Publications

Cationic coatings on titanium surfaces are a promising approach for dental and biomedical implants due to their low-cost antimicrobial effect and no need for antibiotics. These coatings are applied on hydroxylated (-OH) surfaces using silanes, such as 3-aminopropyltriethoxysilane (APTES). However, it is unclear whether the concentration of this organofunctional compound affects surface charge or potential toxicity. This study investigated how different concentrations of APTES in cationic coatings on titanium samples influence electrostatic behavior and interactions with bacteria and mesenchymal stem cells (MSCs). Titanium discs served as controls (Ti group) and were first treated by plasma electrolytic oxidation (PEO) to generate -OH groups (PEO group). Subsequently, APTES was applied at 83.8, 167.6, and 251.4 mM, forming PEO+APTES0.3, PEO+APTES0.6, and PEO+APTES0.9 groups, respectively. Surfaces were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), contact angle, Zeta potential, and profilometry. Microbiological assays assessed initial bacterial adhesion (1 h) and biofilm formation (24 h) using Staphylococcus aureus and Escherichia coli. Cell metabolism was assessed on days 1, 3, and 8, while cell viability was assessed on days 1 and 3 using mesenchymal stem cells. PEO-treated surfaces showed porous morphology, and silanization increased roughness and shifted surfaces toward hydrophobicity. Amines and surface charge changes were confirmed by XPS and Zeta potential. Increasing APTES concentration did not proportionally increase cation number. Crystalline hydroxyapatite oxides were identified following the electrochemical process. SEM, EDS, and FTIR confirmed treatment stability after 28 days of immersion, while tribological tests indicated improved performance for PEO-treated groups. Cationic coatings reduced bacterial adhesion by up to 65%, decreased biofilm Log10 values, and increased dead bacteria proportion. Biocompatibility was confirmed by metabolism and cell viability tests, with the group with lower APTES concentration showing the best performance on day 8, with an 80% higher cell metabolism than day 1. On the other hand, higher concentrations of APTES resulted in reduced cell metabolism. These findings indicate, for the first time, that APTES concentration does not affect electrostatic properties but that lower concentrations are required for cytocompatible cationic coatings.

JTD Keywords: Adhesion, Biofilms, Cationic coating, Cell proliferation, Coatings, Electrostatic interactions, Implant surfaces, In-vitro, Nanoparticles, Osteoblasts, Oxidation, Self-assembled monolayers, Thin-films, Titanium, Wettability

Laser surface micropatterning of dental-grade zirconia (3Y-TZP) was explored with the objective of providing defined linear patterns capable of guiding bone-cell response.A nanosecond (ns-) laser was employed to fabricate microgrooves on the surface of 3Y-TZP discs, yielding three different groove periodicities (i.e., 30, 50 and 100 µm). The resulting topography and surface damage were characterized by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). X-Ray diffraction (XRD) and Raman spectroscopy techniques were employed to assess the hydrothermal degradation resistance of the modified topographies. Preliminary biological studies were conducted to evaluate adhesion (6 h) of human mesenchymal stem cells (hMSC) to the patterns in terms of cell number and morphology. Finally, Staphylococcus aureus adhesion (4 h) to the microgrooves was investigated.The surface analysis showed grooves of approximately 1.8 µm height that exhibited surface damage in the form of pile-up at the edge of the microgrooves, microcracks and cavities. Accelerated aging tests revealed a slight decrease of the hydrothermal degradation resistance after laser patterning, and the Raman mapping showed the presence of monoclinic phase heterogeneously distributed along the patterned surfaces. An increase of the hMSC area was identified on all the microgrooved surfaces, although only the 50 µm periodicity, which is closer to the cell size, significantly favored cell elongation and alignment along the grooves. A decrease in Staphylococcus aureus adhesion was observed on the investigated micropatterns.The study suggests that linear microgrooves of 50 µm periodicity may help in promoting hMSC adhesion and alignment, while reducing bacterial cell attachment.Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.

JTD Keywords: abutment material, alumina toughened zirconia, antibacterial, bacterial adhesion, biofilm growth, cell adhesion, dental implants, hydrothermal degradation, implant surfaces, in-vitro, laser patterning, osseointegration, osteogenic differentiation, part 1, surface topography, y-tzp ceramics, Antibacterial, Antibacterials, Bacteria, Bone, Cell adhesion, Cell culture, Cells adhesion, Ceramics, Chemistry, Degradation resistance, Dental implants, Dental material, Dental materials, Dental prostheses, Human, Human mesenchymal stem cells, Humans, Hydrothermal degradation, Laser patterning, Laser surface, Lasers, Low-temperature degradation, Materials testing, Microscopy, electron, scanning, Nanosecond lasers, Osseointegration, Piles, Scanning electron microscopy, Staphylococcus aureus, Stem cells, Surface analysis, Surface damages, Surface properties, Surface property, Surface topography, Topography, Yttrium, Zirconia, Zirconium