Study On Preparation Of Surface Microporous Structure And Drug Loading Properties Of 316L Stainless Steel

Since the 21st century,the incidence and mortality of cardiovascular diseases has increased year by year,which posing a severe threat to human life.In this situation,the demand of cardiovascular stents has been growing dramatically.At present,the polymer degradable drug-loading stents has been clinically applied on the market.However,this market has mainly dominated by foreign multinational enterprises and the domestic market share is relatively in a lower portion.Besides,the domestic skill in polymer degradation is not mature and inflammation may also be induced at patients'late operation stage.Moreover,the slow rate of degradation also makes it difficult to cope with a series of problems such as the need for clinical drug delivery.In that case,316L stainless steel,as a medical stainless steel,has good biocompatibility,mechanical properties and resistance to body fluid corrosion.This article tends to develop a new generation of non-polymerization based on the nano-porous structure prepared by anodizing 316L stainless steel as a drug carrier,trying to control release effect of the drug through the nano-scale porous structure by using porous drug-loading stent.This paper is supported by the provincial science and technology plan project of Guangdong Province?Study on surface micropore preparation and drug release kinetics of 316L stainless steel coronary stent,2015A010105027?.It mainly studies the surface anodizing pore-forming process and drug loading process of 316L stainless steel,and the porous drug-loaded samples were tested for in vitro release and biocompatibility.The research results are as follows:1.In the preparation of anodized nanoporous structure,the ammonium fluoride concentration ranges from 0.1-0.15mol/L,the anodization voltage ranges from 20-40V,the anodization time ranges from 5-30min,and the anodization temperature ranges from35-40?.The prepared nanoporous structure has the most regular morphology,and its pore size is between 20-30nm,and the pore density is about 11.3×10¹¹-1.5×10¹¹num/cm².The length of the nanopore prepared in this paper can be up to 16.5?m.2.When the oxide film on the surface of the nanopore is not completely oxidized,it will present on the surface of the regular pore structure in the form of a residual covering.The longitudinal structure is characterized by corrosion damage marks in the surface pores,accompanied by the occurrence of joint holes.Then,the overall pore size is not large and the intermediate pore structure is array-like and very regular.Moreover,the outer pore wall is hexagonal honeycomb and the bottom pore is close to the barrier layer.The aperture begins to shrink until it completely disappears.The formation mechanism of nanoporous structure can be explained by the competition between top and bottom dissolution,which is that the process parameters can be adjusted.When the current density is about 1.0 A/dm²,the macroscopic crack and damage of the pore structure would then be avoided,and the neat and ordered nanometer can be obtained Porous array structure subsequently.3.The pore size of the porous structure will decrease with the increase of the cumulative drug loading.The ATR-FTIR test shows that Dex has been successfully loaded.It shows that both porous and porous drug-loaded samples have good wettability.Besides,the corrosion resistance of the modified specimens was improved obviously and the porous specimens oxidized for 5min had the best corrosion resistance.4.The optimum cumulative loading of the drug was 100?g/cm².When porous samples were anodized for 10min and 30min as drug carriers,the release rates were35.89%and 5.27%within 58h respectively.In that case,the drug could continue to be administered slowly after 668 h of continuous release.5.Compared with polished samples and porous samples,the roughness of stainless steel nanoporous drug-loaded samples is the lowest.Among the hemolysis rates,polished samples>porous samples>porous drug-loaded samples.Then,porous drug-loaded samples have the best hemolysis resistance.Platelets that would be adhere to the surface of porous drug-loaded coatings are in less quantity and have better anticoagulant properties.On the surface of CCK-8 and cell compatibility test,Dex could promote the proliferation of endothelial cells and inhibit the proliferation of smooth muscle cells.