| Nanoparticles have been widely used in magnetic resonance imaging (MRI),photo-thermal therapy, catalysis, sensing and other researches owing to their uniquemagnetic, optical and electrical properties.However, it is still a challenge for nanoparticles to meet all the practice demands,tailored surface chemistry, biocompatibility, physical/chemical stability, highperformance, and multi-functionality. The composite nanoparticles prepared bynano-assembly, surface coating and hybridization usually can not only preserve theunique properties of each nanocomponents, but also realize high performance andmulti-functionalities due to the quantum coupling and synergistic effect. In this article,we combined the polyphosphazene (PZS) with magnetic nanoparticles, goldnanoparticles, fluorescein or porphyrin to prepare functionalized PZS nano-materialswith magnetic, photo-thermal and fluorescent properties. And we also explored theirapplications in MRI, photo-thermal therapy and fluorescence detection. The detailsare as follows:(1) Highly cross-linked and biocompatible PZS were used to directly coathydrophilic superparamagnetic Fe3O4nanoparticles by a facile but effective one-potpolymerization. The size and magnetic properties of Fe3O4@PZS nanoparticles can becontrolled by adjusting the mass ratio of Fe3O4and PZS. PZS not only stabilize themagnetic nanoparticles, but also endow them with excellent water dispersibility.Interestingly, the particles are of low cytotoxicity and can be therefore used as anefficient MRI contrast agents.(2) Multifunctional nanoparticles were prepared by directly weldingsuperparamagnetic Fe3O4nanoparticles and Au shells together with highly cross-linked PZS as “glue” in a facile but effective way. The thickness of Au shellsand plasma resonance absorption performance can be controlled by the concentrationof HAuCl4. The as-prepared particles can simultaneously take advantages of bothmagnetization of Fe3O4core for magnetic resonance imaging diagnosis and strongnear-infrared absorption of Au nano-shell for photo-thermal therapy.(3) To improve the MRI property of Fe3O4nanoparticles, we used branchedcarboxylate type phosphazene molecules as stabilizer and pore-foaming agent andprepared Zn2+doped Fe3O4nano-cluster. The effects of concentration of doping agentZn2+(x) on the MRI performance of as-prepared ZnxFe1-xFe2O4nanoparticles wereinvestigated. It was found that the concentration of doping agent Zn2+x=0.41gavethe ZnxFe1-xFe2O4nanoparticle best magnetic performance and thereby best MRIperformance. Meanwhile the Zn0.41Fe0.49Fe2O4nanoparticle possessed mesoporousstructure with a specific surface area of239.2m2/g. It was noted that the high specificsurface area and Electrostatic interaction are beneficial for efficient load ofanti-cancer drug Doxorubicin (DOX). The drug loading ratio of DOX reached40.8%,and the release process of DOX exhibited pH-responsive behavior.(4) The dibromofluorescein (DBF) molecules were covalently fixed ontohexachlorocyclotriphosphazene (HCCP) to construct the highly cross-linked PZSnanoparticles, thus can well overcome the concentration quenching effect. Thefluorescent nanoparticles with solid state luminescence performance have excellentthermal stability and high resistance to photo-bleaching and were responsive to pHand dopamine. Thereby it is promising to use these nanoparticles as di-functionalprobe for pH and dopamine. Also a series of PZS nanoparticles with solid stateluminescence performance were obtained through reaction of HCCP with differentfluorescent molecules.(5) The porphyrin-PZS nanoparticles can be synthesized by fastening the porphyrinmolecules into a stable cross-linked PZS structure. The molecular arrangement of theporphyrin and morphology of these particles were tuned via changing the preparation condition, such as solvent. The porphyrin-PZS nanoparticles prepared in acetone havered fluorescence light and high resistance to photo-bleaching. Interestingly, thenanoparticles exhibit high sensitivity and selectivity for detecting Hg2+ions. |
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