Today, Yaohai Bio-Pharma will introduce a method for purifying Plasmid DNA by ion exchange chromatography.
 
Ion exchange chromatography mainly uses solute molecules to combine with solid phase ion exchangers carrying opposite charges. In the case of changing pH or enhancing ion strength of the eluent, the solute molecules bound with the ion exchanger exchange with ions in the eluent and are elution. Different solute molecules carry different charges, have a strong ability to bind to fixation, and are elution into the solution in a different order, thus separating the various components. Since the negatively charged phosphate groups on the pDNA skeleton can interact with the positively charged ion exchangers on the column, anion exchange (AEC) can be used to purify and isolate pDNA.
 
In addition to purified mRNA, Yaohai Bio-Pharma also has the "RNASci" RNA customized research sample synthesis service platform, which consists of four technical modules: RNADes (mRNA structure design and Optimization), RNASyn (mRNA synthesis and modification), RNAPur (mRNA purification), RNAQua (mRNA Quality analysis and Control). We offer end-to-end, one-stop, customized solutions or stand-alone services from RNA synthesis, strain engineering and construction, upstream and downstream process development, to GMP or non-GMP grade API production. As well as filling and completion services for various modes of mRNA, circRNA, plasmid RNA, recombinant proteins, peptides, enzymes, single domain antibodies (sabs) and VLP.
 
Although plasmid DNA with different topologies has the same total charge number and molecular mass, plasmid DNA with different conformations carries different local charge densities. In a chromatographic environment, the overall interaction between plasmid DNA and chromatographic fixed ligands depends on local charge attraction. The charge density of SC pDNA is much higher than that of relaxed open-loop DNA, so with the increase of the concentration of eluent salts, SC pDNA which has stronger charge attraction with the positively charged column ligands will eluate later than OC pDNA. However, in anion exchange chromatography, other parameters such as hydrogen bonding, dispersion power, and AT content affect the charge density and non-specific adsorption occurs. Therefore, in the process of plasmid purification, the separation selectivity of anion cross-chromatography is not very high, and it needs to be often combined with other chromatographic methods.

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