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DENTIN, APATITE, ND-YAG lasers, STREPTOCOCCUS mutans, SOLID-liquid interfaces, SEMICONDUCTOR lasers, and PULSED lasers

A simple, area-specific coating technique for fluoridated apatite (FAp) on teeth would be useful in dental applications. Recently, we achieved area-specific FAp coating on a human dentin substrate within 30 min by a laser-assisted biomimetic (LAB) process; pulsed Nd:YAG laser irradiation in a fluoride-containing supersaturated calcium phosphate solution (FCP solution). The LAB-processed, FAp-coated dentin substrate exhibited antibacterial activity against a major oral bacterium, Streptococcus mutans. In the present study, we refined the LAB process with a combination of a dental diode laser and a clinically approved light-absorbing molecule, indocyanine green (ICG). A micron-thick FAp layer was successfully formed on the dentin surface within only 3 min by the refined LAB process, i.e., dental diode laser irradiation in the FCP solution following ICG treatment. The ICG layer precoated on the dentin substrate played a crucial role in inducing rapid pseudo-biomineralization (FAp layer formation) on the dentin surface by absorbing laser light at the solid-liquid interface. In the refined LAB process, the precoated ICG layer was eliminated and replaced with the newly formed FAp layer composed of vertically oriented pillar-like nanocrystals. Cross-sectional ultrastructural analysis revealed a smooth interface between the FAp layer and the dentin substrate. The refined LAB process has potential as a tool for the tooth surface functionalization and hence, is worth further process refinement and in vitro and in vivo studies. [ABSTRACT FROM AUTHOR]

Biomedical engineering, Génie biomédical, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Chirurgie (generalites). Transplantations, greffes d'organes et de tissus. Pathologie des greffons, Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases, Technologie. Biomatériaux. Equipements, Technology. Biomaterials. Equipments, Biomatériau, Biomaterial, Génie biomédical, Biomedical engineering, Ingeniería biomédica, Laser, Láser, Matériau revêtement, Coating material, Material revestimiento, Phosphate de calcium, Calcium phosphate, Calcio fosfato, Revêtement, Coatings, Revestimiento, Traitement surface, Surface treatment, Tratamiento superficie, Biomimétique, biomimetic process, calcium phosphate (CaP), coating, laser, and surface modification

Simple, mild, and area-specific calcium phosphate (CaP) coating techniques are useful for the production and surface modification of biomaterials. In this study, an area-specific CaP coating technique for polymer substrates was successfully developed using a liquid-phase laser process. In the proposed method, Nd―YAG laser light (355 nm, 30 Hz, and 1―3 W) irradiated an ethylene-vinyl alcohol copolymer (EVOH) substrate immersed in a supersaturated CaP solution for various periods of time (up to 30 min). The CaP-forming ability increased with an increase in the laser power and irradiation period. At the optimal laser power (3 W), a continuous CaP layer formed within 30 min on the laser-irradiated surface of the EVOH substrate. The formation of CaP was attributed to laser absorption by the EVOH substrate, which promoted the surface modification of EVOH and an increase in the temperature of the solution near the surface of the substrate. The resulting CaP coating showed better cell adhesion property than the naked EVOH substrate. The proposed CaP coating technique is simple (quick and single step) and area specific. Furthermore, the present process is carried out under mild conditions, that is, at normal pressures and temperatures in a safe aqueous medium. These are significant advantages of the proposed CaP coating technique.

CALCIUM phosphate, CHROMITE, SUPERSATURATED solutions, ALLOYS, PULSED lasers, COBALT, CHROMIUM alloys, and DENTAL metallurgy

The biocompatibility and osteoconductivity of metallic biomaterials can be achieved by calcium phosphate (CaP) coating. We recently developed a laser-assisted biomimetic (LAB) process for rapid and area-specific CaP coating on several materials. In the present study, the LAB process was applied to cobalt–chromium (Co−Cr) alloy, a metallic biomaterial widely used in orthopedic and dental applications. The LAB process was conducted by irradiation of unfocused pulsed laser light onto the substrate immersed in supersaturated CaP solution. The LAB-processed substrate formed CaP on the irradiated surface within only 5 min and was coated with a micron-thick CaP layer within 30 min by the effects of laser-induced surface modification and heating. Ultrastructural analysis with transmission electron microscopy revealed that the resultant CaP layer was integrated with the underlying substrate through two intermediate layers, an upper chromium oxide layer and a lower Co-rich (Cr-deficient) alloy layer. The CaP layer was loaded with a large number of cobalt chromite (CoCr2O4) nanoparticles. The results obtained offer new insights into the mechanism of CaP coating in the LAB process and future applications of LAB-processed Co−Cr alloys. [ABSTRACT FROM AUTHOR]

ビワがんしゅ病細菌, 病原性遺伝子psvA, SUMOプロテアーゼ, 細胞内局在性, Pseudomonas_syringae_pv._eriobotryae, Virulence_gene_psvA, SUMO_protease, and Subcellular_localization