Continuous Solvothermal Synthesis Of Magnetic Nanopoarticles In Organic System

As members of nanomaterials family, magnetic nanoparticles (MNPs) have become the subject of intense investigation because of their unique structural, electrical and mechanical properties. In recent years, increasing studies are focused on exploring MNPs' properties for biological applications both at molecular and cellular levels.As a kind of MNPs, ferrite MNPs used in medicine must exhibit several properties, including biocompatibility, non-toxicity, non-carcinogenicity, non-mutagenicity, non-antigenicity, and non-teratogenicity. The solubility and biocompatibility of MNPs will be improved by modification. Up to now, synthesis of ferrite MNPs have attracted wide attention, scientists have established many kinds of synthesis methods. Whether continuous hydrothermal synthesis method can be used to prepare the ferrite MNPs has not been known clearly. We took the lead in this filed and made certain research results. We also prepare water-soluble MNPs by surface modification which explore the possibility of application in biomedical.OBJECTIVES:1. Explore the relationship between the synthesis conditions and the properties of MNPs synthesized by continuous synthesis. Aim to prepare MNPs with good properties by optimizing the reaction conditions.2. Increase the water-solubility and biocompatibility of ferrite nanoparticles by surface modification.METHODS:1. Optimize the Reaction Conditions of Continuous Solvothermal SynthesisThe factors influence the MNPs' size, dispersibility and crystallization includes: environment inside instrument, ratio of materials, reaction temperature, reaction time and reaction pressure. For the environment inside instrument and ratio of materials, we use Autoclave method to optimize the conditions. For reaction temperature, time,and pressure, continuous hydrothermal synthesis method to optimize the conditions.The characterization of TEM, XRD, IR were used to analysis the properties ofmaterials we obtained. Optimize the reaction condition to obtain MNPs with goodproperties.2. Surface Modification of MNPsWe use acetic acid to modify the surface of MNPs by centrifugation process washing the organic shell attached on the surface. The results are characterization by TEM, IR, and elemental analysis. Find an optimization condition of surface modification. RESULTS:1. We found out the optimization conditions of continuous solvothermal synthesis method. We obtained ferrite MNPs with 10±2 ran, mono-dispersibility in cyclohexane and good crystallization.2. We obtained ferrite MNPs with hydrophilic surface after surface modification process. The size and crystallization are remained, and mono-dispersibility well in water.CONCLUSIONS:1. Environment inside instrument. We choose ethanol as the materials for washing instrument, and high concentration of reaction materials as optimization environment inside instrument.2. The ratio of reaction materials. We can prepare products with different composition by changing the ratio of Fe and Ni. The ratio of Fe and Ni remained as 2 : 1,NiFe₂O₄ MNPs obtained.3. The reaction temperature. 180-220℃is the best condition for synthesis of ferrite MNPs, above or below this temperature will not obtain the desired NPs.4. The reaction time. From the results of experiment, we can obtain the desired NPs at 30 min, or the size will be too large and could not get ferrite NPs.5. The reaction pressure. For NiFe₂O₄ MNPs, pressure did not impact the results.6. Surface modification. Increase the water-soluble of NPs through surface modification. This provided a possibility for application in biomedicine. MEANINGS:We took the lead in the filed that synthesis of NiFe₂O₄ ternary system MNPs using continuous solvothermal synthesis method. Explore the relationship between the synthesis conditions and the properties of MNPs, mono-dispersibility, size distribution and the degree of crystallization were studied. This research provides reference for large-scale industrial preparation of NPs. We also obtained water-soluble NiFe₂O₄ MNPs by surface modification. This process increased the NiFe₂O₄ MNPs' biocompatibility and provided a possibility for application in biomedicine. This project can help to understanding the nature of MNPs, and has an important academic significance and social value.