Sodium hyaluronate and layered double hydroxydes supported silver nanoparticles film: preparation and characterization

Layered double hydroxides (LDH) are very attractive materials that, due to their biocompatibility, compositional flexibility and ion exchange properties, have been applied in many technologically important fields such as catalysis, photophisics, phochemistry and biomedicine. New functional materials for electro-chemical devices and antimicrobial application can be obtained using the LDH surface as a substrate for growing and anchoring metallic nanoparticles. In this contest, a method to produce silver nanoparticles supported on the ZnAl-LDH was developed. AgCl, with diameter of 55 nm, were obtained by using AgNO3 as silver source and ZnAl LDH in chloride form as nucleating agent. The AgCl supported on LDH sheets was reduced by different reducing agents (NaBH4, formaldehyde, sodium hyaluronate) resulting in silver nanoparticles with diameter of 10-15 nm. The silver chloride and silver dimension were evaluated by x-ray powder diffraction and transmission electron microscopy (TEM). UV-Vis spectra of the samples upon reduction showed a band centered at 415 nm due to the surface plasmon resonance of silver with dimension of about 10 nm, in agreement with the TEM analysis. The ZnAl-LDH/Ag nanocomposites can be designed as systems for advanced wound care dressing because of their ability to release zinc and silver ions in physiological media. The released ions can performed two functions: accelerate the skin repair process and reduce the risk of infections. The nanocomposites were used as inorganic filler of hyaluronate based films to be applied as advanced dressing. Preliminary antimicrobial tests indicate that the film were able to inhibit the growth of both bacteria and yeasts.