Photoresponsive water‐dispersible polyaniline nanoparticles through template synthesis with copolymer micelle containing coumarin groups

A novel kind of photosensitive water‐dispersible polyaniline (PANI) nanoparticles was designed and prepared by template synthesis using a photo‐responsive vinyl‐coumarin (VM)/2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) copolymer micelle containing coumarin moieties. The resulting PANI nanoparticles exhibited reversible photo‐crosslinking and photo‐decrosslinking behavior similar to coumarin moiety upon irradiation with different UV light as verified by UV–vis absorption. In addition, photoinduced size change of the PANI nanoparticles after 365 nm UV light irradiation was successfully monitored by dynamic light scattering and transmission electron microscopy measurements, further confirming the photosensitivity of the obtained PANI nanoparticles by the incorporation of VM/AMPS copolymer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Magnetite‐polylactic acid core–shell nanoparticles by ring‐opening polymerization under microwave irradiation

The synthesis of magnetic core–shell nanoparticles consisting of magnetite cores surface‐functionalized by glycolic acid covered by polylactic acid was performed by applying the “grafting‐from” strategy, where the polymerization is initiated from the particle surface. The surface initiated ring‐opening polymerization of D,L ‐lactide was initiated by tin (II) 2‐ethylhexanoate using microwave irradiation. Core–shell nanoparticles of high colloidal stability in water were obtained in this way. The morphology of the magnetic core–shell nanostructure was determined by transmission electron microscopy, and the chemical structure was elucidated by Fourier transform infrared spectroscopy (FTIR) and X‐ray photoelectron spectroscopy. Magnetic measurements revealed superparamagnetic behavior and high magnetization values. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Decoration of Electrospun Nanofibers with Magnetic Nanoparticles via Electrospinning and Sol-gel Process

Polyacrylonitrile(PAN)/Fe 3 O 4 composite nanofibers were successfully obtained through electrospinning and sol-gel technology. The resulting magnetic Fe 3 O 4 nanoparticles were homogeneously distributed on the surface of PAN nanofibers and the diameters of polyacrylonitrile nanofibers and nanoparticles were easily controlled, respectively. The distribution of Fe 3 O 4 nanoparticles inside the nanofibrous composite was investigated by field emission scanning electron microscopy and transmission electron microscopy. X-ray diffraction reveals the presence of Fe 3 O 4 nanoparticles in the composite nanofiber. The resulting sample shows a super paramagnetic behavior.     

Biocompatible poly(ethylene glycol)‐poly(γ‐cholesterol‐L‐glutamate) copolymers: Synthesis,characterization, and in vitro studies

A novel amphiphilic poly(ethylene glycol)‐block‐poly(γ‐cholesterol‐L ‐glutamate) (mPEG–PCHLG) diblock copolymer has been synthesized. The mPEG–PCHLG copolymer has good biocompatibility and low toxicity. The mPEG–PCHLG copolymers could aggregate into nanoparticles with PCHLG blocks as the hydrophobic core and PEG blocks as the hydrophilic shell through emulsion solvent evaporation method. The copolymers were characterized by nuclear magnetic resonance spectroscopy, mass spectrum, Fourier transform infrared spectroscopy, and gel permeation chromatography. The particle sizes, size distributions, and zeta potentials of nanoparticles can also be determined by dynamic light scattering and transmission electron microscopy. This work provides a new and facile approach to prepare amphiphilic block copolymer nanoparticles with controllable performances. This novel copolymer may have potential applications in drug delivery and bioimaging applications.© 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Rapid green synthesis of gold nanoparticles using Rosa hybrida petal extract at room temperature

This study reports a green method for the synthesis of gold nanoparticles using the aqueous extract of rose petals. The effects of gold salt concentration, extract concentration and extract quantity were investigated on nanoparticles synthesis. Gold nanoparticles were characterized with different techniques such as UV-vis spectroscopy, FT-IR spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, dynamic light scattering and transmission electron microscopy. Transmission electron microscopy experiments showed that these nanoparticles are formed with various shapes. FT-IR spectroscopy revealed that gold nanoparticles were functionalized with biomolecules that have primary amine group (-NH2), carbonyl group, -OH groups and other stabilizing functional groups. X-ray diffraction pattern showed high purity and face centered cubic structure of gold nanoparticles. Dynamic light scattering technique was used for particle size measurement, and it was found to be about 10nm. The rate of the reaction was high and it was completed within 5 min.     

Surface modified ormosil nanoparticles

Organically modified silanes (ORMOSIL) such as vinyl triethoxysilane readily aggregate in the aqueous cores of reverse micelles where the triethoxysilane moieties are hydrolyzed to form a hydrated silica network and the vinyl groups protruded out from the surface of the nanoparticles toward the hydrophobic side of the micellar interface. These particles are spherical and the size distribution of the particles is relatively narrow, with an average diameter of 87 nm. Surface vinyl silica nanoparticles so formed have been oxidized to surface carboxylic silica nanoparticles, followed by chemical conjugation with polyethyleneglycol amine (PEG amine) through the ethyl-3-(3-dimethylaminopropyl) (EDCI) carbodiimide reaction. The characteristic surface groups have been identified by Fourier transform infrared spectroscopy, while the size and the morphology of the particles have been studied by dynamic light scattering and transmission electron microscopy. It has been found that about 80-85% of the carboxylic groups are PEGylated during the EDCI reaction.     

One-Pot Green Synthesis of Hematite (α-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>) Nanoparticles by Ultrasonic Irradiation and Their In Vitro Cytotoxicity on Human Keratinocytes CRL-2310

Greener and ecofriendly approaches to the synthesis of hematite (α-Fe₂O₃) nanoparticles are important for various biomedical applications. The authors describe on a facile, one-pot method for synthesizing hematite nanoparticles (HNPs) using ultrasonic irradiation of iron(III) oxide solution containing the aqueous root extract of Arisaema amurense, which was used as both reducing and stabilizing agents. The synthesized HNPs were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM). FT-IR analysis indicated the presence of stabilizing groups such as hydroxyl (–OH), C–O, and amide (–NH–) on the surfaces of HNPs. TEM analysis revealed the formation of near spherical HNPs of average size 24.55 ± 6.9 nm. VSM confirmed the ferromagnetic nature of the HNPs with a saturation magnetization (Ms) at 1.25 emu/g and remanent magnetization (Mr) at 0.50 emu/g at 301 K. The electrochemical behavior of glassy carbon (GC)/HNPs electrode was studied using cyclic voltammetry (CV). MTT assays of the HNPs exhibited in vitro concentration-dependent cytotoxicity to human keratinocytes CRL-2310, which indicated the synthesized HNPs are compatible with requirements for in vivo biomedical applications at lower concentrations.     

Novel fabrication of magnetic thermoplastic nanofibers via melt extrusion of immiscible blends

A novel technique of fabricating magnetic thermoplastic nanofibers by the control of the phase separation of immiscible polymer blends during melt extrusion was presented. The magnetic poly(vinyl alcohol‐co‐ethylene) (PVA‐co‐PE)/Fe₃O₄ composite nanofibers were prepared via the melt extrusion of cellulose acetate butyrate matrix and PVA‐co‐PE preloaded with different amounts of Fe₃O₄ nanoparticles. The morphologies of magnetic composite nanofibers were characterized by scanning electron microscopy. The uniform dispersion of Fe₃O₄ nanoparticles in nanofiber matrixes and crystal structures were confirmed using transmission electron microscopy and wide angle X‐ray diffraction. Thermogravimetric analysis was employed to quantify the exact loading amount of Fe₃O₄ nanoparticles in the composite nanofibers. The magnetic measurements showed that composite nanofibers displayed superparamagnetic behavior at room temperature. With increasing content of Fe₃O₄ nanoparticles, the saturation magnetization of the magnetic composite nanofiber significantly improved. The prepared magnetic composite nanofibers might have found potential applications in the sensors and bio‐molecular separation fields. Copyright © 2012 John Wiley & Sons, Ltd.     

Dendron‐like poly(ε‐benzyloxycarbonyl‐L‐lysine)/linear PEO block copolymers: Synthesis,physical characterization,self‐assembly,and drug‐release behavior

Dendron‐like poly(ε‐benzyloxycarbonyl‐L ‐lysine)/linear poly(ethylene oxide) block copolymers (i.e., Dm‐PZLys‐b‐PEO, m = 0 and 3; Dm are the propargyl focal point poly(amido amine) dendrons having 2^m primary amine groups) were for the first time synthesized by combining ring‐opening polymerization (ROP) of ε‐benzyloxycarbonyl‐L ‐lysine N‐carboxyanhydride (Z‐Lys‐NCA) and click chemistry, where Dm‐PZLys homopolypeptides were click conjugated with azide‐terminated PEO. Their molecular structures and physical properties were characterized in detail by FTIR, ¹H NMR, gel permeation chromatography, differential scanning calorimetry, polarized optical microscopy, and wide angle X‐ray diffraction. Both homopolypeptides and copolymers presented a liquid crystalline phase transition for PZLys block, and the transition was irreversible. Moreover, the degree of crystallinity of PEO block within linear copolymers decreased from 96.2% to 20.4% with increasing PZLys composition, whereas that within dendritic copolymers decreased to zero. The secondary conformation of PZLys progressively changed from β‐sheet to α‐helix with increasing the chain length. These copolymers self‐assembled into spherical nanoparticles in aqueous solution, and the anticancer drug doxorubicin‐loaded nanoparticles gave a similar morphology compared with their blank counterparts. The drug‐loaded nanoparticles showed a triphasic drug‐release profile at aqueous pH 7.4 or 5.5 and 37 °C and sustained a longer drug‐release period for about 2 months. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and characterization of micron‐sized monodisperse superparamagnetic polymer particles with amino groups

Micron‐sized monodisperse superparamagnetic polyglycidyl methacrylate (PGMA) particles with functional amino groups were prepared by a process involving: (1) preparation of parent monodisperse PGMA particles by the dispersion polymerization method, (2) chemical modification of the PGMA particles with ethylenediamine (EDA) to yield amino groups, and (3) impregnation of iron ions (Fe²⁺ and Fe³⁺) inside the particles and subsequently precipitating them with ammonium hydroxide to form magnetite (Fe₃O₄) nanoparticles within the polymer particles. The resultant magnetic PGMA particles with amino groups were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X‐ray diffractometry (XRD), and vibrating sample magnetometry (VSM). SEM showed that the magnetic particles had an average size of 2.6 μm and were highly monodisperse. TEM demonstrated that the magnetite nanoparticles distributed evenly within the polymer particles. The existence of amino groups in the magnetic polymer particles was confirmed by FTIR. XRD indicated that the magnetic nanoparticles within the polymer were pure Fe₃O₄ with a spinel structure. VSM results showed that the magnetic polymer particles were superparamagnetic, and saturation magnetization was found to be 16.3 emu/g. The Fe₃O₄ content of the magnetic particles was 24.3% based on total weight. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3433–3439, 2005     

Single‐pulse pulsed laser polymerization–electron paramagnetic resonance investigations into the termination kinetics of n‐butyl acrylate macromonomers

The termination of model mid‐chain radicals (MCRs), which mimic radicals that occur in acrylate polymerization over a broad range of reaction conditions, has been studied by single‐pulse pulsed laser polymerization (SP‐PLP) in conjunction with electron paramagnetic resonance spectroscopy. The model radicals were generated by initiator‐fragment addition to acrylic macromonomers that were preformed prior to the kinetic experiments, thus enabling separation of termination from the propagation reaction, for these model radicals propagate sparingly, if at all, on the timescale of SP‐PLP experiments. Termination rate coefficients of the MCRs were determined in the temperature range of 0–60°C in acetonitrile and butyl propionate solution as well as in bulk macromonomer over the range of 0–100 °C. Termination rate coefficients slightly below those of the corresponding secondary radicals were deduced, demonstrating the relatively high termination activity of this species, even when undergoing MCR–MCR termination. For chain length of 10, a reduction by a factor of 6 is observed. Unusually high activation energies were found for the termination rate coefficient in these systems, with 35 kJ mol^?1 being determined for bulk macromonomer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Preparation of glycopolymer‐substituted gold nanoparticles and their molecular recognition

Glycopolymer‐substituted gold nanoparticles were prepared via living radical polymerization with a reversible addition‐fragmentation chain transfer (RAFT) reagent. Polyacrylamide derivatives with α‐mannose (α‐Man) and N‐acetyl‐β‐glucosamine (β‐GlcNAc) were synthesized and hydrogenated to obtain thiol‐terminated polymer. The thiol‐terminated glycopolymers were mixed with gold nanoparticles to yield the polymer substituted gold nanoparticles with various diameters, which aggregated on addition of saccharide‐recognition proteins (lectins). The aggregation properties were analyzed using transmission electron microscopy and UV spectra. Molecular recognition was studied with E. coli, which induced aggregation of the nanoparticles at the cell periphery. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1412–1421, 2009     

Preparation of glycopolymer‐coated magnetite nanoparticles for hyperthermia treatment

In this article, magnetite nanoparticles (MNPs) coated with glycopolymer bearing glucose moieties were designed with optimal structural, colloidal, and magnetic properties for biomedical applications. MNPs with an average size of 17 ± 2 nm were synthesized by thermal decomposition process and then their surfaces were modified with active vinyl groups. Two different monomers were immobilized onto the surfaces: dopamine methacrylamide, a monomer with properties inspired on mussels adhesive capacity, or unprotected glycomonomer, 2‐{[(D ‐glucosamin‐2N‐yl)carbonyl]‐oxy}ethyl methacrylate. Afterward, the glycomonomer were polymerized at the interface of both vinyl functionalized MNPs by conventional radical polymerization. The resultant hybrid NPs were water dispersible presenting good stability in aqueous solution for long time periods. Moreover, the high density of carbohydrates at the surface of the magnetic NPs could confer targeting properties to the system as demonstrated by studies of their binding interactions with lectins, where the binding activity is higher as the glycopolymer content augments. The magnetic and magneto‐thermal properties of the synthesized hybrid NPs were evaluated. The magnetization curves reveal superparamagnetic features at 300 K, with high values of saturation magnetization. Furthermore, the hybrid glycoparticles show suitable heat dissipation power when exposed to alternating magnetic field conditions. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Preparation and application of magnetic molecularly imprinted nanoparticles for the selective extraction of osthole in Libanotis Buchtomensis herbal extract

In this work, novel magnetic molecularly imprinted polymers were prepared for the selective extraction of osthole from Libanotis Buchtomensis herbal extract. During the synthesis process, double bonds grafted on the surface of Fe₃O₄ nanoparticles could not only drive the temple molecules to locate onto the surface of vinyl‐functionalized magnetic nanoparticles by π–π conjugation, which makes the distribution of binding sites ordered, but also direct the occurrence of imprinting polymerization at the surface of magnetic nanoparticles by the copolymerization of vinyl terminal groups with functional monomers and cross‐linking agent. The characteristics of the resulting polymers were evaluated by transmission electron microscopy, X‐ray diffraction, Fourier‐transform infrared spectroscopy, and vibrating sample magnetometry. Adsorption kinetics, isotherms, selectivity, reproducibility, and reusability were discussed, which suggest that the obtained nanomaterials possess rapid binding kinetics, high adsorption capacity of 17.65 mg/g, and favorable selectivity for the target molecule. Satisfactory reproducibility and reusability were verified as well. Meanwhile, the resultant imprinted nanoparticles were successfully applied to selectively separate osthole from the herbal extract, which show great potential in extracting active ingredients from traditional Chinese medicine.     

RAFT‐mediated synthesis of poly[(oligoethylene glycol) methyl ether acrylate] brushes for biological functions

The synthesis of poly[(oligoethylene glycol) methyl ether acrylate] [poly(OEGA)] brushes was achieved via reversible addition‐fragmentation chain transfer (RAFT) polymerization and used to selectively immobilize streptavidin proteins. Initially, gold surfaces were modified with a trithiocarbonate‐based RAFT chain transfer agent (CTA) by using an ester reaction involving a gold substrate modified with 11‐mercapto‐1‐undecanol and bis(2‐butyric acid)trithiocarbonate. poly(OEGA) brushes were then prepared via RAFT‐mediated polymerization from the surface‐immobilized CTA. The immobilization of CTA on the gold surface and the subsequent polymer formation were followed by ellipsometry, X‐ray photoelectron spectroscopy, grazing angle‐Fourier transform infrared spectroscopy, atomic force microscopy, and water contact‐angle measurements. RAFT‐mediated polymerization method gave CTA groups to grafted poly(OEGA) termini, which can be converted to various biofunctional groups. The terminal carboxylic acid groups of poly(OEGA) chains were functionalized with amine‐functionalized biotin units to provide selective attachment points for streptavidin proteins. Fluorescence microscopy measurements confirmed the successful immobilization of streptavidin molecules on the polymer brushes. It is demonstrated that this fabrication method may be successfully applied for specific protein recognition and immobilization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Polyethyleneimine‐Functionalized Platinum Nanoparticles with High Electrochemiluminescence Activity and Their Applications to Amplified Analysis of Biomolecules

Polyethyleneimine‐functionalized platinum nanoparticles (PtNPs) with excellent electrochemiluminescence (ECL) properties were synthesized and applied to the amplified analysis of biomolecules. These particles were prepared at room temperature, with hyperbranched polyethyleneimine (HBPEI) as the stabilizer. The UV/Vis absorption spectra and transmission electron microscopy images clearly confirmed the formation of monodisperse PtNPs. Such particles proved to possess high stability against salt‐induced aggregation, enabling them to be employed even under high‐salt conditions. Owing to the existence of many tertiary amine groups, these particles exhibited excellent ECL behavior in the presence of tris(2,2′‐bipyridyl)ruthenium(II). An HBPEI‐coated particle possessed an ECL activity that was at least 60 times higher than that of a tripropylamine molecule. Furthermore, these particles could be immobilized on the 3‐aminopropyltriethoxysilane‐treated quartz substrates to amplify the binding sites for carboxyl groups. Through this approach, PtNPs were applied to the amplified analysis of the hemin/G‐quadruplex DNAzyme by using the luminol/H₂O₂ chemiluminescence method.     

Synthesis of amphiphilic graft copolymer brush and its use as template film for the preparation of silver nanoparticles

A microphase‐separated, amphiphilic graft copolymer consisting of a poly (vinyl chloride) (PVC) backbone and poly(oxyethylene methacrylate) (POEM) side chains, (PVC‐g‐POEM at 62:38 wt %) was synthesized via atom transfer radical polymerization (ATRP). Nuclear magnetic resonance (¹H NMR), FTIR spectroscopy, and transmission electron microscopy (TEM) clearly revealed that the “grafting from” method using ATRP was successful and that the graft copolymer molecularly self‐assembled into discrete nanophase domains of continuous PVC and isolated POEM regions. The self‐assembled graft copolymer film was used to template the growth of silver nanoparticles in solid state by introducing a AgCF₃SO₃ precursor and a UV irradiation process. The in situ formation of silver nanoparticles in the graft copolymer template film was confirmed by TEM, UV–visible spectroscopy, and wide angle X‐ray scattering. FTIR spectroscopy and X‐ray photoelectron spectroscopy also demonstrated the selective incorporation and in situ formation of silver nanoparticles within the hydrophilic POEM domains, presumably due to strong interactions between the silver and the ether oxygen in POEM. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3911–3918, 2008     

Spinel copper ferrite nanoparticles: Preparation,characterization and catalytic activity

The magnetic CuFe₂O₄ nanoparticles have been synthesized and characterized by various spectroscopic methods, including X‐ray diffraction (XRD), O K, Cu and Fe K ‐edge X‐ray absorption near edge structure (XANES), energy dispersive X‐ray analysis (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The azide‐alkyne cycloaddition by the reaction of various phenylacetylenes with a mixture of benzyl halides and NaN₃ and also three component (A³) coupling reaction of aldehyde, alkyne and amine catalyzed by CuFe₂O₄ nanoparticles under aerobic conditions led to the formation of the 1,4‐disubstituted‐1,2,3‐triazoles and propargylamines in excellent yields. The catalyst can be recovered by applying an external magnetic field for the subsequent cycloaddition reactions and reused without any tangible loss in catalytic efficiency.     

Effect of Temperature on Thermal Treatment of Silica Coated Magnetic Nanoparticles

In the quest for developing a catalyst with as many desired characteristics, a facile synthetic route was designed for the preparation of mesoporous silica coated magnetic nanoparticles(MSMNP) employing a colloid mill reactor. The composite particles were characterized by the techniques, such as nitrogen adsorption-desorption isotherms, scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction patterns (XRD), thermo-gravimetric analysis(TGA), Fourier transform infrared spectroscopy(FTIR) and vibrating sample magnetometer(VSM), etc. The analysis showed that the resulted MSMNP composites were composed of silica shell layers with open pores connecting channels and NiFe₂O₄ with spinel structure, so the thermal treatment temperature did not show significant effect on pore textural properties, and its specific surface areas were in the range of 443-474 m²/g, while pore volume of about 0.8 cm³/g with an average pore size of around 9.5 nm. The composites with super paramagnetic nature were encapsulated entirely with amorphous silica layers contributing to optimum porosity and abundant surface hydroxyl groups.     

Synthesis and characterization of multiblock partially fluorinated hydrophobic poly(arylene ether sulfone)‐hydrophilic disulfonated poly(arylene ether sulfone) copolymers for proton exchange membranes

Hydrophobic‐hydrophilic sequence multiblock copolymers, based on alternating segments of phenoxide terminated fully disulfonated poly(arylene ether sulfone) (BPS100) and fluorine‐terminated poly(arylene ether sulfone) (6FBPS0) were synthesized and evaluated for application as proton exchange membranes. By utilizing mild reaction conditions the ether–ether interchange reactions were minimized, preventing the randomization of the multiblock copolymers. Tough, ductile, transparent membranes were solution cast from the block copolymers and were characterized with regard to intrinsic viscosity, morphology, water uptake, and proton conductivity. The conductivity values of the 6FBPS0‐BPSH100 membranes were compared to Nafion 212 and a partially fluorinated sulfonated poly(arylene ether sulfone) random copolymer (6F40BP60). The nanophase separated morphology was confirmed by transmission electron microscopy and small angle X‐ray scattering, and enhanced proton conductivity at reduced relative humidity was observed with longer block lengths. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013