Electrophoretic chip for high-fidelity fractionation of double-stranded DNA

We report the high fidelity, on-chip fractionation of selected segments from an electrophoretic flow of separated fragments. dsDNA fragments (10-330 base pairs (bp)) were initially separated using a 6.5 cm long channel with an electric field strength of 150 V/cm. As an example of the fractionation process, a target fragment of 20 bp was selected and extracted from the separation channel. The extraction was confirmed and evaluated by fluorescence imaging. High resolution and extraction fidelity were achieved by introducing new procedures for (i) extraction channel-blocking and (ii) segment transfer with cleaning. These procedures are necessary for the development of a practical, fully automated multitarget fractionation electrophoretic chip. A kind of CCD image processing method was introduced to monitor, control, and evaluate the procedure of fractionation. The resolution limits of the separation and extraction are discussed.     

SYNTHESIS OF POLY(METHYL METHACRYLATE)-graft-POLYSTYRENE BY ATOM TRANSFER RADICAL POLYMERIZATION

The radical copolymerization of methyl methacrylate and 2-hydroxyethyl methacrylate was carried out via atomtransfer radical polymerization (ATRP) initiated by ethyl 2-bromoisobutyrate and catalyzed by CuBr/2,2'-bipyridinecomplex. This polymerization proceeds in a living fashion with controlled molecular weight and low polydispersity. Theobtained copolymer was esterified with 2-bromoisobutylryl bromide yielding a macroinitiator, poly(methyl methacrylate-co-2-hydroxyethyl methacrylate-co-2-(2-bromoisobutyryloxy)ethyl methacrylate), and its structure was characterized by ~1H-NMR. This macroinitiator was used for ATRP of styrene to synthesize poly(methyl methacrylate)-graft-polystyrene. Themolecular weight of graft copolymer increased with the monomer conversion, and the polydispersity remained relatively low.The individual grafted polystyrene chains were cleaved from the macroinitiator backbone by hydrolysis and the hydrolyzed product was characterized by ~1H-NMR and GPC.     

Hyperbranched block copolymer from AB2 macromonomer: Synthesis and its reaction‐induced microphase separation in epoxy thermosets

In this contribution, we reported the synthesis of a hyperbranched block copolymer composed of poly(ε‐caprolactone) (PCL) and polystyrene (PS) subchains. Toward this end, we first synthesized an α‐alkynyl‐ and ω,ω′‐diazido‐terminated PCL‐b‐(PS)₂ macromonomer via the combination of ring‐opening polymerization and atom transfer radical polymerization. By the use of this AB₂ macromonomer, the hyperbranched block copolymer (h‐[PCL‐b‐(PS)₂]) was synthesized via a copper‐catalyzed Huisgen 1,3‐dipolar cycloaddition (i.e., click reaction) polymerization. The hyperbranched block copolymer was characterized by means of ¹H nuclear magnetic resonance spectroscopy and gel permeation chromatography. Both differential scanning calorimetry and atomic force microscopy showed that the hyperbranched block copolymer was microphase‐separated in bulk. While this hyperbranched block copolymer was incorporated into epoxy, the nanostructured thermosets were successfully obtained; the formation of the nanophases in epoxy followed reaction‐induced microphase separation mechanism as evidenced by atomic force microscopy, small angle X‐ray scattering, and dynamic mechanical thermal analysis. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 368–380     

原子转移自由基聚合制备聚(丙二醇-g-苯乙烯)

以氯甲基化苯氧基聚丙二醇 (CMPOPPG)为大分子引发剂 ,由CuCl/bpy催化的苯乙烯原子转移自由基聚合反应合成了聚 (丙二醇 g 苯乙烯 ) .CMPOPPG经环氧丙烷 (PO)与缩水甘油苯基醚 (GPE)的开环聚合和氯甲基化反应制得 .接枝聚合反应具有可控性 .用1H NMR和微库仑分析法对接枝共聚物进行了表征 .结果表明 ,支链分子量可控 ,接枝率可达 8.6.     

Synthesis and characterization of AgBr nanocomposites by templated amphiphilic comb polymer

A novel amphiphilic graft copolymer, poly(vinylidene fluoride-co-chlorotrifluoroethylene)-g-poly(4-vinyl pyridine) (P(VDF-co-CTFE)-g-P4VP) at 65:35 wt.%, respectively, was synthesized via atom transfer radical polymerization (ATRP), as confirmed by nuclear magnetic resonance (¹H NMR) and transmission electron microscopy (TEM). Silver bromide (AgBr) nanoparticles were in situ generated within the self-assembled P(VDF-co-CTFE)-g-P4VP graft copolymer. TEM, UV–visible spectroscopy and X-ray diffraction (XRD) analyses support the successful formation of P(VDF-co-CTFE)-g-P4VP nanocomposites consisting of stabilized AgBr nanoparticles mostly 20–40 nm in size, which is presumably due to the capping action of the coordinating pyridine groups of the graft copolymer. The wavenumber of pyridine nitrogen in FT-IR spectra and the glass transition temperature (T_g) of the graft polymer measured by DSC shifted upon the formation of AgBr nanoparticles, indicating specific interactions between the nanoparticles and the graft copolymer matrix.     

Effect of quasi‐interpenetrating network of polyacrylamide and poly(N,N‐dimethylacrylamide) on separation of dsDNA fragments and basic protein using CE

Quasi‐interpenetrating network (quasi‐IPN) of linear polyacrylamide (LPA) with low molecular mass and poly(N,N‐dimethylacrylamide) (PDMA), which is shown to uniquely combine the superior sieving ability of LPA with the coating ability of PDMA, has been synthesized for application in dsDNA and basic protein separation by CE. The performance of quasi‐IPN on dsDNA separation was determined by polymer concentration, electric field strength, LPA molecular masses and different acrylamide (AM) to N,N‐dimethylacrylamide (DMA) ratio. The results showed that all fragments in Φ×174/HaeIII digest were achieved with a 30 cm effective capillary length at –6 kV at an appropriate polymer solution concentration in bare silica capillaries. Furthermore, EOF measurement results showed that quasi‐IPN exhibited good capillary coating ability, via adsorption from aqueous solution, efficiently suppressing EOF. The effect of the buffer pH values on the separation of basic proteins was investigated in detail. The separation efficiencies and analysis reproducibility demonstrated the good potentiality of quasi‐IPN matrix for suppressing the adsorption of basic proteins onto the silica capillary wall. In addition, when quasi‐IPN was used both as sieving matrix and dynamic coating in bare silica capillaries, higher peak separation efficiencies, and better migration time reproducibility were obtained.     

原子转移自由基活性聚合合成PS-PMA-PS嵌段聚合物

本文采用氯化亚铜/α,α'-联吡啶配位化合物作催化剂.首先在130℃时用1-苯基氯乙烷在引发苯乙烯(St)进行原子转移自由基聚合,再以其产物PS-Cl作为大分子引发剂引发丙烯酸甲酯(MA)在反应温度为120℃时进行聚合,得到两嵌段聚合物PS-PMA-Cl.此两嵌段共聚物在特殊混合溶剂--丙酮/正丙醇(体积比7:3)中仍然可以作大分子引发剂引发苯乙烯进行原子转移自由基聚合,由于聚合体系接近于均相.所以表现出了较高的反应活性,并且合成的聚苯乙烯一聚丙烯酸甲酯一聚苯乙烯(PS-PMA-PS)三嵌段聚合物的分子量与设计值接近、分子量分布比较窄,反应的条件温和,可控性好.最后通过NMR技术对三元嵌段共聚物的结构迸行了表征.     

Preparation of block copolymer by atom transfer radical seeded emulsion polymerization

Poly(i-butyl methacrylate)-polystyrene block copolymer was successfully prepared in an aqueous medium by two-step atom transfer radical polymerization (ATRP), mini-emulsion- and seeded-ATRP, in which ethyl 2-bromoisobutyrate/CuBr/4,4-dinonyl-2,2-dipyridyl initiator system was used. The block copolymer had narrow molecular weight distribution (Mw/Mn=1.1) and the number-average molecular weight measured by gel permeation chromatography agreed with the calculated value.Part CCXLVIII of the series Studies on Suspension and Emulsion     

Antibacterial behaviour of quaternized poly(vinyl chloride)-g-poly(4-vinyl pyridine) graft copolymers

Amphiphilic graft copolymers consisting of poly(vinyl chloride)(PVC) main chains and poly(4-vinyl pyridine)(P4VP) side chains were synthesized via atom transfer radical polymerization(ATRP) using direct initiation of chlorine atoms. The successful synthesis of PVC-g-P4 VP graft copolymers was confirmed by Fourier transform infrared spectroscopy(FTIR) and proton nuclear magnetic resonance(1H-NMR). Transmission electron microscope(TEM) and small angle X-ray scattering(SAXS) analysis showed that PVC-g-P4 VP exhibited microphase-separated, ordered structure with 37.6 nm of domain spacing, which was not observed in neat PVC. For antibacterial applications, the tertiary nitrogen atoms of PVC-gP4 VP was quaternized using 1-bromohexane, as confirmed by FTIR measurements. Bacteria including Escherichia coli(E. coli), Staphylococcus aureus(S. aureus), Bacillus cereus(B. cereus), and Pseudomonas aeruginosa(P. aeruginosa) were completely killed in 24 h on the quaternized PVC-g-P4VP(46% grafting) surface, indicating its excellent antibacterial behavior while it showed to be cytotoxic to mammalian cell.     

用ATRP法和RAFT法制备线形嵌段共聚物

嵌段共聚物是将不同性质的聚合物连接在同一分子内，表现出特殊的性质，受到高分子科学家及工业部门的广泛关注。本文简要介绍了嵌段共聚物的结构、性能以及可能的应用。它有多种制备方法，这里着重介绍近年来通过原子转移自由基聚合(ATRP)和可逆加成-裂解链转移(RAFT)法制备嵌段共聚物的研究现状和进展情况。对于加料顺序、大分子引发剂末端基团、单体的反应活性以及大分子引发剂的引发效率、配体种类、大分子链转移剂的链转移常数等对嵌段共聚反应的影响也进行了讨论。     

酶促开环聚合和原子转移自由基聚合制备新型H型嵌段共聚物

在生物酶催化剂Novozyme-435的作用下, 乙二醇引发己内酯(ε-CL)酶促开环聚合, 再用三乙胺作催化剂, 将PCL端羟基与2,2-二氯代乙酰氯反应, 生成四官能度大分子引发剂, 引发甲基丙烯酸环氧丙酯(GMA)的原子转移自由基聚合(ATRP), 合成了H型三嵌段共聚物(PGMA)2-b-PCL-b-(PGMA)2. 嵌段共聚物的结构通过核磁共振和凝胶渗透色谱(GPC)得到了确证, 其多分散性为1.32, 分子量为32000. 通过差热扫描量热法对嵌段共聚物的热性能进行了研究.     

Synthesis and characterizations of well-defined dendrimer-like copolymers with the second and third generation based on polystyrene and poly(l-lactide)

Dendrimer-like copolymers with two and three generations, (polystyrene)₃-b-(poly(l-lactide))₆ (PSt₃-b-PLLA₆) and PSt₃-b-PLLA₆-b-PSt₁₂ have been successfully prepared using core-first method. The first step of this synthesis is the preparation of three-armed PSt by atom transfer radical polymerization (ATRP) of St using 1,1,1-tri(methylene-α-bromoisobutyryl)propane as initiator. Terminal divergence of the polymers obtained was achieved by the reaction of terminal bromines with branching agent, 2,2-dimethyl-1,3-dioxolane-4-methanol. After deprotection, the polymer with six terminal hydroxyl groups was used in the ring-opening polymerization of LLA. The dendrimer-like copolymer with PLLA as a second generation diverged continuously by the reaction of 6 terminal hydroxyl groups with branching agent, 2,2-bis(methylene-α-bromoisobutyryl)propionyl chloride. The resultant polymer with 12 terminal bromines was used as macroinitiator in the ATRP of St to produce the target dendrimer-like copolymer, PSt₃-b-PLLA₆-b-PSt₁₂. The structures of polymers obtained from each step were confirmed by their ¹H NMR spectra and GPC measurements. DSC results show one for the three-armed PSt, , and for the dendrimer-like copolymer with two generations, C(PSt(PLLA)₂)₃, and , and for the copolymer with three generations, C(PSt(PLLA(PSt)₂)₂)₃.     

窄分布两亲性嵌段共聚物的合成及其胶束化行为研究

利用原子转移自由基聚合合成了具有两亲性的嵌段聚合物聚苯乙烯-b-聚丙烯酸(PS-b-PAA),用FTIR,¹H NMR,SEC对其进行了表征,并利用荧光探针技术研究了其在水溶液中的胶束化行为.进一步的研究表明,PS-b-PAA胶束可对水中存在的多环芳香化合物芘有效地吸收并进而分离和回收.     

以二硫键连接的两嵌段共聚物的制备新方法

报道了一种制备二硫键连接的两嵌段共聚物的新方法.以可逆加成-断裂链转移自由基聚合(RAFT)制备聚苯乙烯大分子链转移剂(PS-RAFT),经伯胺还原得到巯基封端的PS(PS-SH).PS-SH与原子转移自由基聚合(ATRP)引发剂2-溴-2-甲基丙酸-2-(2-吡啶基二硫)乙酯发生交换反应,得到含有二硫键的聚苯乙烯大分子ATRP引发剂(PS-S-S-Br).以PS-S-S-Br引发甲基丙烯酸-2-羟基乙酯(HEMA)的ATRP聚合反应,合成了由二硫键连接的两嵌段共聚物PS-S-S-PHEMA.将PS-S-S-PHEMA可在甲醇中自组装形成以PS为核,PHEMA为壳的球形聚合物胶束,为制备新型含二硫键聚合物提供了新的合成方法.     

MICRON CORE-SHELL PARTICLES PREPARED BY GRAFTING POLYMERIZATION OF METHYL METHACRYLATE FROM NARROW DISPERSE SURFACE OF CHLOROMETHYLATED POLYDIVINYLBENZENE VIA ATRP

Grafting of poly(methyl methacrylate) from narrow disperse polymer particles by surface-initiated atom transfer radical polymerization (ATRP) was investigated. Polydivinylbenzene (PDVB) particles were prepared by dispersion polymerization with poly(N-vinyl pyrrolidone) (PVP) as the stabilizer. Chloromethylated PDVB was used as initiating core sites for subsequent ATRP of methyl methacrylate with CuBr/bpy as catalyst system. It was found that poly(methyl methacrylate) was grafted not only from the particle surfaces but also from within a thin shell layer, leading to particles size increases from 2.38-3.00μm with a core-shell structure particles. The grafted core-shell particles were characterized with FTIR, SEM, DSC.     

Synthesis of Dendritic-Linear Block Copolymers by Atom Transfer Radical Polymerization

Polymers and copolymers with complex, yet well-defined architectures are drawing significant attentions in the search for materials with excellent properties. Of these macromolecular structures, dendritic-linear block copolymers consisting of covalently bound linear and dendritic segments have shown interesting solution, solid-state, and interfacial properties. As a novel polymerization approach, atom transfer radical polymerization (ATRP) has been attracting increasing interest recently, sin…     

SYNTHESIS OF BLOCK COPOLYMER BY INTEGRATED LIVING ANIONIC POLYMERIZATION-ATOM TRANSFER RADICAL POLYMERIZATION(ATRP)*

Alpha-trichloroacetoxy terminated polystyrene oligomer (PS-CH_2CH_2OCOCCl_3) and poly-(styrene-b-butadiene)oligomer [P(S-b-B)-CH_2CH_2OCOCCl_3)] were synthesized by living anionic polymeri-zation using n-butyllithium as initiator.Then the PS-CH_2CH_2OCOCCl_3 (PS-Cl_3) or P(S-b-B)-CH_2CH_2O-COCCl_3 (PSB-Cl_3) was used as the macroinitiator in thepolymerization of (meth)acrylates in the presence of CuX/bpy. AB diblock and ABC triblock copolymers were prepared bythe integrated living anionic polymerization (LAP)-atom transfer radical polymerization (ATRP). The structures of the PSB-Cl_3 and the P(S-b-MMA) were identified by FTIR and ~1H-NMR spectrum, respectively. A new way to design blockcopolymers (the combination of LAP and ATRP) was developed.     

Synthesis of Well-Defined Dendritic-Linear Diblock and Triblock Copolymers by Controlled Free Radical Polymerization

Recently, significant progress has been made in the field of living free radical polymerization such as nitroxide-mediated stable free radical polymerization, atom transfer radical polymerization (ATRP), reverse ATRP and reversible addition-fragmentation chain transfer1. Among them, ATRP has been successfully applied to the synthesis of well-defined comb, gradient, star and dendritic macromolecules. Recent advances have been carried toward new initiators, metals and ligands. As a new cl…     

Block copolymerization of 5,6-benzo-2-methylene-1,3-dioxepane with conventional vinyl monomers by ATRP method

Polystyrene-block-poly(5,6-benzo-2-methylene-1,3-dioxepane) (PSt-b-PBMDO), poly(methyl methacrylate)-block-PBMDO (PMMA-b-PBMDO) and poly(methyl acrylate)-block-PBMDO (PMA-b-PBMDO) were synthesized by two-step atom transfer radical polymerization (ATRP) of conventional vinyl monomers, then BMDO. First, the polymerization of St, or MMA, or MA was realized by ATRP with ethyl α-bromobutyrate (EBrB) as initiator in conjunction with CuBr and 2,2^′-bipyridine (bpy). After isolation, polymers with terminal bromine, PSt-Br, PMMA-Br and PMA-Br, were obtained. Second, the ATRP of BMDO was performed by using macroinitiator, PSt-Br (or PMMA-Br, PMA-Br) in the presence of CuBr/bpy. The structures of block copolymers were characterized by 1H NMR spectra. Molecular weight and polydispersity index were determined on gel permeation chromatograph. Among the block copolymers obtained, PMA-b-PBMDO shows the most narrow molecular weight distribution.