The preparation technology of protein purification fillers has become relatively mature and can achieve large-scale industrial production. Whether it is small-scale protein purification research in the laboratory or large-scale protein drug production in large biopharmaceutical enterprises, appropriate filler specifications and quantities can be selected according to actual needs to meet different levels of purification requirements and ensure the stability of product quality.

The basic working principle of protein purification packing:

（1） Based on charge interaction

Many protein purification fillers carry specific charged groups, such as anion exchange fillers carrying negative charges and cation exchange fillers carrying positive charges. Under certain buffer conditions, protein molecules undergo electrostatic adsorption with fillers based on the nature of their own charge. When the ionic strength or pH value of the buffer changes, the charge attraction between the protein and the filler weakens, causing the target protein to be eluted, while impurity proteins remain on the column or are separated under different elution conditions due to differences in charge properties or binding forces with the filler.

（2） Based on hydrophobic interactions

The surface of hydrophobic protein purification fillers has hydrophobic groups, and there are also hydrophobic regions in protein molecules. In high salt concentration environments, the hydrophobic regions of proteins will approach and bind with the hydrophobic groups of fillers through hydrophobic interactions. As the salt concentration decreases, this hydrophobic interaction weakens, allowing the target protein to be eluted, thereby achieving protein purification. This purification method based on hydrophobic interactions is more effective for purifying proteins with strong hydrophobicity, such as membrane proteins.

（3） Based on affinity specificity

Affinity chromatography packing utilizes the highly specific affinity between proteins and specific ligands to achieve purification. For example, there are specific affinity relationships between enzymes and their substrates, inhibitors, antibodies and antigens, etc. Fix the corresponding ligand on the filler, and when the sample containing the target protein passes through, the target protein will specifically bind to the ligand, while other impurity proteins will not be adsorbed or adsorbed weakly. By changing the elution conditions, such as using competitive ligands or altering the buffer composition, the target protein can be desorbed from the packing and collected, thereby achieving high purification.

（4） Based on the principle of molecular sieve

Molecular sieve type protein purification fillers have a porous structure with specific pore sizes. When the protein mixture passes through the filler, smaller molecular weight proteins can enter the pores of the filler, while larger molecular weight proteins are excluded. During the elution process, small molecular weight proteins have a relatively slow elution speed due to their longer diffusion path within the pores; High molecular weight proteins are quickly eluted, enabling protein separation and purification based on their molecular weight.