Synthesis and self-assembly of temperature and anion double responsive ionic liquid block copolymers

In this paper, double hydrophilic ionic liquid block copolymers (ILBCs), poly(N-isopropylacrylamide)-block-poly[1-methyl-3-(2-methacryloyloxy propylimidazolium bromine)] (PNIPAM-b-PMMPImB), were polymerized by two-step reversible addition-fragmentation chain transfer (RAFT) process. The?composition and molecular weight distributions of ILBCs were characterized using ¹HNMR and gel permeation chromatography (GPC). The self-assembly and temperature- and anion-responsive behaviors of ILBCs were investigated by UV-Vis spectroscopy, TEM and dynamic light scattering (DLS). With increasing the concentration of (CF₃SO₂)₂N^--, the micellization of self-assembling PNIPAM-b-PMMPImB was induced to form a core--shell structure containing the core with hydrophilic PMMPIm-(CF₃SO₂)₂N^-- surrounded by the shell of PNIPAM via the anion-responsive properties of ILBCs. However, upon temperature increasing, PNIPAM-b-PMMPImB formed the micelles composing of PNIPAM core and PMMPImB shell. The ionic liquid segment with strong hydrophilic property enhanced the hydrogen bonding interaction which expanded the temperature range of phase transition and increased the lower critical solution temperature (LCST) of the system. These results indicate that ILBCs prepared in this paper have excellent temperature and anion double responsive properties, and may be applied as a kind of potential environmental responsive polymer nanoparticles.     

刚柔嵌段共聚物自组装制备单分散性微球

刚柔嵌段共聚物聚苯基喹啉 b 聚苯乙烯(PPQ b PS)在选择性溶剂中具有自组装行为。该共聚物在1mg·mL-1的V(三氟乙酸)∶V(二氯甲烷)=1∶1的溶液中形成胶束,室温下易自组装成平均粒径为2μm的微球,微球粒径随着PPQ聚合度的增大而增大,具有单分散性,同时所形成稀溶液的最强吸收波长为376nm。文中对刚柔嵌段共聚物自组装制备单分散性微球的机理进行了初步探讨。     

Hierarchical nanostructures by sequential self-assembly of styrene-dimethylsiloxane block copolymers of different periods

Poly(styrene-block-dimethylsiloxane) (PS-b-PDMS) block copolymers with a period as low as 13 nm have been self-assembled on a template formed from PS-b-PDMS of a 34–40 nm period, which is itself templated by micron-scale substrate features prepared using conventional lithography. This hierarchical process provides a simple method for directing the self-assembly of sub-10 nm features and registering them on the substrate.     

纳米Au在蒙脱石层间的插层组装

以Na基蒙脱石为载体,分别以十二胺和PAA作为插层剂,利用此类插层剂可以捕捉金胶体的特点,使预先制备的金胶体插层于蒙脱石的层间制备组装型纳米金催化剂,并考察了高温焙烧对插层效果的影响。此外,以Au(en2)Cl3作为金的前驱体,研究了利用蒙脱石的阳离子交换特性直接进行纳米金插层组装的可行性。采用X射线衍射(XRD)、荧光分析(XRF)和透射电子显微镜(TEM)对所制备的样品进行了表征,结果表明:基于阳离子交换插层的制备方法未能实现纳米金的插层组装,金颗粒主要负载于蒙脱石片层的外表面,而基于配位俘获机理的插层组装方法所制备的纳米金在蒙脱石层间的插层组装效果良好,高温焙烧虽然导致层间纳米金的迁移,但金的粒径仍然保持在较低的尺寸范围。     

Rod-coil型嵌段共聚物(PANI)98-(PEG)136-(PANI)98自组装的结构调控

研究了(PANI)98-(PEG)136-(PANI)98三嵌段共聚物在N-甲基吡咯烷酮(NMP)、DMF、乙醇和水等选择性溶剂中的自组装行为,以及溶剂、溶液浓度和超声波作用等对其自组装行为的结构调控.结果表明,(PANI)98-(PEG)136-(PANI)98在NMP、DMF、乙醇和水中自组装形成了球形、棒状、网状和纤维带状结构;在乙醇溶剂中,随着(PANI)98-(PEG)136-(PANI)98浓度的提高,自组装形成的网状结构由单层变为多层、立体网状结构和花瓣结构.超声波作用对(PANI)98-(PEG)136-(PANI)98自组装有序结构的形成有明显影响.     

Conductive thin film multilayers of gold on glass formed by self-assembly of multiple size gold nanoparticles

Highly conductive thin films of gold have been fabricated on glass substrates by the deposition of gold nanoparticles of two different diameters. A deposition sequence, alternating between 2.6-nm and 12-nm diameter particles, was used whereby the 2.6-nm particles served to fill in the gaps created by the assembly of the larger 12-nm diameter particles. The resulting thin films, with thicknesses of less than 35 nm, displayed high conductivities, yet were fabricated in substantially fewer deposition cycles than required by previous methods. Analysis of surface morphology performed by atomic force microscopy and scanning electron microscopy showed that the high conductivity is the result of a less porous surface structure than can be achieved through the layering of a single size nanoparticle. Conductivity analysis was performed by 4-point probe with resistivities of 5.00 ± 0.4 × 10^− 6 Ω m for 5 layers and 4.49 ± 0.2 × 10^− 6 Ω m for the 6-layer films.     

刚柔嵌段共聚物聚苯基喹啉-b-聚乙二醇的合成与自组装

以聚乙二醇单甲醚、丁二酸酐、4-氨基苯乙酮、5-乙酰基-2-氨基二苯甲酮为原料合成了以聚苯基喹啉(PPQ)为硬段、聚乙二醇(PEG)为软段的“刚棒-线团”两嵌段共聚物PPQ-b-PEG,通过IR、1^HNMR对其结构进行了表征。并对1mg／ml的PPQ-b-PEG在三氟乙酸／二氯甲烷稀溶液(1：1 TFA：DCM,v／v)的自组装进行了初步研究。结果表明：PPQ-b-PEG能自组装形成直径为4．34μm的聚合物微球。     

Simultaneous synthesis of polyaniline nanorods and magnetite nanoparticles via self-assembly method

In this work, polyaniline (PANI) nanorods and magnetite (Fe₃O₄) nanoparticles have been synthesised by using ammonium persulphate as oxidant via in-situ chemical oxidative polymerisation of aniline in presence of excess of organic sulphonic acid. The resulting PANI/Fe₃O₄ nanocomposites materials were characterised using X-ray diffraction, UV-visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, vibrating sampling magnetometer and thermogravimetric analysis. Spectroscopic results indicated the successful formation of PANI/Fe₃O₄ nanocomposites. As obtained, PANI/Fe₃O₄ nanocomposites have Fe₃O₄ particle size in the range of 3.2–7?nm. Morphologies of PANI/Fe₃O₄ nanocomposites were found to be dependent on the molar ratio of aniline to organic acid. Under certain polymerisation conditions, PANI rods like structures were obtained. PANI/Fe₃O₄ nanocomposites have superparamagnetism and higher thermal stability.     

Development and evaluation of fluorescent gold nanoparticles

Objective: It is difficult to identify the gold nanoparticles (AuNPs) intracellularly due to their non-fluorescent nature. Although gold can quench the fluorescence of any fluorophore, hence it is also difficult to combine gold with a fluorophore such as a semiconductor quantum dots (QDs). The aim of this study was to prepare a single fluorescent stable AuNPs combined with QDs (QDs-Au-NPs) which can be easily detected intracellularly.

Methods: QDs-Au-NPs were prepared via a simple one-step process through controlling the spacing between them using polyethylene glycol (PEG) as space linker in the form of PEGylated QDs. Furthermore, the applicability of this system was evaluated after coating the particles with somatostatin citrate, SST, to active target somatostatin receptors (SSTRs), and identification of the internalized particles via confocal laser scanning spectroscopy.

Results: The results showed that the produced Au shell has a thickness of 2.0?±?0.2?nm and QDs-Au-NPs showed the same fluorescence intensity compared to the unmodified QDs. Additionally, a stable monodisperse QDs-Au-NPs coated with SST were prepared after coating with 11-Mercaptoundecanoic acid. Moreover, cellular uptake study in Human Caucasian breast adenocarcinoma cell lines showed that QDs-Au-SST-NPs could be detected easily using the confocal microscope. In addition, they showed a significant (p?≤?.05) internalization per cell compared to untreated QDs-Au-NPs as detected by flow cytometry.

Conclusion: It could be concluded that the produced QDs-Au-NPs has a strong fluorescence property like QDs which enable them to be easily detected after cells internalization.     

刚柔嵌段共聚物聚苯基喹啉-b-聚苯乙烯的合成及荧光性质

利用原子转移自由基聚合合成了端羧基聚苯乙烯,然后与4氨基苯乙酮反应,生成末端为乙酰基的聚合物,以P2O5为催化剂,将功能化的聚合物与5乙酰基2氨基二苯甲酮共聚,合成出刚柔嵌段共聚物聚苯基喹啉b聚苯乙烯(PPQ-b-PS)。用IR、1HNMR对其结构进行了表征,并对PPQ-b-PS在三氟乙酸/二氯甲烷稀溶液中的荧光性质进行了初步研究。结果表明:1mg·ml-1的PPQ-b-PS(1∶1氟乙酸/二氯甲烷,v/v)在459nm作监控波长下测量的激发光谱,430nm处有最大发射波长,相对强度为509,PPQbPS可实现可见光的激发。最大发射波长随着溶液浓度的升高而变大,即发生了红移,与混合溶剂的配比无关。     

Synthesis,optical properties and self-assembly of gold nanorods

Noble metal nanostructures of different aspect ratios were synthesised and optically characterised at individual nanorod level. Rayleigh scattering spectroscopy/scanning electron microscopy measurements were performed to uniquely correlate optical signatures with nanorod size and shape. Scattering spectra of nanorods were dominated by the intense longitudinal surface plasmon resonance (SPR) band in the near-infrared part of the spectrum. This band was found to be highly shape and size dependent. Droplet evaporation techniques and application of dielectrophoretic forces have been used to organise nanorod dispersions into ordered arrays. Depending on the technique and nanoparticle size used, nanorods were found to form one, two or three dimensional (1D, 2D and 3D) superstructures. Within these superstructures nanorods organised themselves into end-to-end lines (1D), side-to-side fashion (2D) or hexagonal arrangements (3D).     

两亲嵌段共聚物的合成及纳米自组装

首先用苄氧羰基赖氨酸和三光气反应合成苄氧羰基赖氨酸酸酐,然后将聚乙二醇中活性较弱的羟基转化为氨基,最后以双端氨基聚乙二醇作为引发剂,采用阴离子开环聚合合成了聚(Nε-苄氧羰基赖氨酸)-聚乙二醇-聚(Nε-苄氧羰基赖氨酸)(PLL(Z)-PEG-PLL(Z))。PLL(Z)-PEG-PLL(Z)经去保护后得到带正电荷的聚赖氨酸-聚乙二醇-聚赖氨酸(PLL-PEG-PLL)。PLL(Z)-PEG-PLL(Z)在水溶液中自组装形成的聚集体类似于纳米多孔聚集体结构,具有疏松的空洞,原子力显微镜观测其呈球形,其大小为220 nm左右。     

An anisotropic propagation technique for synthesizing hyperbranched polyvillic gold nanoparticles

Of late, many synthesis processes have been studied to develop irregular nano-morphologies of gold nanostructures for biomedical applications in order to increase the efficacy of nanoparticle theranostics, tune the plasmonic absorbance spectra, and increase the sensitivity of biomolecule detection through surface enhanced Raman spectroscopy. Here we report, a novel, non-seed mediated versatile single pot synthesis method capable of producing hyperbranched gold “nano-polyvilli” with more than 50–90 branching nanowires propagating from a single origin within each structure. The technique was capable of achieving precise tuning of the branch propagation where the branching could be controlled by varying the duration of incubation, temperature, and hydrogen ion concentration.

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Microwave-assisted synthesis of ultrafine Au nanoparticles immobilized on MOF-199 in high loading as efficient catalysts for a three-component coupling reaction

Controlled integration of ultrafine metal nanoparticles (MNPs) and metalorganic frameworks (MOFs) has drawn much attention due to their unique physical and chemical properties.However,the development of a one-step strategy for preparing ultrafine MNPs within MOFs still remains a great challenge.Herein,a facile synthetic approach toward the abovementioned composites was developed.In contrast to the conventional approach,these hybrids were prepared by the direct mixing of metal and MOF precursors in the reaction solution assisted by microwave irradiation.Impressively,the Au/MOF-199 composite with uniformly distributed ultrafine Au nanoparticles could be fabricated in only two minutes,and the Au loading could be increased up to a level of 5.13％.The multifunctional Au/MOF-199 catalysts exhibited high turnover numbers (TONs)and turnover frequencies (TOFs) in the three-component coupling reaction of formaldehyde,phenylacetylene,and piperidine (A3-coupling).Owing to the confinement effect of MOF-199,the 5.13％Au/MOF-199 catalyst could be recycled for five runs without serious loss of activity,with no obvious aggregation of Au NPs detected.     

新型含杂萘联苯聚醚砜类嵌段共聚物的合成与性能研究

采用连续缩聚法合成氯端基聚醚砜齐聚物,然后与杂萘联苯构成的类双酚合成的羟端基齐聚物进行缩聚反应,合成了新型PPES-PES嵌段共聚物.用IR、DSC、TGA、X-WAXD等方法对聚合物进行了表征,并研究了聚合物的溶解性能.结果表明该嵌段共聚物具有较高的玻璃化转变温度,较好的热稳定性和良好的溶解性能,为非结晶型聚合物,并可浇铸得到透明、韧性高的薄膜.实验还发现聚醚砜组分含量变化对共聚物的热性能影响很大,对杂萘联苯聚醚砜改性效果明显.     

Amine-terminated TEG-derived PAMAM dendrimer as template for preparation of gold nanoparticles in water

Nano-sized monodisperse gold particles (AuNPs) have received significant attention in the past decade, due to their unique physical properties and good chemical stability, which can lead to a wide variety of potential applications. In this work, TEG-derived PAMAM dendrimers with amine-terminating groups were synthesized and characterized by ¹H NMR and FT-IR. These dendrimers were investigated as the templates for preparation of gold nanoparticles through the reduction of HAuCl₄ by NaBH₄ in water. Stable gold nanoparticles with diameters around 10 nm were obtained in the presence of G2.0 – G5.0 dendrimers and characterized by UV-Vis spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS). The particle size of the produced AuNPs decreased with increasing dendrimer generations. A dendrimer of higher generation has a rigid structure with many end groups on the surface and may play a powerful role in the growth of the AuNPs, as well as having a solid stabilization effect on the AuNPs.     

Ionogel-templated synthesis and organization of anisotropic gold nanoparticles

Photochemical reduction of tetrachloroaurate (AuCl4-) ions in the highly constrained aqueous domains of a nanostructured ionogel template, formed via self-assembly of the ionic liquid 1-decyl-3-methylimidazolium chloride (C10mim+Cl-) in water, results in the formation of anisotropic gold nanoparticles with a variety of sizes and morphologies, which include previously unattainable trigonal prismatic nanorods. Unexpectedly, small-angle X-ray scattering studies of the Au-ionogel composite reveal that the in situ formation of the nanoparticles increases the mesoscopic order of the ionogel, which results in its conversion to a near-monodomain structure. The findings demonstrate that nanostructured, ionic liquid-based gels can be used to template the formation of new nanoparticle morphologies with technologically important optical, electronic, and catalytic properties. It may also be possible to design soft templates that permit the fabrication of highly ordered nanoparticle array-hydrogel composites, thereby enabling control and tuning of the collective properties of the encapsulated nanoparticles.     

Synthesis of poly(ethylene glycol)-SS-poly(ε-caprolactone)-SS-poly(ethylene glycol) triblock copolymers via end-group conjugation and self-assembly for reductively responsive drug delivery

In this study, we describe a simple synthesis route to prepare triblock copolymers with disulfide-linkers, poly(ethylene glycol)-SS-poly(ε-caprolactone)-SS-poly(ethylene glycol) (PEG-SS-PCL-SS-PEG) for application in the reductively responsive release of doxorubicin (DOX). To synthesize PEG-SS-PCL-SS-PEG, two end-groups of PCL-diol were first modified with cystamine to introduce disulfide bonds and subsequently conjugated with PEG-NHS via carbodiimide chemistry. PEG-SS-PCL-SS-PEG fabricated into polymeric micelles with stable structure and different nanoscale sizes via adjusting the PCL chain length, showing obvious reductive responsiveness and fast drug release of encapsulated DOX in the presence of glutathione (GSH). Moreover, DOX-loaded PEG-SS-PCL-SS-PEG micelles exhibited higher therapeutic efficacy than reduction-insensitive PEG-b-PCL micelles in vitro. Thus, end-groups conjugation is a simple and straightforward strategy to introduce intelligent responsiveness in biocompatible block copolymers and improve their therapeutic efficacy.     

One pot synthesis of monodispersed L-glutathione stabilized gold nanoparticles for the detection of Pb2+ ions

Direct mixture of Au³⁺ with glutathione (GSH), which act as both reduction agents and stabilizers, in aqueous solution gave rise to production of gold nanoparticles (Au NPs) with uniform sizes of around 21 nm. The GSH stabilizer Au NPs in solution show immediate aggregation after addition of 1 mol/L NaCl aqueous solution containing Pb²⁺ ions. The Pb²⁺-induced aggregation in Au NP solution is monitored by both colorimetric response and UV-vis spectroscopy. A rather broad linear range (from 0.1 to 30 μmol/L) and low detection limit (0.1 μmol/L) are explored for Au NP sensors used for detection of Pb²⁺ ions. Furthermore, the response of GSH-stabilized Au NPs toward Pb²⁺ ions is specific compared with other possible interferants (Hg²⁺, Mg²⁺, Zn²⁺, Ni²⁺, Cu²⁺, Co²⁺, Ca²⁺, Mn²⁺, Cd²⁺, and Ba²⁺).