The present work is aimed at getting a new insight into biomorphic silicon carbides (bioSiCs) as bone replacement materials. BioSiCs from a variety of precursors were produced, characterized, and loaded with a broad-spectrum antibiotic. The capacity of loaded bioSiCs for preventing and/or treating preformed S. aureus biofilms has been studied. The differences in precursor characteristics are maintained after the ceramic production process. All bioSiCs allow the loading process by capillarity, giving loaded materials with drug release profiles dependent on their microstructure. The amount of antibiotic released in liquid medium during the first six hours depends on bioSiC porosity, but it could exceed the minimum inhibitory concentration of Staphylococcus aureus, for all the materials studied, thus preventing the proliferation of bacteria. Differences in the external surface and the number and size of open external pores of bioSiCs contribute towards the variations in the effect against bacteria when experiments are carried out using solid media. The internal structure and surface properties of all the systems seem to facilitate the therapeutic activity of the antibiotic on the preformed biofilms, reducing the number of viable bacteria present in the biofilm compared to controls. 1. Introduction The pathogenic events taking place on the surface of medical devices are primarily associated with the presence of microorganisms and their biofilms [1, 2]. A biofilm is an intricate community of microorganisms embedded in a polysaccharide matrix, capable of attaching onto different kinds of surfaces developing a hard-to-eradicate infection [3]. The adhesion of bacteria onto a surface (biological or artificial) depends on biophysical properties, such as wettability and/or electrostatic forces, and the production of specific factors such as polysaccharide intercellular adhesins that create links between the bacteria themselves and bacteria surface. Microorganisms reach the implanted medical devices during or immediately after orthopedic surgery, thus leading to further complications [4]. Among postoperative problems, infections caused by S. aureus arise from the worst prognosis the ability of this microorganism to adhere to foreign bodies forming biofilms. The formation of biofilms is a key part in antibiotic resistance [5]. Strategies have been developed to prevent biofilm formation after surgery by surface modification of biomaterials which in turn should modify the bacterial adherence [6] or the load and release of broad-spectrum antibiotics from the
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