Gelatin-Based Matrix For Bioinspired Synthesis Of Magnetite Nanoparticles

Magnetite plays an important role in biomaterials such as MRI contrast agent,photothermal medium,magnetic hyperthermal medium and bioseparation medium et.However,compared with the nanoparticles obtained by biomineralization methods,the magnetite obtained by chemical methods possessed defect which limited the applications of magnetite in biomedicine.So it is very important for us to synthesize the magnetite minerals through biomimetic method.Recently,there are three mainly biomimetic methods to imitate the formation of magnetite and most of them are based on the biomineralization of magnetosome of magnetotactic bacteria.However,most biomineralization process of magnetite based on the magnetotactic bacteria just considers the water as reaction medium and neglects the matrix environment existing in bacteria.In order to explore the influence of matrix environment for the biomineralization of magnetite,this study selected the gelatin hydrogel to imitate the matrix environment and adopted different methods to explore the formation of magnetite,such as immersion method between ferrous and ferric ions,mixture method between ferrous and ferric ions,phase transformations of ferrous precursor method.(1)In the method of immersion method,iron salts could move into the gelatin hydrogel by diffusion method and then provide the site for the nucleation and growth of magnetite.The result showed that the gelatin hydrogel with low concentration was benefit for the ion diffusion and growth of magnetite nanoparticles.The heating effective of magnetite showed a positive correlation relationship with the times of cycle and low concentration of gelatin hydrogel.On the other hand,the immersion method can obtain the magnetite with better heating effective which need to take a long period time.(2)The biomimetic method of mixture based on gelatin hydrogel can obtain the sample with mainly magnetite doping with little precursor minerals.Morphology characteristics showed the nanoparticles were wrapped in gelatin hydrogel and the size of particles was about 20 nm,which was bigger than the particles prepared by traditional in situ co-precipitation method in gelatin(10nm).VSM results demonstrated that the nanoparticles have typical superparamagnetic behavior.Finally,the nanoparticles obtained from biomimetic method can guarantee better magnetic hyperthermia effect than the nanoparticles obtained from the directly co-precipitation method.(3)By changing the idea of biomineralization,we can obtain the iron oxide nanoparticles which showed an obviously chain structure just like magnetosome with the size about 40 nm.The nanoparticles were coated with gelatin matrix that can provide the good biocompatibility for the future application of iron oxides in nanomedicine.