A supramolecular brush polymer via the self-assembly of bridged tris(β-cyclodextrin) with a porphyrin derivative and its magnetic resonance imaging

Abstract

Accurate imaging of soft tissues is one of the ultimate goals in biomedical imaging. Different imaging modalities can improve their disadvantages, and promote the imaging ability. However, once an imaging agent has been prepared, it is usually hard to adjust it according to the actual needs. Herein, we developed a supramolecular brush polymer (SBP) as a versatile imaging agent platform. The SBP platform (SBPP) is constructed by the intermolecular inclusion complexation of bridged tris(β-cyclodextrin) (1) with Mn(III)-porphyrin-bearing poly(ethylene glycol) (PEG) side chains (Mn(III)-TPP), and can further bind other functional groups by host–guest interactions of cyclodextrin and adamantine. The SBPP is characterized by UV/vis absorption spectroscopy, NMR, dynamic light scattering (DLS), atomic force microscopy (AFM) and transmission electron microscopy (TEM). We demonstrated that this SBPP not only has no cellular toxicity against NIH 3T3 cells in in vitro cell experiments, but it also shows an efficient enhanced T₁ relaxivity in in vitro MR imaging experiments. When used as multifunctional imaging agents, different imaging probes and/or targeting agents can be introduced to this SBPP as needed through simple host–guest interactions. In in vitro imaging experiments, it shows accurate imaging of different kinds of cancer cells by choosing on-demand targeting agents. These results suggest a promising strategy for engineering multifunctional imaging agents with SBPs.