Preparation,evaluation, and in vitro release study of O‐carboxymethyl chitosan nanoparticles loaded with gentamicin and salicylic acid

To inhibit the ototoxicity of gentamicin (GM) and overcome the drawback related to chitosan (CS) nanoparticles preparation in acid solution, O‐carboxymethyl chitosan (O‐CMC) nanoparticles loaded with GM and salicylic acid (SA) were prepared by ionic cross‐linking method using calcium chloride as crosslinking agent. The Fourier transform infrared (FTIR) spectroscopy and X‐ray diffraction (XRD) were used to analyze the reaction of O‐CMC and crosslinking agent. The parameters of preparation of the compound nanoparticles including the concentration of O‐CMC, the mass ratio of O‐CMC to calcium chloride, and the feed ratio of SA to GM were investigated. The results showed that the obtained nanoparticles had a high zeta potential and drug‐loading capacity. The nanoparticles were characterized by a spherical morphology, with average size ranging from 148 to 345 nm and a narrow particle size distribution. In vitro release studies in phosphate buffer saline (pH 7.4) evidenced a burst release in the first 1 h, followed by a sustained release in the residual time. The release amount of SA and GM were approximately equal in 24 h, which indicated that the SA‐ and GM‐loaded O‐CMC nanoparticles are a promising carrier system for inhibiting the ototoxicity of GM. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation, characterization and antimicrobial activity of quaternized carboxymethyl chitosan and application as pulp-cap

Quaternized carboxymethyl chitosan (QCMC) was prepared from which carboxymethyl chitosan (CMC) was prepared from chitosan first, then N-quaternary ammonium group was introduced by the reaction of CMC with 2, 3-epoxypropyl trimethylammonium. The structures of the derivatives were characterized by FT-IR, XRD, ¹³C NMR, ¹H NMR and gel permeation chromatography. In vitro antimicrobial activities of QCMC were evaluated against Escherichia coli, which is a Gram-negative bacterium, and Staphylococcus aureus, which is a Gram-positive bacterium. In compared with carboxymethyl chitosan (CMC) and quarternary chitosan (QC) of the same degree of substitusion (DS), we found that QCMC has stronger antimicrobial activity. Then we went deep into study of the relationship between their structure and antimicrobial activity, found that the DS of CMC do little effect to their antimicrobial activity, but as the increase of their DS of quaternization or the decrease of their molecular weight, the antimicrobial activity of QCMC become stronger. QCMC was complexed with calcium hydroxide as pulp-cap. Animal experiment results indicated that QCMC can strongly induce reparative dentine formation and showed a better ability in dentin inducing compared with calcium hydroxide.     

羧甲基纤维素钠/凹凸棒石纳米复合材料的制备与表征

以羧甲基纤维素钠(CMC-Na)为基体,凹凸棒石(AT)为增强材料,采用溶液共混法制备了标题物。研究了凹凸棒石用量对纳米复合材料结构和性能的影响。通过FT-IR、TG、SEM对复合材料进行了表征。试验结果表明,当凹凸棒石用量为羧甲基纤维素钠质量的0.22%时,复合材料的力学性能最佳。由于纳米凹凸棒石的引入,CMC-Na分子某些特征峰的波数发生了变化,复合材料的形貌也发生了改变;羧甲基纤维素钠/凹凸棒石纳米复合材料的热稳定性高于纯羧甲基纤维素钠膜。     

光引发壳聚糖接枝丙烯酸制备高吸水性树脂的研究

采用光引发的方式,将壳聚糖与丙烯酸进行接枝共聚反应,制备出高吸水性树脂,研究了壳聚糖与丙烯酸的质量比、反应温度、反应时间、交联剂用量等对接枝共聚反应的影响。结果表明,影响产品吸水倍率的大小顺序是:壳聚糖与丙烯酸的质量比、反应温度、反应时间、交联剂的用量,最佳用量依次分别为:8 g/g,65℃,2 h,0.3%,在此工艺条件下合成的高吸水性树脂最高吸水率可达301.12;影响接枝率的大小顺序为:壳聚糖与丙烯酸的质量比、反应时间、交联剂用量、反应温度,最佳用量依次分别为:10 g/g,3 h,0.1%,75℃。     

海藻酸钠/羧甲基壳聚糖纺丝溶液的流变性能

采用RT-2000毛细管流变仪,研究了海藻酸钠(SAL)/羧甲基壳聚糖(CMCS)纺丝溶液的流变性能。结果表明:SAL/CMCS纺丝溶液是切力变稀型流体,随着剪切速率(γ)的增加,纺丝溶液的表观粘度(η_a)下降;随着纺丝液中CMCS含量的增加,SAL/CMCS纺丝溶液的η_a和结构粘度指数(△η)下降,非牛顿指数(n)增大;随着纺丝液温度的升高,SAL/CMCS纺丝溶液的η_a和△η下降,n增大。纺丝过程中应控制SAL/CMCS纺丝溶液的温度为35℃,纺丝溶液中CMCS质量分数为15%较适宜。     

化学接枝法制备腻子型吸水膨胀橡胶研究

吸水膨胀橡胶是一种新型的功能高分子材料,过去多用机械共混的方法制备,但是这种方法存在着反复使用性能差的缺点,针对这个问题,本实验采用过硫酸铵/硫代硫酸钠氧化还原引发体系,有效地使丙烯酸钠单体与天然胶乳接枝共聚,制备出吸水倍率相当高的腻子型吸水膨胀天然橡胶。实验结果表明:反应温度、引发剂用量对吸水倍率和接枝率有明显的影响,单体用量对吸水倍率影响较大;反复吸水能力基本保持不变。     

超高相对分子质量聚乙烯接枝丙烯酸的制备

以丙烯酸为单体,采用γ射线辐照引发技术制备了超高相对分子质量聚乙烯接枝丙烯酸(UHMWPE- g-AA);利用傅里叶变换红外光谱和差示扫描量热法表征了接枝物的结构和热性能;用化学滴定法测定了接枝物的接枝率;研究了UHMWPE-g-AA对聚酰胺(PA)1010/UHMWPE-g-AA/UHMWPE共混物力学性能的影响。实验表明：接枝物在1716cm~(-1)处有明显的羰基特征吸收峰,说明AA分子确实被接枝到UHMWPE分子链上;接枝率随单体浓度、辐照剂量及辐照时间的增加而增加;加入UHMWPE-g-AA后,UHMWPE与PA1010的相容性得到了改善,PA1010/UHMWPE-g-AA/UHMWPE共混物的缺口冲击强度是PA1010/UHMWPE共混物的1.5倍,达到72J/m。     

pH-sensitive hydrogel based on carboxymethyl chitosan/sodium alginate and its application for drug delivery

Carboxymethyl chitosan sodium salt (CMCS)/sodium alginate (SA), a pH-sensitive hydrogel composed of CMCS and SA crosslinked by 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide, has been evaluated in vitro as a potential carrier for protein drug delivery of bovine serum albumin (BSA). The crosslinked structures, pore morphologies, and mechanical properties of the composite CMCS/SA hydrogel at different pH have been characterized by Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and dynamic mechanical analysis (DMA). The swelling behavior of the prepared hydrogel was assessed at different pH values, 1.2, 4.0, 6.86, 7.4, and 9.0. The in vitro slow release ability of the CMCS/SA hydrogel was assessed at 37°C and pH 1.2 or pH 7.4 to simulate gastrointestinal and mouth environments in vivo. The efficiency was found to be greater than 90% at pH 7.4. The composite CMCS/SA hydrogel showed no cytotoxic effect toward L-929 cells according to the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide test. These findings demonstrate that the composite hydrogel has promising potential for drug delivery. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46911.     

Polypropylene/polypropylene‐grafted acrylic acid blends for multilayer films: Preparation and characterization

Polypropylene (PP) was functionalized with acrylic acid (AA) and styrene (st) as a comonomer by means of a radical‐initiated melt‐grafting reaction. FTIR, ESCA, and ¹H‐NMR spectroscopies were used to characterize the formation of polypropylene grafted with acrylic acid (PP‐g‐AA) and polypropylene grafted with acrylic acid and styrene (PP‐g‐AAst). The content of AA grafted onto PP was determined by using volumetric titration. Blends of PP with 0–100 wt % of PP‐g‐AA were prepared by melt mixing. The effect of the modified polymer content on the surfaces of cast films was characterized through FTIR–ATR and ESCA analysis as well as contact‐angle, wetting‐tension, and ink‐adhesion measurements. The influence of the content of AA on the melting and crystallization temperature of PP was investigated by DSC. The contact angles of water on cast‐film surfaces of PP/PP‐g‐AA blends decreases with increasing modified polymer content and decreasing PP‐g‐AA molecular weight. A notorious improvement on wetting tension was observed with increasing modified polymer content and decreasing PP‐g‐AA molecular weight. From FTIR–ATR and ESCA spectra of the blends, a calculation was made of the carbonyl index on the films' surfaces. It was found that the higher the carbonyl index, the lower the contact‐angle value for the polypropylene blends. An increase in crystallization temperature of PP was observed when AA monomers were grafted into PP and with increasing PP‐g‐AA content in the blend, probably caused by a nucleation effect of AA monomers that would improve the crystallization capability of PP. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1497–1505, 2001     

丙烯酸接枝改性壳聚糖纤维的制备及性能

在引发剂过硫酸铵(APS)的作用下,采用丙烯酸(AA)接枝改性壳聚糖(CS),制备出CS-AA接枝共聚物,经湿法纺丝将其纺制成纤维,再用戊二醛对纤维进行一定程度的交联,可得到较好力学性能的改性CS纤维。结果表明:CS质量分数(相对AA)为14.3%,APS(相对AA)的摩尔分数为1.0%,反应温度65℃,反应时间6 h,凝固浴中无水乙醇和质量分数为10%氢氧化钠水溶液的体积比为50/50。在此条件下制得的纤维的断裂强度为0.55 cN/dtex,断裂伸长率为367%,经交联处理后纤维的断裂强度达2.03 cN/dtex。     

Synthesis and characterization of chitosan/poly(acrylic acid) polyelectrolyte complex

Polyelectrolyte complex based on chitosan and acrylic acid monomer by photoinitiated free‐radical polymerization in the absence of crosslinker showed a large transition in swelling in response to changes in pH of surrounding medium. Their ability to swell arises from polyelectrolyte interactions and molecular structure of the complex. The main properties of interest that related to the molecular structure, swelling volumes, glass transition temperature, and elastic modulus of the complex were investigated. The effect of water content, the only variable in the sample component, played an important role in molecular structure of the complex and as a consequence, the extent of intermolecular linkage, especially amide bonds which in turn governed the degree of swelling of the polyelectrolyte complex in this study. The decreased degree of swelling and higher temperature shift of glass transition temperature was found with increased water content, whereas increased modulus of elasticity of dry complex was found in lower water content of synthesis component. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1025–1035, 2002     

丙烯酸接枝丁苯胶乳的合成和性能研究

在空气和室温条件下采用氧化-还原引发体系合成丙烯酸接枝丁苯胶乳，对影响丙烯酸接枝率R的因素。接枝胶乳结构及聚已内酰胺（PA-6）/丙烯酸接枝丁苯橡胶（SBR-g-AA)共混物性能进行了探讨，试验得出，各因素对R影响的大小顺序为：引发剂（叔丁基过氧化氢和四亚乙基五胺）质量分数，丙烯酸质量分数，反应时间，接枝后丁苯胶乳粒径稍有增大且分布变宽；SBR-g-AA可改善PA-6的冲击强度和拉伸强度。     

Preparation of poly(acrylic acid)/linseed mucilage/chitosan hydrogel for ketorolac release

Studies of smart and biocompatible hydrogels have resulted in the development of efficient drug-delivery systems controlled by external stimuli. Taking inadequate doses of ketorolac could cause health complications in humans. Therefore, it is necessary the development of a polymeric matrix for controlled drug delivery to extend the release of Ketorolac. In this work, acrylic acid was polymerized using ammonium persulfate as initiator and N,N′-methylenebisacrylamide as a cross-linking agent, and in the presence of chitosan (Chit) and linseed mucilage (LS) biopolymers to obtain a composite of PAAc/LS/Chit hydrogel which was used for adsorption and release of ketorolac. Hydrogel was characterized by cryo-scanning electron microscopy (Cryo-SEM), Fourier transform infrared spectroscopy, and thermogravimetric analysis. The effects of pH on water hydrogel swelling percentage (S), water absorption percentage (W), and ketorolac-releasing kinetics were studied. SEM analysis showed hydrogel pore size pH-depending, with micropore diameters ranging between 5 and 10 nm at acidic pH, while for the hydrogel swollen at pH = 9, bigger pores are observed in the range of 30 to 50 nm. It was observed that S and W increased with the pH of the medium with an S of 608% at a pH of 9 following a Fickian behavior of water diffusion into the hydrogel pore and swelling kinetics represented by a second-order model. Ketorolac kinetic release was well described through the Korsmeyer-Peppas mathematical model, with the release rate increasing with the pH, extending the total release time of drug to 20 h.     

Investigation on preparation of carboxymethyl chitosan modified sodium ferric silicate and its adsorption properties

The layered material of sodium ferric silicate (SFS) has good adsorption properties for cationic dyes, but its stacking properties limit its application. The organic–inorganic composite assembled by macromolecular polymer and inorganic material can improve this situation. Carboxymethyl chitosan (CC) was loaded onto SFS, and the compound was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET), zero energy thermonuclear assembly (Zeta), and Fourier transform infrared spectroscopy (FT-IR). The results showed that CC was successfully supported in the layered structure of SFS, and the adsorption capacity of the composite for methylene blue (MB) was 729.67 mg g⁻¹. The adsorption process was described by pseudo second-order kinetics, Langmuir isothermal equation, and intraparticle diffusion. The adsorption process was endothermic and spontaneous, and the monomolecular adsorption was dominant.     

On the low frequency dielectric behavior of carboxymethyl cellulose and its sodium salt

A dielectric dispersion and frequency loss peak within the low frequency range 0.05–1 kc/s and at temperatures of 283–333 K was observed in the case of the sodium salt of carboxymethyl cellulose and absent in the case of its acid form. The critical frequency of the dielectric absorption was independent of molecular weight and of the presence of low moisture content. The results obtained show that the variation with temperature of the dielectric constant is exponential at low frequency only in the case of the sodium salt of carboxymethyl cellulose. The significance of the results is discussed.     

Preparation and characterization of sodium carboxymethyl cellulose from cotton stalk using microwave heating

BACKGROUND: This paper describes the use of cotton stalk, an agricultural waste, for the preparation of sodium carboxymethyl cellulose (CMC) using microwave heating. The study includes the optimization of pre‐treatment and preparation processes, and the characterization of product. RESULTS: The optimal cotton stalk pre‐treatment condition involved the addition of 12% alkali to extract cellulose for 6 min at a microwave power of 200 W using the ratio of cotton stalk to solvent 1:9, giving 87.52% cellulose. Response surface methodology was applied to optimize the preparation of CMC, with the best conditions for preparation predicted by the model: $m_{\rm {cotton stalk cellulose}}:m_{\rm {sodium hydroxide}}:m_{\rm {sodium chloroacetate}} = {1.0:1.1:1.2}$ with etherification at 195.5 W of microwave power for 1.97 min. Under these conditions, CMC with degree of substitution (DS) 0.77, viscosity 498.0 cps and purity 92% was produced. The results of Fourier transform infrared (FT‐IR) spectroscopy indicated that the product had the characteristics of a high DS. Scanning electron microscopy showed that the particles were nearly clava in shape with length ranging from about 12–100 µm. The product met the quality standards of GB/T1904‐2005. CONCLUSION: Preparation of CMC from cotton stalk using microwave heating can shorten the processing time and may be considered a feasible alternative, contributing to solving environmental problems resulting from cotton stalk. Copyright © 2011 Society of Chemical Industry     

Relationship between molecular structure and moisture‐retention ability of carboxymethyl chitin and chitosan

Carboxymethyl chitins and chitosans (CM‐chitins, CM‐chitosans) of different substitution sites were prepared under different reaction conditions, and partially depolymerized carboxymethyl chitins of various molecular weights from 24.8 × 10⁴ to 0.26 × 10⁴ were obtained by degrading with chemical reagents. Degree of substitution (DS) was estimated by potentiometric titration. Substitution site was confirmed by infrared and ¹³C‐NMR spectra. Molecular weights were determined with gel permeation chromatography and gel permeation chromatography combined with laser light scattering (GPC‐LLS). Moisture‐absorption and retention abilities of these compounds were tested in comparison with those of hyaluronic acid (HA). The results reveal that 6‐carboxymethyl group in the molecular structure of chitin and chitosan is a main active site responsible for moisture retention. Although carboxymethylation at OH‐3 and N position is not essential, they contribute to the ability. Moisture‐retention ability is also related to molecular weight; that is, higher molecular weight helps to improve moisture‐retention ability. 6‐O‐CM‐chitin (chitosan) with a DS above 0.8 and molecular weight higher than 24.8 × 10⁴ has the potential to substitute for HA for use in cosmetics and clinical medicine. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1233–1241, 2002     

Studies on chitosan and poly(acrylic acid) interpolymer complex. I. Preparation,structure, pH-sensitivity,and salt sensitivity of complex-forming poly(acrylic acid): Chitosan semi-interpenetrating polymer network

A novel semi-interpenetrating polymer network (semi-IPN) membrane composed of crosslinked chitosan(cr-CS) and poly(acrylic acid) (PAA) was prepared. Evidence from infrared spectra proved the formation of polyelectrolyte complex through electrostatic interaction between groups from CS and COO⁻ groups from PAA. The semi-IPN membrane swelled at high pH and at low pH exhibited a typical pH-sensitivity. Its swelling degrees in different salt solutions with the same ionic valence and equal ionic strength were on similar levels. Under certain ionic strength (I = 1.5 mol/L), the degree of swelling increased with increased metal ionic valence. Furthermore, the elongation of the semi-IPN membrane could vary reversibly by immersion into CaCl₂ solution and KCl solution alternately. Reasons for the chemomechanical behavior are discussed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1445–1450, 1997     

羧甲基壳聚糖基水溶性高分子紫外线吸收剂的合成与表征

以2,4-二羟基二苯甲酮(UV-O)与氯乙酰氯为原料合成了中间体2-羟基-4-氯乙酸酯基二苯甲酮,然后使其与羧甲基壳聚精反应,合成了一系列含有二苯甲酮结构的羧甲基壳聚糖基紫外线吸收剂(CMC-g-HCBP).采用IR,UV,XRD,1HNMR等对产物进行了结构表征.测定结果表明,接枝产物在240～400 nm内均有较强的紫外吸收,并在332 nm处有最大紫外吸收;产物有较好的光稳定性.     

蔗渣纤维丙烯酸高吸水树脂的制备

以蔗渣纤维为原料,丙烯酸为接枝单体,N,N-亚甲基双丙烯酰胺为交联剂,K2S2O8为引发剂,通过溶液聚合的方法合成了蔗渣纤维（sugarcanebagasse,SCB）与聚丙烯酸（polyacrylicacid,PAA）的接枝共聚高吸水树脂（scB—g—PAA）。研究了丙烯酸用量、引发剂用量、交联剂用量以及中和度对吸水树脂吸水倍率的影响,结果表明,该接枝共聚吸水树脂的最佳合成条件是以丙烯酸用量为标准,蔗渣纤维、K2S2O8、交联剂用量分别是10％、2％、0．1％,中和度为80％,共聚物吸水倍率最高为765．7g·g-1。