RÉSUMÉ
BACKGROUND:Medium-and large-diameter polytetrafluoroethylene artificial blood vessels have been widely used in clinical practice.However,most of the products were imported from other countries.Small-diameter porous polytetrafluoroethylene vessels are easy to form thrombosis and intimal hyperplasia,resulting in an extremely low long-term patency rate,which is difficult to fulfill clinical requirements. OBJECTIVE:To review and summarize the research progress of polytetrafluoroethylene in the field of artificial blood vessels,which can provide a reference for the functional modification of small-diameter polytetrafluoroethylene artificial blood vessels and the improvement of their long-term patency rate. METHODS:The relevant articles published from October 2022 to March 2023 in CNKI,Web of Science,Wiley Online Library,SpringerLink,Science Direct and IOP Science databases were searched by the first author.The search terms in Chinese were"porous polytetrafluoroethylene,vascular graft,electrospinning,medical application,functional modification".The search terms in English were"ePTFE,porous polytetrafluoroethylene,vascular graft,electrospinning,medical application,functional modification".All the articles about the preparation and modification of polytetrafluoroethylene artificial blood vessels were retrieved. RESULTS AND CONCLUSION:The preparation and functional modification of porous polytetrafluoroethylene artificial blood vessels were still research hotspots and difficult problems.From the research progress in and outside China in recent years,the preparation of porous polytetrafluoroethylene artificial blood vessels mainly adopted the rapid thermal stretching method,but the preparation of polytetrafluoroethylene artificial blood vessels by electrospinning was a promising new method.By analyzing and summarizing different functional modification methods,it was found that the long-term patency rate of porous polytetrafluoroethylene artificial blood vessels had been improved.However,the functional modification of small-diameter polytetrafluoroethylene artificial blood vessels still needed further exploration and optimization.
RÉSUMÉ
Objective: To study charge storage stability of electret film made of polypropylene (PP)/porous polytetrafiuoroethylene(PTFE)/polypropylene composite. Methods: The PP/porous PTFE/PP composite electret film was prepared with porous PTFE, polyethylene(PE) and PP by heat melting technique. The charge storage stability of the electret film and transportation were evaluated by using the methods of isothermal surface potential attenuation and open-circuit thermally stimulated discharge (TSD) current spectra. Results: (1) The charge storage stability of PP/porous PTFE/PP composite electret was superior to that of PP electret made under ordinary temperature, because the space charge of PP/porous PTFE/PP electret was transferred from deep trap to flat trap during the heat melting process. (2) Satisfactory charge storage stability was observed in PP/porous PTFE/PP electret when under the condition of high humidity. Conclusion: PP/porous PTFE/PP electret film has satisfactory charge storage stability and can be used as a novel enhancer in transdermal delivery of drugs.