Microwave-Induced Chemotoxicity of Polydopamine-Coated Magnetic Nanocubes

Polydopamine-coated FeCo nanocubes (PDFCs) were successfully synthesized and tested under microwave irradiation of 2.45 GHz frequency and 0.86 W/cm2 power. These particles were found to be non-toxic in the absence of irradiation, but gained significant toxicity upon irradiation. Interestingly, no increase in relative heating rate was observed when the PDFCs were irradiated in solution, eliminating nanoparticle (NP)-induced thermal ablation as the source of toxicity. Based on these studies, we propose that microwave-induced redox processes generate the observed toxicity

Synthesis and polymerization of 1-(2-diallylaminoethyl)pyrimidines

We report the preparation and characterization of three pyrimidine-based monomers, specifically: 1-(2-diallylaminoethyl)uracil, 1-(2-diallylaminoethyl)thymine and 1-(2-diallylaminoethyl)cytosine. Monomer synthesis was initiated by reaction of the pyrimidine with ethylene carbonate to form the hydroxyethyl adduct which was subsequently chlorinated to afford the chloroethyl intermediate. Reaction of the chloroethyl derivatives with diallylamine resulted in the desired monomers. We demonstrated a two-fold increase in the overall yield of the three monomers in comparison to reported procedures. The cyclopolymerization and cyclo-copolymerization of 1-(2-diallylaminoethyl)pyrimidine trifluoroacetate salts in water resulted in low-yield homopolymers. In contrast, the neutral 1-(2-diallylaminoethyl)pyrimidines cyclo-copolymerized with sulfur dioxide and V-50 initiator to yield the corresponding copolymers in higher yields ranging from 30 to 60%

Surface Modification of Multiwalled Carbon Nanotubes with Cationic Conjugated Polyelectrolytes: Fundamental Interactions and Intercalation into Conductive Poly(methyl methacrylate) Composites

This research investigates the modification and dispersion and of pristine multiwalled carbon nanotubes (MWCNTs) through a simple solution mixing technique based on noncovalent interactions between poly­(phenylene ethynylene)-based conjugated polyelectrolytes functionalized with cationic imidazolium solubilizing groups (PIM-2 and PIM-4) and MWCNTs. Spectroscopic studies demonstrated the ability of PIMs to strongly interact with and efficiently disperse MWCNTs in different solvents, mainly due to π interactions between the PIMs and the MWCNTs. Transmission electron microscopy and atomic force microscopy revealed the coating of the polyelectrolytes on the walls of the nanotubes. Scanning electron microscopy (SEM) studies confirm the homogeneous dispersion of PIM-modified MWCNTs in the poly­(methyl methacrylate) (PMMA) matrix. The addition of 1 wt % PIM-modified MWCNTs to the matrix has led to a significant decrease in DC resistivity of the composite (13 orders of magnitude). The increase in electrical conductivity and the improvement in the thermal and mechanical properties of the membranes containing the PIM-modified MWCNTs is ascribed to the formation of MWCNT networks and cross-linking sites that provided channels for the electrons to move in throughout the matrix and reinforced the interface between MWCNTs and PMMA

Synthesis, Cyclopolymerization and Cyclo-Copolymerization of 9-(2-Diallylaminoethyl)adenine and Its Hydrochloride Salt

We report herein the synthesis and characterization of 9-(2-diallylaminoethyl) adenine. We evaluated two different synthetic routes starting with adenine where the optimal route was achieved through coupling of 9-(2-chloroethyl)adenine with diallylamine. The cyclopolymerization and cyclo-copolymerization of 9-(2-diallylaminoethyl)adenine hydrochloride salt resulted in low molecular weight oligomers in low yields. In contrast, 9-(2-diallylaminoethyl)adenine failed to cyclopolymerize, however, it formed a copolymer with SO2 in relatively good yields. The molecular weights of the cyclopolymers were around 1,700–6,000 g/mol, as estimated by SEC. The cyclo-copolymer was stable up to 226 °C. To the best of our knowledge, this is the first example of a free-radical cyclo-copolymerization of a neutral alkyldiallylamine derivative with SO2. These polymers represent a novel class of carbocyclic polynucleotides

Dynamics and Mechanism of Intercalation/De-Intercalation of Rhodamine B during the Polymorphic Transformation of the CdAl Layered Double Hydroxide to the Brucite-like Cadmium Hydroxide

We studied the kinetics of intercalation of a fluorescent probe (rhodamine B (RhB)) during the formation of hierarchal microspheres of cadmium–aluminum layered double hydroxide (CdAlA LDH) and its de-intercalation upon transformation from the LDH phase into the cadmium hydroxide β phase (Cd­(OH)₂) using a reaction-diffusion framework (RDF) where the hydroxide anions diffuse into an agar gel matrix containing the proper salts–fluorescent probe mixture. In this framework, we achieved the stabilization of the CdAlA LDH, which is known to be thermodynamically unstable and transforms into Cd­(OH)₂ and Al­(OH)₃ in a short period. RDF is advantageous as it allows with ease the extraction of the cosynthesized polymorphs and their characterization using X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), solid-state nuclear magnetic resonance (SSNMR), Fourier transform infrared (FT-IR), and energy dispersive X-ray (EDX). The kinetics of inter/de-intercalation is studied using <i>in situ</i> steady-state fluorescence measurements. The existence of RhB between the LDH layers and its expel during the transition into the β phase are examined via fluorescence microscopy, XRD, and SSNMR. The activation energies of intercalation and de-intercalation of RhB are determined and show dependence on the cationic ratio of the corresponding LDH. We find that the energies of de-intercalation are systematically higher than those of intercalation, indicating that the dyes are stabilized due to the probe–brucite sheets interactions. SSNMR is used to shed light on the mechanism of intercalation and stabilization of RhB inside the layers of the LDH