Plasma oxidation of titanium surface and its effect on cell adhesion and proliferation

The titanium surface treated by the sandblasting and acid etching process was plasma-oxidized using vacuum radio frequency glow discharge technology, and the surface morphology of the titanium surface was studied by scanning electron microscope, contact angle measuring instrument and X-ray photoelectron spectrometer. The influence of its chemical composition and valence state; at the same time, the influence of plasma oxide film on titanium surface on cell adhesion and proliferation was studied by in vitro cell culture. The results show that the plasma oxidation treatment retains the microscopic pore structure formed by sandblasting and acid etching on the titanium surface, and obtains a superhydrophilic surface with an average contact angle of less than 10°; Ti4+, Ti3+ and Ti2+ ions appear on the titanium surface, mainly Ti4+ exists; compared to the unoxidized titanium surface, the oxidized titanium surface has a more significant promotion effect on the adhesion and proliferation of osteoblasts, which indicates that the plasma oxide film on the titanium surface has good wettability, which is beneficial to the cell Adhesion proliferation.

Titanium and its titanium alloy are biologically inert metal materials. After being implanted in the body, it is easy to be surrounded by a layer of encapsulated fiber membrane, and it is difficult to form a firm bond with biological tissues. There are also some harmful components in titanium alloys, which can cause abnormalities in the organism. Therefore, improving the biological application of titanium requires surface treatment. Studies have found that the biocompatibility of medical pure titanium is directly related to its surface wettability, so it is particularly important to improve the hydrophilicity of the surface of medical pure titanium. Titanium oxide is a kind of photocatalytic substance. R Wang discovered that the surface of TiO2 can become super hydrophilic by light induction. Lin Zeng used DC magnetron sputtering coating and plasma-enhanced chemical vapor deposition to prepare TiOx thin films, and found that both can greatly reduce the contact angle of the titanium surface. Therefore, oxidizing the titanium surface is a direction to improve the surface wettability of medical titanium materials, and the plasma oxide film can improve the corrosion resistance of the implant in the body and hinder the release of metal ions. At the same time, studies have found that the rough surface can increase the contact area between the droplet and the solid surface and enhance the hydrophilicity. Moreover, the bonding area and bonding strength of the titanium implant with the rough surface and the bone tissue are greater than the smooth surface of the titanium implant. Therefore, in this test, plasma oxidation was performed on the surface of the titanium sample obtained by the sandblasting and acid-etching (SLA) process, and the surface morphology, chemical composition and valence state of the titanium sample after plasma oxidation were analyzed. , Hydrophilicity and adhesion and proliferation of osteoblasts.

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The sample size of the titanium sheet used in the test is 14mm×14mm×3mm, and the material is TA2 (BaoTi Co., Ltd.). The processed titanium specimens were manually cleaned with a cleaning agent to remove processing debris and residual mechanical oil stains, and passed 58μm (250 mesh), 13μm (1000 mesh), 6.5μm (2000 mesh) SiC The sandpaper is polished step by step until the surface shows a white metallic luster, and then is ultrasonically cleaned in detergent, deionized water and absolute ethanol for 5 minutes each, placed in a heating box for drying, and cooled in a ziplock bag for storage.

The surface of the titanium sample is treated by the SLA process to obtain a micro-nano double microscopic pore structure. The specific process flow can be found in the literature. Process parameters: The sandblasting material is titanium sand, the acid is a mixed acid of 60% H2SO4, 10% HCl and deionized water in a volume ratio of 1:1:2, the acid etching time is 20 minutes, and the acid etching temperature is 100°C. Hereinafter, the titanium samples after sandblasting and acid etching are collectively referred to as SLA titanium samples.

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The surface of the SLA titanium sample is bombarded with oxygen ions generated by the vacuum glow discharge of a plasma-enhanced chemical vapor deposition (plasmaenhanced chemical vapor deposition, PECVD) equipment to generate an oxide film. The process is to clean the surface of the sample with Ar plasma for 30 minutes, and then start plasma oxidation. Table 1 shows the plasma oxidation parameters.

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The morphology and cell adhesion of the sample surface were characterized by field emission electron scanning electron microscope (SEM) (JSM-6500F, JEOL, Tokyo, Japan); PHI-5700 X-ray photoelectron spectroscopy produced by ULVAC-PHI was used Analyzer (XPS) analyzes the chemical elements and valence bond status on the sample surface. Use a contact angle measuring instrument (SL200B, Kono Industrial Co., Ltd.) to measure the contact angle of the sample surface, using the θ/2 method, measuring range: 0°<θ<180°, resolution 0.01°, test accuracy ±1°. The sample is oxidized and measured after cooling for 1 hour in the vacuum chamber. 5 different points are measured on the surface of a sample and the average value is taken.

Put the samples into the well plates, and inoculate MC3T3-E1 mouse proto-osteoblasts in good condition on the surface of the samples at a concentration of 2×104/mL. In an environment of 50% CO2, 95% humidity, and 37°C, the cells were cultured for 24 hours. After each sample is taken out, rinse with Phosphate Buffered Saline (PBS) for 3 times, and absorb the liquid, then fix it with 2.5% glutaraldehyde for 2 hours. After washing, drying and spraying gold, use SEM Observe the growth morphology of osteoblasts.

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(1) Under the test parameters, after the sample is subjected to plasma oxidation treatment in the PECVD equipment, TiO2, Ti2O3 and TiO films are formed on the surface of the sample, of which TiO2 is the main component, while retaining the porous embedding obtained by SLA treatment. Set of structure.

(2) Under the test parameters, after the SLA-treated titanium sample is oxidized by plasma, it can obtain a super-hydrophilic surface with a contact angle of less than 10°, and the repeatability is good.

(3) Osteoblast adhesion and proliferation experiments show that the porous structure formed by SLA is beneficial to promote the adhesion and proliferation of osteoblasts; and after further plasma oxidation treatment, the adhesion and proliferation of osteoblasts on the surface of the titanium sample is significantly better For sandblasted samples without plasma oxidation treatment.

Founded in 2015,Zunhua Baorui Titanium Equipment Co.,Ltd. is a manufacturer specializing in pvd vacuum ion coating equipment. The company’s products mainly include large plate coating machine, large tube collating machine, tool coating machine and LOW-E glass production line. Mr.Wang baijiang ,general manager of the company ,has been engaged in vacuum coating industry for more than 30 years. He continuously improve production technology, improve product performance and devote himself to provide customers with better product experience and higher production efficiency.