Functional nanoscale metal–organic particles synthesized from a new vinylimidazole-based polymeric ligand and dysprosium ions

Abstract

With nanoparticles (NPs) getting more and more crucial to various key technologies, it is essential to sustainedly develop new NPs with desirable functionalities. In this regard, nanoscale metal–organic particles (NMOPs) offer a competitive choice due to their highly tunable nature, whereas seeking new organic ligands (e.g. polymeric ones) represents a preferable research direction on NMOPs. With these points in mind, a water- and ethanol-soluble vinylimidazole-based polymer, poly[1-vinylimidazole-co-(poly(ethylene glycol) methacrylate)] (VI-co-PEGMA), was designed, synthesized, and demonstrated to be exactly such a new ligand. The formation of NPs through coordination-driven self-assembly of VI-co-PEGMA and dysprosium ions (Dy³⁺) was studied as functions of the molecular structure of VI-co-PEGMA, Dy³⁺ addition rate, mixing rate and duration, and Dy³⁺/VI-co-PEGMA feed ratio. The as-synthesized NPs exhibit bimodal dysprosium fluorescence and magnetism with a strong dependence on the coordinated Dy³⁺ contents. Moreover, these NPs may also possess guest loading capacity, as indicated by their amorphous nature and the high coordination number of Dy³⁺. By coating the NPs with silica shells, the resultant NP@silica materials further develop an anti-disassembling ability in aqueous media, which is absent from most of the NMOPs based on water-soluble ligands. An application demonstration performed using mouse L-929 cells shows that silica-coated NPs can act as bimodal magneto-fluorescent probes for cellular bioimaging. This work thus represents a meaningful attempt for the development of new functional NPs based on the existing NMOP strategy by using an elaborately designed polymer as the organic linker and Dy³⁺ as the metal center.