Due to the excellent mechanical properties and biocompatibility, titanium (Ti) and titanium alloys have been extensively utilized in dental implantology for maintaining space where new bone tissue will grow in guided bone generation surgery. However, the limited biological activity of titanium alloys restricts their application in certain clinical settings. To enhance the bioactivity and pro-osteogenic effects of Ti alloys, an octacalcium phosphate (OCP) coating was deposited to the surface of 3D-printed titanium sheets (3D-PTs) with polydopamine (PDA) as an adhesive. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), selective area electron diffraction (SAED), and contact angle analysis were employed to evaluate the physicochemical properties and wettability of fabricated coatings. Meanwhile, the interface bonding strength between the OCP/PDA coating and 3D-PTs was evaluated via adhesion strength tests. Additionally, the biocompatibility of the OCP/PDA coating was investigated by culturing rat bone marrow mesenchymal stem cells (BMSCs) on the coating directly, followed by cytoskeleton immunofluorescence staining and CCK-8 assays.
The surface modification protocol initiated with meticulous substrate preparation, involving sequential ultrasonication in acetone, ethanol, and deionized water to eliminate organic contaminants and oxidation layers. Subsequently, the 3D-PTs were immersed in a 2 g/L dopamine solution (pH 8.5) and gently shaken at 57 ℃ for 6 hours to induce spontaneous polymerization, forming a conformal PDA film that served dual purposes as both molecular anchor and mineralization template. Transitioning to the biomimetic phase, the PDA-coated 3D-PTs were immersed in a supersaturated calcium phosphate solution at 37 ℃ for 48 hours for the OCP layer, during which the action of Catechol functional groups directed the epitaxial growth of OCP crystallites. Post-processing protocols ensured material stability through ambient drying and steam sterilization, preparing specimens for comprehensive physicochemical evaluation and biological validation.
Advanced characterization techniques demonstrated successful fabrication of the OCP/PDA coating with robust adhesion to 3D-PTs. Following the preparation of the PDA coating, spherical PDA polymer particles were observed on the 3D-PT surface via SEM. EDS revealed an increased nitrogen (N) peak, and Raman spectroscopy displayed characteristic peaks at 1 350 cm-1 and 1 580 cm-1, confirming the successful deposition of PDA on the 3D-PT surface. After the OCP/ PDA coating was prepared, SEM images revealed rhomboid plate-like crystals. EDS analysis indicated new calcium (Ca) and phosphorus (P) peaks with a Ca/P ratio of 1.43. XRD, TEM, and SAED results further demonstrated characteristic peaks corresponding to the (0-10), (002), and (420) crystal planes, collectively confirming the successful formation of OCP. Additionally, contact angle measurements indicated that the OCP/PDA/3D-PT group exhibited significantly enhanced hydrophilicity compared to the 3D-PT group. The adhesion strength of the OCP/PDA coating was classified as level 1 according to the GB/T9286 standard. Furthermore, biological validation experiments substantiated the clinical relevance of these surface modifications. Cytoskeleton immunofluorescence staining and CCK-8 assays demonstrated that the composite coating exhibited excellent biocompatibility. These findings highlight the potentially expanded application of this coating in dental practice, particularly in severe bone defect repair cases. Further investigations will focus on the molecular biological mechanisms of the ceramic composite coating to promote bone regeneration.
Key words
calcium phosphate coating /
polydopamine /
bonding strength /
wettability /
titanium alloy /
biocompatibility
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References
[1] CHEN H Z, JIANG N, ZHANG J, et al.Micron/ Submicron Scaled Hierarchical Ti Phosphate/Ti Oxide Hybrid Coating on 3D Printed Scaffolds for Improved Osteointegration[J]. ACS Biomaterials Science & Engineering, 2023, 9(3): 1274-1284.
[2] KIM J, KIM S, SONG I.Octacalcium Phosphate, a Promising Bone Substitute Material: A Narrative Review[J]. Journal of Yeungnam Medical Science, 2024, 41(1): 4-12.
[3] SUZUKI O, SHIWAKU Y, HAMAI R.Octacalcium Phosphate Bone Substitute Materials: Comparison between Properties of Biomaterials and Other Calcium Phosphate Materials[J]. Dental Materials Journal, 2020, 39(2): 187-199.
[4] LI C L, YAO X H, HANG R Q, et al.Facile Preparation of Nanostructured Octacalcium Phosphate Coatings on Micro-Arc Oxidized Magnesium with Different Functionalities for Bone Repair Application[J]. Colloids and Surfaces B: Biointerfaces, 2021, 197: 111426.
[5] JIANG P L, LIANG J H, SONG R, et al.Effect of Octacalcium-Phosphate-Modified Micro/Nanostructured Titania Surfaces on Osteoblast Response[J]. ACS Applied Materials & Interfaces, 2015, 7(26): 14384-14396.
[6] ITALIANO A E V, TRANQUILIN R L, MARIN D O M, et al. Synthesis of Calcium Phosphate by Microwave Hydrothermal Method: Physicochemical and Morphological Characterization[J]. International Journal of Biomaterials, 2024, 2024: 2167066.
[7] KOKUBO T, ITO S, HUANG Z T, et al.Ca, P-Rich Layer Formed on High-Strength Bioactive Glass-Ceramic A-W[J]. Journal of Biomedical Materials Research, 1990, 24(3): 331-343.
[8] LI M H, WANG M J, WEI L F, et al.Biomimetic Calcium Phosphate Coating on Medical Grade Stainless Steel Improves Surface Properties and Serves as a Drug Carrier for Orthodontic Applications[J]. Dental Materials, 2023, 39(2): 152-161.
[9] WU H, ZHAO C C, LIN K L, et al.Mussel-Inspired Polydopamine-Based Multilayered Coatings for Enhanced Bone Formation[J]. Frontiers in Bioengineering and Biotechnology, 2022, 10: 952500.
[10] FARDJAHROMI M A, EJEIAN F, RAZMJOU A, et al.Enhancing Osteoregenerative Potential of Biphasic Calcium Phosphates by Using Bioinspired ZIF8 Coating[J]. Materials Science and Engineering: C, 2021, 123: 111972.
[11] 孙仪庭, 陈思悦, 陈昱, 等. 聚多巴胺仿生掺锶羟基磷灰石涂层的制备及对骨髓间充质干细胞生物学特性的影响[J]. 口腔颌面修复学杂志, 2021, 22(1): 2-8.
SUN Y T, CHEN S Y, CHEN Y, et al.Mussel-Inspired Strontium-Substituted Apatite Coating: To Promote Proliferation and Osteogenic Differentiation of Bone Marrow Mesenchymal Stem Cells[J]. Chinese Journal of Prosthodontics, 2021, 22(1): 2-8.
[12] HOU H H, LEE B S, LIU Y C, et al.Vapor-Induced Pore- Forming Atmospheric-Plasma-Sprayed Zinc-, Strontium-, and Magnesium-Doped Hydroxyapatite Coatings on Titanium Implants Enhance New Bone Formation-an in Vivo and in Vitro Investigation[J]. International Journal of Molecular Sciences, 2023, 24(5): 4933.
[13] KURDI A, ALMALKI D, DEGNAH A, et al.Microstructure and Micro-Mechanical Properties of Thermally Sprayed HA-TiO2 Coating on Beta-Titanium Substrate[J]. Materials, 2025, 18(3): 540.
[14] ZANG M, LI L, SUN X M, et al.Characterization, Mechanical Properties, Corrosion Behavior and Bone-Like Apatite Formation Ability of Fluorine Substituted Hydroxyapatite Coating[J]. Journal of the Mechanical Behavior of Biomedical Materials, 2024, 151: 106364.
[15] BARRÈRE F, LAYROLLE P, VAN BLITTERSWIJK C A, et al. Biomimetic Coatings on Titanium: A Crystal Growth Study of Octacalcium Phosphate[J]. Journal of Materials Science Materials in Medicine, 2001, 12(6): 529-534.
[16] ELLIES L G, NELSON D G A, FEATHERSTONE J D B. Crystallographic Changes in Calcium Phosphates during Plasma-Spraying[J]. Biomaterials, 1992, 13(5): 313-316.
[17] SUN Y T, LI Y X, ZHANG Y, et al.A Polydopamine- Assisted Strontium-Substituted Apatite Coating for Titanium Promotes Osteogenesis and Angiogenesis via FAK/ MAPK and PI3K/AKT Signaling Pathways[J]. Materials Science and Engineering: C, 2021, 131: 112482.
[18] MURARI G, BOCK N, ZHOU H, et al.Effects of Polydopamine Coatings on Nucleation Modes of Surface Mineralization from Simulated Body Fluid[J]. Scientific Reports, 2020, 10(1): 14982.
[19] FENG Q L, WANG H, CUI F Z, et al.Controlled Crystal Growth of Calcium Phosphate on Titanium Surface by NaOH-Treatment[J]. Journal of Crystal Growth, 1999, 200(3/4): 550-557.
[20] LU X, LENG Y.TEM Study of Calcium Phosphate Precipitation on Bioactive Titanium Surfaces[J]. Biomaterials, 2004, 25(10): 1779-1786.
[21] WANG M J, XU C F, XU D, et al.Calcium Phosphate Loaded with Curcumin Prodrug and Selenium Is Bifunctional in Osteosarcoma Treatments[J]. Journal of Functional Biomaterials, 2024, 15(11): 327.
[22] WANG P, YIN H M, LI X, et al.Simultaneously Constructing Nanotopographical and Chemical Cues in 3D- Printed Polylactic Acid Scaffolds to Promote Bone Regeneration[J]. Materials Science and Engineering: C, 2021, 118: 111457.
[23] LI S F, ZHANG M L, SUN J, et al.Preparation and Characterization of Superior Hydrophilic PVDF/DA Membranes by the Self-Polymerization Approach of Dopamine[J]. Frontiers in Chemistry, 2023, 11: 1162348.
[24] OJSTRŠEK A, CHEMELLI A, OSMIĆ A, et al. Dopamine-Assisted Modification of Polypropylene Film to Attain Hydrophilic Mineral-Rich Surfaces[J]. Polymers, 2023, 15(4): 902.
[25] SINGER F, SCHLESAK M, MEBERT C, et al.Corrosion Properties of Polydopamine Coatings Formed in One-Step Immersion Process on Magnesium[J]. ACS Applied Materials & Interfaces, 2015, 7(48): 26758-26766.
[26] TANG Y M, TAN Y, LIN K L, et al.Research Progress on Polydopamine Nanoparticles for Tissue Engineering[J]. Frontiers in Chemistry, 2021, 9: 727123.
[27] FAN L L, ZHANG Y M, HU J J, et al.Surface Properties of Octacalcium Phosphate Nanocrystals Are Crucial for Their Bioactivities[J]. ACS Omega, 2021, 6(39): 25372-25380.
[28] QI J, WANG Y L, CHEN L P, et al. 3D-Printed Porous Functional Composite Scaffolds with Polydopamine Decoration for Bone Regeneration[J]. Regenerative Biomaterials, 2023, 10: rbad062.
Funding
National Natural Science Foundation of China (82100965, 52175422); Shanghai Municipal Health Commission Health Industry Clinical Research Fund (202240194); Shandong provincial colleges and universities youth innovation technology support program (2024KJJ008); Binzhou Medical University "Stomatology +X" university integrated innovation project (KQRH2024MS006)
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