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.
Résumé
Objective: To study the influence of electret on surface charge of fibroblast cells (3T3 cells) and to probe the relationship between cell growth, apoptosis and cell surface charge. Methods: Electrets Teflon PTFE, ±300 V,±1 000 V were used to treat 3T3 cells for 24, 48 and 72 h. Then the influences of electrets on cell cycle and surface charge of 3T3 cells were studied by flow cytometry and electrophoresis, respectively. Results: (1) After 24 h action of negative electrets, electrophoretic mobility (or surface charge) and cell number in S phase of 3T3 cells were significantly increased compared with those in control group. (2) Effect of negative electrets enhancing cell growth and increasing cell surface charge was in proportional to the surface potential of electret. (3) Surface charge density of apoptotic cell was reduced by electret. (4) After 24 h action of positive electret, the cell number in S and G2 phase were decreased and cell surface charge was also reduced. Conclusion: Negative electret can improve cell growth and increase cell surface charge density. Positive electret can restrain cell growth and reduce cell surface charge density. Surface charge of apoptotic cell is less than that of normal cell.
Résumé
Objective: To study the influence of electret on surface charge of fibroblast cells (3T3 cells) and to probe the relationship between cell growth, apoptosis and cell surface charge. Methods: Electrets Teflon PTFE, ±300 V,±1 000 V were used to treat 3T3 cells for 24, 48 and 72 h. Then the influences of electrets on cell cycle and surface charge of 3T3 cells were studied by flow cytometry and electrophoresis, respectively. Results: (1) After 24 h action of negative electrets, electrophoretic mobility (or surface charge) and cell number in S phase of 3T3 cells were significantly increased compared with those in control group. (2) Effect of negative electrets enhancing cell growth and increasing cell surface charge was in proportional to the surface potential of electret. (3) Surface charge density of apoptotic cell was reduced by electret. (4) After 24 h action of positive electret, the cell number in S and G2 phase were decreased and cell surface charge was also reduced. Conclusion: Negative electret can improve cell growth and increase cell surface charge density. Positive electret can restrain cell growth and reduce cell surface charge density. Surface charge of apoptotic cell is less than that of normal cell.