海藻酸钙冻干多孔膜的制备研究

海藻酸钙冻干多孔膜的制备研究郝晓丽;夏延致;纪全;孔庆山;隋坤艳【摘要】采用冷冻干燥法制备海藻酸钙多孔膜,考察海藻酸钠的浓度和交联时间对多孔膜的形貌和吸水性能的影响.结果表明:冷冻干燥法制备的海藻酸钙多孔膜具有贯通、开放的多孔结构.在试验范围内,质量百分比浓度为2%的海藻酸钠经质量百分比浓度5%的氯化钙交联10 min得到的多孔膜孔结构最为理想,对蒸馏水的吸水率高达1 123%.【期刊名称】《科学技术与工程》【年(卷),期】2010(010)011【总页数】3页(P2800-2802)【关键词】海藻酸钙;冷冻干燥;多孔膜;吸水性能【作者】郝晓丽;夏延致;纪全;孔庆山;隋坤艳【作者单位】青岛大学纤维新材料与现代纺织国家重点实验室培育基地,青岛,266071;青岛大学纤维新材料与现代纺织国家重点实验室培育基地,青岛,266071;青岛大学纤维新材料与现代纺织国家重点实验室培育基地,青岛,266071;青岛大学纤维新材料与现代纺织国家重点实验室培育基地,青岛,266071;青岛大学纤维新材料与现代纺织国家重点实验室培育基地,青岛,266071【正文语种】中文【中图分类】TQ432.74Alginate is naturally derived from brown sea algae，possessed a linear chains of a-L-guluronnic acid andβ-D-mannuronic acid.The addition of calcium ions to an aqueous solution of sodium alginate results in the formation of“egg-box”structure［1］.Alginate is hence hydrophilic，biocompatible，and biodegradable.It has been implicated in food industry，wound dressings and drug carriers［2—4］.With regards to the excellent film forming properties of alginate，some kinds of film materials have been achieved.Recently，biomaterials used as wound dressings are usually required to possess porous structure. Several preparation methods have been reported for porous films，including porogen leaching［5］，saturation and release of CO［2 6 ］and freeze-drying ［7］.The porous Ca-alginate films produced by freeze-drying method has been report recently［8］.The aim of this paper was to investigate the influence of experimental conditions，such as Na-alginate concentration and cross-linked time on the forming of porous films.The morphology characters and water absorbency were studied to ensure optimum conditions for porous Ca-alginate film preparation.1 Material and method1.1 MaterialNa-alginate was purchased from Qingdao MingYue algae chemicalCo.(Qingdao，China).Other reagents were all analytical grade.1.2 Preparation of porous Ca-alginate filmThe Na-alginate were dissolved in distilled water at room temperature to prepare 1%—2%(w/w)solutions，which were stored at 4℃ for at least 24 h to ensure the elimination of the entrained air.Then 25 g of the Na-alginate solution was poured into the Petri-dish and froze at－5℃overnight then lyophilized at－50℃for 24 h.The porous Na-alginate film was directly immersed in 5%(w/w)Calcium solution to cross-link for(2—30)min，then porous Ca-alginate film dried at room temperature.Table 1 lists the composition of the films prepared.1.3 MorphologyThe morphologies of porous films were investigated by scanning electron microscopy(SEM，JEOL，JSM—6390LV).Specimens were placed on the Cu mount and coated with gold coating apparatus.Table 1 Composition of the porous filmsFilm stype Na-alginaeConc./wt%cross-linked time/min water absorbency/%F1－2 1 2 799 F1－10 1 10 930 F1－30 1 30 914 F2－2 2 2 851 F2－10 2 10 1 123 F2－30 2 30 997 1.4 Water absorbencyTo measure the equilibrium water absorbency of porous films，pre-weighted dry sample of 1cm2 unite squarewas immersed in distilled water for 24 h.After the removal of the excess of water，the weight of wet sample was measured quickly.Then the water absorbency was determined according to the following equation:Where Ww and Wd represent the weight of wet and dry sample respectively.2 Results and discussion2.1 MorphologyIn general，porosity，mean pore size are essential elements of biomaterials having open-pored structures.In our work，the films possess relatively homogeneous morphology.Figure 1 showed representative SEM images of surface of porous films.In scanning electron microscopy，the surface of the films is even and somewhat regular，showing the inter-connected pore structure ranging in size from(100—300)μm.The average pore size of F1—10(Fig.1 a)is larger than that of F2—10(Fig.1 b).In other hand，the thickness of F1—10 is smaller than that of F2—10.In addition，the F2—10 is denser than F1—10.In light of characteristics above，2%is the optimum Na-alginate concentration.Fig.1 Transversal Cross-sectional SEM photos of the films，(a)F1—10，(b)F2—102.2 Water absorbencyThe Water absorbency of the porous Ca-alginate film is excellent.All the films swell equipmently quickly.Table 1 shows that with the increase in concentration，the water absorbency also increased.Water absorbency of F1—10 is 930%，and water absorbency of F2—10 is up to 1 123%.If we compare the films with the same Na-alginate concentrations and the different cross-linked time，for example F2—2，F2—10 and F2—30，water absorbency shows a trend of first increase then decdrease.This tendency might be attrib-uted to the increasing porosity of films.The suitable cross-linked pore structure could provide open means of wateraccess，but the excessive cross-linked pore structure could not sustain much water within pores.3 ConclusionIn conclusion，the porous Ca-alginate films can be successfully preparedby the freeze-drying method.The films possess interconnected pores rang from(100—300)μm and show excellent water absorbency.By comparison of porous Ca-alginate films regarding the morphology and water absorbency，we points out that the film prepared of 2%Na-alginate and cross-linked for 10min has suitable pore structure and excellent water 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