| Cardiovascular and cerebrovascular disease due to atherosclerosis is the “numberone killer of harm to human health”. Percutaneous coronary intervention (PCI) is thetreatment of cardiovascular and cerebrovascular disease narrow lesions producingminimally invasive treatment thechniques. At present, drug-eluting stents (DESs) arethe most widely used. Compared with early bare-metal stents (BMSs), DESs are moreeffective in treating coronary artery diseases, especially in inhibiting restenosis.However, delayed endonthelialization, inflammation, and hypersensitivity triggersubacute or late adverse events, caused a higher death rate, and thereby raise moreconcerns over the long-term safety of DESs. These problems are mostly associated withcurrent DES design. It is critically important to further improve and optimize DESdesign and apply newer strategies for developing next generation DES.These three components including metal stent backbone, active pharmacologicagent, and drug carrier should be harmoniously orchestrated to create a clinicallydesirable device that can eradicate ISR and other adverse complications. Stent coatingplays an extremely important role in the DES research. The one hand, the coating is anintermediary between the target vessel wall and stent platform; other hand, the coatingas a pharmaceutical carrier can be effectively modified stent surface to improvebiocompatibility. This study analyzes the existing ultrasonic atomizing spray deviceworks in the laboratory, and summarizes the problems in the application. We optimizedthe device, so that the processing parameters can be adjusted and equipment andenvironmental pollution is reduced. Then, optimize the preparation process of chitosancoating of316L SS stent with the improved device. Finally, examines the quality ofchitosan coating from macro to micro, and preliminary evaluated the safety of thecoating by in vitro expansion experiments and cell compatibility test.The main content and results of experimental study:①Trough the optimization design of atomization module, transmission system,semi-closed system, atomization capacity of the device becomes more stable and themist particles become smaller (1~3μm). The stent may allow free movement in the axial(0~0.55m/s)/radial (0~542rpm). Mist particles flying situation is improved. Itsapplicability and safety are improved effectively.②Pickling pretreatment of316L SS stent surface before painting can remove dirt effectively and micro-roughened the surface. Thus, Coating adhesion capacity has beenimproved. Improved spraying device can be used with the preparation of chitosancoating. The coating amount can be measured by spectrophotometry measurable.Analysis of orthogonal test results showed that the number of process engineering,carrier gas pressure, stent radial speed, feed rate extremely significant affect coatingamount. Filter out the best process parameter combinations(n=25, P=2psi, r=60rpm,v=1mm/s).③To Prepare chitosan coating under optimal process parameters, The macro qualitytesting found that the coating does not exist spraying corners, no coated failure occurred,smooth coating surface through the optical microscope. Microscopic observation ofthe coating found effective to repair small defects of the stent surface coatings, evenexcellent, effectively reducing the stent wire surface roughness using scanning electronmicroscopy, dispersive spectrometer, an atomic force microscope. Using in vitroexpansion experiments, cell adhesion and cell proliferation assay preliminarily verifiedthe coating has a good implant security. |
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