Crosslinked chiral nanoparticles were successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) miniemulsion polymerization of 6-O-p-vinylbenzyl-1,2:3,4di-O-isopropylidene-D-galactopyranose (VBPG) using linear poly(VBPG) as the macro-RAFT agent. The polymerization of VBPG in the absence of crosslinker was first studied and the kinetic results showed that the molecular weights of the obtained poly(VBPG) increased linearly with the monomer conversion and was in good consistency with the corresponding theoretical ones while there remained a relative narrow polydispersity. The effect of the amount of crosslinker, divinylbenzene, on the nanoparticle size and chiral separation properties of the obtained nanoparticles were investigated in detail using four racemates 6-3-Amino-1,2propanediol, D,L-arabinose, D,L-tartaric acid, and D,L-mandelic acid.
Yellow CdS/wax nanocomposite spheres were fabricated in an aqueous solution by an emulsion method, in which the CdS nanoparticles were adsorbed on the surface of a wax core with positive charge by electrostatic self-assembly. A thin shell of SiO 2 was then coated to the yellow CdS/wax spheres by the hydrolysis of Na 2 SiO 3 in the same aqueous solution to enhance the optical and mechanical properties and the charge load of the composite spheres. The product was characterized by transmission electron microscopy, scanning electron microscope, atomic force microscopy, thermogravimetric analysis, and X-ray powder diffraction, which showed that the SiO 2 walls of spheres were compact and part of CdS crystals dispersed inside, the density of composite spheres being about 1.3 g/cm 3 , which match most of the suspensions. Fourier transform infrared spectroscopy, and energy dispersive X-ray spectrometry showed the component of composite spheres. Dynamic light scattering showed the diameter distribution of composite spheres was between 100∼400 nm. Zeta-potential measurement proved that the SiO 2 /CdS/wax spheres had a higher charge load, and Ultraviolet-visible spectra showed that the SiO 2 /CdS/wax spheres had a better optical property. Therefore, this type of composite spheres had the merits of low density and strong durability in environments. The response behavior of the microencapsulated electronic ink of the composite spheres has been measured. This novel method is expected to produce various inorganic/organic nanocomposite spheres with potential application in the fields of electronic paper and other material science.
Two chiral amphiphilic diblock copolymers with different relative lengths of the hydrophobic and hydrophilic blocks, poly(6‐O‐p‐vinylbenzyl‐1,2:3,4‐Di‐O‐isopropylidene‐D‐galactopyranose)‐b‐poly(N‐isopropylacrylamide) or poly(VBCPG)‐b‐poly(NIPAAM) and poly(20‐(hydroxymethyl)‐pregna‐1,4‐dien‐3‐one methacrylate)‐b‐poly(N‐isopropylacrylamide) or poly(MAC‐HPD)‐b‐poly(NIPAAM) were synthesized via consecutive reversible addition‐fragmentation chain‐transfer polymerizations of VBCPG or MAC‐HPD and NIPAAM. The chemical structures of these diblock copolymers were characterized by 1H nuclear magnetic resonance spectroscopy. These amphiphilic diblock copolymers could self‐assemble into micelles in aqueous solution, and the morphologies of micelles were investigated by transmission electron microscopy. By comparison with the lower critical solution temperatures (LCST) of poly(NIPAAM) homopolymer in deionized water (32 °C), a higher LCST of the chiral amphiphilic diblock copolymer (poly(VBCPG)‐b‐poly(NIPAAM)) was observed and the LCST increased with the relative length of the poly(VBCPG) block in the copolymer from 35 to 47 °C, respectively. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7690–7701, 2008
Doxorubicin (DOX) is a commonly used anticancer drug, but it is inefficient as a therapeutic due to a lack of targeting. Peptide-tuned self-assembly of DOX offers a strategy to improve targeting for greater efficacy. In this work, we designed and prepared an amphiphilic tumor cell-targeting peptide, P14 (AAAAFFFHHHGRGD), able to encapsulate DOX by self-assembly to form tumor cell-targeting and pH-sensitive nano-micelles. The results showed a critical P14-micelle concentration of 1.758 mg l−1 and an average particle size of micelles of 121.64 nm, with entrapment and drug-loading efficiencies of 28.02% ± 1.35% and 12.06% ± 0.59%, respectively. The prepared micelles can release 73.52 ± 1.27% DOX within 24 h in pH 4.5 medium, and the drug cumulative release profile of micelles can be described by the first-order model. Compared with free DOX, the micelles exhibited an increased ability to inhibit tumor cell growth and cause tumor apoptosis in vitro, with IC50 values of DOX and P14-DOX micelles against human breast cancer cells (MCF-7) of 0.91 ± 0.07 and 0.75 ± 0.06 μg ml−1, respectively, and cellular apoptotic rates of DOX and P14-DOX micelles of 70.3% and 42.4%, respectively. Cellular uptake experiments revealed high concentrations of micelles around and inside MCF-7 cells, demonstrating that micelles can target tumor cells. These results indicate the excellent potential for the application of this amphiphilic peptide as a carrier for small-molecule drugs and suggest a strategy for the design of effective anti-tumor drugs.
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