Synthesis And Application Of Magnetic Response Surfactant

Owing to unique magnetic responsive property, magnetic surfactant is touted as having great potentials in many fields. Not only the magnetic surfactants themselves but also their aqueous solutions all show magnetic response towards the applied magnetic field, which have potential applications in the preparation of magnetic emulsion and the magnetic migration of biomacromolecule. The traditional magnetic emulsion and magnetic separation are realized by introducing magnetic nanoparticles or ferrofluid. However, this method limits their applications in gene therapy and biotechnology realms because of their low biocompatibility and stability, and the complicated preparation process. In order to overcome the drawbacks of magnetic nanoparticles, magnetic sugar-based surfactants were synthesized so as to prepare magnetic emulsion and realize the migration of DNA and protein without the introduction of magnetic nanoparticles. In addition, we have proved that the utilization of nonmagnetic AuNP can complex with magnetic surfactants, and effectively boost the migration impact of DNA and protein, which can be used to provide theoretical basis for DNA targeting migration and gene therapy. The details are as follows:1. Synthesis of magnetic sugar-based surfactantMagnetic sugar-based surfactants [H-G-Cl_n]FeCl₄/[Cl_n-G-Cl_n]FeCl₃Br （n=8,12,16） were synthesized, and firstly characterized by 1H NMR, FT-IR, elemental analysis, Raman spectrum and vibrating sample magnetometer（VSM） to confirm their structure and paramagnetic property. Moreover, their aggregation behavior of air-liquid interface were investigated by surface tension、 electrical conductivity, indicating that with the increasing hydrophobic chain, the cmc decreases gradually but the γcmc has obvious difference. In addition, compared with [H-G-Cl_n]FeCl₄, [Cl_n-G-Cl_n]FeCl₃Br have higher efficiency of lowering the surface tension, especially for [C,2-G-C,2]FeCl₃Br.2. Study on the magnetic property of magnetic surfactant solution and magnetic emulsionThe pre-synthesized magnetic surfactants [H-G-Cl_n]FeCl₄/[Cl_n-G-Cl_n]FeCl₃Br （n=8,12,16） aqueous solution was investigated by DLS and negative staining/freeze etching-TEM to prove the formation and morphology of aggregates. Besides, the magnetic responsive property of these surfactants and the effect on the surface tension induced by magnetic field were studied through VSM and pendant drop profiles. Then, using the magnetic surfactant solution as emulsifier successfully prepared normal magnetic emulsion and magnetic Janus emulsion, and their stability and morphology were investigated by DLS and polarizing microscope, indicating that the normal magnetic emulsion can shift with the move of magnet. The stability and morphology of magnetic Janus emulsion can be regulated by adjusting different components. What’s more, the applied magnetic field could disrupt its stability and morphology.3. Interaction between magnetic surfactant and biomoleculeTake magnetic surfactants [H-G-Cl₁2]FeCl₄/[Cl₁2-G-Cl₁2]FeCl₃Br for instance, the interaction between biomolecules （DNA or Protein） and magnetic surfactant was investigated. The migration of DNA molecule induced by magnetic surfactant under the applied magnetic field was characterized by UV-vis and CD spectrum, suggesting that the sole magnetic surfactant can form complex with DNA and have a higher compaction effect but that the efficiency of magnetic migration is very low. To escalate the ability of magnetic migration toward DNA/protein, we found that introducing AuNP can achieve this goal. In addition, the discrepancy of magnetic migration resulting from the different preparing methods of AuNP was studied so as to explore the features and mechanism of magnetic migration towards biomolecule, which is beneficial for the study on DNA targeting transportation and release, and the protein separation.