采用共沉淀法和水热法制备了不同结构的超顺磁性Fe3O4@SiO2纳米颗粒，对其进行表征，研究了其吸附DNA的性能及磁分离性能. 结果表明，20?750 nm范围内粒径较大的颗粒与DNA结合时可提供更多单位平面结合位点，使结合的稳定性和结合几率增加，DNA结合量提高. 不同核?壳结构的Fe3O4@SiO2纳米颗粒的磁分离响应时间不同，内核大小相近时，壳层厚度增加会导致颗粒在磁场中受到的磁力与阻力的比值减小，磁响应时间增加，DNA回收率降低. 粒径约为200 nm的Fe3O4@SiO2纳米颗粒用于纯化全血中DNA最好，提取率为95.2%，磁响应时间为10 s.
DNA purification is considered to be a critical step in biomedical applications such as genetic therapy and clinical diagnosis. These years, the magnetic silica beads are widely used in DNA purification due to the advantages of averting the use of some toxic organic solvents and being easy to auto-magnetic separation. Among them, magnetic Fe3O4@SiO2 nanoparticles (NPs) were widely used because of their stability, monodispersity, selectivity, and high separation efficiency in magnetic field. However, the shape and structure of particles may affect the DNA isolation efficiency, such as the DNA adsorption capacity and recovery rate. It has not yet been fully explored. In this work, a series of Fe3O4 NPs with different core diameters were synthesized firstly by co-precipitation and hydrothermal methods, and then further coated by silica through St?ber method. The resultant Fe3O4@SiO2 NPs were characterized by SEM, TEM, IR and BET, respectively. The DNA adsorption capacity of Fe3O4@SiO2 NPs were studied by UV?Vis, and the magnetic separation properties were also determined by magnetic response time. The results showed that in the range of 20?750 nm of particle size, the larger size particles could provide more unit planar binding sites when combining with DNA, which increased the combination stability and binding probability. Thus, the DNA binding capacity of the particles increased with the increase of particles size. In addition, the magnetic response time of Fe3O4@SiO2 NPs with different core?shell structures were also different. When the size of the core was similar, the thicker SiO2 shell around would weaken the dipole?dipole interactions between particles and reduce particles aggregation, thus the magnetic response time of NPs increased, leading to a low recovery rate within a limited operating time. Comparing the DNA adsorption capacity and recovery efficiency of particles. The Fe3O4@SiO2 NPs around 200 nm was the optimal choice for blood DNA purification, which had high recovery rate (95.2%) in a short magnetic response time (10 s).
[1]Berensmeier S.Magnetic particles for the separation and purification of nucleic acids[J].Applied Microbiology and Biotechnology, 2006, 73(3):495-504 [2] Zhong Z, Yao X, Gao X, et al.Polydopamine-immobilized polypropylene microfuge tube as a pH-responsive platform for capture/release of DNA from foodborne pathogens[J].Analytical Biochemistry, 2017, 534:14-18 [3]Kim J, Johnson M, Hill P, et al.Microfluidic sample preparation: cell lysis and nucleic acidpurification[J].Integrative Biology, 2009, 1(10):574-586 [4]Tian H, Hühmer A F R, Landers J P.Evaluation of Silica Resins for Direct and Efficient Extraction of DNA from Complex Biological Matrices in a Miniaturized Format[J].Analytical Biochemistry, 2000, 283(2):175-191 [5] Sosa-Acosta J R, Silva J A, Fernández-Izquierdo L, et al.Iron Oxide Nanoparticles (IONPs) with potential applications in plasmid DNA isolation[J].Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018, 545:167-178 [6] Vuosku J, Jaakola L, Jokipii-Lukkari S, et al.Does Extraction of DNA and RNA by Magnetic Fishing Work for Diverse Plant Species?[M]. 27. 2004: 209-15. [7]Borlido L, Azevedo A M, Roque A C A, et al.Magnetic separations in biotechnology[J].Biotechnology Advances, 2013, 31(8):1374-1385 [8]Otto P.MagneSil? Paramagnetic Particles: Magnetics for DNA Purification[J].JALA: Journal of the Association for Laboratory Automation, 2002, 7(3):34-37 [9]Lundqvist M, Sethson I, Jonsson B-H.Protein Adsorption onto Silica Nanoparticles:? Conformational Changes Depend on the Particles' Curvature and the Protein Stability[J].Langmuir, 2004, 20(24):10639-10647 [10]Satzer P, Svec F, Sekot G, et al.Protein adsorption onto nanoparticles induces conformational changes: Particle size dependency,kinetics,and mechanisms[J].Engineering in Life Sciences, 2016, 16(3):238-246 [11]Liu Z L, Wang H B, Lu Q H, et al.Synthesis and characterization of ultrafine well-dispersed magnetic nanoparticles[J].Journal of Magnetism & Magnetic Materials, 2004, 283(2-3):258-262 [12]Sun H, Zeng X, Liu M, et al.Synthesis of size-controlled Fe3O4@SiO2 magnetic nanoparticles for nucleic acid analysis[J].J Nanosci Nanotechnol, 2012, 12(1):267-73 [13]Yuan Q, Li N, Chi Y, et al.Effect of large pore size of multifunctional mesoporous microsphere on removal of heavy metal ions[J].Journal of Hazardous Materials, 2013, 254-255(1):157-165 [14]Sun X, Yang L, Dong T, et al.Removal of Cr(VI) from aqueous solution using amino‐modified Fe3O4–SiO2–chitosan magnetic microspheres with high acid resistance and adsorption capacity[J].Journal of Applied Polymer Science, 2016, 133(10):43078- [15]Ja G.Validity of nucleic acid purities monitored by 260nm280nm absorbance ratios[J].Biotechniques, 1995, 18(1):2- [16]Moeser G D, Roach K A, Green W H, et al.High‐gradient magnetic separation of coated magnetic nanoparticles[J].AIChE Journal, 2004, 50(11):2835-2848
