Effect of surface modification of conductive high-molecular polypyrrole titanium on the growth, proliferation and functional differentiation of osteoblasts

Journal of Clinical Stomatology, January 2003, Vol. 19, No. 1, Basic Research.

Effect of surface modification of conductive high-molecular polypyrrole titanium on the growth, proliferation and functional differentiation of osteoblasts Jia Jun Yao Yueling, Song Yingliang, Xu Youlong, Wang Zhaoguo Osteoblasts were inoculated on the surface of the material and 100mV anodic electrical stimulation was applied. Immunofluorescence staining, alkaline phosphatase (APL) activity, and osteocalcin (OC) synthesis assay were used to observe the growth and functional expression of osteoblasts on the surface of Ppy coating. Osteoblasts were coated with polypyrrole on Ti and Ti surfaces. The substrates can all grow well. On the 7th, 14th, 21st, and 28th days of culture, the ALP activity and the amount of OC secretion in the anodic electrical stimulation group (Ti+Ppy+electric stimulation, Ti+electric stimulation) were significantly higher than those in the control group. Electric stimulation group (Ti+Ppy, Ti) (P Oral implant restoration is currently the most promising prosthetic restoration method. How to promote the early attachment and growth of osteoblasts on the surface of implants in the initial stage of implant healing, and to fully express osteoblasts The function is to improve the binding efficiency and strength of the implant and bone tissue, and shorten the key to the healing time of the first phase.In the clinical study, micro current stimulation is obviously used in the treatment of delayed bone healing, bone nonunion and osteoporosis. The role of the promotion of bone callus growth Polypyrrole (Ppy) is a kind of functional polymer with excellent biocompatibility. In the fields of chromaffin cell culture, stimulated nerve regeneration, artificial blood vessel transplantation, and organ cell tissue engineering, etc., the growth of osteoblasts has not been reported in the combined application of Ppy and electrical stimulation. Effect of Ppy coating on the surface of pure titanium on the growth, colonization and functional differentiation of rat osteoblasts in vitro. Preliminary study on the mechanism of Ppy-promoted osteoblast growth under electrical stimulation and the construction of Ppy-based implant material surface biological activity transition Prepare a series of layers of research.

Materials and Methods 1TA2 pure titanium (Northwestern Nonferrous Metals Research Institute) machined into circular specimens of 12mm in diameter and 1mm in thickness. Metallographic sandpaper was graded from 280 to 800. The laser welding machine welded 0.3mm TA2 pure titanium wire. Round Test Fund Project: National Natural Science Foundation of China (39700164) Fourth Military Medical University Doctoral Dissertation Project (2001006) Jun Jun, Yao Yueling, Song Yingliang, Wang Yuguo) Xi'an Jiaotong University Electronic Information 1994-2 (Engineering School Dragon) WcJoalElectronicPublishing side, and set aside a fixed length for clamping and electrode lead site throughout the operation of the Journal of Clinical Stomatology, January 2003, Vol. 19, No. 1 in the process are clamped with titanium tongs to prevent contamination of heterogeneous elements.

2Pyrrole (Sigma, USA) was vacuum distilled at 62[deg.] C. to give a white monomer.

Electro-Electrical Appliances Co., Ltd.) In TA, the surface of pure titanium specimens was subjected to constant current electrochemical polymerization of polypyrrole, the electrolyte was 0.1 mo/L NaCl (Xi'an Chemical Reagent Factory), 0.1mo/LPyrrole aqueous solution, HCl (Xi'an Chemical Reagent Factory) adjusted the pH Value to 25 or so.

The round TA2 pure titanium sample is the working electrode, the platinum slice is the counter electrode, and the saturated calomel electrode is the reference electrode. Before the polymerization, nitrogen gas was applied for 20 min to remove the oxygen from the solution. The polymerization current was 1×10 3 mA/cm 2 . The coating thickness was calculated from the amount of electricity passed during the polymerization. Each unit passed approximately 400 mA/cm 2 of electricity, approximately 1 Pm thick. Layer 15. At the 7th, 14th, 21st, and 28th days of culture, the ALP activity of the anodic electrical stimulation group (Ti+Ppy+electric stimulation, Ti+electric stimulation) was significantly higher than that of the non-electric stimulation group (Ti+Ppy). ,Ti) (p<0.05) There was no significant difference in ALP activity between Ti+Ppy group and Ti group at each time point (p>0.05).

3. Effects on OC secretion of osteoblasts As indicated, cultured on the 7th, 14th, and 21th day, the anodic electrical stimulation group (Ti+Ppy+electric stimulation, Ti+electron 6 osteocalcin secretion assay: grouping and detection The time point was the same as 2. The activity of stimulating coffee c was significantly higher than that of the group without thorns (Ti+Ppy. Journal of Clinical Stomatology, Vol. 19, No.1, Jan. 2003, 2003). OC activity of the Ti+Ppy+ group Significantly higher than Ti+ electrical stimulation group (;Electro-osteoporosis plays an important role in bone remodeling, micro-direct current stimulation can induce osteoblast activity during the early formation of bone interface. Low-energy, low-frequency electric field can promote osteogenic Cellular proliferation, secretion of growth factors, and synthesis of extracellular matrices can therefore be used to deliver electrical stimulation to the site of bone damage through electroactive biomaterials and provide a physical template for cell growth and tissue repair.Ppy on the surface of titanium metal Chemical polymerization follows the mechanism of cationic free radicals, the charge transfer takes place between the polymer film and the metal electrode, the polymer loses its electrons to the oxidation state, and the counter-ion (PE) in the electrolyte is doped into the polymer film. Since the neutrality of the polymer is maintained without affecting the redox state of the polymer, the balance ion can be easily diffused into and out of the surface of the polymer film by the doping and dedoping processes with the change of the external electric field, which is the most attractive for the conductive polymer. Note the electrochemical performance.) Different from the conventional metal crystal conductive material, which belongs to the molecular conductive material, it has richer electrochemical performance than ordinary metal electrets.The advantage of using Ppy to build bioelectrically active coatings is through doping molecules and Controlled power-up methods, electrical stimulation intensity, and duration of action provide localized directional electrical stimulation to obtain different surface characteristics.

In addition, the extracellular matrix proteins and growth factors can not only bind to the surface polymer groups of Ppy via side chains and ligands, but also the drugs and bioactive molecules doped by ion bonding can also be electrochemically controlled. Release, to achieve quantitative release of biomolecules, thereby acting on cells to achieve the expected cell adhesion, colonization, and differentiation properties, and achieve surface functionalization and controllability. In our previous study, HE staining and SEM observations showed that osteoblasts grew well on a polypyrrole-coated substrate on an ITO glass surface, and calcium salt deposition was formed on the Ppy coating surface. In this experiment, immunofluorescence observations also showed that osteoblasts cultured in vitro can form good adhesion and spreading morphology on pure titanium and pure titanium Ppy coatings. Therefore, polypyrrole has a significant inhibitory effect.

Alkaline phosphatase ALP is an early marker of osteoblast differentiation and functional maturation. It plays an important role in the transition restriction point of osteoblasts towards maturation. The change of ALP activity in osteoblasts can be used to understand the differentiation and maturity of osteoblasts. The ability of cells to osteogenic mineralization. ALP promotes the formation of hydroxyapatite nucleation, crystallization, and colonization of bone tissue by promoting the formation of high concentrations of P ions in the body, thereby initiating the process of extracellular matrix mineralization and calcium and phosphorus deposition. Osteocalcin OC is present in mature and well-developed mineralized stroma, representing osteoblast differentiation and mineralization maturation, and initiates and promotes the differentiation and maturation of osteoclasts. Its secretion often means the beginning of a new round of bone metabolism. The experimental results showed that only a small amount of ALP activity and OC secretion were detected in osteoblasts at 3 days, and there was no significant difference between the four groups. This is because the osteoblasts cultured in vitro were at the time of colonization. ALP Activities with OC are not yet active and their expression is low. When cultured on the 7th, 14th, 21st, and 28th days, osteoblasts entered cell differentiation and functional maturation, and the expression of ALP activity and OC secretion was significantly high. The ALP activity and OC secretion of anodic electrostimulation group (Ti+Ppy+electrical stimulation, Ti+electrical stimulation) were significantly higher than that of non-electrical stimulation group. The ALP activity and OC secretion of Ti+Ppy+ electrostimulation group were higher than that of Ti+Py The results of the stimulation group (p 0.05) accorded with the previous research results. The micro-electrical stimulation may advance the differentiation and maturation of osteoblasts. 1910. At present, at the cellular level, the mechanisms involved in the stimulation of bone formation by electrical stimulation are: The membrane signal receiving system activates adenylyl cyclase, accelerates cAMP cycle, and adds DNA synthesis; electric field induces ion gradient distribution; membrane permeability and open calcium channels are altered by messengers, hormones, and matrix. These observations cannot completely explain the high expression of ALP activity and OC secretion in the Ti+Ppy+ electrostimulation group, but the results of the test using pure Ppy coating alone did not promote the proliferation and differentiation of osteoblasts. Under the action of an electric field, the surface characteristics of Ppy, such as surface roughness, contact angle, and surface energy, will change. Therefore, the effect of Ppy on the adsorption of osteoblast growth factor and extracellular matrix proteins will also change dynamically and influence Colonization and differentiation of cells. Although the mechanism of Ppy promoting cell growth is still not very clear, we have speculated from the experimental results that the strong promotion of Ppy on the proliferation and differentiation of osteoblasts is the result of the combined effect of Ppy coating itself and electrical stimulation.

In summary, Ppy as a new type of electroactive biomaterial has good biocompatibility. Ppy can apply the electrical stimulation signal to osteoblasts cultured in vitro, and can significantly increase ALP activity and OC synthesis. The exact mechanism of action needs to be further studied.

The coating has good biocompatibility, no clinical study on osteoblasts cultured in vitro. Journal of Oral Medicine, Volume 19, No.1, January 2003 Volume loss and morphological changes of ceramics after different interface treatment. Li Mingzhe, Li Hong Zhao Yun Feng Fanxinping and alumina glass infiltrated the surface of the ceramic, and the volume loss was calculated, and the interface changes were observed with an electron microscope. RESULTS Blasting changed the surface structure of alumina glass infiltrated ceramics, and the volume loss of alumina ceramics was smaller than that of VitaMark. The results of sandblasting on the interface of alumina glass infiltrated ceramics are beneficial to improve the bonding strength. Sandblasting conditions are well controlled and will not affect edge suitability. For VitaMark1, sandblasting should be avoided. Alumina glass infiltrating ceramics is 3-4 times the flexural strength of feldspar porcelain and glass ceramics. It is a traditional porcelain-fused metal. An ideal alternative to the underlying metal of the restoration. Since there are only *funds in the alumina matrix material: National Natural Science Foundation of China (39970799) Sichuan University West China School of Stomatology (Li Hong, Zhao Yunfeng, Fan Xinping) Few silicas are used for the etching of traditional ceramic materials. The application of the interface method of silicon coupling agent alone is not satisfactory for improving the bonding effect of the alumina glass infiltrated ceramic. The above study shows that sandblasting can achieve higher bond strength, but the volume loss of ceramics and the change of interface structure after sandblasting are worthy of further discussion.

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