Micro- and Nanotechnology Technology Offers Page 3

RAMOT at Tel Aviv University Ltd. posted this:

Silver exhibit antibacterial activity in either ionic or metallic forms, albeit by two different mechanisms: silver ions penetrating the bacterial cell interact with the respiratory chain and with cellular DNA. Metallic silver – mostly applied as silver nano-crystals – affects primarily cell membrane by physically 'puncturing' it or by slow release of silver ions resulting from oxidative environment. Both forms - silver nano-crystals or silver ions attached to ion exchanging polymers, mostly applied as impregnated dressings, suffer from poor migration from the supplied 'reservoir' to and into their targeted microbial biofilm. While ionic silver has poor migration due to interaction with chloride and other anions, resulting in insoluble salt precipitation, silver nano crystals migration is physically restricted. We have recently developed novel protein-silver hybrids, comprised of a biologically active glucose oxidase core, coated with a thin (~1.5nm) outer layer of metallic silver. The silver-glucose oxidase hybrid retains enzymatic activity and serves as a unique antibacterial agent, generating silver ions in situ. The soluble silver–glucose oxidase hybrid diffuses into the targeted biofilm vicinity and penetrate into its larger pores. Upon scavenging of glucose traces inside the biofilm, the glucose oxidase core of the hybrid produces hydrogen peroxide, capable of locally oxidizing and dissolving metallic silver, thus affecting enzymatically attenuated in situ silver ions release from the hybrid's silver coating into the immediate vicinity of the targeted cells, resulting in effective disinfection. Project ID : 10-2011-255