Development of diclofenac potassium gel from hydrophobically modified HPMC

An improved topical gel was developed which could allow fast release of drug and having appropriate organoleptic (texture) and rheological properties (viscosity). In vitro release of diclofenac potassium from hydrophobically modified hydroxypropyl methyl cellulose (hm-HPMC, 90L grade) based gels (F1, F2 and F3 at 1, 1.5 and 2 % (w/v) concentration, respectively) was compared with conventional hydrophilic hydroxypropyl methylcellulose (HPMC, 50 mPa s) based gels (F4 and F5 at 12 and 15 % (w/v) concentration, respectively). This study was performed in Franz diffusion cell using cellulose dialysis membrane. The hm-HPMC-based gels of higher viscosity release remarkable quantity of the drug in comparison to conventional hydrophilic HPMC-based gels of lower viscosity. So in the drug-release process polymer concentration is more important and a determinant factor compared to viscosity. Texture profile and viscosity of hm-HPMC-based gels were compared with a commercial gel and all the rheological data obtained from the experiments confirm the suitability of these hm-HPMC-based gels for use as a topical drug delivery system. In order to achieve percutaneous penetration of drug, permeation enhancers (n-octanol and propylene glycol) were added in hm-HPMC-based gels. Both enhancers have shown enhancement of drug penetration through rat skin. Propylene glycol at both lower concentration (2 %) and higher concentration (5 %) exhibited a greater increase in the permeation flux as well as more antinociceptive activity than formulations without enhancer or with n-octanol as enhancer.     

Inhomogeneities in poly(acrylamide) gels: position-dependent elastic modulus measurements

Summary The inhomogeneities in poly(acrylamide) (PAAm) gels and the formation mechanism of inhomogeneities were investigated using the results obtained by the mechanical measurements. The gels in the form of rods of 5.6 mm in diameter were prepared at various crosslinker (N,N'-methylene(bis)acrylamide) content. The initial monomer concentration was set to 5.1 w/v %. The results show that the elastic modulus of PAAm gels varies depending on the location, at which the mechanical measurements are carried out. The modulus increases with increasing distance from the bottom of the gel rod. The extent of modulus variation along the gel increases with increasing crosslinker content from 2.6 to 9 % BAAm. Received: 23 January 2001/Revised version: 17 May 2001/Accepted: 17 May 2001     

Surface patch binding‐induced exfoliation of nanoclays and enhancement of physical properties of gelatin organogels

Nanoclay‐containing organogels were prepared by exfoliating layered silicate nanoclay (Laponite^® and montmorillonite, aspect ratio 30 and 250) in organogels made in glycerol solutions. Zeta potential of the binding profile between clay and gelatin chains in the milieu of glycerol was consistent with a surface patch binding mechanism. To achieve customized thermal and viscoelastic properties, optimum binding of nanoclay to gelatin was probed, and it was noticed that [clay] = 0.03% (w/v) and [glycerol] = 30% (v/v) produced the best results. Gelation temperature T_gel (Laponite organogels) increased from 28 to 34 °C (ca 21% change) with a concomitant increase in gel elastic modulus from 400 to 1200 Pa (ca 300% change). For montmorillonite organogels, it was possible to raise T_gel further to 43 °C (56% change). X‐ray diffraction data and Cole–Cole plots indicated that clay platelets were homogeneously exfoliated in the organogel matrix. Thus, the thermoviscoelastic properties of gelatin organogels could be modulated to raise the gelation temperature to 43 °C, and gel strength to 1200 Pa by the addition of nanoclay whose concentration may not exceed 0.03% (w/v). Considering the wide application of gelatin gels in pharmaceuticals, food preservation and personal care products, the aforesaid enhancement in physical properties is significant. © 2016 Society of Chemical Industry     

Novel polyurethane‐based thermosensitive hydrogels as drug release and tissue engineering platforms: design and in vitro characterization

Poloxamer P407 (P407) is a Food and Drug Administration approved triblock copolymer; its hydrogels show fast dissolution in aqueous environment and weak mechanical strength, limiting their in vivo application. In this work, an amphiphilic poly(ether urethane) (NHP407) was synthesized from P407, an aliphatic diisocyanate (1,6‐hexanediisocyanate) and an amino acid derived diol (N‐Boc serinol). NHP407 solutions in water‐based media were able to form biocompatible injectable thermosensitive hydrogels with a lower critical gelation temperature behavior, having lower critical gelation concentration (6% w/v versus 18% w/v), superior gel strength (G′ at 37 °C about 40 000 Pa versus 10 000 Pa), faster gelation kinetics (<5 min versus 15–30 min) and higher stability in physiological conditions (28 days versus 5 days) compared to P407 hydrogels. Gel strength and PBS absorption at 37 °C increased whereas dissolution rate (in phosphate‐buffered saline (PBS) at 37 °C) and permeability to nutrients (studied using fluorescein isothiocyanate–dextran model molecule) decreased as a function of NHP407 hydrogel concentration from 10% to 20% w/v. By varying the concentration, NHP407 hydrogels were thus prepared with different properties which could suit specific applications, such as in situ drug/cell delivery or bioprinting of scaffolds. Moreover, deprotected amino groups in NHP407 could be exploited for the grafting of bioactive molecules obtaining biomimetic hydrogels. © 2016 Society of Chemical Industry     

Preparation and swelling properties of crosslinked sodium polyacrylate

Crosslinked sodium polyacrylate as a superabsorbent was prepared by inverse suspension polymerization with cyclohexane as the continuous phase and sorbite anhydride monostearic acid ester (span‐80) as the dispersant. The crosslinking degree was regulated by NaOH. The distilled water absorbency (WA) of the polymer gel was about 700 times its own weight if the gel was allowed to swell at room temperature for 24 h. WA under various conditions, such as varying pH, temperature, reaction time, neutralization, and cyclohexane concentration, was investigated and optimized. Our results revealed that the optimal reaction conditions were 55°C, 25‐min reaction time, 85% neutralization, and a 7:1 (v/v) cyclohexane/monomer ratio. Our results also showed that such synthesized polymer gels have a high WA and a good water‐retention ability under different pressures. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1515–1520, 2001     

海水基耐温聚丙烯酰胺压裂液的性能优化

以丙烯酰胺、丙烯酸和2-丙烯酰胺-2-甲基丙磺酸（AMPS）三元共聚物（PSAM）为稠化剂,乳酸锆为交联剂开发出一种海水基耐高温压裂液,考察了PSAM的水解度、相对分子质量、AMPS含量、稠化剂和交联剂的浓度、配比等因素对冻胶形成及耐温耐剪切性能的影响,通过测试不同条件下冻胶的储能模量（G'）随时间的变化,研究了Ca²⁺浓度和AMPS含量对交联动力学的影响。交联动力学的研究表明,随AMPS含量加大,PSAM交联速度降低,达到交联平衡所需时间延长,随Ca²⁺浓度增高,交联反应速度越快,冻胶初始强度越高;耐温性能测试表明,当稠化剂中羧酸基含量与交联剂中锆离子含量之比n（-COOH）/n（Zr⁴⁺）≈1时,体系的耐温耐剪切性能最优,高含量AMPS提升压裂液的耐温耐剪切性能。在优化稠化剂结构条件下,稠化剂质量分数为0.6%、交联剂质量分数为0.3%配制的海水基压裂液,在150℃、170 s^-1下剪切120 min后,黏度保持在150 mPa·s以上,耐温耐剪切性能优秀。     

水溶性环氧树脂体系的氧化锆凝胶浇注成型

研究了氧化锆凝胶浇注成型工艺中,水溶性环氧树脂凝胶剂对浆料的流变性和固化过程的影响.结果表明:环氧树脂的加入增加了浆料的黏度,但可制备固体含量为53.7%(体积分数),黏度为0.60Pa·s(剪切速率为100 s-1),适合浇注的浆料;为得到较高弹性模量的凝胶,固化剂(二丙三胺)最佳加入量为3.4%(质量分数);环氧树脂溶液的聚合过程和氧化锆浆料的固化过程对温度都具有较大的依赖性,利用这些依赖性可控制浆料的制备、浇注和固化过程.30℃时,浆料中环氧树脂的聚合反应在8min后开始,20min后浆料失去流动性,1 h后浆料完全固化,湿坯弹性模量达到1.96MPa.固化温度越高,浆料固化越快,固化后湿坯的弹性模量就越高.     

Enzymatic cross-linking of alkali extracted arabinoxylans: gel rheological and structural characteristics

Ferulated arabinoxylans were alkali-extracted from wheat bran at different incubation times (0.0, 0.5, 1.0, 1.5 and 2.0 h). Wheat bran ferulated arabinoxylans (WBAX) arabinose-to-xylose ratio, ferulic acid content, intrinsic viscosity and viscosimetric molecular weight values decreased as the incubation time of extraction increased. WBAX enzymatic cross-linking capability was affected by incubation time while an increase in WBAX concentration from 5 to 6% (w/v) favored gelation. The WBAX gels formed presented a macroporous structure with mesh size ranging from 40 to 119 nm and hardness values varying from 1.7 to 5 N.     

酸和碱预处理对麻竹酶水解糖化的影响

研究了121℃下硫酸和氢氧化钠预处理对麻竹酶水解还原糖收率的影响,测定了不同预处理液质量分数和预处理时间对还原糖收率的影响,以及预处理后的预处理液中还原糖含量。结果表明,氢氧化钠预处理能显著提高还原糖收率,在氢氧化钠质量分数为2%,预处理时间60min时还原糖收率可达0.367g/gDS。硫酸预处理对还原糖收率的提高幅度不大。但硫酸预处理后的预处理液中还原糖含量较高,在硫酸预处理液质量分数为2%,预处理时间为90min时还原糖收率可达0.152g/gDS。两种预处理方法在121℃下的还原糖收率均高于100℃下的还原糖收率。     

歧化松香钾皂的制备与性能

以歧化松香为主要原料,在较低的温度(75～95℃)下,溶入KOH水溶液,并进行皂化反应,制备固体份质量分数45%的歧化松香钾皂。研究了反应温度、皂化时间、酸值、添加复合助剂TX-A对反应速度、去氢枞酸钾含量,以及黏度、结晶、胶凝等产品性能的影响。得出歧化松香钾皂化的较佳制备条件为:酸值12mgKOH/g、皂化时间分别为120min(未加TX-A)、98min(加TX-A)、反应温度85℃、TX-A加入量为反应物质量的0 2%。制备出的歧化松香钾皂产品,在性能上完全符合行业标准ZBB72003—84的要求,并且结晶、胶凝性质有所改善,加纳色号标准降低两个等级。     

Formation, structure, and rheological properties of ricinelaidic acid-vegetable oil organogels

Vegetable oil-based organogels were formed using ricinelaidic acid (12-hydroxy-9-trans-octadecenoic acid, REA). Gelation kinetics, gel structure, and stability were studied. Gelation occurred with as little as 0.5% (w/w) REA, depending on temperature and oil composition. Phase diagrams were constructed using canola, sesame, and DAG oils. Lower gelation tendencies were correlated with the presence of potential hydrogen-bonding moieties in the oils. REA concentration had a significant influence on gelation kinetics and gel rheology. At 5°C, the 0.5% canola oil gel behaved like a weak, viscoelastic network composed of entangled strands. Between 1.0 and 5.0% REA, solid-like, viscoelastic gels were formed. The 24-hour G′ _LVR (storage modulus in the linear viscoelastic region) was highly dependent on concentration and less so on temperature. Values for gelation time indicated a change in behavior below 2% REA and above 20°C. Polarized light microscopy revealed that the gels were formed through the interactions of long, thin, and birefringent fibers. Structural analysis using X-ray diffractometry (XRD) indicated the presence of repeating REA dimers and increasing order with concentration and gel storage time. Increases in gel opacity, birefringence, XRD scattering, and fiber clustering were observed during storage.     

Carboxylmethylcellulose/bentonite composite gels: Water sorption behavior and controlled release of herbicide

The composite gels were prepared by adding bentonite or its acid‐activated derivative into the carboxylmethylcellulose (CMC) gel, and the resulted products were characterized with infrared spectroscopy. Different from ordinary swellable hydrogels, the CMC/bentonite hydrogel beads shrinked in water. The water sorption of dried gels was limited below 120% of their own weight, and a sorption equilibrium reached quickly within 20–40 min. The water of swollen gels exists mainly in bound status according to the DSC analysis. The release experiments in water were carried out to evaluate the release of herbicide metolachlor from gel formulations. The release mechanism dominated by a Fickian diffusion might be related to the quick and limited swelling of dried gels. Addition of bentonites in CMC gel is beneficial for slowing the release of metolachlor, especially when the acid‐activated bentonite was added. The time taken for 50% of metolachlor to be released, t₅₀ was prolonged to 158 h for the composite gel formulation based on acid‐activated bentonite from the 61.1 h for pure CMC gel formulation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Purification Process,Physicochemical Properties,and Fatty Acid Composition of Black Soldier Fly (Hermetia illucens Linnaeus) Larvae Oil

This study presented a refining process and reported on fatty acid composition and the physicochemical properties of the oil from black soldier fly larvae (BSFL). Crude larvae oil was purified through four steps consisting of degumming, neutralization, bleaching, and deodorization. Optimum degumming conditions that give the highest phospholipid weight and oil consisted of water concentration of 7% (v/v), followed by addition of H₂SO₄ at a concentration of 0.5% (v/v). Optimum conditions for saponification that maximize saponification value and free fatty acid (FFA) value were 0.4 mg NaOH/100 g oil, 1 hour, and 80 °C of NaOH quantity, reaction time, and temperature, respectively. The oil was then dehydrated using 10 mg Na₂SO₄/g oil. The bleaching process that gives maximum oil yield consisted of activated carbon at concentration of 5% (w/w), followed by centrifugation at a speed of 5000 rpm (radius = 86 mm) for 30 min. The contents of lauric acid, linoleic acid, and linolenic acid in purified oil were 28.8%, 11.1%, and 0.4%, respectively. Physicochemical properties of the refined oil included viscosity of 96 ± 0.14 cP (measured at 20 °C), FFA value of 0.45 ± 0.017%, acid value of 0.9 ± 0.043 mg KOH g⁻¹, saponification value of 215.78 mg KOH g⁻¹, iodine value of 53.7 gI₂/100 g, and peroxide index of 133 mEq kg⁻¹.     

Measurement of malondialdehyde by high performance liquid chromatography with fluorescence detection

A method has been developed to measure malondial-dehyde (MDA) in biological systems. MDA was reacted with 2-thiobarbituric acid (TBA) in the presence of butylated hydroxytoluene (BHT) to minimize formation of artifacts. Initial separation of the TBA-MDA adduct was accomplished by isobutanol extraction. Further elimination and separation of interfering substances was achieved by high performance liquid chromatography. The mobile phase consisted of a 1∶1 (v/v) mixture of methanol and water with 0.05% (w/v) tetrabutyl ammonium dihydrogen phosphate added as an ion pairing reagent. At a flow rate of 1 ml/min, the TBA-MDA adduct was eluted from a 15-cm, c-18, reversed phase column in approximately 4.9 min. The TBA-MDA adduct was quantitated with a fluorescence detector set at 515 nm excitation and 550 nm emission. Using this method, picomole quantities of MDA can be easily detected in plasma and liver samples.     

Understanding the role of d-Allulose and soy protein addition in pectin gels

d -Allulose (a monosaccharide and C3 epimer of fructose), one of the common rare sugars is getting attention due to its low caloric values. In this study, d -Allulose was used as a replacement of sucrose at different ratios (d -Allulose/Sucrose: 35/0, 20/15, 10/25, 0/35) to formulate pectin-based soft confectionery gels. Soy protein isolate was also added to increase the protein content. Physical properties, such as hardness, moisture content, pH, and color, were measured for the gels. Higher hardness values were obtained for the soy protein containing gels due to pectin–soy protein interaction (p < 0.05). Also, higher moisture content was observed in soy protein containing gels (p < 0.05). In addition, nuclear magnetic resonance T₂ relaxation times were measured at low field (~0.5 T) to determine how the water distribution in the samples changed and to observe how d -Allulose affected the polymer–water interactions. The study also showed that the presence of d -Allulose increased the crystallization tendency (% crystallinity of 7.9) of the pectin gels. X-ray diffraction results showed the d -allulose peaks at 33.76 and 48.68^oθ. Morphologies of the gels were also examined by scanning electron microscope. Sugar type and soy protein isolate addition were found to have significant impact on the gel formulations.     

Long-Term Stability of Glucose Responsive Dextran Methacrylate-Concanavalin A Methacrylamide Gels as Part of an Implantable Artificial Pancreas

A closed loop implantable insulin delivery device that delivers insulin to the peritoneum in an automated fashion linked to changing glucose levels has been developed and previously tested in diabetic rats and pigs. The device delivers insulin via a glucose-sensitive gel that comprises of photopolymerized acrylic derivatives of dextran and concanavalin A and acts as both a sensor and controller of the amount of insulin released. In this work the long-term stability of these acrylic polymerized gels and also dextran and concanavalin A mixtures has been shown at 20°C and 37°C by rheological characterization when stored with and without 0.1% w/w glucose. Acrylic gels were found to have a stable complex viscosity for over 730 days at these temperatures indicating that over time they do not undergo degradation. Mixtures and polymerized gels were also dialyzed in the presence of chymotrypsin, which is present in the peritoneum (device implant site) to assess gel integrity across a range of pore size dialysis membranes. Polymerized acrylic gels contained in dialysis membranes of 50 kDa were found to be resistant to degradation over a long time (>500 days). These results show that these gels would be ideal candidates as part of an implantable insulin delivery device.     

Effect of extraction conditions on yield and degree of esterification of durian rind pectin: An experimental design

The effect of time (1 and 4 h), pH (2.0 and 2.5) and temperature (80 and 90 °C) on yield and degree of esterification (DE) of durian rind pectin was investigated. The yield and DE of the extracted pectin ranged from 2.1 to 10.3% (w/w, based on dry weight of durian rind) and 45.6–64.8% respectively. Yield was significantly affected by time, temperature and pH, and interactions between temperature and pH, and heating time and pH. DE was significantly affected by heating time and pH, and interactive effects of temperature and pH, and heating time and pH. The extraction yield was not related to DE. By considering pectin yield and DE, the acid extraction of durian rind pectin at 80 °C, for 4 h and at pH 2.5 could be suitable.     

Optimization of the Aqueous Enzymatic Extraction of Wheat Germ Oil Using Response Surface Methodology

A process of aqueous enzymatic extraction of wheat germ was carried out by a multi-enzyme preparation consisting of cellulase, pentosanase, neutrase and fungal amylase (CPNF, 2:1:2:1 w/w/w/w). Hydro-thermal heating (at 112 °C for 60 min) was more effective than oven-drying regarding emulsified oil yield. Wheat germ was ground with a rate of 10,000 rpm for 90 s. The adding level (w/w) of multi-enzyme preparation of CPNF was 1.6%. Response surface methodology was used to obtain the desired data in the process optimization. The optimal set of variables was water to wheat germ ratio (v/wt, mL/g) of 3.46, pH of 5.24, temperature of 48.49 °C and time of 6 h. The emulsified oil yield was 86.74% at the optimal levels of the tested factors. Compared with organic solvent extracted oil, the content of free fatty acid of AEE extracted oil was higher and the color was slightly darker, while the peroxide value was lower and the oxidative stability was higher owing to high content of α-tocopherol. This technique for recovering oil from fresh wheat germ with enzymes is a significant improvement in both oil yield and quality over the traditional organic solvent process.     

Chitin Extraction from Black Tiger Shrimp (Penaeus monodon) Waste using Organic Acids

Abstract

In chitin extraction from black tiger shrimp shell waste, HCl is the commonly used decalcifying agent. However, it is considered a harsh chemical. An alternate was found by using organic acids. Conditions for deproteinization were: 1 M NaOH at 95°C for 6 h and solid‐to‐solvent ratio of 1∶15 (w/v). Demineralization involved treatment with 0.25 M HCl at ambient temperature for 30 min with agitation. The optimal solid‐to‐acid ratio was 1∶30 (w/v) and this led to 86.5±1.2% purification of chitin. With the same conditions, the optimal ratio of mixed acids (0.25 M HCOOH and 0.25 M C₆H₈O₇ at 1∶2 (v/v)) was 1∶28 (w/v) with chitin purification of 88.1±1.8%.     

稻壳制备高纯高表面积SiO2的研究

稻壳在稀盐酸中沸煮、干燥后,于540℃煅烧,制得了一种高纯高表面积SiO2。ICP-AES测定结果表明了该SiO2中杂质的质量含量为5.6×10-6,激光粒度仪测定其体积平均粒径为19.67μm,BET法研究表明了它的比表面积为280m2/g。并利用XRD研究了稻壳在制备过程中的结构变化。