| DNA is the source of all lives, and the extraction and purification of DNA havebeen more and more riveted people’s attention.The combination containing DNA iscomplex and it is a very difficult to effectively purify DNA with high purity and highconcentration. Comparing to the traditional manual extraction and organic solventpurification, adsorption method has the advantages of low price, simple operation andwithout organic solvent pollution.Cyclodextrin has unique structure of tapered hollowcylindrical stereoscopic, so the modified Cyclodextrin can be used for preparation ofvarieties of Cyclodextrin derivatives and the purification of DNA. The adsorptionexperiments for DNA and the factors of solution acidity, ionic strength, adsorptiontime, DNA initial concentration and etc, which can affect the DNA adsorption werediscussed.The adsorption Isotherms were fitted with various adsorption model and theadsorption mechanism of modified Cyclodextrin were studied.1.With Toluene2,4–diisocyanate（TDI） as the crosslinking agent,TDIcross-linked β-CD was prepared.The conditions such as the adsorption solutioncomposition, solution acidity, crosslinking reagent concentration,which can effectDNA recovery were investigated. Under the optimal conditions,including in neutraladsorption solution containing2.0mol·L-1NaCl and20%PEG8000,and with TE bufferas elution solution, the recovery rate of DNA can achive to100%by usingTDI-crosslinked β-CD.The electrophoresis and UV determination showed that DNAhad been extracted and purified with higher concentration and highly purity.2.The AE-β-CD microspheres were prepared with epichlorohydrin ascrosslinking agent, and with ethylene diamine as madification agent.The aminogroups were grafted onto the surface of AE-β-CD.The masking AE-β-CD wereprepared by using formaldehyde as amino protective agent.Two adsorbents werecharacterized by using FTIR and XPS.The results indicated that the ethylenediaminewas successfully modified onto the adsorbent surface.Under the optimal conditionssuch as in the pH5.5buffer solution containing2.0mol·L-1NaCl and shaking time for 10mins at5℃,the DNA adsorption ratio achived to57.6%and22.1%for AE-β-CDand masking AE-β-CD,respectively. When PEG was added in the adsorption solution,the recovery ratio of DNA was increased to54.3%and76.4%for AE-β-CD andmasking AE-β-CD,respectively.The results of gel electrophoresis and UV-visspectrophometer showed that two adsorbents can be applied to extraction andpurification of DNA with higher purity from fresh corn.3.The adsorbent（IDA-β-CD） was prepared with iminodiacetic acid（IDA） asmadification agent.Then three affinity adsorbents were obtained by chelating withZn2+, Cu2+and Fe3+,respectively.The amount of metal ions chelated on IDA-β-CD ishigher than that on β-CD.When the adsorption solution cantains2.0mol·L-1ofNaCl,the solution acidity was fixed at pH5.0and at low temperatures,the DNAmaximum adsorption capacities for Zn-IDA-β-CD, Cu-IDA-β-CD and Fe-IDA-β-CDwere achived to63.66,88.47and18.34mg.g-1,respectively.The adsorption isotherms ofthree adsorbents were fitted with Langmuir and Freundlich model, respectively.Theresults indicated that the adsorption processes were found to agree well the Freundlichmodel with multi-molecur layer adsorption.4.The PMIDA-β-CD adsorbent was prepared with epichlorohydrin andPMIDA as cross-linking and modification agent, respectively.Then three newadsorbents were obtained by chelating with Zn2+, Cu2+and Fe3+,respectively.TheFTIR and determination of the amount on the surface of modified adsorbent used tocharacterize three adsorbents.The results shows that PMIDA was grafted onto theadsorbent surface.The DNA maximum adsorption capacifies for Zn-PMIDA-β-CDCu-PMIDA-β-CD and Fe-PMIDA-β-CD PMIDA can achived to14.86,17.84and16.49mg.g-1,respectively.The adsorption prosses for three adsorbents was fitted withLangmuir and Freundlich models, respectively.The adsorption isotherms were foundto agree well Freundlich model with multi-molecur layer adsorption. |
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