Mussels exhibit robust adhesion capability with varied materials mainly due to the strong affinity of catechol moieties in their adhesive proteins. Nanoscale ionic materials (NIMs) are special organic inorganic hybrid materials comprising a charged oligomer corona attached to inorganic nanoparticle cores, which can behave from glassy solids to liquids in the absence of any solvent. Herein, Fe3O4 nano-scale ionic materials (NIMs) exhibiting inorganic-organic core-shell structure and liquid-like behavior were obtained by using a mussel-inspired bifunctional ligand of 3,4-dihydroxybenzenepropanoic acid (DHPA), which could link Fe3O4 nanoparticles core and cationic organic shell, respectively. A simplified one-step aqueous co-precipitation method to prepare DHPA decorated Fe3O4 nanoparticles is developed, which shows advantages in productivity and is more environmental friendly compared with the traditional core preparation first and then surface modification. This research proposes a simple and effective approach to obtain solvent-free NIMs with tailorable core-shell structure using versatile adhesion of mussel mimetic adhesives and various available ion pairs. (C) 2018 Elsevier Inc. All rights reserved.