To develop a suitable method for the mass production of polyaniline (PANI) nanofibers, the preparation of PANI nanofibers was carried out by high gravity chemical oxidative polymerization (HGCOP) in a rotating packed bed (RPB) for the first time. The influences of operating conditions, e.g., aniline concentration, high-gravity level, reaction temperature, and dopants, on the morphology of PANI nanofibers were investigated in detail. FTIR, UV−vis, XRD, molecular weight, and conductivity analyses were performed to characterize the products. Advantages of this new method are discussed. PANI nanofibers were successfully obtained in a wide range of aniline concentration (0.1−0.5 M) and reaction temperature (0−60 °C). The nanofibers kept small diameters of 30−50 nm and uniform morphology even when synthesized with a high initial aniline concentration of 0.5 M. This method provides a significant improvement to the rapid mixing route to prepare PANI nanofibers in large scale, moreover, it has potential applications in the synthesis of other conductive polymers.
Nitroxides have great potential as magnetic resonance imaging (MRI) contrast agents for tumor detection. Polyacetylenes(PAs) containing 2,2,6,6-tetramethyl-piperidine oxyl (TEMPO) and poly(ethylene glycol) were synthesized via metathesis polymerization of the corresponding substituted acetylenes to be used for targeted bimodal MRI /optical imaging of tumors. The poly(ethylene glycol) in the polyacetylenes enables covalent conjugation of carboxyl fluorescein and folic acid (FA) with hydroxyl groups to develop targeted multifunctional organic radical contrast agents (ORCAs). In vitro studies confirm the excellent binding specificity and subsequent enhanced cellular internalization of the targeted ORCAs (PA-TEMPO-FI-FA) without cytotoxicity. In vivo T1-weighted MRI demonstrates the active tumor targeting ability of PA-TEMPO-FI-FA to generate specific contrast enhancement in mice bearing HeLa tumors. Moreover, longitudinal optical imaging displays high tumor accumulation after 1 h post-injection of PA-TEMPO-FI-FA. These results indicate that multifunctional ORCAs may provide a tumor-targeted delivery platform for further molecular imaging guided cancer therapy.
A hypervalent iodine-promoted intermolecular diamination reactions of C60 with sulfamides or phosphoryl diamides affords two classes of novel C60-fused cyclic sulfamide or phosphoryl diamide derivatives. The reaction between C60 and sulfamides can be effectively controlled to selectively synthesize diamination products or azafulleroids under PhIO/I2 or PhI(OAc)2/I2 conditions, respectively. Moreover, phosphoryl diamides were first used as an amine source in the diamination of alkenes.
An I2-catalyzed hydroxylation of β-dicarbonyl moieties using air as the oxidant under photoirradiation has been developed for the easy preparation of α-hydroxy-β-dicarbonyl compounds. The transformation was completed with only 1 mol % of I2. With α-unsubstituted malonates, the hydroxylated dimerization product was afforded as the predominant product along with a minor product, α,α-dihydroxyl malonate.
Novel PPE nanoparticles self-assembled from amphiphilic poly(phenyleneethynylenes) would be a promising drug delivery system for therapeutic delivery and/or bioimaging.
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