Influence of nanohydroxyapatite surface properties on Staphylococcus epidermidis biofilm formation

Abstract

Nanohydroxyapatite (nanoHA), due to its chemical properties, has appeared as an exceptionally promising bioceramic to be used as bone regeneration material. Staphylococcus epidermidis have emerged as major nosocomial pathogens associated with infections of implanted medical devices. In this work, the purpose was to study the influence of the nanoHA surface characteristics on S. epidermidis RP62A biofilm formation. Therefore, two different initial inoculum concentrations (Ci) were used in order to check if these would affect the biofilm formed on the nanoHA surfaces. Biofilm formation was followed by the enumeration of cultivable cells and by scanning electron microscopy. Surface topography, contact angle, total surface area and porosimetry of the biomaterials were studied and correlated with the biofilm data. The surface of nanoHA sintered at 830 o C (nanoHA830) showed to be more resistant to S. epidermidis attachment and accumulation than that of nanoHA sintered at 1000 o C (nanoHA1000). The biofilm formed on nanoHA830 presented differences in terms of structure, surface coverage and EPS production when compared to the one formed on nanoHA1000 surface. It was observed that topography and surface area of nanoHA surfaces had influence on the bacterial attachment and accumulation. Ci influenced bacteria attachment and accumulation on nanoHA surfaces over time. The choice of the initial inoculum concentration was relevant proving to have an effect on the extent of adherence thus being a critical point for human health if these materials are used in implantable devices. This study showed that the initial inoculum concentration and surface material properties determine the rate of microbial attachment to substrata and consequently are related to biofilm-associated infections in biomaterials.

Anti-sessile bacterial and cytocompatibility properties of CHX-loaded nanohydroxyapatite

“…NanoHA discs, 10 mm diameter and 1 mm height, were prepared as previously described [32]. Briefly, nanoHA discs were produced using 150 mg of dry power under uniaxial compression stress of 2 MPa.…”

“…The CHX mass adsorbed per unit area of nanoHA discs (Qe, mg/m 2 ) versus final equilibrium con-centration of CHX in solution (Ce, mg/L) was plotted, and Langmuir and Freundlich adsorption isotherms were fitted to the experimental data. The specific surface area of nanoHA discs (4.9 m 2 /g) was previously obtained by Barros et al [32].…”

“…Four replicas of each material were transferred to glass beakers containing 20 mL of 0.9% NaCl and were sonicated for 10 min in an ultra-sonic bath (Transsonic 420 ELMA, 70 W, 35 kHz) to detach the bacteria [32]. Then, the suspension was serially diluted and the Colony Forming Units (CFUs) were estimated by spread plating in Plate Count Agar (PCA) using 10 L of each dilution.…”

Antibacterial activity of standard and N-doped titanium dioxide-coated endotracheal tubes: an in vitro study

“…The inoculum size we used had a similar CFU count compared to a previous study (17) and has been shown to be able to initiate biofilm formation in vitro . (26) The filter was later inserted in the ETT segment. A small bacterial inoculum was chosen to simulate the initial colonization of the tube, subsequently leading to the formation of biofilm.…”

Heparinized nanohydroxyapatite/collagen granules for controlled release of vancomycin

“…The heat treatment cycle used was as follows: heating rate of 1 C/min till 600 C with 1 h plateau, followed by a heating rate of 4 C/min till 830 C with 1 h plateau. 19 Afterward, the samples were naturally cooled inside the furnace.…”