompatibility of the polymer were improved after grafting glucosamine hydrochloride to the side chains of the conjugated polymer. As a fluorescent model system of chitosan, its interaction with single‐stranded DNA was studied by spectrofluorometric titration.

     

A Water‐Soluble Conjugated Polymer for Protein Identification and Denaturation Detection

Rapid and sensitive methods to detect proteins and protein denaturation have become increasingly needful in the field of proteomics, medical diagnostics, and biology. In this paper, we have reported the synthesis of a new cationic water‐soluble conjugated polymer that contains fluorene and diene moieties in the backbone ( PFDE ) for protein identification by sensing an array of PFDE solutions in different ionic strengths using the linear discriminant analysis technique (LDA). The PFDE can form complexes with proteins by electrostatic and/or hydrophobic interactions and exhibits different fluorescence response. Three main factors contribute to the fluorescence response of PFDE , namely, the net charge density on the protein surface, the hydrophobic nature of the protein, and the metalloprotein characteristics. The denaturation of proteins can also be detected using PFDE as a fluorescent probe. The interactions between PFDE and proteins were also studied by dynamic light scattering (DLS) and isothermal titration microcalorimetry (ITC) techniques. In contrast to other methods based on conjugated polymers, the synthesis of a series of quencher or dye‐labeled acceptors or protein substrates has been avoided in our method, which significantly reduces the cost and the synthetic complexity. Our method provides promising applications on protein identification and denaturation detection in a simple, fast, and label‐free manner based on non‐specific interaction‐induced perturbation of PFDE fluorescence response.     

Fluorescence‐Amplifying Assay for Irradiated DNA Lesions Using Water‐Soluble Conjugated Polymers

A new platform has been developed for DNA lesion detection using a cationic conjugated polymer (CCP). DNA that contains two adjacent thymine bases is irradiated with ultraviolet light to allow for the formation of cyclobutane pyrimidine dimers and pyrimidine–pyrimidone dimers. The DNA lesions block the primer extension, and the base labeled with fluorescein cannot be incorporated into the DNA strand. Addition of the CCP leads to inefficient fluorescence resonance energy transfer (FRET) from CCP to fluorescein. For the case without DNA lesions, successful primer extension allows for efficient FRET between them. In view of the FRET signal changes, the DNA lesions can be detected. This new protocol offers a convenient detection for DNA lesions in aqueous solution without any isolation and washing steps.

     

Synthesis of Water‐Soluble Dendritic Conjugated Polymers for Fluorescent DNA Assays

Summary: Cationic water‐soluble dendritic poly(fluorene)s with positively charged amines on the exterior (PFP‐G_0–2) can be prepared by a macromonomer (generation‐by‐generation) approach. The charge densities of PFP‐G_0–2 can control their distances to DNA by electrostatic interactions. The PFP‐G₂ with higher generation of dendritic side chains possesses a higher charge density, and gives rise to efficient fluorescence resonance energy transfer (FRET) to a signaling fluorescein labeled at the terminus of DNA. These new conjugated polymers form less aggregates and yield more efficient FRET in a tetrahydrofuran/H₂O mixed solvent as compared to in pure water. The sensitivity of the DNA sensor is improved by utilizing highly dendritic conjugated polymers.

Structure of the dendritic conjugated polymer PFP‐G₂.     

Nonenzymatic Electrochemical Biosensor Based on Novel Hydrophilic Ferrocene‐terminated Hyperbranched Polymer and its Application in Glucose Detection

We designed a novel water soluble topological structure polymer‐ferrocene‐ terminated hyperbranched polyurethane (HPU‐Fc) with good water solubility. The redox behaviors and the electrochemical kinetics parameters of HPU‐Fcs were explored by cyclic voltammetry (CV) according to electrochemical principle. The topological structure polymer was applied for the design and engineering of non‐enzymatic glucose sensor. The designed sensor showed good response to glucose concentration with good stability, favorable accuracy and high selectivity. The electrode was also used to detect glucose in blood samples, and the glucose contents detected by the electrode were in good agreement with those from the hospital where a common automatic biochemical analyzer (HF240–300) was used. This finding makes HPU‐Fc a promising biosensor for directly sensing glucose.     

Simultaneous Detection and Removal of Mercury Ions in Aqueous Solution with Fluorescent Conjugated Polymer‐Based Sensor Ensemble

A water‐soluble, sulfur‐containing fluorescent conjugated polymer exhibits a visible fluorescence color change for detection of mercury in the presence of thymine. A new concept provides the design of a sensor ensemble using a simple combination method. This strategy avoids the need for complicated design and synthesis of a recognition group, eliminating the tedious synthetic efforts for the preparation of a sensor material.

     

基于共轭高分子复合物能量转移的非标记DNA检测

非标记DNA检测是一种高灵敏度、高选择性的DNA检测方法, 具有重要的科学和社会意义. 本文采用交叉偶联法制备了水溶性阳离子共轭聚合物: 聚(9,9-双(6'-N,N,N-三甲胺盐-己烷基)-芴亚苯基)(PFP); 利用氧化加成聚合反应制备了水溶性阴离子共轭聚合物: 聚(3-噻吩乙酸钠)(P3TSA). 通过核磁共振氢谱(¹H NMR)、傅立叶变换红外光谱(FTIR)等对其结构进行了表征. PFP与P3TSA通过静电相互作用形成稳定的高分子复合物. 利用紫外-可见光谱(UV-vis)和荧光发射光谱证明共轭高分子复合物能够发生能量转移. 保持PFP的浓度不变, 高分子复合物能量转移效率(ETEF)随着P3TSA浓度的增加而逐渐增大. 选取ETEF较高的样品, 考察了DNA探针用量对高分子复合物ETEF的影响. 随着DNA探针浓度的增加, ETEF逐渐减弱. 最后, 利用0.2 nmol DNA探针进行了DNA杂交配对检测. 实验结果表明, 这种检测方法可以明显区分完全互补配对、双碱基错配和非完全互补配对的目标DNA. 简而言之, 我们成功发展了一种基于共轭高分子复合物能量转移、具有高选择性的非标记DNA检测方法.     

一种可用于检测苦味酸的水溶性共轭聚合物荧光传感器的制备及应用

制备了一种高灵敏的水溶性荧光共轭聚合物(PPE-OBS), 将其用于苦味酸的荧光检测. 利用质谱、 核磁共振波谱和红外光谱等方法对PPE-OBS进行了表征, 并对其检测苦味酸的条件进行了优化. 结果表明, 在硼酸-氢氧化钠缓冲溶液(pH=9.5)中作用20 min, 苦味酸对PPE-OBS荧光的猝灭效率最大. 在最优条件下, PPE-OBS检测苦味酸的线性范围为1.0~60 μmol/L(R²=0.999), 检出限为0.831 μmol/L(S/N=3). 将PPE-OBS制成荧光试纸用于检测环境样品中的苦味酸, 获得了较好的检测结果.     

共轭二茂铁席夫碱配合物的制备和电化学性质研究

合成了2个共轭二茂铁席夫碱配合物，用元素分析、红外光谱、紫外光谱、核磁共振等对它们进行了表征及电化学性质 研究，并用X射线衍射测定了它们的晶体结构。配合物1存在反演中心，其晶体属单斜晶系，P2₁/c空间群。晶体学数据为：a=1.148 5(2) nm，b=0.857 75(17) nm，c=1.194 4(2) nm，β=99.980(5)°,V=1.158 8(4) nm³,Z=2，μ=1.499 mm^-1,D_c=1.562 g·cm^-3，R₁=0.068 9，wR₂=0.128 0。     

A Novel Thin Film Resistive Humidity Sensor Based on Soluble Conjugated Polymer:(propionic acid)-co-(propargyl alcohol)

In recent years, humidity sensors have found wide applications in industrial and agricultural production, process control, household electric appliances, etc., therefore the research on humidity sensitive materials has attracted more and more attentions, and many polymers, including polymer electrolytes, conjugated polymers have been investigated as sensing materials1-3. However the doped conjugated polymers in general were insoluble and can not be used to prepare thin film humidity sensors, wh…     

Fluorescence Logic‐Signal‐Based Multiplex Detection of Nucleases with the Assembly of a Cationic Conjugated Polymer and Branched DNA

An energy‐transfer cascade is generated from a cationic conjugated polymer (PFP) and negatively charged, Y‐shaped DNA labeled with three dyes at its termini (fluorescein (Fl), Tex Red, and Cy5). Multistep fluorescence resonance energy transfer regulates the fluorescence intensities of PFP and the dyes. Different types of logic gates can be operated by observing the emission wavelengths of different dyes with multiplex nucleases as inputs.

     

Recent Progress in the Development of Conducting Polymer‐Based Nanocomposites for Electrochemical Biosensors Applications: A Mini‐Review

Among various immobilizing materials, conductive polymer‐based nanocomposites have been widely applied to fabricate the biosensors, because of their outstanding properties such as excellent electrocatalytic activity, high conductivity, and strong adsorptive ability compared to conventional conductive polymers. Electrochemical biosensors have played a significant role in delivering the diagnostic information and therapy monitoring in a rapid, simple, and low cost portable device. This paper reviews the recent developments in conductive polymer‐based nanocomposites and their applications in electrochemical biosensors. The article starts with a general and concise comparison between the properties of conducting polymers and conducting polymer nanocomposites. Next, the current applications of conductive polymer‐based nanocomposites of some important conducting polymers such as PANI, PPy, and PEDOT in enzymatic and nonenzymatic electrochemical biosensors are overviewed. This review article covers an 8‐year period beginning in 2010.     

A Selective Electrochemical Sensor for the Detection of Cd(II) Based on a Carbon Paste Electrode Impregnated with a Novel Ion-imprinted Hybrid Polymer

An electrochemical sensor (CPE-IIHP) was developed for Cd(II) using a carbon paste electrode (CPE) impregnated with an ion-imprinted hybrid polymer (IIHP). A CPE-NIHP was also prepared for comparison. DPASV was used to optimize the sensor response and quantify Cd(II). The sensor presented a wide linear range from low concentrations of Cd(II): 1 to 100 μg L⁻¹ and high concentrations of Cd(II): 2.75 to 5.0 mg L⁻¹. Ions such as Co(II), Pb(II), Ni(II), Zn(II), Fe(II), Fe(III), Sn(II) and Cu(II), showed no variation in the Cd(II) signal. The CPE-IIHP was successfully applied in river and drinking water analysis, revealing the great potential for its application.     

A Water‐Soluble π‐Conjugated Polymer with up to 100 mg · mL−1 Solubility

A cationic water‐soluble polyfluorene (P2) containing a high density of tetraalkylammonium side chains in polymer backbone was synthesized and characterized. The polymer shows excellent water solubility up to 100 mg · mL⁻¹ as well as high photoluminescence (PL) quantum yield of 44% in water. The relatively high cationic density and appropriate side chain length of the polymer are the key factors to achieve such high water solubility. The reduction potential of P2 is decreased as compared with its neutral polymer, reflecting the enhanced electron injection abilities. The standard NPB/Alq₃ device using such a polymer as the electron injection layer shows nearly three‐fold enhancement in the electroluminescence (EL) efficiency.

     

An Isoindigo‐Based “Double‐Cable” Conjugated Polymer for Single‐ Component Polymer Solar Cells

An isoindigo‐based “double‐cable” conjugated polymer bearing perylene bisimide side units was developed via Stille polymerization for application in single‐component polymer solar cells, in which a power conversion efficiency of 1% with broad photo‐response from 300 nm to 800 nm was achieved. There is no evidence of large phase separation confirmed by AFM images and photoluminescence (PL) spectra. The space charge limit current measurements and light intensity dependence measurements indicate that the low electron mobility and the significant recombination of photogenerated charge carriers in active layer mainly account for the low performance of our solar cells. Our results suggest that these “double‐cable” are promising candidates for use in single‐component polymer solar cells with NIR photoresponse.     

Microparticle‐Supported Conjugated Polyelectrolyte Brushes Prepared by Surface‐Initiated Kumada Catalyst Transfer Polycondensation for Sensor Applications

A ‘grafting‐from’ approach to synthesize microparticle‐supported conjugated polyelectrolyte brushes is presented. Poly(3‐bromohexylthiophene) is selectively grown from monodisperse organosilica microparticles by surface‐initiated Kumada catalyst‐transfer polycondensation (SI‐KCTP) and then ionizable amino groups are introduced by a two‐step polymer analogous transformation. Optical properties of the resulting microparticle‐supported conjugated polyelectrolyte brushes were found to be dependent on the surrounding chemical environment and thus the particles are promising materials for sensor applications.

     

An Amphiphilic Polymer‐ and Carbon Nanotube‐Modified Indium Tin Oxide Electrode for Sensitive Electrochemical DNA Detection with Low Nonspecific Binding

We herein report an amphiphilic polymer‐, carboxylated multiwalled carbon nanotube (CNT)‐, silane polymer‐, and streptavidin‐modified indium tin oxide (ITO) electrode that allows low nonspecific binding and efficient immobilization of DNA, along with good electrocatalytic activities and low background‐current levels. The low nonspecific binding results from the well‐covering of the CNT and ITO surface with the amphiphilic polymer and silane polymer, as well as the poly(ethylene glycol) groups of the polymers. The streptavidin for DNA immobilization is covalently attached to the carboxylic acid groups of the amphiphilic polymer and CNT. A low surface coverage of CNT on the ITO electrode provides the good electrocatalytic activities and low background‐current levels. The fabricated electrode enables us to achieve a detection limit of 100 pM in DNA detection.