Preparation Of Magnetic Core-shell And Mesoporous Silica Nanoparticles For DNA Separation

Recently,preparation and application of Magnetic Mesoporous Silica Nanoparticles?MMSN?has been a hot topic due to their larger surface area and specific porous channel,which can dramatically increase the binding capacity of target molecule onto the surface and pore.Furthermore,the tunable pore sizes with narrow distributions,well-defined surface properties,and low toxicity make mesoporous silica materials an ideal host for adsorption applications.In the meantime,surface modification of mesoporous silica provides a satisfied surface for ionic?electrostatic?interaction and thus enhances their adsorption ability by introducing different functional groups such as amines,thiols,and carbohydrates.It has been demonstrated that the amine-functionalized surface would present positive charge at acidic condition due to the protonation of amine groups,which could bind phosphate groups of DNA through electrostatic interaction without any extra binding agents.Consequently,this offers an effective strategy to realize the rapid separation of DNA by using amine-functionalized magnetic nanoparticles.In this study,we report a modified approach for the functionalized magnetic mesoporous silica nanoparticles?MMSN?using polymer microspheres incorporated with magnetic nanoparticles in the presence of cetyltrimethy-lammonium bromide?CTAB?and the core-shell magnetic silica nanoparticles Fe₃O₄@SiO₂.These particles were functionalized with amino groups via the addition of aminosilane?EDPS?directly to the particle sol.At last,we successfully fabricated the MMSN with larger mesochannels when using cyclohexane as organic swelling agent.And the morphologies,magnetic properties,dispersity,pore size,and Zeta potential are characterized by transmission electron microscopy?TEM?,vibrating sample magnetometer?VSM?,nitrogen sorption measurements and dynamic light scattering?DLS?.The results revealed that these nanoparticles own uniform particle size and pore size,and good dispersion.We then evaluate their DNA separation abilities and find the capacity of DNA binding significantly increased?MMSN@EDPS,210.22 ?g/mg?compared with normal magnetic silica spheres?Fe₃O₄@SiO₂@EDPS,138.44 ?pg/mg?by using ultraviolet and visible spectrophotometer?UV?.In addition,DNA adsorption capacity of MMSN@EDPS is also compared with commercial kit used for DNA separation.Apparently the capacity of our MMSN@EDPS is at least comparable to commercial kit?246.08 ?g/mg?.What's more,the facile experiment conditions in synthesis and adsorption processes also facilitate our MMSN@EDPS nanoparticle to be an ideal adsorbent.