Monoolein cubic phase containing alginate/cystamine gel for controlled release of epidermal growth factor

Monoolein (MO) cubic phase including alginate and cystamine in its water channel controlled the release of epidermal growth factor (EGF) by responding to changes in pH value and the reductive conditions of the release medium. The crosslinking degree of alginate gel with cystamine and the complex coacervation of alginate and EGF were investigated by using light scattering. TEM micrographs of cubic phases revealed MO bilayers along with water channels. Differential scanning calorimetry indicated that the cubic-to-hexagonal phase transition took place at 60.2?°C. Additives such as stearyl trimethyl ammonium chloride and cystamine decreased the transition temperature by a few to more than 10?°C. The release of EGF loaded in cubic phases was completed in 5?h and, thereafter, no significant additional release was observed. The release % of EGF loaded in MO cubic phase containing alginate and cystamine increased not only with the increase of pH but also glutathione concentration. The MO cubic phase containing alginate/cystamine gel can be used as a carrier for the delivery of peptide and protein drugs.     

Monoolein cubic phase containing disulfide proteinoid and its reduction-responsive release property

Monoolein (MO) cubic phase, which can release its payload in answering to reducing condition, was prepared by including a disulfide proteinoid composed of Asp, DL-leucine (Leu), and dithiodipropionic acid (DTPA) in its water channel. On the TEM micrograph, the cubic phase could accommodate the proteinoid with no change in its bilayer structure. The phase transition temperature of the cubic phase was about 58.7°C, and it was little affected by the proteinoid. The release degree of allura red loaded in the cubic phase was higher at a higher dithiothreitol (DTT) concentration. The proteinoid would be broken down by the reducing agent, facilitating the release.     

Monoolein cubic phase containing azobenzene and its UV/visible light irradiation-dependent release property

Monoolein (MO) cubic phase, whose MO/azobenzene mass ratios were 1:0, 1:0.0025, 1:0.005, and 1:0.025, was prepared by a melt-hydration method. According to the polarized optical micrographs and the differential thermograms, the phase transition temperature of the cubic phase was lower as the content of azobenzene was higher, and it decreased upon the subsequent irradiation of UV light for 1 hour and visible light for 1 hour. The photoirradiation significantly promoted the release of methylene blue (a water-soluble dye) loaded in the cubic phase only when the MO/azobenzene mass ratio was 1:0.025. The photoirradiation could promote the release of Nile red (an oil-soluble dye) even when the MO/azobenzene mass ratio was less than 1:0.025. The higher photo-susceptibility of Nile red release was possibly because the dye would be intercalated in the MO lipid matrix and the photoirradiation could affect the lipid matrix property.     

Tripolyphosphate-responsive release property of monoolein cubic phase containing sodium dodecyl sulfate and oligo chitosan

Tripolyphosphate (TPP)-responsive MO cubic phase was prepared by immobilizing oligo chitosan in the water channel through its electrostatic attraction with sodium dodecyl sulfate (SDS). The phase transition temperature (PTT) increased with increasing the content of SDS. The PTT of cubic phase whose SDS content was 0%, 0.21%, 0.42%, 0.84%, and 1.68%, determined by polarized microscopy, was about 69.5°C, 72°C, 75°C, 80.5°C, and 95°C, respectively. The PTT did not markedly deviate from that determined by differential scanning calorimetry. The release degree for 72 h of dye (i.e., amaranth and methylene blue) was dependent on the pH value of release medium (pH 3.0 and pH 7.0). Moreover, the release degree significantly increased when the TPP concentration in the release medium increased to 0.4% (w/v). Oligo chitosan was electrostatically complexed with TPP and the complexation took place extensively at the oligo chitosan/TTP mass ratio of 1:0.125 and 1:0.25 and at the oligo chitosan concentration of 1.6% (w/v), evidenced by optical spectroscopy and scanning electron microscopy. It was thought that the complexation was responsible for the TPP concentration-dependent release.     

Effect of tris(hydroxymethyl) aminomethane on the phase behavior of poly(ethylene imine)/cinnamic acid conjugate and the release property of cubic phase containing the conjugate

The upper critical solution temperature (UCST) of poly(ethylene imine)/cinnamic acid (PEI/CA) conjugate decreased as the tris(hydroxymethyl) aminomethane (THMAM) concentration increased. On the optical micrographs of PEI/CA mixture solutions at 25°C, the microspheres were found when the THMAM concentration was 0?mM and 100?mM, but hardly found at 200?mM. Monoolein (MO) cubic phase containing PEI, CA, and THMAM exhibited a bilayer structure on the TEM micrograph. The release degree of methylene blue loaded in the cubic phase was not strongly dependent on THMAM concentration at 25°C and 37°C, but strongly dependent on the concentration at 50°C.     

Thermo- and UV Photo-Triggerable Monoolein Cubic Phase Bearing Poly(Hydroxyethyl Acrylate-co-Coumaryl Acrylate-co-Octadecyl Acrylate)

Thermo- and UV photo-triggerable monoolein (MO) cubic phases were developed by incorporating poly(hydroxyethyl acrylate-co-coumaryl acrylate-co-octadecyl acrylate) (P(HEA-CA-ODA)) in the cubic phases. P(HEA-CA-ODA)s, for which the HEA/CA/ODA molar ratio was 98.6:0:1.4, 96.7:2.0:1.3, 96.2:2.6:1.2, 95:3.8:1.2, and 92.8:6.1:1.1, calculated on the ¹H NMR spectra, were prepared by a free radical reaction. The air–water interfacial tension was inversely proportional to the CA content of the copolymer. The copolymers for which the CA content was 2.6%, 3.8%, and 6.1% exhibited their phase transition temperature in an aqueous solution in the temperature range from 25°C to 40°C. As the CA content was more, the temperature sensitivity was higher and the phase transition temperature was lower. The UV light (254 nm, 6 W)-induced dimerization degree of CA was proportional to its content in the copolymers. The release of fluorescein isothiocyanate-dextran from cubic phases containing P(HEA/CA/ODA)s was promoted by UV light irradiation, possibly due to the photo-induced collapse of the copolymer chains. The release from cubic phases incorporating copolymers, for which the CA content was 3.8% and 6.1%, was enhanced by increasing the releasing medium temperature from 23°C to 37°C, possibly due to the thermal collapse of the copolymer chains.     

Thermosensitive phase behavior and drug release of in situ gelable poly(N-isopropylacrylamide-co-acrylamide) microgels

In situ gelable poly(N-isopropylacrylamide-co-acrylamide) microgels were prepared by precipitation polymerization in the presence of various amounts of N,N′-methlenebisacrylamide as a crosslinker. The diameters of microgels were in the range of 200–300 nm with narrow distributions as determined by photo correlation spectroscopy. The equilibrium swelling ratio and thermosensitive properties of the microgels increased with decreasing crosslinker content. The volume phase transition of microgels dispersions at high concentrations were investigated by phase diagrams. The microgels dispersions experienced four phases when the temperature was increased: semitranslucent swollen gel, clear flowable suspension, cloud flowable suspension, and white shrunken gel. The related phase transition temperatures were influenced by crosslinker content and the concentration of the microgel dispersions. Herein, the gelation temperature was changed by more than 20 °C, shrinking temperatures were slightly changed by about 3 °C, and cloud point temperatures showed almost no change. The three phase transition temperatures of microgels dispersed in phosphate-buffered saline solutions were lower than that in water. As drug carriers, the release rates of bleomycin from bleomycin-loaded microgel dispersions exhibited diffusion control at human body temperature.     

大茴香醛改性海藻酸钠凝胶的制备及释药性能

在酸催化下使海藻酸钠与对甲氧基苯甲醛(又名大茴香醛)发生缩醛化反应,使其疏水改性,并将其制备成凝胶。利用红外(FTIR)、荧光、透射电镜(TEM)、扫描电镜(SEM)、紫外、热重分析(TGA)对产物进行了表征。结果表明,大茴香醛成功地与海藻酸钠发生了反应。该凝胶可以作为药物载体对牛血清白蛋白进行包埋释放,结果发现,改性后的产物其载药率和缓释性能比未改性的海藻酸钠有了一定的提高。     

海藻酸酮膜表面的配位结构及催化MMA聚合的性能

将海藻酸钠(SA)与CuCl2.2H2反应得到一种配位聚合物海藻酸酮(Cu-An)。以ESR、电导率、IR和SPS方法对此配位聚合物进行表征,确定了组成与结构：同时研究了甲基丙烯酸甲酯(MMA)在该配位聚合物膜、HSO3^-和水体系催化引发作用下的聚合反应历程。结果表明,配位聚合物的中心离子Cu^2^+与两个海藻酸(An)链节单元上的两个羧羟基氧原子和两个离解氢原子的羧羟基氧原子以共价型配位,配位数为4.MMA在上述的催化引发体系中是按照自由基加聚反应历程进行聚合的,PMMA呈无规结构。Cu-An在催化引发体系中起着催化剂的配位催化作用。     

Preparation of microparticles composed of cinnamoyl gelatin and cinnamoyl alginate by spray-drying method and effect of UV irradiation and pH value on their release property

Microparticles composed of cinnamoyl gelatin (CinGel) and cinnamoyl alginate (CinAlg) were prepared as a UV irradiation- and pH-responsive carrier by a spray-drying method. CinGel and CinAlg were prepared by a condensation reaction. Using a colorimetric method, the gelatin to CA mass ratio and the alginate to CA mass ratio were calculated to be 1:0.04 and 1:0.02, respectively. The complexation of CinGel and CinAlg in aqueous solution took place when the medium was acidic (e.g., pH 4.0) and the maximum complexation was obtained when the CinGel/CinAlg mass ratio was 7:3. On SEM photographs, some spray-dried CinGel/CinAlg particles were spherical and others were irregularly shaped, and the diameter was a few to tens of micrometers. The release degrees of amaranth loaded in UV-treated microparticles were lower than those of the dye loaded in UV-untreated ones, possibly because of the photo cross-linkage of CinGel and CinAlg. Regardless of whether the microparticles were UV-treated, the release degree at pH 4.0 was significantly lower than the release degree at pH 6.0 and pH 8.0, possibly because of complexation of CinGel and CinAlg under the acidic condition.     

海藻酸钠的疏水改性及在药物控释中的应用

海藻酸盐是一种由β-D-甘露糖酸盐(M)和α-L-古罗糖酸盐(G)连接而成的天然高分子,广泛存在于各类棕色海藻中,可与多价阳离子形成凝胶,成胶条件温和,该凝胶在生物体内以酶解方式生成甘露糖醛酸和葡萄糖醛酸,对机体无毒性、无免疫原性,适合作为释放或包埋药物、蛋白质与细胞的微胶囊.     

Composite microparticle drug delivery systems based on chitosan, alginate and pectin with improved pH-sensitive drug release property

Composite microparticle drug delivery systems based on chitosan, alginate and pectin with improved pH sensitivity were developed for oral delivery of protein drugs, using bovine serum albumin (BSA) as a model drug. The composite drug-loaded microparticles with a mean particle size less than 200 μm were prepared by a convenient shredding method. Since the microparticles were formed by tripolyphosphate cross-linking, electrostatic complexation by alginate and/or pectin, as well as ionotropic gelation with calcium ions, the microparticles exhibited an improved pH-sensitive drug release property. The in vitro drug release behaviors of the microparticles were studied in simulated gastric (pH 1.2 and pH 5.0), intestinal (pH 7.4) and colonic (pH 6.0 and pH 6.8 with enzyme) media. For the composite microparticles with suitable compositions, the releases of BSA at pH 1.2 and pH 5.0 could be effectively sustained, while the releases at pH 7.4, pH 6.8 and pH 6.0 increased significantly, especially in the presence of pectinase. These results clearly suggested that the microparticles had potential for site-specific protein drug delivery through oral administration.     

Pickering emulsions stabilized by hydrophobically modified alginate nanoparticles: Preparation and pH-responsive performance in vitro

pH-responsive Pickering emulsions were prepared, taking the hydrophobic modified calcium alginate nanoparticles (MCA) of pH sensitivity as emulsifiers. The MCAs were obtained via gelation between Ca²⁺ in emulsion and alginate sodium that reacted with diacetone acrylamide since alginate sodium was too hydrophilic to be used as a stabilizer. The effect of MCA characteristics, Ca²⁺ content, and pH on the preparation and property of emulsion was evaluated. Then, the released behaviors of MCA-stabilized emulsion loading oil-soluble drug of curcumin were investigated in vitro. The results demonstrated that Pickering emulsions released curcumin intestine-specifically (37% in 4 hours with a pH of 6.8), compared with the one in the gastric fluid (3% in 4 hours with a pH of 1.5), proving that MCA had similar pH sensitivity to alginates and probably as the promising candidate in oral drug controllable release.     

The controlled release behavior and pH‐ and thermo‐sensitivity of alginate/poly(vinyl alcohol) blended hydrogels

Poly(vinyl alcohol) (PVA) was blended with sodium alginate (Alg) in various ratios and crosslinked with calcium chloride and made into hydrogel membranes. The dependence of the swelling behavior of these Alg‐Ca/PVA hydrogels on pH was investigated. The temperature‐dependent swelling behavior of the semi‐interpenetrating network (semi‐IPN) hydrogels was examined at temperatures from 2 to 45°C and the enthalpy of mixing (ΔH_mix) was determined at various temperatures. The molecular structure of the hydrogels was studied by infrared spectroscopy and their water structure in the semi‐IPN hydrogels was measured by differential scanning calorimetry (DSC). The influence of Ca²⁺ content on the network structure of Alg‐Ca/PVA hydrogels was investigated in terms of the compressive elastic modulus, effective crosslinking density, and the polymer–solvent interaction parameter based on the Flory theory. The loading of alizarin red S (ARS) followed the Langmuir isotherm mechanism and the release kinetics of ARS from the Alg‐Ca/PVA hydrogels followed the Fickian diffusion mechanism. Copyright © 2008 John Wiley & Sons, Ltd.     

Photoinduced phase transitions and helix untwisting in the SmC* phase of a novel cinnamoyl-based liquid crystal

A photoinduced phase transition and helix untwisting in a new liquid crystal forming the SmC* phase were studied in detail. The compound consists of a cinnamoyl photosensitive fragment with C?=?C double bond capable of photoisomerisation and photocycloaddition. It was shown that ultraviolet (UV) irradiation (365 nm) induces an extreme decrease in phase transitions temperatures (SmC*–SmA*, SmA*–N*, N*–I). Vertically aligned samples in the SmC* phase cause selective light reflection in the visible spectral range. The light action results in a noticeable helix untwisting that causes a shift in the selective light reflection peak to the long-wavelength spectral region. The temperature dependence of spontaneous polarisation P _s was measured and it was found that UV irradiation induces a decrease in the values of P _s. Photo-optical phenomena taking place in the liquid crystal are attributed to the formation of photoproducts having low anisometry, which disrupts mesophases.     

Modified Pechini synthesis of Na3Ce(PO4)2 and thermochemistry of its phase transition

Effect of the synthesis conditions of Pechini technique on crystallinity and purity of Na₃Ce(PO₄)₂ compound was investigated. Nano-sized cerium-sodium phosphate obtained when EDTA was used as an additional chelating agent for Ln³⁺. The total enthalpy change of Na₃Ce(PO₄)₂ phase transition was determined as 14.2±0.7 kJ mol⁻¹ for sample synthesized by conventional solid-solid reaction. The phase transition process was confirmed to occur at 1060°C or in temperature range 920–1060°C depending on thermal treatment of powders.     

The molten phase conductance and the thermotropic phase transition in lead(II), zinc(II) and cadmium(II) 10-hydroxyoctadecanoates

The electrical conductances and heats of phase changes in lead(II), zinc(II) and cadmium(II) 10-hydroxyoctadecanoates are measured. The soaps are prepared by metathesis in alcohol solution from 10-hydroxyoctadecanoic acid which in turn is prepared from the oxidation of cis-9-octadecenoic (oleic) acid with concentrated sulphuric acid.The Arrhenius plot for lead(II) 10-hydroxyoctadecanoate shows a maximum, a behaviour that had earlier been interpreted to be due to complex formation. A similar plot for zinc(II) 10-hydroxyoctadecanoate is linear while that for cadmium(II) 10-hydroxyoctadecanoate presents a discontinuity which is interpreted, with the aid of the differential scanning calorimetric (DSC) spectra and optical examination, to be suggestive of the formation of an intermediate phase between the solid and the liquid phases. The low conductances of the soaps in comparison with the literature data on some metal caboxylates indicate the existence of extensive intermolecular hydrogen bonding in the molten phase. Both lead(II) and zinc(II) 10-hydroxyoctadecanoates melt directly from the solid to the liquid phase while their cadmium(II) counterpart passes through the gel-like phase before melting into the liquid. The mesophase of cadmium(II) 10-hydroxyoctadecanoate is transformed to the liquid phase with a relatively low enthalpy change and the behaviour is associated with the cylindrical micekkar structures of the liquid phase that have their formative stage from the gel-like mesophase.     

Evaluation of the protection and release rate of bougainvillea (Bougainvillea spectabilis) extracts encapsulated in alginate beads

There is a growing demand in the food industry for natural food products to replace synthetic ingredients. Motivated by this fact, the present work studied the extraction of coloring compounds from Bougainvillea spectabilis under aqueous and ethanolic conditions, and the encapsulation of the extract in alginate beads. Ethanolic extraction was more efficient as reflected by the higher values for total phenols (6.78?±?0.24?mg EAG/g), betacyanins (5.04?±?0.13?mg/g), betaxanthines (1.35?±?0.06?mg/g,) and inhibition capacity (81.31?±?4.23%). FTIR analysis suggested the presence of interactions between the extract and the alginate chains. The release kinetics of compounds in alginate beads was measured under aqueous and ethanolic conditions at 25.0?°C and at 70.0?°C. Color was also monitored, showing that the color parameters followed a kinetics pattern similar to the released extract. However, the release of betalains exhibited a mixed behavior, reflecting interactions between the different compounds of the bougainvillea extract and the alginate chains. The extracts released from the beads were characterized to determine the preservation of their properties during encapsulation, concluding that the encapsulation is efficient to protect and release the bioactive compounds from bougainvillea extracts.     

多羟基化合物键合亲水色谱固定相的制备及其分离性能

用硅胶与氨丙基三甲氧基硅烷反应,再与δ-葡萄糖酸内酯反应,制备了一种多羟基化合物键合的新型亲水色谱固定相。以水-有机溶剂(乙醇、乙腈、四氢呋喃)为流动相,通过改变流动相中有机溶剂的种类及浓度、缓冲盐浓度和柱温,考察了该固定相对6种强极性中药组分的保留行为和保留机理。当水的比例在0～40%(v/v)范围时,溶质的保留随着流动相中水的比例的增大而减小,属于典型的亲水色谱分离模式;而当流动相中水的比例在0～100%(v/v)范围内变化时,溶质的保留随着水的比例变化呈“U”形曲线,属于亲水色谱和反相色谱的混合保留机理。缓冲盐的浓度和pH效应说明,所选用的中药组分与所制备的固定相间还存在弱的静电作用。该固定相对6种中药组分以及丹参注射液具有良好的分离性能,表明其在强极性中药有效成分的分离及其他强极性物质的分离分析中具有一定的应用前景。     

The rotation and the phase transition in solid C60

The interaction between C60's in solid C60 has been calculated by (exp-6-1) potential, and the cause and the controlled factor of the high rapid rotations of C60 's were discussed. In order to describe the disordered degree of C60 rotation, an equivalent M is introduced. The phase transitions at the ~260 K and at the ~90 K are studied from the viewpoint of C60 rotation. The potential barriers of the ordered rotation below the ~260 K and the disordered rotation above the ~260 K have been given, and the effect of the external pressure on the temperature of phase transition has also been given.