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Recently, biotin (vitamin H) has been described as a ligand for active targeting and it has been found that many cancer cells overexpress the biotin receptor. In this study a biotin‐conjugated block copolymer, biotin‐poly(2‐ethyl‐2‐oxazoline)‐block‐poly{N '‐[N‐(2‐aminoethyl)‐2‐aminoethyl]aspartamide} (biotin‐pEtOx‐b‐pASP(DEA) is synthesized by a living cationic polymerization of the pEtOx‐block followed by the nucleophilic ringopening polymerization of the pASP‐block. The biotin moiety is coupled to the pEtOx‐b‐pASP precursor by a Cu(I) mediated azide‐alkyne click chemistry and finally, the diethylamine (DEA) side chain is introduced by a polymer analogous reaction. The final polymer P1 formed polyplexes in the presence of plasmid DNA that are characterized with respect to N/P ratio, size, zeta potential, and shape compared to a control polymer P2 without biotin. In addition, HEK293 cells are transfected with these polyplexes and the number of fluorescent HEK293 cells is evaluated to assess the influence of polymer nature on the activity of the micelles. Flow cytometric analysis revealed a significantly higher uptake of the biotin‐PEtOx‐PASP(DEA)/pDNA micelle than the PEtOx‐PASP(DEA)/pDNA micelle against HEK293 cells at a low N/P ratio of 20, consistent with the transfection results whereas at higher N/P ratio no difference can be observed anymore between the two polymers. [ABSTRACT FROM AUTHOR]

Herein, the synthesis of three different macromolecular DO3A@Gn conjugates based on poly(2‐oxazoline)s is presented. Therefore, poly(2‐methyl‐2‐oxazoline) is synthesized by a ring‐opening, cationic polymerization and the polymerization is terminated with DO3A(tBu)3. The best results are obtained after 48 h at 120 °C with degree of termination of 86%. After deprotection of the DO3A ligand and complexation with Gn3+, relaxivity as measured with a magnetic field strength of 9.4 T (400 MHz) reveals values for r1 of up to 2.32 mm−1 s−1. The concept is extended to a block copolymer based on 2‐heptyl‐2‐oxazoline and 2‐methyl‐2‐oxazoline that is again terminated with DO3A(tBu)3 to form micelles with a size of 12.6 ± 0.7 nm after DO3A(tBu)3 termination and deprotection of the 1,4,7,10‐tetraazacyclododecane‐N,N,N,N‐tetraacetic acid ligand. After complexation with Gn3+, relaxivity r1 is 10.1 mm−1 s−1 as determined from the slope of the plot of 1/T1 against the gadolinium(III) concentration at 9.4 T. Finally, crosslinked nanoparticles are prepared from amphiphilic macro‐monomers that form micelles in water and are crosslinked throughout the core in the presence of azoisobutyronitrile (AIBN). The nanoparticle is 32.9 ± 7.8 nm in size after Gn3+ complexation and reveals a relaxivity r1 of 6.77 mm−1 s−1. [ABSTRACT FROM AUTHOR]

We report on the synthesis of core–shell microparticles (CSMs) with an acid catalyst in the core and a base catalyst in the shell by surfactant‐free emulsion polymerization (SFEP). The organocatalytic monomers were separately copolymerized in three synthetic steps allowing the spatial separation of incompatible acid and base catalysts within the CSMs. Importantly, a protected and thermo‐decomposable sulfonate monomer was used as acid source to circumvent the neutralization of the base catalyst during shell formation, which was key to obtain stable, catalytically active CSMs. The catalysts showed excellent performance in an established one‐pot model cascade reaction in various solvents (including water), which involved an acid‐catalyzed deacetalization followed by a base‐catalyzed Knoevenagel condensation. The CSMs are easily recycled, modified, and their synthesis is scalable, making them promising candidates for organocatalytic applications. [ABSTRACT FROM AUTHOR]

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Here, we report the first polymer resin supported Cu(I)/bipyridine/ N-oxyl catalyst systems for the aerobic oxidation of alcohols at room temperature with ambient air. We chose polystyrene-poly(ethylene glycol) copolymer (TentaGel®) and Merrifield resin as support materials because of their different swelling properties in polar and nonpolar solvents. The bromo functionalized TentaGel resin TG1 or Merrifield resin MR1 were functionalized with 4,4′-dimethoxy-2,2′-bipyridine (MeObpy) to give the ligand modified polymer resin TG2/MR2 that was loaded with CuI(Br) to give the final CuI(Br)/bipyridine support TG3/MR3. These resins were characterized by Fourier transform infrared, SEM, SEM energy dispersive X-ray spectroscopy and elemental analysis. Catalytic activity and recyclability of TG3 was investigated in acetonitrile and cyclohexane and displayed high activities in acetonitrile but also high metal leaching. In cyclohexane as solvent leaching was reduced to 1% − 2%, and catalytic activity was still at 75% after the fifth run. MR3 was consequently tested in cyclohexane and toluene. In both solvents low metal leaching was observed with higher activity in toluene as solvent, showing still over 90% conversion after the seventh run with 9-azabicyclo[3.3.1]nonane N-oxyl (ABNO) and 80% with 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO). © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]