| Magnetic particles is a kind of composite particles which composed of magnetite and some matrix such as organic or inorganic materials. Magnetic composite particles have the properties of superparamagnetism, surface effects and can be modified with functional groups. Therefore, they are widely used in research of immunology detection, nucleic purification, cell sorting, drug carrier and biological enzyme immobilization. Herein, two kinds of magnetic silica particles modified with cationic group (DEAE and His) were successfully prepared and used for genome DNA purification from 200μL human whole blood.First, iron oxide nano-particles were synthesized by water-in-oil microemulsion technique, and in situ formed SiO2 as a shell on Fe3O4 particle surface. Based on core-shell structure magnetic silica nanoparticles (Fe3O4/SiO2), diethylaminoethyl (DEAE) and L-histidine (L-His) was modified on the particles and formed anion exchange magnetic silica particles respectively.Using the particles modified with DEAE and L-His as carriers, genomic DNA was extracted from 200μL human whole blood, the steps including the lysis of whole blood, amount of the particles added, washing and eluting were optimized and the results show as follow:.(1) 3-5μg genome DNA was obtained using 1.5 mg of DEAE-magnetic particles from 200μL human whole blood, the ratios of obtained genomic DNA were in the range of 1.70～1.90. However, the step of elution of this method need high salt concentration and need further ethanol precipitation to get genome DNA sample without salt.(2) 3～4μg genome DNA was obtained using 1 mg of His-magnetic particles from 200μL human whole blood, the ratios of obtained genomic DNA were in the range of 1.65-1.80. The genome DNA yielded after the step of elution can be directly used in biological downstream applications. Because the elution step depends on the pH of the elution buffer using TE of pH 8.5. |
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