Microfluidic Preparation And Application Of Micro-nano Magnetic Composite Microspheres

Due to the miniaturization of the reaction device,precisely controlling the exchange of substances,microfluidic technology provides a powerful platform for the preparation,functionalization and morphology controlling of nano-and micro-scale materials,especially the precise regulation of inorganic nanoparticles.We here assembled a simple and efficient microfluidic device to obtain the composite emulsion with high dispersion,multi-structure and multi-functionalization.Based on these home-made devices,we prepared alginate calcium microspheres and Fe3O4@SiO2@mSiO2 nanoparticles,revealed the effect of flow rate ratio,reaction time,and other factors on the materials morphology and average diameter.Comparing with the traditional method,the microfluidic device has the advantages of flexible assembly,rapid reaction,uniform particle size,adjustable size and magnetic response.Firstly,we aimed to assemble a simple,portable and economical L-junction microfluidic device to realize the adjustment and tunability of homogeneous round-shaped particles synthesis.We synthesized two microparticles,including magnetic alginate microparticles(MAM)and chitosan-coated magnetic alginate(CMAM)used for drug release under a mild condition.Comparing with the traditional method,the MAM synthesized via this microfluidic approach has uniform size distribution,adjustable diameter as well as tunable magnetism,and displays excellent pH-sensitive release of the model drug amoxicillin.Moreover,the effect of particle size on the drug release rate was studied,the results showed that the smaller particles had a faster release rate than the bigger materials due to their larger specific area,leading to more frequency to interact with the solution.The positively charged polysaccharide polymer chitosan was coated on the surface of MAM by electrostatic adsorption to obtain CMAM.Due to the presence of chitosan,the pores on the surface of MAM were well blocked,so the drug release time of CMAM was extended to twice that of MAM,and the drug controllable and sustained release were successfully achieved via kinetic analysis.The cumulative drug release was measured by UV-Vis spectrophotometer,the cumulative release of MAM was 82.2%and that of CMAM was 49.1%within 100 min.Within 420 min,the cumulative release MAM was 95.9%,while that of CMAM was 77.1%,showing that CMAM exhibits typically slow release characteristics,following Higuchi and Korsmeyer-Peppas release dynamics models.Bacteriostasis test showed that the AMOX-loaded magnetic microspheres had good inhibitory over Staphylococcus aureus and Escherichia coli.In summary,this microfluidic approach provides a convenient and efficient fluidic design for the well-controlled synthesis of microscale particles,which is a potential choice used for controlled and sustained drug release.Secondly,we built a droplet-based microfluidic device to efficiently and rapidly synthesize Fe3O4@SiO2@mSiO2 composite nanoparticles.Moreover,methylene blue(MB)was explored as the absorbate to assess the removal efficiency of our homemade composite nanoparticles.By means of transmission electron microscopy(TEM),fourier infrared spectroscopy(FTIR),vibrating sample magnetometer(VSM),powder X-ray diffraction(XRD),the morphology,composition,magnetic properties,and surface property of Fe3O4@SiO2@mSiO2 nanoparticles were characterized.The results show that the material possess superparamagnetism,core-shell and mesoporous structure.The effect of Fe3O4@SiO2@mSiO2 nanoparticles on the adsorption capacity of MB under different pH and different temperatures was revealed.This unique structure of composite nanoparticle provides not only good dispersion and stability for the magnetic core,but also porous shell,facilitating the absorption of MB via the outer layer.The maximum adsorption capacity of MB is as high as 101.9 mg/g in solutions(pH 10).In addition,the magnetic core drive the directional removal of nanomaterials under the external magnetic field,simplifying the separation step.Using the magnet easy separation through the acidic ethanol solution,repetitive adsorption efficiency can still reach 88%.Therefore,Fe3O4@SiO2@mSiO2 nanoparticles are expected to be practical application in the removal and separation of organic dyes.In summary,we assembled simple,portable,low-cost fluidic device to synthesize macroscale magnetic alginate particle and nanoscale Fe3O4@SiO2@mSiO2 composites.The results show microfluidic device we designed and assembled here is suitable for the controlling of morphology and properties to meet the demand of potential applications.The challenges and prospects of microfluidics were briefly introduced and discussed at the end of the article.