Effect of Zwitterionic Surfactant Ligand Monolayer on Magnetic Hyperthermia Properties of Monosize Fe3O4 Nanoparticles

Abstract

Here Brown relaxation time was altered to enhance magnetic hyperthermia value. Narrow size distributed, hydrophobic Fe3O4 nanoparticles were synthesized by solvothermal reflux method. It is reported that the existing both single step and two-step ligand exchange protocols could not replace hydrophobic surfactant ligand completely. Hence, as-synthesized samples were transferred into hydrophilic by completely removing the hydrophobic surfactant on the nanoparticles by high polar ionic liquids and ligated short-chain bidentate zwitterionic dopamine sulfonate on nanoparticles surface. The short molecules will fast up the Brown relaxation time compared to long molecule surfactant such as polyethylene glycol (PEG). The resultant sample shows magnetic hyperthermia value of 558 Js− 1g− 1 of Fe content at 316 kHz and 35.33 kA/m, at 2 mg/mL. The obtained hyperthermia is very high compared to long-chain PEG ligated Fe3O4 nanoparticles. It is attributed to relaxation time difference of long-chain PEG ligated Fe3O4 and short molecule zwitterion surfactant stabilized Fe3O4. Present hyperthermia results are the first report on zwitterionic dopamine sulfonate anchored Fe3O4 superparamagnetic nanoparticles.