AgNPs embedded in silica matrix: a way to impair the microbial adhesion on dielectric surfaces

Kremena Makasheva (1) , Marvine Soumbo (2) , Adriana Scarangella (2) , Christina Villeneuve-Faure (3) , Caroline Bonafos (4) , Christine Roques (5)

1 LAPLACE-ScIPRA - Sciences et Ingénierie des Plasmas Réactifs et des Arcs
2 LAPLACE - LAboratoire PLasma et Conversion d'Energie
3 LAPLACE-DSF - Diélectriques Solides et Fiabilité
4 CEMES - Centre d'élaboration de matériaux et d'études structurales
5 LGC - Laboratoire de Génie Chimique

The emergence and selection of antibiotic-resistant bacteria is an ever increasing Public Health problem. Microbial adhesion and subsequent biofilm formation are at the origin of hospital-acquired infections (HAIs), known also as healthcare-associated infections (HCAIs), often leading to septic complications and even lethal issues and entailing large economical losses for the health-care systems. This threat is of particular concern when compared with the very limited number of new antimicrobial agents in the pipeline of the pharmaceutical industry and the ability of micro-organisms to be less sensitive under biofilm organization. In this context, new strategies oriented to the prevention of environmental contamination of medical devices, catheters, implants, etc., are under scrutiny. A possible solution is related to silver nanoparticles (AgNPs)-containing surface coatings as antimicrobial agents. The AgNPs are embedded in the coating and progressively conducted to the surface, thus providing continuous inhibition of the microbial adhesion over long term.Silver, and particularly AgNPs, exhibit inherent antimicrobial properties. Recently, the AgNPs proved the largest antimicrobial activity against bacteria, viruses and eukaryotic micro-organisms. The biological activity of AgNPs is closely related to ionic Ag (Ag+) release or to direct contact of the micro-organisms with AgNPs, resulting in protein denaturation at different cell locations. On the other hand, the uncontrolled use of AgNPs hides environmental risks due to the AgNPs-toxicity. Modulation of the silver ion release from AgNPs allows delivery of the appropriate dose of Ag+ for biomedical uses and environmental protection. The successful and sustainable use of nanocomposite materials containing AgNPs is mostly supported by the knowledge of how to use them safely prior to their large distribution. To that end a better understanding of the molecular mechanisms of interaction of AgNPs with micro-organisms, considering also the environment (presence of proteins of different nature), is highly demanded in order to better describe the AgNPs antimicrobial activity.In this work we exploit the multifunctionality of AgNPs as plasmonic antenna when embedded at a controlled nanometric distance from the free surface of thin SiO2 layers and as biocide agents because of their strong toxicity towards micro-organisms to study the adhesion of Candida albicans IP48.72 on dielectric surfaces. The present study focuses on evaluation of the shear-induced detachment of the yeast C. albicans in contact with plasma mediated thin silica (SiO2) layers containing AgNPs. The experiments are performed in presence of two different proteins, Bovin Serum Albumin (BSA) and Fibronectin (Fn), to assess their respective contributions. The environment alters the C. albicans adhesion on solid surfaces depending on the protein nature. Through the release of Ag+ ions, the AgNPs embedded close to the SiO2 surface strongly reduce the adhesion forces of C. albicans and lead the dead of adhered cells. Surprisingly, cell death does not weaken the major impact of protein nature on cell adhesion. Further work will be directed to consideration of more complex protein organizations, such as intermixed proteins/proteins and proteins/micro-organisms systems.

Domaines: Sciences de l'ingénieur [physics]

Kremena Makasheva, Marvine Soumbo, Adriana Scarangella, Christina Villeneuve-Faure, Caroline Bonafos, et al.. AgNPs embedded in silica matrix: a way to impair the microbial adhesion on dielectric surfaces. 15th IEEE International Conference on Nano/Micro Engineered & Molecular Systems (IEEE NEMS 2020), Sep 2020, San Diego, United States. ⟨hal-03092475⟩