engleski

Multilayers of Polyaminoacids and Silver Nanoparticles as Antimicrobial Coatings for Orthopaedic Implants

Orthopaedic implant failure is a major health problem. The main cause is nosocomial infections, which are further complicated by the increased incidence of antimicrobial resistance (AMR). This fact motivates the research of alternative approaches in the development of antimicrobial materials and, in particular, new surface coatings that can locally prevent microbial adhesion and proliferation. [1] Recently, multilayers of biocompatible polyelectrolytes containing antimicrobial components have been investigated because of their wide application on different types of implants. In this study, a multilayer of poly-L-glutamic acid (PGA) and poly-L-lysine (PLL) with incorporated silver nanoparticles (AgNPs) was formulated and physiochemically characterised. AgNPs were selected because they have antimicrobial properties and do not promote the development of AMR.[2] AgNPs were synthesised by reduction of silver nitrate with polyvinylpyrrolidone as stabilising agent. [3] The synthesised nanoparticles were characterised by transmission electron microscopy (TEM) and UV-Vis spectroscopy. Their stability in ultrapure water and buffer (HEPES/NaCl) with the addition of PGA or PLL was determined by monitoring the hydrodynamic diameter and zeta potential during 24 hours. The most stable suspension was used for the layer-by-layer assembly of polyaminoacids multilayer with or without incorporated AgNPs, structured as follows: (PLL-PGA)10 and [(PLL-PGA)2 (PLL-AgNP) (PLL- PGA)2]2, respectively. The assembly was monitored by quartz-crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM). The QCM-D measurements showed that the adsorption of the consecutive individual layers of polyaminoacids and nanoparticles was accompanied by a stepwise decrease in frequency, indicating successful assembly of the multilayer. Both in the presence and absence of AgNPs, the exponential growth regime was observed. The increase in dissipation indicated the viscoelastic properties of the both type multilayers. AFM micrographs after five adsorbed bilayers showed granular structures that became larger and denser after adsorption of additional layers. The difference in the morphology of the multilayers with and without incorporated AgNPs indicates their successful incorporation. In summary, the results indicate that AgNPs can be successfully incorporated into polyaminoacids’ multilayers, which is of potential interest not only for the development of new coatings for orthopaedic implants but also for other biomedical materials.

poly-L-glutamic acid ; poly-L-lysine ; multilayers ; silver nanoparticles ; layer-by-layer ; implants

nije evidentirano