Due to their properties such as superparamagnetism, high surface area, large surface-to-volume ratio, easy separation under external magnetic fields, iron magnetic nanoparticles have attracted much attention in the past few decades. Various modification methods have been developed to produce biocompatible magnetic nanoparticles for protein immobilization. This review provides an updated and integrated focus on the fabrication and characterization of suitable magnetic iron nanoparticle-based nano-active materials for protein immobilization.

During the past few years, nanoparticles have been used for various applications including, but not limited to, protein immobilization, bioseparation, environmental treatment, biomedical and bioengineering usage, and food analysis. Among all types of nanoparticles, superparamagnetic iron oxide nanoparticles, especially Fe₃O₄, have attracted a great deal of attention due to their unique magnetic properties and the ability of being easily chemical modified for improved biocompatibility, dispersibility. This review covers recent advances in the fabrication of functional materials based on Fe₃O₄ nanoparticles together with their possibilities and limitations for application in different fields.

We successfully synthesized two new metal coordination polymers [Cd3(bdc)3(L)3(H2O)3]n (1) and [Co(tda)(L)]n (2) (H2bdc = 1,2-benzenedicarboxylic acid, H2tda = 2,5-thiophendicarboxylic acid, and L = 3,5-bis(benzimidazol-1-yl)pyridine), which were then characterized by IR, and elemental, X-ray powder diffraction, and X-ray single-crystal diffraction analysis. Complex 1 possesses a uninodal three-connected hcb Shubnikov hexagonal plane net with {63} topology. Complex 2 features a three-connected topological net with {82·10} topology (so-called ‘tongue-and-groove’ structure). A typical T-shaped molecular bilayer motif, which has rarely been reported previously, was successfully constructed by strategically selecting H2tda as the second ligand. In addition, the solid-state photoluminescent spectra of 1 and 2 were measured at room temperature.