| Postoperative adhesion(POA)is a common and serious complication associated with many kinds of operations,such as plastic surgery,abdomen,pelvis,tendon repair surgery.In addition,POA can lead to chronic abdominal pain,secondary infertility,intestinal obstruction and other serious complications,greatly reducing the quality of life of patients.In order to prevent the formation of post-operative adhesion,many strategies have been proposed,among which a new method is the physical barrier composed of polymer materials.Through the interconnection of damaged tissues,polymer barriers can effectively reduce the formation of fibrous tissue between normal organs.The new generation of anti-adhesion membranes can largely meet the patients'anti-adhesion needs in the clinical stage of surgical repair,so as not to make secondary adhesion bring huge economic and spiritual burden to patients.Developing a new generation of absorbable anti-adhesion membrane is an inevitable trend in the field of biomedicine in the future.In this paper,traditional polylactic acid(PLA)adhension film was modified by introducing chain units of dioxanone(PDO),glycolide(GA)or caprolactone(CL)into chain backbone to obtain polymer materials with good biodegradability,biocompatibility,flexibility and not easy to lose.After that,we characterized the chemical structure,surface morphology,thermodynamic properties,functional groups structure,molecular weight,and mechanical properties of the synthesized copolymer materials by means of ~1H-NMR,SEM,DSC,FTIR,Ubbelohde viscosimetry and tensile test.In PBS buffer solution,the degradation experiments of the polymer films were carried out in vitro.During the degradation process,the mass preservation rate,molecular weight,water absorption rate,surface smorphology,glass transition temperature and pH value of buffer solution of the copolymer films were carefully studied.Firstly,traditional PLA film material was modified by introducing CL segment unit.The random copolymers of P(LA85-co-CL15),P(LA80-co-CL20)and P(LA75-co-CL25)with three molar ratios were prepared by traditional open-copolymerization.It was found that,the introduction of CL could effectively improve the brittleness of original PLA film.With the increase of CL molar ratio,the stress to yield of the copolymer films decrease,while the elongation to break increased significangly.The degradation experiments showed that in the initial eight weeks,little change was observed for the mass preservation rate,while after eight weeks,significant mass loss was observed.Accompaning the degradation,the ester bonds of the polymer backbone were hydrolyzed to prduce hydroxyl and carbonoxylic groups,and film surfaces appeared with holes with increased size and decreased glass transition temperature.Secondly,we introduced the flexible CL,and fast degradable GA and PDO chain units,and modify PLA by traditional open copolymerization.The two types of random copolymers of P(LA70-co-CL25-co-GA5),P(LA65-co-CL25-co-GA10),P(LA75-co-CL20-co-PDO5)and P(LA70-co-CL20-co-PDO10)with four molar ratios were prepared.It was found that the introduction of flexible CL together with fast degradable GA and PDO,could obtain adhension materials with both flexibility and appropriate degradation properties.The degradation experiments showed that in the initial degradation period,the fast degradable component first hydrolyze,leading to the sharp decrease of polymer molecrlar weight.Accompaning the degradation,water absorption rate,surface smorphology,thermal properties and pH value of buffer solution of the copolymer films changed correspondingly with more flexible polymer backbone and decreased glass transition temperature.In all,to overcome the problems including brittleness,difficulty to handle,slow degradation and ease to incur second adhension for PLA film,we introduce the flexible CL component and fast degradable component GA or PDO to modify PLA and obtain new copolymer adhension films with flexibility and appropriate degradation property with potential application value. |
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