Oral Implantology and Regenerative Dental Medicine, Tokyo Medical and Dental University, 113-8510 Tokyo, Japan.
International Apatite Institute Co., 101-0061 Tokyo, Japan.
Mater Sci Eng C Mater Biol Appl. 2020 Jun;111:110772. doi: 10.1016/j.msec.2020.110772. Epub 2020 Mar 3.
Nano-hydroxyapatite (nano-HA) coating has been proved to be effective to modify the titanium surface for better bone formation. A simple and economical nano-HA coating method that filling the nano-HA particles into the porous titanium substrate by using vacuum suction was introduced in this study. Two kinds of nano-HA modified titanium surfaces, nano-HA filled type (nHA-f) and nano-HA coated type (nHA-c), were prepared by a 2-step and 3-step protocol, respectively. Nano-HA modified titanium surfaces with and without thermal treatment were compared. The physicochemical properties including morphology, elemental composition, coating thickness, adhesion strength and in vitro mineralization ability were characterized. The SEM results showed that nano-HA particles were effectively filled into the porous titanium substrate under the function of vacuum suction in the nHA-f and nHA-f-heat groups. The thickness of the nano-HA layer was about 1 μm and 7-8 μm in the nano-HA filled type and nano-HA coating type, respectively. Localized separation between the nano-HA layer and the titanium substrate was observed in the thermal-treated groups, which may increase the risks of detachment. In the in vitro mineralization test, the unheated groups (nHA-f and nHA-c) showed promoted calcium phosphate compounds deposition than the heated groups (nHA-f-heated and nHA-c-heated) because of the active biological behavior of the amorphous nano-HA; the nHA-f group with a thin nano-HA layer showed no difference to the thick coating group (nHA-c) at the early stage, which was due to the effect of the porous structure as a cage to protect the nano-HA particles from fast dissolution. In conclusion, the vacuum spray method is effective to create a thin amorphous nano-HA layer with improved adhesion strength and sustained-release ability to induce mineralization by filling the nano-HA particles into the porous titanium substrate without thermal treatment.
纳米羟基磷灰石（nano-HA）涂层已被证明可有效修饰钛表面以促进更好的成骨。本研究采用真空抽吸将纳米 HA 颗粒填充到多孔钛基体中，介绍了一种简单、经济的纳米 HA 涂层方法。采用两步法和三步法分别制备了两种纳米 HA 改性钛表面：纳米 HA 填充型（nHA-f）和纳米 HA 涂覆型（nHA-c）。比较了未经热处理和经热处理的纳米 HA 改性钛表面。对形貌、元素组成、涂层厚度、结合强度和体外矿化能力等理化性能进行了表征。SEM 结果表明，在真空抽吸的作用下，纳米 HA 颗粒可有效填充到多孔钛基体中。在 nHA-f 和 nHA-f-heat 组中，纳米 HA 层的厚度约为 1 μm 和 7-8 μm。热处理组中观察到纳米 HA 层与钛基底之间的局部分离，这可能增加了脱落的风险。体外矿化试验中，未加热组（nHA-f 和 nHA-c）较加热组（nHA-f-heat 和 nHA-c-heat）显示出促进钙磷化合物沉积的作用，这是由于无定形纳米 HA 的活性生物行为所致；薄纳米 HA 层的 nHA-f 组与厚涂层组（nHA-c）在早期没有差异，这是由于多孔结构作为一种笼状结构的作用，可保护纳米 HA 颗粒免受快速溶解。总之，真空喷涂法可通过将纳米 HA 颗粒填充到多孔钛基体中而无需热处理来有效制备具有改善的结合强度和缓释能力的薄无定形纳米 HA 层，以诱导矿化。
