CN1128251C - Bioactive composite Ca-P ceramics/chitosan film on metal surface and electrochemical co-deposition process for preparing it - Google Patents

Abstract

The invention relates to a method for preparing a composite film layer on the surface of a metal material by an electrochemical deposition method. The components of the electrodeposition solution are 0.01-0.15mol/L Ca(NO ₃ ) ₂ , 0.01-0.05mol/L NH ₄ H ₂ PO ₄ and 1%-10% chitosan solution, and the pH value of the solution is 3.1-5.2 , The electrodeposition condition is a constant voltage of 1-20V or a constant current of 1-10mA, a temperature of 30-60°C, and a deposition time of 0.1-10h. Chitosan is introduced into the calcium phosphorus ceramics coated on the surface of the metal substrate, so that the surface of the ceramic composite film on the metal surface has excellent biocompatibility, bioactivity and biodegradability, and its ceramic crystal plane has a preferred orientation and high crystallinity , the structure is tight. The bonding force between the composite film layer and the metal substrate reaches 2.60MPa, which meets the clinical requirements.

Description

Electrodeposition solution and method for preparing calcium phosphorus ceramics/chitosan bioactive composite film layer on metal surface

The invention relates to a method for preparing high-performance living medical materials by electrochemical co-deposition method.

In recent years, artificial bone graft materials prepared by coating calcium-phosphorous ceramic coatings on the surface of titanium-based metals have attracted much attention because they have both suitable mechanical properties of the base material and good biocompatibility of the coating. A variety of methods for coating bioactive ceramic coatings on medical metal surfaces have been developed, such as plasma spraying, electrophoretic deposition and electrochemical deposition (Wang Yulin et al., Electroplating and Fine Decoration, 1998, 20:20). It is commonly used to apply calcium phosphorus ceramic coating on the metal surface by plasma spraying method, but the high temperature (instantaneous temperature can reach 6,000-10,000°C) during the spraying process of plasma can cause serious phase change, decomposition or turtle formation of hydroxyapatite. It is difficult to obtain a coating layer similar to natural bone hydroxyapatite in composition and structure (M Weinlaender, J.mater.Sci.Mater.Med.1992, 3:138). Studies have shown that the biocompatibility and bioactivity of hydroxyapatite coating prepared by conventional plasma spraying method are obviously reduced. The electrochemical deposition method has the advantages of mild preparation conditions, convenient control, and the advantages of obtaining a hydroxyapatite coating that is similar in chemical composition and crystal structure to human bone tissue. The electrochemical deposition method can also prepare implants with complex shapes, which is superior to the linear plasma spraying method. However, the current ceramic coatings prepared by electrodeposition are all calcium-phosphorus coatings, and the bonding force between the ceramic coating itself and the coating and the metal substrate is poor, which restricts its clinical application as a biomedical implant material. develop.

The purpose of the present invention is to provide a kind of electro-deposition solution and its electrochemical method that can be used to prepare calcium-phosphorus ceramics/chitosan composite membrane layer with strong binding force with metal substrate on metal surface and have excellent biological properties and mechanical properties. Co-deposition preparation method.

The components of the electrodeposition solution that can be used to prepare the calcium-phosphorus ceramics/chitosan composite film layer on the metal surface in the present invention are 0.01-0.15mol/L Ca(NO ₃ ) ₂ , 0.01-0.05mol/L NH ₄ H ₂ PO ₄ and chitosan solution, the pH value of the solution is 3.1-5.2, and the chitosan solution accounts for 1%-10% of the total electrodeposition solution.

The preparation method of said electrochemical co-deposition is as follows: first prepare an electrodeposition solution, mix Ca(NO ₃ ) ₂ and NH ₄ H ₂ PO ₄ solution, add deionized water, and prepare a Ca(NO ₃ ) ₂ 0.01- 0.15mol/L, NH ₄ H ₂ PO ₄ 0.01~0.05mol/L electrolyte, adjust the pH value of the electrolyte to 3.1~5.2, add 1%~10% of the total electrodeposition solution to the electrolyte polysaccharides. The surface of the metal base material is mechanically polished and cleaned, the metal base material is used as the cathode, and the platinum electrode is used as the anode, the electrodeposition solution is added, heated, and constant voltage or constant current cathode electrodeposition is carried out. The electrochemical deposition condition is constant voltage 1 ～20V or constant current 1～10mA, temperature 30～60℃, deposition time 0.1～10h.

The present invention adds natural organic macromolecule chitosan (CTS) in the artificial bone grafting material---metal surface coating calcium phosphorus ceramic coating layer, and its molecular formula is

Chitosan (CTS) is a derivative of chitin, which can be biodegraded, has no immune reaction, and is non-toxic to the human body. It is an ideal medical biomaterial. The introduction of chitosan can make the metal surface ceramic composite membrane surface have excellent biocompatibility, bioactivity and biodegradability. The surface morphology, composition and structure of the electrodeposited layer were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR) diffuse reflectance, X-ray photoelectron spectroscopy (XPS), etc. It proves that the electrodeposited ceramic crystal plane has a certain preferred orientation, the crystallinity of the deposited layer is high, and the crystal structure is arranged in an orderly manner with multiple overlapping sheets, and the structure is tight. The adhesion-tensile test is used to measure the bonding force between the composite film layer and the metal substrate , its binding force reaches 2.60MPa, which is about 4 times higher than that of a single calcium-phosphorus ceramic electrochemical deposition coating, and basically meets the mechanical requirements of clinical applications.

Figure 1 is a 100×SEM topography of the calcium-phosphorus ceramic/chitosan composite film layer.

Figure 2 is a 1000×SEM topography of the calcium-phosphorus ceramic/chitosan composite film layer.

Figure 3 is a 3000×SEM topography of the calcium-phosphorus ceramic/chitosan composite film layer.

Fig. 4 is a SEM topography diagram of a pure calcium-phosphorus ceramic coating layer.

Figure 5 is an XRD diffraction spectrum.

Figure 6 is an XPS spectrum.

The present invention will be further described below in conjunction with embodiment.

Example 1: After mixing Ca(NO ₃ ) ₂ and NH ₄ H ₂ PO ₄ solutions, add ionized water to prepare 50 mL of electrolyte solution, the concentration of Ca(NO ₃ ) ₂ in the electrolyte solution is 0.045mol/L, NH ₄ H ₂ PO ₄ is 0.025mol/L, adjust the pH value of the electrolyte solution to 3.5 with dilute ammonia solution at room temperature, then add 2.5mL chitosan solution to the electrolyte solution; mechanically polish and clean the surface of the titanium-based alloy base material Clean, with the titanium-based alloy as the cathode and the platinum electrode as the anode, add the electrodeposition solution prepared above, and deposit at 30°C for 1 hour at a constant potential of 2.5V.

Use X-ray diffraction (XRD) to compare and analyze the obtained calcium-phosphorus ceramics/chitosan composite film layer and common calcium-phosphorus ceramics, from the XRD diffraction pattern of Fig. 5, it can be observed that adding chitosan and not adding chitosan The change of the structure of the electrodeposited layer of sugar, the spectral line 2 in the figure is the general calcium-phosphorus electrodeposited layer without chitosan, its main component is calcium hydrogen phosphate (DCPD) containing two crystal waters, its peak intensity is the same as that of the standard Compared with the powder XRD (line 3) data, there is a certain difference, indicating that the electrodeposited ceramic crystal plane has a certain preferred orientation. The position of the diffraction peak of the electrodeposited layer after adding chitosan does not change (see line 1), but the relative peak intensity of the diffraction peak has a great change, especially the peak at 2θ=11.7 ° is very strong, which It is due to the steric hindrance and inductive effect of chitosan on the surface that DCPD has an obvious preferred orientation on the (020) crystal plane.

Figures 1 to 3 are the typical electron microscope morphology of different multiples of the deposited layer after adding chitosan. From the figure, it can be seen that the deposited layer is in the form of branch veins, and the crystallinity of the deposited layer is very high, and its crystals are multi-layered. The structure between layers is tight. A porous deposition layer with a good crystal structure can be obtained by cathodic electrodeposition. From a biomedical point of view, this porous structure with a good crystal structure is very beneficial to improve the biological activity and biocompatibility of calcium phosphorus ceramics. The deposition layer The specific surface area is large, which is conducive to forming a large-area osseointegration interface and strong chemical interaction with human tissues as implant materials. A good crystal structure on the surface is also beneficial to promote interfacial osteogenesis induction. However, the crystals of the calcium-phosphorus ceramic deposition layer obtained from the pure calcium-phosphorus solution are stacked irregularly in a single piece (see Figure 4), and the structure is loose.

Figure 6 is the change of N concentration on the surface of the deposition layer detected by surface energy spectroscopy (XPS) before and after adding chitosan. Spectral line 1 is the calcium-phosphorus ceramic composite film layer with chitosan added, and spectral line 2 is without chitosan. Calcium-phosphorus ceramic layer, map analysis shows that after adding chitosan, the peak of N1s is obviously enhanced at 398.3ev, which proves that there is chitosan in the deposition layer, and chitosan may form organic/inorganic hybrid deposition with calcium-phosphorus compound layer.

In addition, the bonding-tensile experiment was used to test the bonding force between the metal substrate and calcium-phosphorus ceramics. AB fast-curing epoxy resin was used to bond the surface of the sample and the metal tensile block. The machine measures the shear tension between the deposited layer and the substrate. The results show that the mechanical properties of the calcium-phosphorus ceramic/chitosan composite film prepared by the electrochemical co-deposition method are significantly improved, and the bonding force between the deposited layer and the substrate is about 4 times higher than that of the simple calcium-phosphorus ceramic coating, reaching 2.60MPa , basically meet the mechanical requirements of clinical application. The following table shows the experimental data of the coating/substrate bonding force: sample Adhesion (MPa) Crack location calcium phosphorus deposit 0.66 Coating—titanium plate Calcium Phosphorus Deposition+(CTS) 2.60 Coating—titanium plate

Example 2: The concentration of Ca(NO ₃ ) ₂ in the prepared electrodeposition solution is 0.01mol/L, NH ₄ H ₂ PO ₄ is 0.05mol/L, the pH value is 4.8, and the chitosan content is 2%. Electrodeposition The conditions are a constant current of 2mA, a temperature of 45°C, and a deposition time of 0.5h. All the other are with embodiment 1.

Embodiment 3: with embodiment 1, only change Ca(NO ₃ ) _{Concentration} of 0.15mol/L in electrodeposition solution, NH ₄ H ₂ PO _0.01mol /L, pH value 5.2, chitosan content is 10%, the electrodeposition condition is a constant current of 5mA, a deposition temperature of 60°C, and a deposition time of 2h.

Claims (5)

1, electric depositing solution is characterized in that its component is 0.01～0.15mol/L Ca (NO ₃) ₂, 0.01～0.15mol/L5mol/LNH ₄H ₂PO ₄And chitosan, chitosan solution accounts for 1%～10% of electric depositing solution total amount, and the pH value of solution is 3.1～5.2.

2, electric depositing solution as claimed in claim 1 is used for preparing in the metallic surface bioactive composite Ca-P ceramics/chitosan film layer.

3, the preparation method of bioactive composite Ca-P ceramics/chitosan film on metal surface layer is characterized in that at first preparing electric depositing solution, with Ca (NO ₃) ₂And NH ₄H ₂PO ₄Solution mixes the back and adds deionized water, is mixed with to contain Ca (NO ₃) ₂0.01～0.15mol/L, NH ₄H ₂PO ₄0.01 the electrolytic solution of～0.05mol/L, regulating electrolyte PH value is 3.1～5.2, adds in electrolytic solution that to account for the electric depositing solution total amount be 1%～10% chitosan; With metal base material surface mechanical grinding, clean up, with the metal base material negative electrode, platinum electrode is an anode, adds people's electric depositing solution, in 30～60 ℃, constant voltage 1～20V or continuous current 1～10mA carry out cathode electrodeposition, depositing time 0.1～10h.

4, the preparation method of bioactive composite Ca-P ceramics/chitosan film on metal surface layer as claimed in claim 3 is characterized in that the pH value of electrolytic solution is regulated with dilute ammonia solution under room temperature.

5, the preparation method of bioactive composite Ca-P ceramics/chitosan film on metal surface layer as claimed in claim 3 is characterized in that said metal base material is a titanium base alloy.

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