Synergistic Enhancement of Fluorescence and Magnetic Resonance Signals Assisted by Albumin Aggregate for Dual-Modal Imaging.

Dual-modal fluorescence and magnetic resonance imaging (FLI/MRI) is important for the early diagnosis of malignant tumors. However, facile and opportune strategies to synergistically enhance fluorescence intensity and magnetic resonance (MR) contrast have rarely been reported. Herein, we present a facile strategy using albumin aggregates (AAs) to synergistically enhance the fluorescence intensity by aggregation-induced emission (AIE) and MR contrast with prolonged rotational correlation time (τR) of Gd(III) chelates and the diffusion correlation time (τD) of surrounding water molecules. The amphiphilic dual-modal FLI/MRI probe of NGd was facilely loaded into albumin pockets and then formed AAs to generate a supramolecular structure of NGd-albumin aggregates (NGd-AAs), which show excellent biocompatibility and biosafety, and exhibit superior fluorescence quantum yield and r1 over NGd with 6- and 8-fold enhancement, respectively. Moreover, compared with the clinical MRI contrast agent Gd-DOTA, r1 of NGd-AAs showed a 17-fold enhancement. Therefore, NGd-AAs successfully elicited high-performance dual-modal FLI/MRI in vitro and in vivo and high contrast MR signals were observed in the liver and tumor after intravenous injection of NGd-AAs at a dosage of 6 μmol Gd(III)/kg body weight. This generic and feasible strategy successfully realized a synergistic effect for dual-modal FLI/MRI.