Surface polyPEGylation of Eu3+ doped luminescent hydroxyapatite nanorods through the combination of ligand exchange and metal free surface initiated atom transfer radical polymerization

• Published in: Applied surface science 2017-03, Vol.399, p.499-505
• Main Authors: Zeng, Guangjian, Liu, Meiying, Heng, Chunning, Huang, Qiang, Mao, Liucheng, Huang, Hongye, Hui, Junfeng, Deng, Fengjie, Zhang, Xiaoyong, Wei, Yen
• Format: Article
• Language: English
• Subjects: Bioimaging applications; Ligand exchange reaction; Luminescent hydroxyapatite nanorods; Metal free ATRP; Photocatalysts
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2016.12.107

•Surface modification of HAp nanorods through the combination of ligand exchange reaction and metal free SI-ATRP.•HAp-polyPEGMA displayed high water dispersibility, good biocompatibility and biological imaging capability.•Metal free ATRP can overcome the toxic and fluorescence quenching effects of metal catalysts of conventional ATRP. The Eu3+ doped luminescent hydroxyapatite (HAp) nanorods with uniform size and morphology can be synthesized by hydrothermal route. However, these HAp nanorods are coated by hydrophobic oleylamine, which makes them difficult to be dispersed in aqueous solution and impede their biomedical applications. In this work, Eu3+ doped luminescent polymers functionalized HAp nanorods were prepared through the combination of ligand exchange reaction and metal free surface initiated atom transfer radical polymerization (ATRP) method. In this procedure, the amino group functionalized HAp nanorods were first prepared by ligand exchange reaction using adenosine monophosphate (AMP) as ligand. Then the Br-containing initiators (HAp-Br) were introduced onto the surface of HAp-AMP nanorods through the amidation reaction. Finally, polymers functionalized HAp nanorods were prepared by metal free ATRP method using poly(ethylene glycol) methacrylate (PEGMA) as monomer and 10-phenylphenothiazine (PTH) as organic photocatalyst. The properties of these obtained HAp nanocomposites (HAP-polyPEGMA nanorods) were characterized by means of transmission electron microscopy, Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis in detail. The cell imaging of these HAP-polyPEGMA nanorods was examined using laser scanning confocal microscope to evaluate their biomedical applications. We demonstrated for the first time that hydrophobic luminescent HAp nanorods can be functionalized with polyPEGMA through the combination of ligand exchange reaction and metal free surface initiated ATRP. As compared with the traditional ATRP, the metal free ATRP can overcome the toxic and fluorescence quenching effects of metal catalysts such as copper ions. More importantly, the strategy described in this work should also be utilized for fabrications of many other luminescent polymer nanocomposites due to its good monomer adoptability.