| Having excellent mechanical function and biocompatibility, silicone rubber has been wildly used since the middle of the twentieth century. But as the wildly use of silicone rubber products, the unfavorable factors of it being implanted into human body were acrousing more and more concern, while biomaterial-centered infection is the main problem to influence the effect of clinical application, and the bacteria to adhere, breed and form biomembrane on the surface of silicone rubber is the main reason of BCI. Investigator had found that the molecule of silicone rubber presents helicity, and the homopolar R base occupies the lateral part of the helix. The polarity of the molecule is very low, and has strong hydrophobicity. The hydrophobicity has been defined as one of the most important character in adherion phenomenon. In order to get good hydrophilicity and decrease the bacterial adherence of the material surface, it is necessary to do modification to the hydrophobicity of silicone rubber, so as to receive better curative effect in the clinical application of the silicone rubber.This study begin with changing the superficial hydrophobicity of silicone rubber, using ultraviolet superficial graft technique to treat medical silicone rubber. Through contact angle measurement and staphylococcus co-cultivation to the modified silicone rubber, this study attempts to detect its hydrophobicity changing status and the effect of bacterial adherence after modification.(1) Superficial modification and contact angle measurement of silicone rubber pieces. Using ultraviolet light polymerized grafting technique, under the effect of photocoupler benzophenone, couple PEG1000and acrylic acid to the surface of silicone rubber, form derivate with light active group, and then progress photochemical reaction, use1000W high voltage mercury lamp irradiate one hour to the surface of silicone rubber, couple the PEG1000and acrylic acid onto the surface of silicone rubber. Add surface active agent OS-10in a group of material with PEG1000, use contact angle measuring equipment to measure each pieces’superficial contact angle of measuring groups after reaction, and use one-factor analysis of variance to analyse the data. It is found that only the use of ultraviolet radiation has no obvious change of surfacial hydrophilicity (P>0.05), graft polyethylene glycol1000and acrylic acido can obviously degrade the hydrophobicity of silicone rubber (P<0.001), the added surface acting agent OP-10can degrade the hydrophobicity of silicone rubber to some extent than others (P0.001).(2) Co-cultivate with staphylococcus aureus. Put all groups of silicone rubber pieces into bacterial adherence experiment after grafting, staphylococcus aureus is the most frequent bacteria correlate with BCI, thus select staphylococcus aureus type strain ATCC25923to cultivate with silicone rubber pieces, and put staphylococcus aureus strain into rabbit blood culture-medium and bouillon culture-medium to cultivate one day. Use scanning electron microscope to count four pieces of each group, and use oscillator to shake down the bacteria of the other four pieces, and then done centrifuge to the bacteria liquid, get the sediment to make smears and then observe them under microscope and count the number of bacteria. From the result we found the bacterial number about staphylococcus aureus on the surface of silicone rubber pieces decreased obviously (P<0.001), the extent of decrease is direct proportion to the extent of the change of contact angle. Two groups of silicone rubber pieces which only added PEG1000or acrylic acid have no obvious statistic differences about the ability of bacterial adherence (P>0.05), the group which added PEG1000and OP-10has the greatest improvement (P<0.001). |
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