P(NIPA-co-AM)超大孔水凝胶的制备及其性能

以N-异丙基丙烯酰胺(NIPA)、丙烯酰胺(AM)为单体,过硫酸铵为引发剂,N,N'-亚甲基双丙烯酰胺为交联剂,采用泡沫分散聚合法制备N-异丙基丙烯酰胺与丙烯酰胺共聚物[P(NIPA-co-AM)]超大孔水凝胶,研究了丙烯酰胺、引发剂、交联剂、盐酸、碳酸氢钠用量对水凝胶溶胀、退溶胀性能的影响,通过DSC、SEM、FTI...     

聚N-异丙基丙烯酰胺水凝胶的微波合成与性能

以水为溶剂,N-异丙基丙烯酰胺(NIPAM)为单体,N,N-亚甲基双丙烯酰胺(Bis)为交联剂,分别通过微波合成法和水浴加热法制备了聚N-异丙基丙烯酰胺(PNIPAM)水凝胶,研究了交联剂浓度、反应时间、反应温度等对反应的影响,及PNIPAM水凝胶在不同温度和pH值下的溶胀性变化。研究结果表明,与水浴加热法相比,微波合成法缩短了反应时间,从10h缩减至1h左右;适当延长反应时间和提升反应温度有利于提高单体转化率。微波法合成PNIPAM的最佳条件为:H2O为溶剂,100℃~110℃反应40 min~60 min,交联剂m(Bis)/m(NIPAM)=5/100,单体转化率97%~98%。而且,微波合成法制备的水凝胶具有更显著的温度和pH敏感性能。     

N-羟甲基丙烯酰胺/丙烯酸智能水凝胶的合成及性能研究

以N-羟甲基丙烯酰胺(N-MAM)和丙烯酸(AA)为聚合单体,过硫酸铵(APS)和N,N,N′,N′-四甲基乙二胺(TEMED)为引发体系,N,N-亚甲基双丙烯酰胺(MBA)为交联剂采用自由基水溶液聚合法合成了p(N-MAM-co-AA)水凝胶。研究了APS、MBA的用量、单体浓度与单体配比、溶液pH值和温度对水凝胶溶胀性能的影响,同时还研究了凝胶的溶胀-退溶胀动力学。     

壳聚糖接枝丙烯酸/丙烯酰胺水凝胶的制备及性能

以丙烯酸(AA)、丙烯酰胺(AM)两种单体同时对壳聚糖(CTS)进行接枝改性,合成了具有环境响应性的壳聚糖水凝胶,讨论了各合成因素对凝胶溶胀性能的影响及凝胶对pH值、离子强度和温度的响应性。结果表明,当反应时间为2h~2.5 h、单体与CTS质量比为8∶1、反应温度在60℃左右、引发剂用量为0.35%(占单体和CTS总量的百分比,下同)、交联剂用量为0.125%时,制得的水凝胶最高溶胀度可达224 g/g,而且该凝胶同时具有pH值、离子强度和温度敏感性。     

壳聚糖交联温敏性水凝胶的制备与性能

利用N-马来酰化壳聚糖(N-MACH)为交联剂,以N-异丙基丙烯酰胺(NIPAAm)、衣康酸(IA)为单体,利用水溶液自由基聚合反应合成了P(NIPAAm-co-IA)水凝胶。研究了水凝胶的相转变性质、低临界溶解温度(LCST)和溶胀性能。该类水凝胶在32℃左右具有明显的相转变特性,其LCST随衣康酸用量的增加而增大,交联剂的用量对水凝胶的LC-ST值无显著影响。水凝胶的溶胀性能具有较为明显的温度依赖性和介质依赖性,其饱和溶胀度与NIPAAm/IA的比例、交联密度及溶胀介质有关。     

温度敏感性P(NtBA-co-AAm)聚合物和水凝胶的合成及表征

以N-叔丁基丙烯酰胺(Nt BA)和丙烯酰胺(AAm)为反应单体,过硫酸铵(APS)为引发剂,在50℃时通过自由基聚合反应合成了具有温度敏感性的聚(N-叔丁基聚丙烯酰胺-co-丙烯酰胺)(P(Nt BA-co-AAm))线型聚合物及水凝胶。为提高凝胶的溶胀性能,以硅胶微粒和聚乙二醇400(PEG400)为造孔剂,合成了一系列大孔P(Nt BA-co-AAm)水凝胶。用差热分析仪分析了P(Nt BA-co-AAm)共聚物的热力学性能,通过红外光谱、扫描电镜表征了P(Nt BA-co-AAm)凝胶的结构。研究了进料中单体配比和交联剂用量对水凝胶溶胀性能的影响以及不同温度下水凝胶的溶胀动力学。结果表明,进料中Nt BA与AAm的摩尔比越高,共聚物及水凝胶的相转变温度越低;增加交联剂的用量,水凝胶的溶胀率降低;大孔凝胶的溶胀率和去溶胀率较传统凝胶有较大提高,同时对外界温度变化的响应更迅速。     

Poly(DMAM-co-AA)水凝胶的合成

以N,N-二甲基丙烯酰胺(DMAM)与丙烯酸(AA)为单体,N,N-亚甲基双丙烯酰胺(NMBA)为交联剂,过硫酸铵为引发剂,采用水溶液聚合法合成了DMAM和AA的共聚物水凝胶。实验证明,加热温度、引发剂用量和反应体系中单体总浓度对聚合产物的吸水能力没有明显影响,但随着对反应溶液的加热温度升高、引发剂用量增大、单体总质量分数增大,聚合反应能够达到的最高温度就越高,达到最高温度的时间缩短。DMAM和AA的物质的量比偏离1越远,水凝胶的吸水能力越强。交联剂的质量分数为0.5%时,水凝胶的吸水能力最大。     

前端聚合法制备聚(N-乙烯基己内酰胺-co-N,N-二甲基丙烯酰胺)智能水凝胶

本工作采用前端聚合法制备聚(N-乙烯基己内酰胺-co-N,N-二甲基丙烯酰胺)智能水凝胶,针对两种单体,即N-乙烯基己内酰胺( N-VCL)和N, N-二甲基丙烯酰胺(DMAA),研究了单体物质的量比、交联剂和引发剂用量对前端聚合参数以及共聚水凝胶性能的影响,并用阿司匹林作为模型药物,评价了共聚物水凝胶对阿司匹林的负载和缓释效果.实验表明,共聚产物具有温度敏感性,相转变温度在25～40 ℃之间,单体N,N-二甲基丙烯酰胺(DMAA)加入之后,凝胶对温度刺激的敏感性响应更为明显.随单体DMAA含量的增加,波温、波速也升高,温室溶胀率增加.当n(N-VCL) ∶ n(DMAA)=5 ∶5时,水凝胶的温敏性最好;随交联剂用量的增大,共聚凝胶室温溶胀能力、温敏性均有所降低;随引发剂用量的增加,相变温度升高.随单体DMAA比例增加,在25 ℃和37 ℃两种温度下凝胶载药量均增加,但就释药效果而言,在37 ℃下凝胶释药效率更高,总释药率也更高.     

新型聚丙烯酰胺/碳纤维/石墨导电水凝胶的制备

以N,N'-亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂,丙烯酰胺为单体,碳纤维与石墨为导电填料,采用水溶液聚合法制备了聚丙烯酰胺/碳纤维/石墨高吸水性复合材料,吸水后形成导电水凝胶.考察了交联剂用量、引发剂用量、单体浓度、反应温度、吸水倍率及导电填料用量对凝胶电导率的影响.实验结果表明,当交联剂用量为0.06%(质量分数),引发剂用量为1.0%(质量分数),单体浓度为50%(质量分数),反应温度为80℃,导电填料为35%(质量分数)时,水凝胶的电导率最高可达4.32mS/cm.并采用FTIR及SEM对样品结构及形貌进行表征.     

明胶/聚(N-异丙基丙烯酰胺)水凝胶的制备及其在药物控释中的应用

以马来酸酐改性后的明胶(N-马来酰化明胶)(明胶-g-MA)为交联剂与N-异丙基丙烯酰胺共聚制备了一系列水凝胶。研究了交联剂用量对水凝胶溶胀性的影响,结果表明交联剂用量为45%(质量分数)时水凝胶具有最高的溶胀率,水凝胶的平衡溶胀率随温度升高逐渐降低,温敏性随缓冲液中NaCl浓度增加逐渐增强。包埋在水凝胶样品内的牛血清蛋白(BSA)具有良好的缓释效果,其累积释放率随交联剂用量增加而降低,高于相变温度时释放速度加快。     

SA分子量及用量对SA/PNIPAAm semi-IPN水凝胶溶胀性能的影响

研究了海藻酸钠(SA)的分子量及用量对SA/聚(N-异丙基丙烯酰胺)半互穿网络(SA/PNIPAAm semi-IPN)水凝胶的平衡溶胀度、溶胀速率和消溶胀速率的影响。结果发现,水凝胶平衡溶胀度随着凝胶网络中SA组分分子量以及用量的增加而增大;在pH=1.0条件下,SA/PNIPAAm semi-IPN水凝胶的溶胀速率随着SA的分子量以及用量的增加而降低,在pH=7.4条件下,水凝胶的溶胀速率随着SA的分子量以及用量的增加而增大;SA用量较低时,分子量的大小对SA/PNIPAAm semi-IPN水凝胶的消溶胀速率有很大影响,随着SA用量的增加,分子量大小对水凝胶消溶胀速率的影响作用降低。     

Swelling and diffusion characteristics of modified poly (N-isopropylacrylamide) hydrogels

Thermo-responsive hydrogels are capable of swelling changes to external temperature. A series of modified poly (N-isopropylacrylamide) (PNIPA) hydrogels was synthesized by free radical polymerization in aqueous solution. Acrylamide (AAm) was used to increase the lower critical solution temperature (LCST), while sodium alginate (SA) was used to improve the swelling performance of the hydrogels. Experiments show that 5.5% mass ratio of AAm increased the LCST by about 9 °C above that of conventional PNIPA. Also, SA significantly improved the equilibrium swelling ratio associate with temperature change. Trypan blue diffusion revealed significant differences in the fluid release obtained from hydrogels with modified LCST and swelling properties. The implications of the modified fluid release and swelling characteristics are also discussed for the device design of thermo-sensitive hydrogels for localized drug delivery.     

明胶/海藻酸钠(京尼平交联)互穿网络膜的制备与性能

为了提高海藻酸钠与明胶各自的性能,首先,以海藻酸钠和明胶为原料,以京尼平、CaCl2为交联剂,采用分步交联法制备了明胶/海藻酸钠互穿网络膜。然后,利用FTIR对明胶/海藻酸钠互穿网络结构进行了表征与分析,根据FTIR结果推测了互穿网络结构形成的机制。最后,探讨了京尼平的加入量和明胶与京尼平的质量比对互穿网络膜力学性能和交联度的影响,及海藻酸钠与明胶的质量比对互穿网络膜力学性能、断面形貌、热稳定性和吸水保水性能的影响。结果表明:当明胶与京尼平的质量比为200∶1、海藻酸钠与明胶的质量比为2∶1时,互穿网络膜具有最佳的力学性能、吸水保水性能和相容性;此外,互穿网络膜的力学性能也优于纯海藻酸钠膜与纯明胶膜的。明胶的加入提高了互穿网络膜在低温区的热稳定性,但降低了高温区的热稳定性。海藻酸钠与明胶之间可能以分子间作用力、氢键及离子键等相互作用,提高了二者各自的初始分解温度与最大热分解温度。研究解决了海藻酸钠与明胶力学性能差的问题,为拓展海藻酸钠在医用领域的应用提供参考。     

可生物降解海藻酸钠高吸水性树脂的性能与结构

用土壤掩埋法和微生物降解法对聚丙烯酸盐/海藻酸钠高吸水性树脂的生物降解性能进行了研究,结果表明,树脂能被土壤和微生物降解,海藻酸钠含量为10%的树脂在土壤中埋置60 d后降解率达37.6%,在芽孢杆菌培养液中60d的降解率则超过50%,且降解速度随海藻酸钠含量的提高而加快。TG表明,树脂的热稳定性较好。IR初步表明,树脂为丙烯酸盐与海藻酸钠的接枝共聚物。     

肉桂精油-海藻酸钠可食性抗菌膜的研制

以海藻酸钠为成膜材料,并添加不同质量浓度的肉桂精油来制备可食性抗菌膜。根据膜的力学性能和抑菌性能,确定了可食性膜中添加海藻酸钠、甘油和肉桂精油的最佳质量分数,以及可食性抗菌膜的最佳干燥温度和干燥时间。实验结果表明：在海藻酸钠的质量浓度为20mg／mL,甘油的添加质量分数为1．0％,肉桂精油的添加质量分数为2．0％,干燥温度为50℃和干燥时间为4．5h的条件下,所制备的膜具有最佳的力学性能和抑菌性能。     

Antibiotic drug release behavior of poly (vinyl alcohol)/sodium alginate hydrogels

Poly (vinyl alcohol)/sodium alginate hydrogels were prepared by freeze-thaw followed by calcium ion crosslinking. Chloramphenicol release behavior from the poly (vinyl alcohol)/sodium alginate hydrogels in mimic conditions of gastrointestinal tract was examined. The effects of composition, number of freeze-thaw cycles and calcium ion concentration on drug release process were investigated. The results showed that the cumulative release amount of chloramphenicol from the hydrogels (crosslinked through 4 freeze-thaw cycles and immersed in 2 % calcium chloride solution) decreased from 84.3 % to 72.3 % as sodium alginate content increased from 0 % to 75 %. For the hydrogels containing 50 % sodium alginate and immersed in 2 % calcium chloride solution after the freeze-thaw cycles, cumulative release amount of chloramphenicol decreased from 83.5 % to 76.6 % as the freeze-thaw cycles increased from 2 to 6. Cumulative release amount of chloramphenicol from the hydrogels containing 50 % sodium alginate and with 4 freeze-thaw cycles decreased from 79.8 % to 75.6 % when concentration of calcium chloride solution increased from 1 % to 4 %.     

Investigation of swellable poly (N-isopropylacrylamide) based hydrogels for drug delivery

The thermo-sensitive properties of poly (N-isopropylacrylamide) (PNIPA) hydrogels are modified by the addition of hydrophilic acrylamide comonomers and an interpenetrating network of sodium alginate for drug delivery applications near 37 °C. A mathematical model is presented to describe the mass transport kinetics during the hydrogel drug delivery process, which is accompanied by a volume change during phase transition. In this model, the transport in the polymer matrix is described by Fick's second law in cylindrical coordinates, with concentration dependent diffusion coefficients. The moving boundary problems caused by the polymer matrix swelling are also solved by numerical simulation. The models show that the Trypan blue release from the modified PNIPA-based hydrogels is strongly concentration dependent. The sodium alginate component is also shown to effectively facilitate the diffusion process. The results from the simulation are in good agreement with the measurements of diffusion and swelling observed from in vitro experiments. The implications of this work are also discussed for practical drug delivery systems.     

交联海藻酸钠磁性微球的制备及固定化胰蛋白酶研究

制备了交联海藻酸钠磁性微球,并以磁性微球为载体,戊二醛为交联剂,将胰蛋白酶固定化;利用透射电镜、粒度分析、红外分析对交联海藻酸钠磁性微球进行了表征;探讨给酶量、戊二醛浓度和pH值对固定化酶活性的影响;与自由酶比较,考察了固定酶的酶学性质.结果表明:交联海藻酸钠磁性微球是固定化胰蛋白酶的良好载体,固定化酶最适宜的条件是吸附时间12h,给酶量为100mg/0.1g磁性载体、交联剂戊二醛浓度为5%、溶液pH值为6,同时将酶固定化后,酶的稳定性和催化性能均有所提高.     

Drug release behaviors of a pH/temperature sensitive core-shelled bead with alginate and poly(N-acryloyl glycinates)

In this study, a pH/temperature sensitive bead with core-shelled structure, as a drug carrier, was prepared by grafting of N-acryloylglycinates on the surface of sodium alginate beads. The pH and temperature sensitivity of the beads originate from sodium alginate (SA) and copoly(N-acryloylglycinates), respectively. Here, indomethacin (IMC) was selected as a drug model molecule and loaded in SA beads. The release of IMC was systematically investigated as a function of temperature, pH, and SA concentration. The amount of IMC released from beads was as high as 61.6%in pH = 7.4 phosphate buffer solution (PBS) over 620 min, whereas only 27.9% IMC diffused into the pH = 2.1 PBS. In addition, the release rates of IMC at 37.5°C were faster than that at 20.0°C and decreased with increasing SA concentration in the beads. The result indicates that the sensitive beads have the potential to be used as an effective pH/temperature-controlled delivery system in the biomedical fields.     

Drug release behaviors of a pH/temperature sensitive core-shelled bead with alginate and poly(<Emphasis Type="Italic">N</Emphasis>-acryloyl glycinates)

In this study, a pH/temperature sensitive bead with core-shelled structure, as a drug carrier, was prepared by grafting of N-acryloylglycinates on the surface of sodium alginate beads. The pH and temperature sensitivity of the beads originate from sodium alginate (SA) and copoly(N-acryloylglycinates), respectively. Here, indomethacin (IMC) was selected as a drug model molecule and loaded in SA beads. The release of IMC was systematically investigated as a function of temperature, pH, and SA concentration. The amount of IMC released from beads was as high as 61.6%in pH = 7.4 phosphate buffer solution (PBS) over 620 min, whereas only 27.9% IMC diffused into the pH = 2.1 PBS. In addition, the release rates of IMC at 37.5°C were faster than that at 20.0°C and decreased with increasing SA concentration in the beads. The result indicates that the sensitive beads have the potential to be used as an effective pH/temperature-controlled delivery system in the biomedical fields.