Physical-Chemical Coupling Coassembly Approach to Branched Magnetic Mesoporous Nanochains with Adjustable Surface Roughness.

Self-assembly processes triggered by physical or chemical driving forces have been applied to fabricate hierarchical materials with subtle nanostructures. However, various physicochemical processes often interfere with each other, and their precise control has remained a great challenge. Here, in this paper, a rational synthesis of 1D magnetite-chain and mesoporous-silica-nanorod (Fe 3 O 4 &mSiO 2 ) branched magnetic nanochains via a physical-chemical coupling coassembly approach is reported. Magnetic-field-induced assembly of magnetite Fe 3 O 4 nanoparticles and isotropic/anisotropic assembly of mesoporous silica are coupled to obtain the delicate 1D branched magnetic mesoporous nanochains. The nanochains with a length of 2-3 µm in length are composed of aligned Fe 3 O 4 @mSiO 2 nanospheres with a diameter of 150 nm and sticked-out 300 nm long mSiO 2 branches. By properly coordinating the multiple assembly processes, the density and length of mSiO 2 branches can well be adjusted. Because of the unique rough surface and length in correspondence to bacteria, the designed 1D Fe 3 O 4 &mSiO 2 branched magnetic nanochains show strong bacterial adhesion and pressuring ability, performing bacterial inhibition over 60% at a low concentration (15 µg mL -1 ). This cooperative coassembly strategy deepens the understanding of the micro-nanoscale assembly process and lays a foundation for the preparation of the assembly with adjustable surface structures and the subsequent construction of complex multilevel structures.