Preparation, Properties And Applications Of Functionalized Polyphosphazene Nanoparticles

Polyphosphazene is a kind of organic-inorganic hybrid polymer material, which hasa unique backbone structure with alternating single and double P-N bonds，bearing twoorganic side groups linked to the phosphorus atoms. Cross-linking polyphosphazenematerials are of great interest for researchers because of their excellent thermal stability,biocompatibility and tremendous flexibility to functionalize through chemicalmodification for various applications. Based on our group’s previous work, here wecombined the hexachlorocyclotriphosphazene molecule with fluorescein, magneticnanoparticles and thermal sensitive polymers to design and prepare functionalizedpolyphosphazene nano-materials with fluorescence, magnetism and thermal sensitivity,respectively. We analyzed their structure and performance, and explored their potentialapplications. The details are as follows:(1) Dibromofluorescein molecules were covalently fixed ontohexachlorocyclotriphosphazene to construct the highly cross-linked polyphosphazenenanopartices, thus can well overcome the concentration quenching effect. Themorphology of these particles was tuned via changing the preparation conditions, such assolvent, monomer concentration and molar ration. The synthesized nanoparticles havebright yellow fluorescence light even in solid state with the emission peak at560nm. Thefluorescent particles have high resistance to photobleaching, temperature, pH and proteindisturbing. Interestingly, the particles are of low cytotoxicity and can be therefore used asbiological labeling and imaging.(2) The core-shell structure of Fe3O4@PZS@pNIPAM nanoparticles with a layer ofthermal-sensitive p(N-isopropyl acrtylamide) polymer as the shell and superparamagneticFe3O4particles as the core were successfully synthesized. The particles have a magnetic saturation value of32.7emu/g. They can be used in protein adsorption: the proteins tendto adsorpt onto the surface of nanoparticles at pH4.8and above37℃(the maximumadsorption quantity is258mg/g), but are inclined to desorpt under30℃in alkalinesolution (residual amount is about38mg/g).(3) Fe3O4colloidal nanocrystal clusters (CNCs) assembled into one dimensionalnanochains with the induction of the applied magnetic field, and then coated with across-linked polyphosphazene (PZS) layer via a facile one-pot reaction at the same time.The resulting Fe3O4@PZS nanochains are stable in structure. The thickness of the PZSlayer can be easily adjusted by changing the amount of PZS monomers and Fe3O4clusters. The length of nanochains can also be tuned via control the magnetic fieldinduction time. The nanochains showed a high magnetic saturation value, goodthermostability and superparamagnetism. They have potential applications as MRIcontrast agent, magnetic stir and separation.