Biocompatible zwitterionic copolymer-stabilized magnetite nanoparticles: a simple one-pot synthesis, antifouling properties and biomagnetic separation.

A simple one-pot synthesis of biocompatible and antifouling magnetite nanoparticles (Fe 3 O 4 NPs) was developed. The process involves co-precipitation and in situ coating of zwitterionic copolymer poly[(methacrylic acid)- co -(2-methacryloyloxyethyl phosphorylcholine)] (PMAMPC). The influence of one-step and two-step coating methods on the performance of modified Fe 3 O 4 NP was investigated. The PMAMPC-Fe 3 O 4 NP with a narrow particle size distribution obtained from the two-step approach were highly stable in aqueous media within a wide range of pH. The particles exhibited superparamagnetic behavior with high saturation magnetization values so that they could be easily separated from solution by a magnet. Their antifouling characteristics against 2 selected proteins, lysozyme (LYZ) and bovine serum albumin (BSA), as a function of copolymer molecular weight and composition were also evaluated. Moreover, taking advantage of having carboxyl groups in the coated copolymer, the PMAMPC-Fe 3 O 4 NP were conjugated with a model biomolecular probe, biotin. The biotin-immobilized PMAMPC-Fe 3 O 4 NP were then tested for their specific capturing of a target molecule, streptavidin. The results have demonstrated the potential of PMAMPC-Fe 3 O 4 NP prepared by the two-step in situ coating method for probe immobilization and subsequent biomagnetic separation of target molecules. The fact that the developed functionalizable magnetite nanoparticles are biocompatible and antifouling also opens up the possibility of their use in other biomedical-relevant applications.