One-step microwave preparation of well-defined and functionalized polymeric nanoparticles

Well-defined colloidal polymeric nanoparticles are important in advanced biomedical and optical technologies. We report a facile microwave methodology to prepare narrowly dispersed cross-linked polymeric nanoparticles at high solids content through a surfactant-free emulsion polymerization process. The nanoparticle size was controlled by using cross-linkers with enhanced reactivity through a one-step microwaving process, significantly simplifying the nanoparticle synthetic process. The successful size control was realized by confining the cross-linking to intraparticle cross-linking rather than interparticle cross-linking. We also discovered that the superheating/dielectric heating effect associated with microwave irradiation could be utilized to effectively reduce the nanoparticle size.     

Inverse miniemulsion ATRP: a new method for synthesis and functionalization of well-defined water-soluble/cross-linked polymeric particles

A new methodology for the synthesis and functionalization of nanometer-sized colloidal particles consisting of well-defined, water-soluble, functional polymers with narrow molecular weight distribution (M(w)/M(n) < 1.3) was developed, utilizing atom transfer radical polymerization (ATRP) of water-soluble monomers in an inverse miniemulsion. The optional introduction of a disulfide-functionalized cross-linker allowed for the synthesis of cross-linked (bio)degradable nanogels. Dynamic light scattering (DLS) and atomic force microscopy (AFM) measurements indicated that these particles possessed excellent colloidal stability. ATRP in inverse miniemulsion led to materials with several desirable features. The colloidal particles preserved a high degree of halogen chain-end functionality, which enabled further functionalization. Cross-linked nanogels with a uniformly cross-linked network were prepared. They were degraded to individual polymeric chains with relatively narrow molecular weight distribution (M(w)/M(n) < 1.5) in a reducing environment. Higher colloidal stability, higher swelling ratios, and better controlled degradability indicated that the nanogels prepared by ATRP were superior to their corresponding counterparts prepared by conventional free radical polymerization (RP) in inverse miniemulsion.     

Factors affecting the synthesis of polymeric nanostructures from template assisted admicellar polymerization

Template assisted admicellar polymerization (TAAP) utilizes a surfactant layer adsorbed on a surface to localize a monomer to the surface prior to polymerization of the monomer. Nanostructures are formed by restricting adsorption to the uncovered sites of an already-templated surface, in this case, to the interstitial sites between adsorbed latex spheres. This work studies the factors affecting the synthesis of polymeric nanostructures from TAAP for three different monomers, aniline, pyrrole, and methyl methacrylate, and three different surfaces, highly ordered pyrolytic graphite (HOPG), gold, and SiO2. Among the parameters discussed are the effects of monomer and surfactant concentration, surfactant chain length, polymerization time and temperature, and solution ionic strength. Control of the aforementioned parameters allows some control over the nanostructure morphology. Polymer nanopillars, nanorings, honeycombs, and "honeytubes" have been synthesized. Important conclusions regarding the conditions favoring admicellar polymerization relative to polymerization in solution are drawn from the experimental results as well. Sample characterization includes scanning electron microscopy (SEM), Raman spectroscopy, and alternating current (ac) impedance measurements.     

Greener synthesis of new ammonium ionic liquids and their potential as extracting agents

New hydrophobic ionic liquids were synthesized from tricaprylmethylammonium chloride (Aliquat 336^©) and selected Bronsted acids by a sustainable, simple and cost-saving deprotonation-metathesis route. Prepared ionic liquids were evaluated as potential extracting agents for cadmium from different aqueous solutions. High efficiency and selectivity were reached for the extraction of cadmium from a natural river matrix with tricaprylmethylammonium thiosalicylate, [A336][TS], a thiol-containing task specific ionic liquid.     

Neuron cells uptake of polymeric microcapsules and subsequent intracellular release

Neuron cells uptake of biodegradable and synthetic polymeric microcapsules functionalized with aggregates of gold nanoparticles incorporated into their shells is demonstrated in situ. In addition to traditionally used optical microscopy, electron microscopy is used both for higher-resolution imaging and for confirming the uptake by focused ion beam cross-sectioning of specific cells in situ. Subsequently, physical methods of release are compared to chemical methods wherein laser-induced intracellular release of dextran molecules into the cytosol of hippocampal neuron cells is studied in comparison to biodegradation. Implications of this work for neuroscience, bio-medicine and single cell studies are discussed.     

Microfluidic-based nanoparticle synthesis and their potential applications

A lot of substantial innovation in advancement of microfluidic field in recent years to produce nanoparticle reveals a number of distinctive characteristics, for instance, compactness, controllability, fineness in process, and stability along with minimal reaction amount. Recently, a prompt development, as well as realization in the production of nanoparticles in microfluidic environment having dimension of micro to nanometers and constituents extending from metals, semiconductors to polymers, has been made. Microfluidics technology integrates fluid mechanics for the production of nanoparticles having exclusive with homogenous sizes, shapes, and morphology, which are utilized in several bioapplications such as biosciences, drug delivery, and healthcare including food engineering. Nanoparticles are usually well-known for having fine and rough morphology because of their small dimensions including exceptional physical, biological, chemical, and optical properties. Though the orthodox procedures need huge instruments, costly autoclaves, use extra power, extraordinary heat loss, as well as take surplus time for synthesis. Additionally, this is fascinating to systematize, assimilate, in addition, to reduce traditional tools onto one platform to produce micro and nanoparticles. The synthesis of nanoparticles by microfluidics permits fast handling besides better efficacy of method utilizing the smallest components for process. Herein, we will focus on synthesis of nanoparticles by means of microfluidic devices intended for different bioapplications.     

Kumada chain-growth polycondensation as a universal method for synthesis of well-defined conjugated polymers

Kumada chain-growth polycondensation (KCGP) is a novel method for the synthesis of well-defined conjugated polymers. Because the Ni-catalyst can transfer in an intramolecular process to the propagating chain end, the polymerization follows chain-growth mechanism. With this newly developed method, various conjugated polymers, such as polythiophenes, poly(p-phenylene) (PPP), polypyrrole (PPy), and polyfluorene with controlled molecular weights and relatively narrow polydispersities (PDIs), have been prepared. Especially, the polymerizations for poly(3-alkylthiophene)s (P3ATs), PPP, and PPy exhibited quasi-living characteristics, which allows preparing polymer brushes, fully-conjugated block copolymers, and macroinitiators and macro-reactants for the synthesis of rod-coil block copolymers. In the current review, the progress in this new area is summarized.     

Microwave assisted organic synthesis (MAOS) of small molecules as potential HIV-1 integrase inhibitors

Integrase (IN) represents a clinically validated target for the development of antivirals against human immunodeficiency virus (HIV). In recent years our research group has been engaged in the stucture-function study of this enzyme and in the development of some three-dimensional pharmacophore models which have led to the identification of a large series of potent HIV-1 integrase strand-transfer inhibitors (INSTIs) bearing an indole core. To gain a better understanding of the structure-activity relationships (SARs), herein we report the design and microwave-assisted synthesis of a novel series of 1-H-benzylindole derivatives.     

Lipase-catalysed one-pot synthesis of thiazole-based Betti bases and their evaluation as potential cholinesterase inhibitors

Research on Chemical Intermediates - A series of 1-[aryl-(thiazol-2-ylamino)-methyl]-naphthalen-2-ol derivatives were synthesized using porcine pancreatic lipase as a catalyst. The major assets of...     

Protein-assisted synthesis of double-shelled CaCO3 microcapsules and their mineralization with heavy metal ions

Calcium carbonate (CaCO(3)) is one of the most abundant and important biominerals in nature. Due to its biocompatibility, biodegradability and nontoxicity, CaCO(3) has been investigated extensively in recent years for various fundamental properties and technological applications. Inspired by basic wall structures of cells, we report a protein-assisted approach to synthesize CaCO(3) into a double-shelled structural configuration. Due to varying reactivities of outer and inner shells, the CaCO(3) microcapsules exhibit different sorption capacities and various resultant structures toward different kinds of heavy metal ions, analogical to biologically controlled mineralization (BCM) processes. Surprisingly, three mineralization modes resembling those found in BCM were found with these bacterium-like "CaCO(3) cells". Our investigation of the cytotoxicity (MTT assay protocol) also indicates that the CaCO(3) microcapsules have almost no cytotoxicity against HepG2 cells, and they might be useful for future application of detoxifying heavy metal ions after further study.     

Use of alcohols as reducing agents for synthesis of well-defined polymers by AGET-ATRP

Alcohols have been demonstrated to be efficient reducing agents for AGET-ATRP for the first time. Well-controlled polymerizations have been successfully achieved with the typical characteristics of "living"/controlled radical polymerization.     

Microwave assisted synthesis of substituted furan-2-carboxaldehydes and their reactions

A series of 5-unsubstituted and 5-substituted furfurylidenes have been prepared, under thermal and non-thermal microwave irradiation methods, via condensation of furfural and its derivatives with some of active methylene compounds. Furthermore, various condensate products from these furfurylidenes, which contain halogen or sulpher atoms, were also prepared. Structural elucidation of the synthesized compounds were determined on the basis of various spectroscopic methods.     

Solid-phase synthesis of graphitic carbon nanostructures from iron and cobalt gluconates and their utilization as electrocatalyst supports

We present a novel and facile synthesis methodology for obtaining graphitic carbon structures from Fe(II) and Co(II) gluconates. The formation of graphitic carbon can be carried out in only one step by means of heat treatment of these organic salts at a temperature of 900 degrees C or 1000 degrees C under inert atmosphere. This process consists of the following steps: (a) pyrolysis of the organic gluconate and its transformation to amorphous carbon, (b) conversion of Fe(2+) and Co(2+) ions to Fe(2)O(3) and CoO and their subsequent reduction to metallic nanoparticles by the carbon and (c) conversion of a fraction of formed amorphous carbon to graphitic structures by Fe and Co nanoparticles that act as catalysts in the graphitization process. The removal of the amorphous carbon and metallic nanoparticles by means of oxidative treatment (KMnO(4) in an acid solution) allows graphitic carbon nanostructures (GCNs) to be selectively recovered. The GCNs thus obtained (i.e. nanocapsules and nanopipes) have a high crystallinity as evidenced by TEM/SAED, XRD and Raman analysis. In addition, we used these GCNs as supports for platinum nanoparticles, which were well dispersed (mean Pt size approximately 2.5-3.2 nm). Most electrocatalysts prepared in this way have a high electrocatalytical surface area, up to 90 m(2) g(-1) Pt, and exhibit high catalytic activities toward methanol electrooxidation.     

Direct synthesis of branched gold nanocrystals and their transformation into spherical nanoparticles

We report a facile synthesis of branched gold nanocrystals by the addition of a suitable amount of NaOH to an aqueous solution of cetyltrimethylammonium bromide (CTAB), HAuCl(4), and ascorbic acid. The branched nanocrystals were formed within minutes of reaction and showed monopod, bipod, tripod, and tetrapod structures. They are crystalline and have smooth surfaces. These gold multipods are kinetically controlled products and are thermodynamically unstable. The branched nanocrystals quickly transformed into spherical nanoparticles within 1 h of reaction, and the process was essentially complete after 2 days. The morphological transformation has been monitored by both UV-vis absorption spectroscopy and electron microscopy. The appearance of two major absorption bands for the branched gold nanocrystals eventually became only a single band at 529 nm for the spherical nanoparticles. The resulting nanoparticles are single crystals with diameters of 20-50 nm and do not show a faceted structure. When the freshly prepared branched nanocrystals are kept in a refrigerator at 4 degrees C, their multipod structure can be preserved for over a month without significant spectral shifts.     

Nanoassembly of biocompatible microcapsules for urease encapsulation and their use as biomimetic reactors

Biocompatible polypeptide capsules with high enzyme loading and activity prepared by templating mesoporous silica spheres were used as biomimetic reactors for performing CaCO3 synthesis exclusively inside the capsule interior via urease-catalyzed urea hydrolysis.     

Nanostructuring of a polymeric substrate with well-defined nanometer-scale topography and tailored surface wettability

This study demonstrates a simple and highly reproducible method for fabricating well-defined nanostructured polymeric surfaces with aligned nanoembosses or nanofibers of controllable aspect ratios, showing remarkable structural similarity with interesting natural biostructures such as the wing surface of Cicada orni and the leaf surface of Lotus. Our studies on the present biomimetic surfaces revealed that the wetting property of the nanostructured surface of a given chemical composition could be systematically controlled by rendering nanometer-scale roughness. The nanofabricating method we developed can be readily extended to other thermoplastic polymeric materials (e.g., light-emitting polymers, conducting polymers, block copolymers, liquid crystalline polymers), and it could be applied to developing a new generation of optical and electronic devices.     

An efficient microwave assisted synthesis of novel class of Rhodanine derivatives as potential HIV-1 and JSP-1 inhibitors

(Z)-5-(2-(1H-Indol-3-yl)-2-oxoethylidene)-3-phenyl-2-thioxothiazolidin-4-one (7a-q) derivatives have been synthesized by the condensation reaction of 3-phenyl-2-thioxothiazolidin-4-ones (3a-h) with suitably substituted 2-(1H-indol-3-yl)-2-oxoacetaldehyde (6a-d) under microwave condition. The thioxothiazolidine-4-ones were prepared from the corresponding aromatic amines (1a-e) and di-(carboxymethyl)-trithiocarbonyl (2). The aldehydes (6a-h) were synthesized from the corresponding acid chlorides (5a-d) using HSnBu₃.     

Pd-mediated new synthesis of pyrroles: their evaluation as potential inhibitors of phosphodiesterase 4

A sequential Pd-mediated multi-component reaction followed by Suzuki or Heck or Sonogashira coupling in a single pot has been developed for the synthesis of functionalized pyrroles as potential inhibitors of PDE4.     

Synthesis of well-defined polymers with protected silanol groups by atom transfer radical polymerization and their use for the fabrication of polymeric nanoparticles

Copper-mediated atom transfer radical polymerization (ATRP) of a protected silanol group-holding methacrylate, methacryloxypropyltrimethoxysilane (MOPS), was investigated. In a dry condition using carefully distilled solvent and monomer, the polymerization proceeded in a living fashion providing a low-polydispersity polymer with a predicted molecular weight. The ATRP in conjunction with the sequential monomer addition of methyl methacrylate (MMA) and MOPS afforded a block copolymer of the type PMMA-b-poly(MMA-r-MOPS). The heat treatment of a solution of the block copolymer in the presence of a catalytic amount of ammonia gave a polymeric core-shell nanoparticle with a shell of PMMA moieties and a core of the poly(MMA-r-MOPS) blocks cross-linked via the condensation of the trimethoxysilane groups of the MOPS moieties.