Tris(2-carboxyethyl)phosphine hydrochloride (TCEP hydrochloride) is a novel reducing and deprotectant of thiolated DNA. Sulfur atoms at the end of sulfhydrylated DNA tend to form dimers in solution, especially in the presence of oxygen. This dimerization greatly reduces the efficiency of some coupling reaction experiments (such as DNA immobilization in biosensors); The addition of tris(2-carboxyethyl) phosphine hydrochloride (TCEP hydrochloride) to the DNA solution and removal after a period of reaction can reduce the dimerization of DNA.