Structural and biological evaluation of lignin addition to simple and silver-doped hydroxyapatite thin films synthesized by matrix-assisted pulsed laser evaporation

Abstract

We report on thin film deposition by matrix-assisted pulsed laser evaporation of simple hydroxyapatite (HA) or silver (Ag) doped HA combined with the natural biopolymer organosolv lignin (Lig) (Ag:HA-Lig). Solid cryogenic target of aqueous dispersions of Ag:HA-Lig composite and its counterpart without silver (HA-Lig) were prepared for evaporation using a KrF* excimer laser source. The expulsed material was assembled onto TiO2/Ti substrata or silicon wafers and subjected to physical-chemical investigations. Smooth, uniform films adherent to substratum were observed. The chemical analyses confirmed the presence of the HA components, but also evidenced traces of Ag and Lig. Deposited HA was Ca deficient, which is indicative of a film with increased solubility. Recorded X-ray Diffraction patterns were characteristic for amorphous films. Lig presence in thin films was undoubtedly proved by both X-ray Photoelectron and Fourier Transform Infra-Red Spectroscopy analyses. The microbiological evaluation showed that the newly assembled surfaces exhibited an inhibitory activity both on the initial steps of biofilm forming, and on mature bacterial and fungal biofilm development. The intensity of the anti-biofilm activity was positively influenced by the presence of the Lig and/or Ag, in the case of Staphylococcus aureus, Pseudomonas aeruginosa and Candida famata biofilms. The obtained surfaces exhibited a low cytotoxicity toward human mesenchymal stem cells, being therefore promising candidates for fabricating implantable biomaterials with increased biocompatibility and resistance to microbial colonization and further biofilm development.

Antimicrobial dental implant functionalization strategies —A systematic review

“…Pathogens found at infected oral implant sites, including S. mutans 90) , S. aureus 93,94) , S. oralis 43) , P. gingivalis and A. actinomycetemcomitans 84) were killed or significantly reduced upon contact with silver-implanted surfaces. All tested silver surfaces, such as hydroxyapatite (HA)-silver-surfaces 42,44,[46][47][48][49][50][51]91,161) or plasma sprayed silver-implanted HA 45,95) shared good antimicrobial activity.…”

“…Dextran and polyethylene glycol (PEG) surfaces have been shown to be effective in suppressing protein adhesion, platelet adhesion, bacterial adhesion and biofilm formation of oral relevant pathogens, such as S. aureus, S. sanguinis, L. salivarius S. mutans and S.gordonii 29,96,[101][102][103]107) . Lignin, a complex, amorphous organic polymer found in plant tissues, exhibits antibacterial activity against S. aureus, P. aeruginosa and C. famata 51) . Polypyrrole-coated titanium surfaces exhibit a three-fold greater repellent effect than a common TiAl 6V alloy against E.coli and S. aureus 104) .…”

“…Peptide-functionalized polymers exhibit a selective biointeraction pattern that may be useful in dental implantology, as they can enhance attachment of fibroblasts and osteoblasts while reducing non-specific protein adsorption, thus resulting in reduced bacterial adherence. Lignin, PEG, and silicon-doped surfaces exhibit improved osteoconductive characteristics, with high adhesion rates for epithelial and osteoblastic cells 51,97,101) . However, polypyrrole surfaces reduce cell proliferation and adhesion of eukaryotic cells 104) .…”

New Substituted Benzoylthiourea Derivatives: From Design to Antimicrobial Applications

“…The compounds were solubilized in DMSO to a final concentration of 10 mg/mL and further sterilized by filtration (using 0.22 µm filter membranes). The quantitative assay of the minimal inhibitory concentration (MIC, µg/mL) was performed by the microdilution method in 96 multi-well plates [59]. In this purpose, serial binary dilutions (ranging between 1024 and 8 µg/mL) were achieved in nutrient broth/YPG (yeast peptone glucose) and each well was seeded with microbial inoculum of 0.5 McFarland density.…”

Composite Coatings Based on Renewable Resources Synthesized by Advanced Laser Techniques

“…Until now, biocomposite coatings based on the renewable lignin were studied by electrophoretic deposition (EPD) only [36,37], and the results revealed that the obtained composite exhibited enhanced stability and improved interconnected structure, with an increased coating cohesion [53]. For electrophoretic deposition (EPD) method, it was applied a constant voltage (at optimized parameters 60 V for 45 s), and it were obtained uniform composite coatings with good adhesion and mechanical properties without any phase transformation [67].…”