Porath first discovered in 1975 that transition state metal ions immobilized on a substrate can achieve both specific binding effects through coordination with residues such as histidine, cysteine, tryptophan on the protein surface. The metal chelate affinity technique has become a powerful tool for the research and development of biopharmaceuticals because of its high selectivity, high adsorption capacity, mild conditions, high selectivity, excellent separation efficiency, reproducibility and versatility.The Nickel coated plate, a solid-state support for the purification / enrichment / capture of histidine (His) - tagged proteins through the chelation immobilization of Ni2 + combined with triacetic acid nitrate (NTA), are one of the most commonly used metal chelate affinity techniques.