Abstract:

As the ligand and biological acceptable parts, polyhexamethylene biguanide hydrochloride(PHMB) are used for stabilizing Ag³⁺. A series of micron-sized quadricovalent cationic Ag(Ⅲ)-PHMB complexes was synthesized via oxidation of the monovalent silver, followed by stabilization of the oxidized high valence silver ions through complexation with PHMB. From the experimental result of agar well-diffusion method, it can be concluded that the antibacterial activity of Ag(Ⅲ)-PHMB complex is enhanced with increasing viscosity-average relative molecular mass of PHMB and weakened with the increase of the size of Ag(Ⅲ)-PHMB complex. The experimental results reveal that the complex yields the maximum antibacterial activity when the viscosity-average relative molecular mass of ligand is 5428. Though broth dilution method, micron-sized Ag(Ⅲ)-PHMB complex displays excellent antibacterial performance in low mass concentration towards Gram-positive and Gram-negative prokaryotes for excellent antibacterial activity of Ag³⁺. Compared with AgO, AgNO₃ and PHMB, Ag(Ⅲ)-PHMB complex has lower minimal inhibitory concentration(MIC). With the increase of mass concentration, however, because of the reduction of the growth ratio of contacting area between Ag(Ⅲ)-PHMB complex and bacteria and the release radio of antimicrobial active substance, antibacterial activity of micron-sized Ag(Ⅲ)-PHMB complex shows slowly increasing rate.

Key words: Ag(Ⅲ)-polyhexamethylene biguanide hydrochloride complex, viscosity-average relative molecular mass, antibacterial performance