肉桂精油微囊化及其在果蔬保鲜中的应用

目的以壳聚糖、海藻酸钠为壁材,以肉桂精油为芯材,采用复凝聚法制备壳聚糖微胶囊,并将其应用于水果保鲜中。方法通过光学显微镜、扫描电子显微镜、傅里叶转化红外光谱等,确定微胶囊的最佳工艺参数、芯壁比及添加质量分数,并以芒果为实验对象,研究添加不同微胶囊质量分数的壳聚糖溶液对芒果保鲜效果的影响。结果当壳聚糖/海藻酸钠质量比为1∶2,氯化钙质量分数为1%,p H值为5,戊二醛质量分数为60%,交联时间为60 min,芯壁比为4∶1时,制备形成的壳聚糖微胶囊成球效果较好;微胶囊在壳聚糖溶液中的添加质量分数为4%时,以其涂膜的芒果保鲜效果最佳。结论肉桂精油经囊化后有效减少了气味、延缓了挥发,在果蔬保鲜中有较重要的现实研究意义。     

微胶囊化脂肪酶型TTI的制备及其性能研究

针对脂肪酶在时间-温度指示剂的应用中存在热稳定性能差,温度、pH值对其活性影响较大等问题,采用离子凝胶技术制备脂肪酶微胶囊。应用单因素试验和正交试验相结合的方法,以海藻酸钠、壳聚糖、氯化钙浓度为变量,优化脂肪酶微胶囊的制备工艺,对原脂肪酶与脂肪酶微胶囊的热稳定性能、最适温度与pH值进行研究,采用红外光谱（FTIR）、扫描电镜（SEM）对脂肪酶微胶囊结构及形貌进行分析,并对脂肪酶微胶囊在时间-温度指示剂中的应用做出初步研究。得到了脂肪酶微胶囊最佳制备工艺条件为：海藻酸钠质量浓度30 g/L,壳聚糖质量浓度6 g/L,氯化钙浓度0.3 mol/L。脂肪酶微胶囊的热稳定性比原脂肪酶有明显提高。脂肪酶微胶囊制备工艺稳定、可靠,具有应用于时间-温度指示剂中的实用价值。     

Preparation of turmeric oil-loaded chitosan-alginate biopolymeric nanocapsules

Preparation of chitosan-alginate nanocapsules containing turmeric oil was carried out by emulsification of turmeric oil in aqueous sodium alginate solution and gelification with calcium chloride and chitosan, followed by solvent removal. The process parameters were optimized by variation of the molecular weight of chitosan, the chitosan/alginate mass ratio, and the order of addition of calcium chloride and chitosan in the formulation. The nanocapsules were characterized based on average size, zeta potential, morphology, percent recovery, loading capacity of turmeric oil, nanocapsule yield, and stability at 4 °C and 25 °C. The characteristics of the nanocapsules were dependent on the molecular weight and amount of chitosan. Chitosan with a low molecular weight was required to produce small nanocapsules. At a fixed chitosan/alginate mass ratio of 0.1:1, addition of chitosan after calcium chloride was found to be optimal for improving the physical stability, percent recovery of turmeric oil and nanocapsule yield, while maintaining the loading capacity of the turmeric oil.     

C6位选择性氧化竹浆纤维的壳聚糖改性处理

采用H_3PO_4/HNO_3-NaNO_2氧化体系对竹浆纤维C6位进行选择性氧化,然后与壳聚糖溶液交联反应制备生态的抗菌壳聚糖改性竹浆纤维。固相CP/MAS 13 C核磁共振分析显示,H_3PO_4/HNO_3-NaNO_2已将竹浆纤维C6位上的伯羟基选择性氧化成羧基,且红外光谱和扫描电镜测试表明,壳聚糖的氨基与氧化竹浆纤维分子上的羧基发生酰胺化反应,壳聚糖分子通过C-N化学键共价交联在竹浆纤维上,并在竹浆纤维表面形成壳聚糖薄膜。通过分析H_3PO_4/HNO_3-NaNO_2氧化和壳聚糖处理过程中竹浆纤维羧基含量、机械强力、壳聚糖含量等指标,得出最佳工艺参数。Kjeldahl定氮分析得出壳聚糖在氧化竹浆纤维上的最大含量为3.92%。壳聚糖接枝竹浆纤维的断裂强度变化不明显,但其断裂伸长率降低。抗菌试验结果显示,与壳聚糖处理的原竹浆纤维抗菌性相比,壳聚糖改性竹浆纤维对大肠杆菌和金黄色葡萄球菌的抗菌效果明显提高,抑菌率均在96%以上,且壳聚糖改性竹浆纤维具有良好的抗菌耐洗涤性能。     

致孔剂对聚乳酸多孔凝胶性能的影响

以不同相对分子质量(M_w=1.0×10~5,2.0×10~5,3.0×10~5)的外消旋聚乳酸(PDLLA)为原料,三氯甲烷作溶剂,分别在去离子水和氯化钠作致孔剂条件下制备多孔凝胶。重点考察了致孔剂对多孔凝胶的力学性能影响。结果表明,用水作致孔剂的多孔凝胶(P_W),相比于用氯化钠作致孔剂的多孔凝胶(P_S),其压缩模量平均增加57%,拉伸强度提高60%,断裂伸长率增加5倍,柔韧性提高。并且,P_W表现出亲水性能。此外,通过溶剂置换法测定出相应孔隙率,P_S孔隙率为80%左右,P_W为40%左右。     

壳聚糖与L-丙交酯接枝共聚物的均相和非均相合成

以1-丁基-3-甲基咪唑氯盐([BMIM]Cl)、1-丁基-3-甲基咪唑醋酸盐([BMIM]Ac)为均相介质,以二甲基亚砜为非均相介质,研究了L-丙交酯与壳聚糖接枝共聚物的合成,并考察其接枝反应的反应效率,利用红外光谱(FT-IR)、热重分析(TGA)、差示扫描量热仪(DSC)、X射线衍射分析(XRD)等对接枝共聚物进行了表征。结果表明,均相反应能缩短反应时间,具有更高的反应效率,且在[BMIM]Cl中更高;均相接枝共聚物趋于无定型,但其热稳定性高于非均相接枝共聚物。     

Guanidine分子在燃料电池用阴离子交换膜中的应用

以壳聚糖(CS)和2,3-环氧丙基三甲基氯化铵(GTA)为原料,制备季铵化壳聚糖(QCS),将其与小分子游离胍(Guanidine)共混,借助戊二醛(GA)的化学交联作用,将季铵化壳聚糖中的氨基以及胍中的氨基交联,形成网状结构,由此制得含有不同含量Guanidine分子的交联QCS-G阴离子交换膜。实验过程中,对该膜的含水率、溶胀度、力学强度、电导率及耐碱稳定性等进行了详细的考察。结果表明,游离胍的引入可有效地提高膜的电导率和耐碱稳定性,同时降低了膜的溶胀度及含水率。其中小分子游离胍质量分数为2.5%的膜(QCS-G2.5%)在70℃时的电导率可达到6.58×10~(-2)S/cm;在10 mol/L NaOH溶液中浸渍72 h后该膜70℃测得的电导率损失仅为3.8%,离子交换量损失仅为3.82%,表明该膜的耐碱性能较好。     

壳聚糖季铵盐/有机累托石纳米复合材料的抗菌性能研究

合成了壳聚糖季铵盐, 并通过溶液插层法将其插层进入有机累托石层间制备纳米复合材料, 研究表明, 当壳聚糖季铵盐与有机累托石的质量比为2∶1时, 其获得了4.8nm的最大层间距. 抗菌结果显示, 在偏酸、中性及偏碱性条件下, 所有的纳米复合材料都具有较好的抗菌性能, 且与有机累托石的含量和层间距成正比. 与壳聚糖季铵盐及有机累托石相比, 纳米复合材料对革兰氏阳性菌、革兰氏阴性菌及真菌的抗菌性能大大提高, 对金黄色葡萄球菌和枯草芽孢杆菌的最小抑制浓度仅为0.00313% (W/V), 且能在30min内杀死90%以上的金黄色葡萄球菌, 80%以上的大肠杆菌. 最后, 通过TEM和SEM结果探讨了其抗菌机理.     

Effect of the Type of Base and Number of Reaction Steps on the Degree of Quaternization and Molecular Weight of N-Trimethyl Chitosan Chloride

N-Trimethyl chitosan chloride (TMC), a chemically modified derivative of chitosan, is the first chitosan derivative shown to be an effective absorption enhancer for peptide and protein drugs across mucosal epithelia. TMC is synthesized by reductive methylation with methyl iodide in the presence of a strong base such as sodium hydroxide. In this reaction, the primary amino group on the C-2 position of chitosan is changed to a quaternary amino group. The charge density, as determined by the degree of quaternization, and probably also the molecular weight of TMC are important factors that influence the absorption enhancement effect and toxicity of this polymer. The molecular weight of the starting polymer decreases during the synthesis procedure due to factors such as the strong alkaline environment and elevated experimental temperatures. This study investigated the effects of two different bases, sodium hydroxide and dimethyl amino pyridine, together with a varying number and duration of reaction steps, on the degradation and the degree of quaternization of TMC polymers. ¹H-NMR (nuclear magnetic resonance) spectra showed a major increase in the degree of quaternization (21%-59%) of TMC with an increase in the number of reaction steps when sodium hydroxide was used as the base. Intrinsic viscosity values indicated that the use of dimethyl amino pyridine did not cause polymer degradation to the same extent as sodium hydroxide, but that the degree of quaternization of TMC stayed low (7.3%-9.6%) even when the number of reaction steps was increased. A combination of the two bases did not reduce polymer degradation, while the degree of quaternization was limited to relatively low values (12.5%-34.4%).     

马来酰壳聚糖/纳米SiO2纳米微球的制备及热性能

由甲壳素脱乙酰得到壳聚糖,然后以碳酸钠催化马来酸酐酰化,得到壳聚糖酰化物钠盐。纳米二氧化硅经高分子表面活性剂聚二甲基二烯丙基氯化铵(PDDA)处理,其与聚合物相容性得到提高,然后利用静电作用使其与马来酰壳聚糖钠盐复合。经红外光谱(IR)、扫描电镜、热重分析分析,结果表明得到了分布均一的球形包覆物,粒径处于1 nm~100nm范围内,说明得到了复合物纳米微球,且复合后产物的热性能较马来酰壳聚糖有了显著提高。     

Synergistic pseudo-hydroxide extraction: synergism and anion selectivity in sodium extraction using a crown ether and a series of weak lipophilic acids

The nature of the weak lipophilic acid used in synergistic combination with a model crown ether cation host was shown to have a strong effect on the strength and selectivity of sodium hydroxide separation from alkaline aqueous salt solutions. Sodium ion-pair extraction employing only cis-syn-cis-dicyclohexano-18-crown-6 (1) in nitrobenzene (NB) was correlated with the standard Gibbs energy (deltaG(p)o) of anion partitioning into NB and was notably weak and nonselective for the hydroxide ion, in accord with Hofmeister bias. The Hofmeister order can be selectively overcome for NaOH by utilization of acid-base chemistry coupled with complexation of sodium ion in the NB phase. Upon addition of a lipophilic organic acid into the solution of 1 in NB, sodium extraction was selectively enhanced due to the initiation of an exchange reaction between the aqueous sodium ion and the ionizable proton of the organic acid. A series of weak lipophilic hydroxy acids (HA) including fluorinated alcohols and phenols was tested. The resulting synergistic pseudo-hydroxide extraction correlates with the pKa of the employed HA; the most acidic cation exchangers provide the greatest synergism. The synergistic factor obtained using a fluorinated benzyl alcohol 7 was as high as 256. Ion-pair extraction of neutral sodium salts was not changed or only mildly enhanced by addition of HA into the NB solution of 1. This enhancement was explained by hydrogen bonding of HA with the anion as related to the hardness of the anion and the acidity of HA. In comparison with the synergism observed for NaOH, this enhancement was weak and unable to overcome the Hofmeister effect. Examination of extraction selectivity revealed that the combination of 1 and 7 preferentially extracted NaOH over all other sodium salts, including the normally preferred nitrate and perchlorate salts. Quantitative recovery of NaOH from the NB phase was demonstrated via hydrolysis of the organic acid upon a single contact of the loaded solvent with water.     

Chitosan derivatives with thickening properties obtained by reductive alkylation

Chitosan derivatives were prepared by reductive alkylation using glutaraldehyde and 3-amino-1-propanol. The reducing agent used was sodium borohydride. Tests of solubility, stability and viscosity were performed to evaluate the effect of the molar ratio of the reactants and the presence of nitrogen in the reaction system. The ¹H NMR characterization of chitosan derivatives confirmed the presence of hydrophobic groups grafted onto the chitosan backbone. The rheological behavior of the polymers was studied as a function of polymer concentration, temperature and ionic strength of the medium. It was observed that the chemical modification of chitosan resulted in derivatives with thickening action, and the polymer solubility in acetic acid aqueous solution decreased with the increase of the glutaraldehyde and 3-amino-1-propanol molar ratio in relation to chitosan. The atmosphere of nitrogen and a larger amount of reducing agent in the reaction system contributed to the increase in solubility, stability and viscosity of the polymer in solution. The chitosan derivative solutions were significantly more viscous than the chitosan solution and showed higher thermal stability in the presence of salt, which could be explained by the hydrophobic groups grafted onto the chitosan backbone.     

The Macromolecular Polymers for the Preparation of Hydrodynamically Balanced Systems—Methods of Evaluation

Evaluation of macromolecular polymers used as excipients for the preparation of hydrodynamically balanced systems (HBS) was carried out. Hard gelatine capsules were filled with polymeric substances belonging to various chemical groups (chitosan, sodium alginate, hydroxypropylmethycellulose—HPMC). The following properties of the HBS were investigated: density, hydration, erosion and floating force. The solvent penetration process into the HBS was visualized using magnetic resonance imaging (MRI) technique. Densities of the HBS in hydrochloric acid (0.1 M) ranged from 0.37 g/cm³ to 0.71 g/cm³. Each polymer demonstrated different hydration/erosion abilities and floating properties. The maximum floating force (F_{float max}) for capsules size 0, ranged from 26.7 mN (sodium alginate) to 64.7 mN (chitosan). HBS formulations also varied in time to reach maximum floating force (T_{float max}). HPMC and sodium alginate formulation reached F_{float max} within half an hour after immersion, while in the case of chitosan formulations (deacetylation degree (d.d.) 66% and d.d. 93%), the time was 184 minutes and 218 minutes respectively. The floating properties of the dosage forms were reliant on type of the polymer and the medium—fasted state simulated gastric fluid (FaSSGF) or fed state simulated gastric fluid (FeSSGF). The size of the HBS influenced the floating force value. The mechanisms of erosion and swelling of the polymeric matrices play a dominant role in flotation of the dosage forms.     

Effect of the Type of Base and Number of Reaction Steps on the Degree of Quaternization and Molecular Weight of N-Trimethyl Chitosan Chloride

N-Trimethyl chitosan chloride (TMC), a chemically modified derivative of chitosan, is the first chitosan derivative shown to be an effective absorption enhancer for peptide and protein drugs across mucosal epithelia. TMC is synthesized by reductive methylation with methyl iodide in the presence of a strong base such as sodium hydroxide. In this reaction, the primary amino group on the C-2 position of chitosan is changed to a quaternary amino group. The charge density, as determined by the degree of quaternization, and probably also the molecular weight of TMC are important factors that influence the absorption enhancement effect and toxicity of this polymer. The molecular weight of the starting polymer decreases during the synthesis procedure due to factors such as the strong alkaline environment and elevated experimental temperatures. This study investigated the effects of two different bases, sodium hydroxide and dimethyl amino pyridine, together with a varying number and duration of reaction steps, on the degradation and the degree of quaternization of TMC polymers. ¹H-NMR (nuclear magnetic resonance) spectra showed a major increase in the degree of quaternization (21%–59%) of TMC with an increase in the number of reaction steps when sodium hydroxide was used as the base. Intrinsic viscosity values indicated that the use of dimethyl amino pyridine did not cause polymer degradation to the same extent as sodium hydroxide, but that the degree of quaternization of TMC stayed low (7.3%–9.6%) even when the number of reaction steps was increased. A combination of the two bases did not reduce polymer degradation, while the degree of quaternization was limited to relatively low values (12.5%–34.4%).     

Preparation and optimization of a novel microbead formulation to improve solubility and stability of curcumin

Curcumin is an active ingredient which is poorly water-soluble, leading to a low oral bioavailability. The aim of this research was to prepare a novel microbead formulation, and to solubilize, solidify, and improve storage stability of curcumin. Firstly, curcumin was solubilized with Kolliphor^TM RH40 and then microencapsulated by cross linking of sodium alginate with calcium chloride. A three-factor, three-level Box–Behnken design was employed to acquire the optimum microbead formulation, namely the best entrapment efficiency and in vitro curcumin release. The independent variables were sodium alginate concentration, calcium chloride concentration, and the weight of curcumin solution, while the dependent variables were entrapment efficiency and in vitro curcumin release. The optimized microbead formulation was 2.06% sodium alginate, 24.33% calcium chloride, and 1.28 g curcumin solution (containing curcumin and RH40 with a ratio of 1:22, g/g). Results showed that high concentrations of sodium alginate and calcium chloride could increase the entrapment efficiency. In vitro curcumin release decreased with increasing of sodium alginate as well as decreasing of calcium chloride. In conclusion, the optimum microbead formulation increased the solubility of curcumin and enhanced its stability, and achieved a high entrapment efficiency and in vitro curcumin release.     

Spray-Dried Chitosan as a Direct Compression Tableting Excipient

The objective of this study was to prepare and evaluate a novel spray-dried tableting excipient using a mixture of chitosan and lactose. Three different grades of chitosan (low-, medium-, and high-molecular-weight) were used for this study. Propranolol hydrochloride was used as a model drug. A specific amount of chitosan (1, 1.9, and 2.5 g, respectively) was dissolved in 50 mL of an aqueous solution of citric acid (1%) and later mixed with 50 mL of an aqueous solution containing lactose (20, 19.1, and 18.5 g, respectively) and propanolol (2.2 g). The resultant solution was sprayed through a laboratory spray drier at 1.4 mL/min. The granules were evaluated for bulk density, tap density, Carr index, particle size distribution, surface morphology, thermal properties, and tableting properties. Bulk density of the granules decreased from 0.16 to 0.13 g/mL when the granules were prepared using medium- or high-molecular-weight chitosan compared with the low-molecular-weight chitosan. The relative proportion of chitosan also showed a significant effect on the bulk density. The granules prepared with 1 g of low-molecular-weight chitosan showed the minimum Carr index (11.1%) indicating the best flow properties among all five formulations. All three granules prepared with 1 g chitosan, irrespective of their molecular weight, showed excellent flow properties. Floating tablets prepared by direct compression of these granules with sodium bicarbonate showed 50% drug release between 30 and 35 min. In conclusion, the spray-dried granules prepared with chitosan and lactose showed excellent flow properties and were suitable for tableting.     

Spray-dried chitosan as a direct compression tableting excipient

The objective of this study was to prepare and evaluate a novel spray-dried tableting excipient using a mixture of chitosan and lactose. Three different grades of chitosan (low-, medium-, and high-molecular-weight) were used for this study. Propranolol hydrochloride was used as a model drug. A specific amount of chitosan (1, 1.9, and 2.5 g, respectively) was dissolved in 50 mL of an aqueous solution of citric acid (1%) and later mixed with 50 mL of an aqueous solution containing lactose (20, 19.1, and 18.5 g, respectively) and propanolol (2.2 g). The resultant solution was sprayed through a laboratory spray drier at 1.4 mL/min. The granules were evaluated for bulk density, tap density, Carr index, particle size distribution, surface morphology, thermal properties, and tableting properties. Bulk density of the granules decreased from 0.16 to 0.13 g/mL when the granules were prepared using medium- or high-molecular-weight chitosan compared with the low-molecular-weight chitosan. The relative proportion of chitosan also showed a significant effect on the bulk density. The granules prepared with 1 g of low-molecular-weight chitosan showed the minimum Carr index (11.1%) indicating the best flow properties among all five formulations. All three granules prepared with 1 g chitosan, irrespective of their molecular weight, showed excellent flow properties. Floating tablets prepared by direct compression of these granules with sodium bicarbonate showed 50% drug release between 30 and 35 min. In conclusion, the spray-dried granules prepared with chitosan and lactose showed excellent flow properties and were suitable for tableting.     

Preparation of H-oleoyl-carboxymethyl-chitosan and the function as a coagulation agent for residual oil in aqueous system

In this study, H-form oleoyl-carboxymethyl-chitosan (H-O-CMCS) was prepared as a coagulation agent to clean up the residual oil from the waste-water of oil extraction (WWOE). The Fourier transform infrared (FTIR) spectra confirmed the formation of an amide linkage between amino groups of carboxymethyl chitosan (CMCS) and carboxyl groups of oleic acid. The adsorption capacities of four absorbents (H-O-CMCS, chitosan, activated carbon and polyaluminium chloride (PAC)) for the residual oil were investigated. Compared with chitosan, activated carbon and PAC, H-O-CMCS was more effective in removing the residual oil from WWOE, which could successfully wash up almost 99% of residual oil from WWOE at the dosage of 0.2 g/L, the mixing time of 3 min, 500 rpm, and a broader range of pH (the system temperature ⩽ 45°C). In similar conditions, comparatively, chitosan, activated carbon and PAC could wash 90%, 82% and 92% of residual oil from WWOE, respectively.     

Preparation of H-oleoyl-carboxymethyl-chitosan and the function as a coagulation agent for residual oil in aqueous system

In this study, H-form oleoyl-carboxymethyl-chitosan (H-O-CMCS) was prepared as a coagulation agent to clean up the residual oil from the waste-water of oil extraction (WWOE). The Fourier transform infrared (FTIR) spectra confirmed the formation of an amide linkage between amino groups of carboxymethyl chitosan (CMCS) and carboxyl groups of oleic acid. The adsorption capacities of four absorbents (H-O-CMCS, chitosan, activated carbon and polyaluminium chloride (PAC)) for the residual oil were investigated. Compared with chitosan, activated carbon and PAC, H-O-CMCS was more effective in removing the residual oil from WWOE, which could successfully wash up almost 99% of residual oil from WWOE at the dosage of 0.2 g/L, the mixing time of 3 min, 500 rpm, and a broader range of pH (the system temperature ≤45°C). In similar conditions, comparatively, chitosan, activated carbon and PAC could wash 90%, 82% and 92% of residual oil from WWOE, respectively.     

新型纳米ZnO抗菌复合材料的制备与应用

以2,3-环氧丙基三甲基氯化铵(EPTAC)为季铵化试剂,与壳聚糖反应制备了壳聚糖季铵盐。以硝酸锌和六亚甲基四胺为原料,采用均匀沉淀法制备纳米ZnO。以羧甲基纤维素钠为纳米ZnO的分散剂,再添加水溶性的壳聚糖季铵盐,用流延的方法制得壳聚糖季铵盐/纳米ZnO复合膜,并对复合膜的力学性能、抗菌性能和膜形貌等进行了研究。