부산대학교 도서관

A new antibacterial coating made of poly( l-lysine)/hyaluronic acid (PLL/HA) multilayer films and liposome aggregates loaded with silver ions was designed. Liposomes filled with an AgNO 3solution were first aggregated by the addition of PLL in solution. The obtained micrometer-sized aggregates were then deposited on a PLL/HA multilayer film, playing the role of a spacer with the support. Finally, HA/PLL/HA capping layers were deposited on top of the architecture to form a composite AgNO 3coating. Release of encapsulated AgNO 3from this composite coating was followed and triggered upon temperature increase over the transition temperature of vesicles, found to be equal to 34 °C. After determination of the minimal inhibitory concentration (MIC) of AgNO 3in solution, the antibacterial activity of the AgNO 3coating was investigated against Escherichia coli. A 4-log reduction in the number of viable E. colicells was observed after contact for 120 min with a 120 ng/cm 2AgNO 3coating. In comparison, no bactericidal activity was found for PLL/HA films previously dipped in an AgNO 3solution and for PLL/HA films with liposome aggregates containing no AgNO 3solution. The strong bactericidal effect could be linked to the diffusion of silver ions out of the AgNO 3coating, leading to an important bactericidal concentration close to the membrane of the bacteria. A simple method to prepare antibacterial coatings loaded with a high and controlled amount of AgNO 3is therefore proposed. This procedure is far superior to that soaking AgNO 3or Ag nanoparticles into a coating. In principle, other small bactericidal chemicals like antibiotics could be encapsulated by this method. This study opens a new route to modify surfaces with small solutes that are not permeating phospholipid membranes below the phase transition temperature. [ABSTRACT FROM AUTHOR]