Synthesis of polyethylenimine (PEI) functionalized silver nanoparticles by a hydrothermal method and their antibacterial activity study

• We report a hydrothermal method to prepare PEI-functionalized Ag nanoparticles.
• The size of PEI-Ag nanoparticles can be tuned by temperature and growth method.
• PEI-Ag possesses excellent antibacterial activity, exceeds commonly used agents.

In this study, we report a facile, one-step hydrothermal method to synthesize PEI-functionalized Ag nanoparticles in which no extra reducing agent is needed and PEI serves as a reducing agent and a stabilizing agent. The obtained Ag colloids have been characterized by TEM, UV absorption spectra and laser particle size analyzer. We found that the size of Ag nanoparticles can be tuned through the alteration of the temperature and growth mode. Under an acidic condition, PEI-functionalized Ag nanoparticles are positively charged. More importantly, the Ag colloids exhibited stronger antibacterial activity in the bactericidal test. Its bactericidal efficiency exceeds the commonly used antibacterial agents such as Erythromycin, chloramphenicol and penicillin as well as AgNO3 solution. These results prove that our synthesis method is very efficient to produce a stable PEI-functionalized Ag colloid with excellent antibacterial activity.