Is nanomaterial- and vancomycin-loaded polymer coating effective at preventing methicillin-resistant Staphylococcus aureus growth on titanium disks? An in vitro study

PurposePeriprosthetic joint infections induced by methicillin-resistant Staphylococcus aureus (MRSA) pose a major socioeconomic burden. Given the fact that MRSA carriers are at high risk for developing periprosthetic infections regardless of the administration of eradication treatment pre-operatively, the need for developing new prevention modalities is high.MethodsThe antibacterial and antibiofilm properties of vancomycin, Al2O3 nanowires, and TiO2 nanoparticles were evaluated in vitro using MIC and MBIC assays. MRSA biofilms were grown on titanium disks simulating orthopedic implants, and the infection prevention potential of vancomycin-, Al2O3 nanowire-, and TiO2 nanoparticle-supplemented Resomer (R) coating was evaluated against biofilm controls using the XTT reduction proliferation assay.ResultsAmong the tested modalities, high- and low-dose vancomycin-loaded Resomer (R) coating yielded the most satisfactory metalwork protection against MRSA (median absorbance was 0.1705; [IQR = 0.1745] vs control absorbance 0.42 [IQR = 0.07]; p = 0.016; biofilm reduction was 100%; and 0.209 [IQR = 0.1295] vs control 0.42 [IQR = 0.07]; p < 0.001; biofilm reduction was 84%, respectively). On the other hand, polymer coating alone did not provide clinically meaningful biofilm growth prevention (median absorbance was 0.2585 [IQR = 0.1235] vs control 0.395 [IQR = 0.218]; p < 0.001; biofilm reduction was 62%).ConclusionsWe advocate that apart from the well-established preventative measures for MRSA carriers, loading implants with bioresorbable Resomer (R) vancomycin-supplemented coating may decrease the incidence of early post-op surgical site infections with titanium implants. Of note, the payoff between localized toxicity and antibiofilm efficacy should be considered when loading polymers with highly concentrated antimicrobial agents

Fine tuning of PEDOT electronic properties using solvents

Non-destructive method of spectroscopic ellipsometry (SE) from IR to FUV was applied to study PEDOT/PSS thin films deposited by spin coating from aqueous dispersions of the material with different N,N-Dimethylformamide (DMF) volume percent. In our work we used the Tauc-Lorentz model to describe the dielectric function of PEDOT/PSS:DMF films in the Vis-FUV energy region. First, the spectrum analysis showed that the thickness and the fundamental band gap Eg of the film is being decreased with the increase of DMF content in the dispersion. Taking into account that the heating temperature is below the boiling point of DMF we assume that DMF molecules are incorporated in the film volume and act as dopants. Further more, this means that carrier concentration is being increased and thus we have higher electrical conductivity. The existence of DMF molecules in the film proved from FTIR SE, which can probe the bonding structure of the materials. The results showed lowering of peak intensity assigned to PEDOT/PSS and appearing of peaks assigned to DMF in the imaginary part of spectrum. In conclusion, SE is a potential tool for the evaluation of electronic properties for conductive polymers

X-ray diffuse scattering investigation of thin films

X-ray Diffuse Scattering (XDS) is presented, a technique, which determines the roughness, morphology and nanoparticle distribution of thin films. XDS is complementary to X-ray Diffraction and Reflectivity (XRD-XRR). The ability of XDS is demonstrated to investigate the films' nanoscale surface structure and to determine additional geometrical features such as correlation length and fractal characteristics. It is shown that XDS can be used for the study of the surface morphology, as well as, phase identification of amorphous materials and combined with XRR for quantitative analysis of composite films using the Distorted Wave Born Approximation (DWBA) with the concept that the film surface behaves like a Self-Affined medium. As model systems we study nanocrystalline Boron Nitride (BN) and amorphous Carbon (a-C) films. XDS spectra of BN films containing both cubic and hexagonal phases exhibit two set of Yoneda peaks, located at angles characteristic of the corresponding BN densities, while BN films containing only hexagonal phase exhibit one characteristic set. This indicates that the two BN phases are not atomically mixed. The opposite: strong atomical mixture of sp(2) and sp(3) components, was found in a-C films by XDS. Additionally, the growth mechanism for a-C films deposited with or without ion bombardment assistance is predicted and discussed. (C) 2003 Elsevier B.V. All rights reserved.Materials Science and Engineering B-Solid State Materials for Advanced Technolog