Research On Preparation Of Nanoparticles Based On Fe₃O₄ Magnetic Responsiveness And Their Interfacial Adsorption

Magnetic Fe₃O₄ nanoparticles have been widely used in drug delivery,wastewater treatment and catalyst carriers due to their low toxicity,good biocompatibility and magnetic responsiveness.However,naked Fe₃O₄ nanoparticles are easy to aggregate,which affects their performance.Therefore,Fe₃O₄nanoparticles were surface-functionalized to form surfactant particles,and their adsorption on the interface was explored.Firstly,nanoparticles with Fe₃O₄@SiO₂-PDA-n were prepared and their adsorption on the leaf interface was investigated.The samples were characterized by FT-IR,XPS,particle size,Zeta potential charge and TGA.The results showed that the more dopamine(DA)was added during the synthesis process,the greater the amount of polydopamine(PDA)loaded on Fe₃O₄@SiO₂ particles.Using rhodamine B as the drug model,after 3minutes of water washing,the fluorescence intensity of the rhodamine remaining on the leaves was observed through a fluorescence microscope.The Fe₃O₄@SiO₂-PDA-n nanoparticles loaded with PDA were more than Fe₃O₄@SiO₂ without loading PDA.This may be because PDA can form multiple covalent and non-covalent interactions with various adhesive substrates,thus having strong adhesion.Secondly,Fe₃O₄@SiO₂-PDA-n and Ugi-Alg are used to synergistically stabilize the emulsion and explore its adsorption on the oil-water interface.The effects of PDA on the stability,viscosity,viscoelasticity,droplet size and drug release of the prepared emulsion were analyzed by visual inspection,multiple light scattering instrument,rotational rheometer,confocal and gas chromatograph.The results show that the TSI(Turbiscan Stability Index)of the emulsion with Fe₃O₄@SiO₂-PDA-n nanoparticles loaded with PDA is 3.83,which is much lower than the 6.81 of Ugi-Alg/Fe₃O₄@SiO₂ emulsion without loading PDA,and as the loading of PDA increases,the stability of the emulsion is better and better.The results of viscosity and viscoelasticity are consistent with the stability analysis.As for the emulsion droplets,the size of the emulsion co-stabilized by PDA nanoparticles is smaller than that of the emulsion co-stabilized by Ugi-Alg/Fe₃O₄@SiO₂.For the drug release of emulsion,Ugi-Alg/Fe₃O₄@SiO₂-PDA-n has a higher drug encapsulation rate,because more micelle particles are adsorbed on the oil-water interface and the size of emulsion droplets is small,which promotes the increase of the number of droplets.Finally,we prepared the flocculant Fe₃O₄@DQn and explored the electrostatic adsorption between Fe₃O₄@DQn and microalgae.The structure of Fe₃O₄@DQn was characterized by FT-IR,XPS,TGA and Zeta potential charge.Results show that Fe₃O₄@DQn has excellent dispersibility compared with naked Fe₃O₄,the zeta potential charge of Fe₃O₄@DQn increases as the amount of N-[3-(Trimethoxysilyl)propyl]ethylenediamine(TMPED)increases but decreases as p H increases.The capture efficiency also shows the same trend.Harvesting efficiency is as high as 98.42%within 2 min and recycled five times is 92.31%.The maximal adsorption capacity(K_F)reaches 21.822 mg/mg-Fe₃O₄@DQ3 for C.pyrenoidosa.Fe₃O₄@DQn has high harvesting efficiency,time-saving process,and cycling stability because of the increased electrostatic attraction and contact area due to abundant positively charged active sites and superior dispersion behavior of Fe₃O₄@DQn.