Lilin Zhou

Core–shell structural iron oxide hybrid nanoparticles: from controlled synthesis to biomedical applications

Superparamagnetic iron oxide nanoparticles have received great research attention due to their wide spectrum of potential applications. Core–shell structures with iron oxide nanoparticles as the core and with covalently grafted organic polymers as the shell, which has specific functions, such as biocompatibility, fluorescence, and biological activity have been synthesised. These nanostructured compounds could find numerous biomedical applications. This feature article provides a review on the synthetic methodologies for building such magnetic core–shell structures, and on their applications in targeted drug delivery, enhanced magnetic resonance imaging (MRI), enzyme immobilization, hyperthermia and biosensors. Promising future directions of this active research field are also discussed.

β-Cyclodextrin-modified hybrid magnetic nanoparticles for catalysis and adsorption

β-Cyclodextrin-modified hybrid magnetic nanoparticles (Fe3O4@SiO2-PGMACD) were synthesized via the combination of atom transfer radical polymerization on the surfaces of silica coated iron oxide particles (Fe3O4@SiO2) and ring-opening reaction of epoxy groups. The feasibility of using Fe3O4@SiO2-PGMACD as separable immobilized catalyst and adsorbent was demonstrated. It was found: (1) the prepared Fe3O4@SiO2-PGMACD could be used as catalyst in substrate-selective oxidation of alcohols system and the catalytic efficiency was close to pure β-Cyclodextrin of equal quantity; (2) the resulting particles appeared remarkably dominant adsorption capacity compared with poly(glycidyl methacrylate) grafted magnetic nanoparticles (Fe3O4@SiO2-PGMA) in the removal of bisphenol A from aqueous solutions. The results suggest that the novel fabricated nanoparticles could serve as bifunctional materials in catalysis or adsorption and subsequently become potential multifunctional materials.

Facile and Efficient Fabrication of Photoresponsive Microgels via Thiol–Michael Addition

A photoresponsive microgel is designed by the combination of a noncovalent assembly strategy with a covalent cross-linking method. End-functionalized poly(ethylene glycol) with azobenzene [(PEG-(Azo)(2))] was mixed with acrylate-modified β-CD (β-CD-MAA) to form photoresponsive inclusion complex through host-guest interaction. The above photoresponsive complex was cross-linked by thiol-functionalized PEG (PEG-dithiol) via Michael addition click reaction. The photoreversibility of resulted microgel was studied by TEM, UV-Vis spectroscopy, and (1)H NMR measurements. The characterization results indicated that the reversible size changes of the microgel could be achieved by alternative UV-Vis irradiations with good repeatability.

Evaluation of effect of magnetostriction on residual stress relief by pulsed magnetic treatment

Abstract Previous studies have considered magnetostriction to be the essential factor causing residual stress changes during pulsed magnetic treatment. In the present study, magnetostriction was measured and recorded, and it was found that the shift of strain in magnetic treatment was in the elastic range. Also, residual stresses were measured to determine whether a greater amplitude of magnetostriction would lead to increased stress relief. The experimental results show that there was a range of intensity of magnetic field suitable for reducing residual stresses. Outside this range, the stress would remain steady, or even rise. Since the magnetostriction altered little after magnetic saturation while the effects of residual stress relief differed markedly, mode of dislocation movement in the magnetic field was suggested to be an important factor affecting stress relief besides magnetostriction in pulsed magnetic treatment.