Evaluation of Microbial Adhesion and Biofilm Formation on Nano-Structured and Nano-Coated Ortho-Prosthetic Materials by a Dynamic Model

• Main Authors: Simone Leonetti, Benedetta Tuvo, Beatrice Campanella, Stefano Legnaioli, Massimo Onor, Emilia Bramanti, Michele Totaro, Angelo Baggiani, Serena Giorgi, Gaetano Pierpaolo Privitera, Nicola Piolanti, Paolo Domenico Parchi, Beatrice Casini
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: International Journal of Environmental Research and Public Health
• Subjects: biofilm; drip flow biofilm reactor; implantable device-related infections; titanium and cobalt-chrome nano-structured materials; silver nanoparticles; quorum sensing
• Online Access: https://www.mdpi.com/1660-4601/17/3/1013

The bio-engineering technologies of medical devices through nano-structuring and coating was recently proposed to improve biocompatibility and to reduce microbial adhesion in the prevention of implantable device-related infections. Our aim was to evaluate the ability of new nano-structured and coated materials to prevent the adhesion and biofilm formation, according to the American Standard Test Method ASTM-E2647-13. The materials composition was determined by X-ray Fluorescence and Laser Induced Breakdown Spectroscopy. Silver release was evaluated by Inductively Coupled Plasma Mass Spectrometry analysis. The gene expression levels of the Quorum Sensing <i>Las</i> and <i>Rhl</i> system were evaluated by the &#916;&#916;Ct method. The Log bacterial density (Log CFU/cm²) on TiAl6V4 was 4.41 &#177; 0.76 and 4.63 &#177; 1.01 on TiAl6V4-AgNPs compared to 2.57 &#177; 0.70 on CoCr and 2.73 &#177; 0.61 on CoCr-AgNPs (P &lt; 0.0001, A.N.O.V.A.- one way test). The silver release was found to be equal to 17.8 &#177; 0.2 &#181;g/L after the batch phase and 1.3 &#177; 0.1 &#181;g/L during continuous flow. The <i>rhlR</i> gene resulted in a 2.70-fold increased expression in biofilm growth on the silver nanoparticles (AgNPs) coating. In conclusion, CoCr showed a greater ability to reduce microbial adhesion, independently of the AgNPs coating. The silver release resulted in promoting the up-regulation of the <i>Rhl</i> system. Further investigation should be conducted to optimize the effectiveness of the coating.