温度和pH值对智能水凝胶溶胀行为的影响

以N-马来酰化壳聚糖(N-MACH)为交联剂,N-异丙基丙烯酰胺(NIPAAm)为单体,羧甲基纤维素钠(CMC)为半互穿材料,分别合成了PNIPAAm和PNIPAAm/CMC半互穿网络智能水凝胶,研究了两种水凝胶在不同温度的去离子水和不同pH值的缓冲溶液中的溶胀现象,结果表明介质温度和pH值对水凝胶的溶胀行为有显著影响。在温度和pH值一定时,水凝胶的溶胀率随着交联剂用量的增加而下降,随着CMC用量的增加而上升。     

粒状聚N-异丙基丙烯酰胺/壳聚糖水凝胶的制备、性能及其应用

用反相悬浮聚合法,合成了具有温度/pH敏感性的聚N-异丙基丙烯酰胺/壳聚糖粒状半互穿网络(PNIPA/CS semi-IPN)水凝胶,研究了该水凝胶在不同温度、不同pH介质以及不同组成下的溶胀率变化.结果表明:该水凝胶的最低临界溶液温度(LCST)与PNIPA水凝胶基本相同,均在33℃左右,pH=3时溶胀率达到最大,具有明显的温度和pH敏感性.壳聚糖(CS)的不同比例也对凝胶的溶胀率产生很大影响.振荡实验表明:凝胶粒子具有温度响应可逆性.同时进行了乳酸吸附与释放的初步研究,当PNIPA/CS质量比为10时,最大吸附达到168.29 mg(g dry gel)-1,释放率为31.74%.     

温度及pH敏感性互穿网络水凝胶的制备研究

采用分步法制备了聚丙烯酸/N-异丙基丙烯酰胺互穿网络水凝胶,研究了互穿网络水凝胶的溶胀性能。结果表明,当水溶液的pH增大时,水凝胶的溶胀率显著增加。在一定的温度范围内,水凝胶的溶胀率随温度升高而减小。聚丙烯酸/N-异丙基丙烯酰胺互穿网络水凝胶表现出显著的温度及pH敏感双重特性。     

具有pH及温度敏感性的互穿网络水凝胶的合成及其性能研究

用自由基聚合合成了具有两亲性的N-异丙基丙烯酰胺(NIPAm)与衣康酸(IA)共聚物水凝胶(NIPAm-co-IA),利用互穿网络(IPN)技术合成了壳聚糖(CS)异丙基丙烯酰胺与衣康酸互穿网络水凝胶IPN(CS/NIPAm-co-IA).研究表明, IPN(CS/NIPAm-co-IA)水凝胶具有良好的pH及温度敏感性,研究了其对辅酶A的控制释放,发现其对辅酶A具有良好的控制释放作用.     

聚丙烯酸/聚乙烯醇互穿网络水凝胶制备及其对结晶紫的控制释放性能的研究

以过硫酸铵为引发剂,采用溶液聚合和连续的互穿网络技术,制备了一系列聚丙烯酸(PAA)/聚乙烯醇(PVA)互穿网络水凝胶。测量了水凝胶在不同pH缓冲溶液中的溶胀性能。以结晶紫为模板药物,考察了在不同的pH缓冲溶液中的PAA/PVA互穿网络水凝胶控释作用。结果表明,药物的释放量可以通过改变体系的pH值加以调控。     

pH敏感性P(AAm-co-AA)半互穿网络水凝胶的制备、表征及溶胀动力学研究

以N,N-亚甲基双丙烯酰胺(N,N-MBA)为交联剂、过硫酸钾(KPS)为引发剂,采用自由基交联共聚法合成了具有pH敏感性的半互穿网络水凝胶聚丙烯酰胺-co-丙烯酸[P(AAm-co-AA)],通过傅立叶红外光谱、差热分析研究了水凝胶的结构及热稳定性.水凝胶的溶胀研究表明,随着缓冲溶液pH值的增大平衡溶胀率增大;在不同...     

P(AAm-co-AA)/Ag复合材料制备及表征

以N,N-亚甲基双丙烯酰胺(N,N-MBA)为交联剂,过硫酸钾(KPS)为引发剂,采用交联共聚方法合成了具有pH敏感性的半互穿网络丙烯酰胺-co-丙烯酸水凝胶P(AAm-co-AA),利用水凝胶网络结构作为纳米反应器,自组装制备了纳米复合水凝胶P(AAm-co-AA)/Ag。水凝胶的溶胀行为研究表明,AAm与AA的质量比影响P(AAm-co-AA)/Ag水凝胶平衡溶胀率。     

pH敏感瓜胶/聚丙烯酸半互穿网络水凝胶研究

制备了瓜胶/聚丙烯酸(GG/PAA)的半互穿网络(sem i-IPN)水凝胶,以N,N-亚甲基双丙烯酰胺(MBA)为交联剂,考察了加料量、溶胀介质pH对平衡溶胀率(ESR)的影响。结果表明:GG/PAA半互穿网络水凝胶的ESR在pH≤3时较小,pH>4后增加较快,pH=8.2时达最大值,继续增加pH,ESR又呈下降趋势,体系具有pH敏感性。在pH相同条件下,ESR随GG用量增加而减小,随丙烯酸(AA)用量增加而增大。pH=8.2、ρ(GG)从5 g/L增加到25 g/L时,ESR从3 142降低到1 026;当ρ(AA)用量从125 g/L增加到375 g/L时,ESR从1 195增加到2 611。m(MBA)∶m(AA)=(0.5∶100)~(1.2∶100)时,ESR略有增加。GG/PAA半互穿网络水凝胶的溶胀动力学表明,该类凝胶满足在胃液pH环境中溶胀率较小、小肠部位pH环境中溶胀率较高的要求,因此,通过调整配方,结合瓜胶只被结肠部位细菌降解的特性,GG/PAA半互穿网络水凝胶有望成为一种理想的靶向结肠给药载体。     

聚苯胺/碳纳米管杂合水凝胶的合成及膨胀性能研究

合成了一种以甲基丙烯酸-丙烯酰胺共聚网络P(AAm-co-MAA)为基体,以聚苯胺为互穿组分(PANI)的半互穿网络杂合水凝胶。研究表明,当将PANI和MWNTs-COOH被引入到P(AAm-co-MAA)网络中后得到的P(AAm-co-MAA)/PANI/MWCNT-COOH半互穿网络杂合水凝胶则能保持较好的膨胀性,同时发现,依靠调节PA-NI/MWNTs-COOH的含量可以使杂合水凝胶膨胀性增加。这为研究杂合水凝胶的力学性能和pH敏感性提供了一个窗口。     

PAA/PNIPAAm互穿网络水凝胶的微波合成与性能研究

以微波为辐射源,对丙烯酸(AA)水溶液进行辐照制得了PAA水凝胶。将脱水后的PAA水凝胶浸泡于含引发剂过硫酸钾(K_2S_2O_8)和交联剂N,N’-亚甲基双丙烯酰胺(BIS)的N-异丙基丙烯酰胺(NIPAAm)水溶液中,待溶胀平衡后取出,进行第二次微波辐照反应,制备了聚丙烯酸/聚N-异丙基丙烯酰胺互穿聚合物网络(PAA/PNIPAAm IPN)水凝胶,并对其溶胀性能进行了研究。研究结果表明,合成的IPN水凝胶兼具pH敏感性和温度敏感性,有望在药物控制释放领域得到应用。     

Preparation and characterization of tetracycline‐loaded interpenetrating polymer networks of carboxymethyl cellulose and poly(acrylic acid): water sorption and drug release study

Tetracycline (TC)‐loaded ionic interpenetrating polymer networks (IPNs) of carboxymethyl cellulose (CMC) and crosslinked poly(acrylic acid) (PAA) were prepared and characterized by infrared spectral analysis, differential scanning calorimetry and scanning electron microscopy techniques. The prepared IPNs were evaluated for in vitro blood compatibility by clot formation and hemolysis methods and their water imbibitions capacity was determined. Fractional release dynamics of tetracycline was also investigated from loaded IPNs of CMC and PAA. The entrapped drug was examined for antibacterial activity and structural integrity and effects of various parameters such as percentage loading of the drug, chemical composition of the carrier IPN, pH and temperature of the release medium were investigated on the release profiles of TC. The drug was also released in different simulated biological fluids. Copyright © 2005 Society of Chemical Industry     

Smart carboxymethylchitosan hydrogels that have thermo‐ and pH‐responsive properties

Thermo‐responsive poly(N‐isopropylacrylamide) (poly(NIPAAm)) and pH‐responsive poly(N,N′‐diethylaminoethyl methacrylate) (poly(DEAEMA)) polymers were grafted to carboxymethylchitosan (CMC) via radical polymerization to form highly water swellable hydrogels with dual responsive properties. Ratios of CMC, NIPAAm to DEAEMA used in the reactions were finely adjusted such that the thermo and pH responsiveness of the hydrogels was retained. Scanning electron microscopy (SEM) indicated the formation of an internal porous structure for the swollen CMC hydrogels upon incorporation of poly(NIPAAm) and poly(DEAEMA). Effect of temperature and pH changes on water swelling properties of the hydrogels was investigated. It was found that the water swelling of the hydrogels was enhanced when the solution pH was under basic conditions (pH 11) or the temperature was below its lower critical solution temperature (LCST). These responsive properties can be used to regulate releasing rate of an entrapped drug from the hydrogels, a model drug, indomethacin was used to demonstrate the release. These smart and nontoxic CMC‐based hydrogels show great potential for use in controlled drug release applications with controllable on‐off switch properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41505.     

Preparation and properties of physically crosslinked sodium carboxymethylcellulose/poly(vinyl alcohol) complex hydrogels

A series of physically crosslinked complex hydrogels of poly(vinyl alcohol) (PVA) and sodium carboxymethylcellulose (CMC) were prepared via physical mixing and a freeze/thaw technique. The morphology of the CMC/PVA complex gels was analyzed with differential scanning calorimetry and wide‐angle X‐ray diffraction. It was found that the crystallinity and melting temperature of the complex gels decreased, whereas the glass‐transition temperature increased, with an increase in the content of CMC. The reswelling of the complex gels was pH‐responsive and relied on the content of CMC and the freeze/thaw cycles. A network structure model of the complex gel was presented. PVA crystalline regions served as physical crosslinks; the interaction between CMC and PVA resulted in intramolecular entanglements. It was also found that the model drug hemoglobin was released completely from the complex hydrogels in 4 h, and its release rate increased with an increase in the content of CMC. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Calcium‐carboxymethyl chitosan hydrogel beads for protein drug delivery system

In this study, carboxymethyl chitosan (CMC) hydrogel beads were prepared by crosslinking with Ca²⁺. The pH‐sensitive characteristics of the beads were investigated by simulating gastrointestinal pH conditions. As a potential protein drug delivery system, the beads were loaded with a model protein (bovine serum albumin, BSA). To improve the entrapment efficiency of BSA, the beads were further coated with a chitosan/CMC polyelectrolyte complex (PEC) membrane by extruding a CMC/BSA solution into a CaCl₂/chitosan gelation medium. Finally, the release studies of BSA‐loaded beads were conducted. We found that, the maximum swelling ratios of the beads at pH 7.4 (17–21) were much higher than those at pH 1.2 (2–2.5). Higher entrapment efficiency (73.2%) was achieved in the chitosan‐coated calcium‐CMC beads, compared with that (44.4%) in the bare calcium‐CMC beads. The PEC membrane limited the BSA release, while the final disintegration of beads at pH 7.4 still leaded to a full BSA release. Therefore, the chitosan‐coated calcium‐CMC hydrogel beads with higher entrapment efficiency and proper protein release properties were a promising protein drug carrier for the site‐specific release in the intestine. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3164–3168, 2007     

Synthesis and evaluating of carbon nanoallotrope-biomacromolecule gel composites as drug delivery systems

This work was done to assess the role of precursors (agro and graphite) on performance of carbon nanoallotropes-biomacromolecules composite as drug delivery for controlling the release of niacin. In this respect graphene oxide and bagasse-based carbon oxide were synthesized and chelated with chitosan (Cs-GO and Cs-Co). These gel composites were characterized by many techniques [morphology, differential scanning calorimetry, Fourier-transform infrared spectroscopy, swelling, encapsulation efficiency (EE) and loading (L) % of niacin. Another series of experiments was carried out for studying the role of replacing part of carbon nanoallotrope by carboxymethyl cellulose (CMC) on performance of produced drug carries, these systems were coded as Cs-GO-CMC and Cs-Co-CMC. The data showed that, the Cs-GO gel composite provided maximum release of NA, at 5 h, for pH's simulated gastric and intestinal fluids; pH. 2.1 and pH 7.4 (1120 mg/L and 757 mg/L). The incorporation of CMC is not acceptable as it provided low drug release together with burst release of NA-drug, and consequently possible caused tissue irritation or toxicity in the human body. The Cs-GO and Cs-CO systems with relatively low drug loading were recommended for their better controllability system to NA release, which prolonging benefit of human with niacin. The NA release from all investigated gels followed Fickian and non-Fickian diffusion mechanisms.     

Carboxymethyl chitosan-graft-phosphatidylethanolamine: Amphiphilic matrices for controlled drug delivery

Modified carboxymethyl chitosan (CMC) containing phosphatidylethanolamine (PEA) groups were synthesized by a 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC)-mediated coupling reaction. The structure of the modified CMC exhibiting an amphiphilic character was analysed by FT-IR and ¹H NMR. CMC-g-PEA beads were prepared with sodium tripolyphosphate (TPP) by ionic-crosslinking. The beads sizes were in range from 800 to 1200 μm and encapsulation efficiencies of drug were more than 68%. The morphologies of CMC-g-PEA beads were examined with scanning electron microscopy (SEM). The release experiments were performed using ketoprofen as an hydrophobic model drug. The drug dissolution kinetics showed longer release times for CMC-g-PEA beads: 20 h (at pH 1.4) and 45 h (at pH 7.4). The amount of the drug release was much higher in acidic solution than in basic solution due to the swelling properties of the matrix at acidic pH. These results suggest that modified CMC with PEA may become a potential delivery system to control the release of hydrophobic drugs.     

Effect of attapulgite contents on release behaviors of a pH sensitive carboxymethyl cellulose‐g‐poly(acrylic acid)/attapulgite/sodium alginate composite hydrogel bead containing diclofenac

A series of pH‐sensitive composite hydrogel beads, carboxymethyl cellulose‐g‐poly(acrylic acid)/attapulgite/sodium alginate (CMC‐g‐PAA/APT/SA), were prepared by combining CMC‐g‐PAA/APT composite and SA, using Ca²⁺ as the ionic crosslinking agent and diclofenac sodium (DS) as the model drug. The effects of APT content and external pH on the swelling properties and release behaviors of DS from the composite hydrogel beads were investigated. The results showed that the composite hydrogel beads exhibited good pH‐sensitivity. Introducing 20% APT into CMC‐g‐PAA hydrogel could change the surface structure of the composite hydrogel beads, decrease the swelling ability, and relieve the burst release effect of DS. The drug cumulative release ratio of DS from the hydrogel beads in simulated gastric fluid was only 3.71% within 3 hour, but in simulated intestinal fluid about 50% for 3 hour, 85% for 12 hour, up to 90% after 24 hour. The obtained results indicated that the CMC‐g‐PAA/APT/SA hydrogel beads could be applied to the drug delivery system as drug carriers in the intestinal tract. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

羧甲基纤维素-大豆分离蛋白农药缓释颗粒的制备及性能

为提高农药利用率、精确控制农药释放,设计了一种pH响应型缓释颗粒。以3-氨丙基三乙氧基硅烷（APTES）为桥连接羧甲基纤维素（CMC）与大豆分离蛋白（SP）得到羧甲基纤维素-大豆分离蛋白（CMC-SP）,然后利用分子自组装法负载阿维菌素（AVM）形成载药颗粒（CMC-SP@AVM）。采用红外光谱（FTIR）、扫描电镜（SEM）、热重分析（TGA）等手段对改性产物结构和形貌进行表征,并对CMC-SP@AVM的载药性能、缓释性能、抗紫外性能、杀虫活性进行了探究。结果表明,CMC-SP@AVM具有近似椭圆形的结构,CMC-SP@AVM的平均粒径为104nm;对AVM的包封率达41.9%,并赋予AVM优异的抗紫外光分解性能,强紫外光照射120h后,CMC-SP@AVM中AVM的残留率比未包封的AVM高117%,其药物释放具有pH响应特性,pH越大,释放速率越快;药物释放过程符合Elovich模型。在相同AVM浓度下CMC-SP@AVM的杀虫活性与原药无显著差异。     

Aggregation and Phase Separation Phenomenon of Amitriptyline Hydrochloride Under the Influence of Pharmaceutical Excipients

The interaction between the amphiphilic drug amitriptyline hydrochloride (AMT) and the nonionic surfactants used in drug delivery has been investigated. Herein, we report the micellization behavior of AMT in presence of ethoxylated alkyl phenols in aqueous medium and the clouding phenomenon in the absence and presence of different nonionic surfactants in buffer solution. The values of critical micelle concentration (CMC) of AMT obtained using the conductivity method, decrease as nonionic surfactant concentration increases. With an increase in temperature, the CMC first increases and then decreases. At 303.15 K, the maximum CMC values were obtained with or without nonionic surfactant. The results obtained indicate attractive interactions (synergism) between the two mixing amphiphiles in solution. The experimentally obtained critical micelle concentration (CMC) values are always lower than ideal CMC values. Micellar mole fraction (X₁) values, calculated by different proposed models, show the contribution of nonionic surfactant concentration. At a fixed drug concentration (50 mmol kg^?1) and pH (=6.7) nonionic surfactants show continuous increase in cloud point (CP). Increase in drug concentration and pH, in the presence of fixed amounts of nonionic surfactant, increases and decreases the CP, respectively.     

Preparation and properties of a dually responsive hydrogels based on polyampholyte for oral delivery of drugs

Novel of temperature and pH sensitive hydrogels composed of polyampholyte (casein) and poly(N-isopropylacrylamide) were successfully synthesized via free radical polymerization. The swelling behavior of the obtained hydrogel was investigated and it was found that the synthesized hydrogel has a sensitivity to temperature, pH, and the crosslinker content. The drug release of this hydrogel was determined with salicylic acid employed as the model drug. It found that the release of salicylic acid from the hydrogel particles was affected by temperature, pH, and the crosslinker content in the copolymer hydrogels. Therefore, the novel pH and temperature sensitive hydrogel seem to be of great promise in pH and temperature sensitive oral drug release systems.