Investigations On The Separation And Purification Of DNA With Polyethyleneimine-modified Nano FePO₄

In present work, a rapid and efficient solid-phase extraction protocol is developed for the purification of DNA by using PEI-FePO4s as an extraction medium.Firstly, a cationic hyperbranched polymer polyethyleneimine (PEI) was immobilized on the surface of nano-FePO4 via electrostatic interaction. The obtained PEI-FePO4 nano-material was characterized by means of FT-IR, SEM and surface charge analysis (Zeta potential).The performances of the obtained PEI-FePO4 nano-material in the separation and purification of DNA were subsequently investigated. At pH 4.0, an adsorption efficiency of 100% for 50 mg L-1 DNA in a 1.0 mL solution is achieved by using 2.0 mg of PEI-FePO4 as sorbent, meanwhile, nearly no adsorption of protein was observed under the same conditions. The adsorption equilibrium of DNA onto PEI-FePO4 nano-material could be reached within 30 s, and the adsorption behaviors fits Langmuir adsorption model, corresponding to a theoretical adsorption capacity of 66.81 mg g-1. The retained DNA could be readily recovered by a BR buffer of pH 10, giving rise to a recovery of 85%.The developed separation and purification system was thus used for the selective isolation of DNA from simulated λDNA samples, human whole blood and E. coli lysate. Successful PCR amplifications of 500 bp λDNA fragment,543 bp human P53 gene and 700 bp GFP gene were achieved by using the purified DNA samples as templates. The results indicate that the purity of DNA extracted from the complex matrix using the developed separation/purification method fulfill the requirements of downstream PCR analysis.