自组装海藻酸钠纳米粒在正常小鼠体内分布的研究

目的:研究自组装海藻酸纳米粒(sSAN)在小鼠的体内分布情况,探讨sSAN作为维生素D3药物载体的可行性。方法:用异硫氰基荧光素(FITC)标记sSAN和负载维生素D3的海藻酸纳米粒(sSAN-VD3),将两种标记好的纳米粒分别给予小鼠灌胃,在不同的时间将小鼠处死,分别取血清和肝、肺、肾、脾,各脏器经匀浆后,用荧光分光光度计测定其荧光强度,计算血清和各组织中sSAN和sSAN-VD3的含量。结果:经灌胃给药后在小鼠血清、肝、肾、肺中均检测到上述药物,而脾中没有检测到。给药后0.5h和1h,sSAN-VD3-FITC及sSAN-FITC在肝、肺和血清中的含量持续增加,以1h时达峰值浓度,给药2h、4h后,两种制剂的浓度逐渐降低。在肾脏中的含量随着时间的延长逐渐增加,于2h时达峰值浓度,随后逐渐降低。结论:sSAN及sSAN-VD3经小鼠灌胃给药后均可吸收入血,而且口服吸收后在肝、肺、肾和血清中均有一定的分布。     

Solution properties of sodium alginate

Sodium alginate fractions derived from three different sources—Laminaria hyperboria (75% guluronate), Fucus vesicularus (95% mannuronate), and Azotobacter vinelandii (85% mannuronate)—were investigated in aqueous solution over a wide range of ionic strength and pH using the techniques of light scattering, viscometry, and osmometry. Light-scattering data extrapolated to infinite ionic strength yielded b₀ = 4.7 ± 0.3 and 3.0 ± 0.2 nm for the unperturbed effective bond lengths of the guluronate- and mannuronate-rich samples, respectively. These values are in the same ratio as predicted by conformational analysis, although lower by a factor of 0.7, probably due, in part at least, to the fact that measurements cannot be made on pure homopolymers. A comparison of the light-scattering and the viscosity data indicated that Φ in the Flory-Fox equation is lower than for more flexible polymers and increases with molecular weight, probably due to decreasing hydrodynamic permeability. Mark-Houwink exponents obtained from data extrapolated to infinite ionic strength were found to be considerably greater than 0.5, and we attribute this entirely to a variation in Φ. Comparison of the results obtained for the two mannuronate-rich samples indicated that the value of Φ and its variation with molecular weight can, in the case of alginates, differ markedly for chains, which, although having chemical differences, have similar chain statistics.     

Adjuvanticity effect of sodium alginate on subcutaneously injected BCG in BALB/c mice

Bacillus Calmette-Guerin (BCG) is the only available vaccine against tuberculosis. The research for an improved vaccine is currently a very active field of investigation. In the present study, adjuvanticity effect of sterile sodium alginate on subcutaneous BCG vaccination in BALB/c mice was investigated. Mice were vaccinated subcutaneously with BCG plus alginate and the immune response and protective effect were compared to those of mice vaccinated with BCG alone by the same route. Proliferative and delayed-type hypersensitivity responses, IFN-γ, specific anti-mycobacterium total IgG, IgG1 and IgG2a production were significantly higher in mice immunized subcutaneously with BCG plus alginate in comparison with results of mice immunized with BCG alone. Following systemic infection with BCG, mice vaccinated with BCG plus alginate had lower mean bacterial count compared to those vaccinated with BCG alone. The immune responses induced by subcutaneous administration of BCG plus alginate were significantly better than the responses induced by standard BCG vaccination.     

Some properties of alginate gels derived from algal sodium alginate

Alginic acid in soluble sodium alginate turns to insoluble gel after contact with divalent metal ions, such as calcium ions. The sodium alginate character has an effect on the alginate gel properties. In order to prepare a suitable calcium alginate gel for use in seawater, the effects of sodium alginate viscosity and M/G ratio (the ratio of D-mannuronate to L-guluronate) on the gel strength were investigated. The wet tensile strengths of gel fibers derived from high viscosity sodium alginate were higher than those from low viscosity sodium alginate. The tensile strength increased with diminishing sodium alginate M/G ratio. Among the gel fibers tested, the gel fiber obtained from a sodium alginate I-5G (1% aqueous solution viscosity = 520 mPa·s, M/G ratio = 0.6) had the highest wet tensile strength. After 13 days treatment in seawater, the wet tensile strength of the gel fiber retained 36% of the original untreated gel strength. For sodium alginates with similar viscosities, the seawater tolerance of low M/G ratio alginate was greater than that of the high M/G ratio one. This study enables us to determine a suitable calcium alginate gel for use in seawater.     

High molecular weight chitosan and sodium alginate effect on secretory acid proteinase of Candida albicans

The effect of high molecular weight chitosan (HMWCh) and sodium alginate (NaAL) on acid proteinase secretion of Candida albicans (one of culture collection and five isolates) was evaluated. The secretion of acid proteinase was induced in the presence and the absence of these polymers in different concentrations and their enzymatic activity was determined. HMWCh and NaAL significantly diminished the enzymatic activity (>76% for the collection strains and > 89% for the isolates, p < 0.05). HMWCh did not modify protein concentrations, but NaAL did. It can be concluded that both polymers can inhibit the proteinase activity of Candida albicans.     

pH-induced self-assembly and capsules of sodium alginate

In this investigation, we used a kind of polyelectrolyte, sodium alginate, as a model biomacromolecule to investigate the aggregation behaviors in aqueous solution after partial protonation of carboxylate groups in the alginate molecules. It is demonstrated that the alginate assemblies with core-shell structure can be generated by the partial protonation of carboxylate groups in sodium alginate chains using the protons released gradually from the reaction of K(2)S(2)O(8) with water at 70 degrees C in aqueous solution. The partial cross-linked alginate assemblies are pH sensitive and can change to hollow structure in the medium with relatively high pH value. This approach avoids use of block or grafted copolymers as the precursors or any other template to prepare assemblies and capsules, and provides a functional surface for subsequent chemical reaction at the surface (e.g., for binding biomolecules and for surface grafting). Such unique assemblies are also expected to be useful in biomedical fields.     

Optimization of covalent immobilization of pectinase on sodium alginate support

Pectinase was immobilized on a sodium alginate support using glutaraldehyde and retained 66% activity. The optimal pH for activity shifted from 3.0 to 3.5 after immobilization; however, the optimum temperature remained unchanged at 40°C. The immobilized enzyme also had a higher thermal stability and reusability than the free enzyme, and retained 80% of initial activity after 11 batch reactions.     

Biocomposite films based on alginate and organically modified clay

Sodium alginate/sodium montmorillonite hybrid films were prepared by casting from the suspension of sodium alginate and different clay samples. Clay samples had been modified with a cationic surfactant, a cationic polymer, and a small polar molecule, respectively. Benzethonium chloride, polyethyleneimine and urea were used as clay modifiers. The composite films begin to disintegrate at a higher temperature and with less weight loss than the pure alginate films. This suggests an enhancement of the film thermal stability due to the modification of the alginate with clay samples.     

The immune stimulatory effect of sodium alginate on the white shrimp Litopenaeus vannamei and its resistance against Vibrio alginolyticus

The total haemocyte count (THC), differential haemocyte count (DHC), phenoloxidase activity, respiratory burst (release of superoxide anion), superoxide dismutase activity, phagocytic activity and clearance efficiency to the pathogen Vibrio alginolyticus were measured when the white shrimp Litopenaeus vannamei (9.4-11.3 g) were injected individually with sodium alginate at 10, 20 or 50 microg g(-1). No significant differences in THC, DHC and superoxide dismutase activity were observed among the shrimp injected with saline and those injected with sodium alginate at 10, 20 or 50 microg g(-1). However, L. vannamei injected with sodium alginate at 20 microg g(-1)increased its phenoloxidase activity and respiratory burst after 2 days and one day, respectively. L. vannamei injected with sodium alginate at 50 microg g(-1)maintained a higher phagocytic activity and clearance efficiency to V. alginolyticus after 4 days. In another experiment, L. vannamei which had been injected with sodium alginate, were challenged with V. alginolyticus at 2x10(5)colony-forming units (CFU) shrimp(-1)and then placed in seawater of 34 per thousand. The survival of shrimp that received sodium alginate at either dose was significantly higher than that of control shrimp at the termination of the experiment (6 days after the challenge). It is therefore concluded that L. vannamei received sodium alginate at 10 microg g(-1)or more and increased its immune ability and resistance from V. alginolyticus infection.     

Immunomodulatory effect of sodium alginate enriched diet in kelp grouper Epinephelus brneus against Streptococcus iniae

The effect of diets containing sodium alginate at 0, 0.5, 1.0, and 2.0 g kg^?1 following challenge with Streptococcus iniae in kelp grouper Epinephelus bruneus were assessed with reference to survival rate and innate immune parameters such as alternative complement, lysozyme, natural haemagglutination, respiratory burst, superoxide dismutase, and phagocytic activities on week 1, 2, and 4. Fish fed with sodium alginate containing diet at 1.0 and 2.0 g kg^?1 after being challenged with S. iniae had higher survival rates of 75% and 60%, respectively than those fed with control diet (0 g kg^?1). With any enriched diet the percentage of macrophages significantly decreased from week 1–4, while the percentage of neutrophils and lymphocytes significantly increased. The alternate complement activity, natural haemagglutination, and phagocytic activities of infected fish fed with sodium alginate containing diet at 1.0 g kg^?1 on week 2 and 1.0 and 2.0 g kg^?1 diets on week 4 were significantly higher when compared to the control. The lysozyme, respiratory bursts, and superoxide dismutase activities of fish fed with enriched diets at 1.0 and 2.0 g kg^?1 were significantly increased on week 2 and 4. We therefore recommend that at 1.0 or 2.0 g kg^?1 dietary administration of sodium alginate can enhance innate immunity and disease resistance in kelp grouper against S. iniae.     

The interaction of sodium alginate with univalent cations

The M/G ratio, dyad and triad frequencies in the sodium alginate chain, were determined from ¹³C-nmr spectra. The interactions of sodium alginate in solution with the univalent cations K⁺ ion and Na⁺ ion have been investigated by viscometry and membrane osmometry. The dependencies of intrinsic viscosity, Huggins constant, and second virial coefficient on ionic strength were observed, and the maximums in reduced viscosity were obtained in low KCl and NaCl concentrations, respectively. These show that the electroviscous effects play an important role in polyelectrolyte solution, and the effect of the Na⁺ ion on aqueous solution of sodium alginate is greater than the K⁺ ion. The experimental observations are interpreted in terms of ion-pair formation with carboxyl groups of mannuronate and isolated guluronate residues and cooperation “egg-box” binding between polyguluronate chain sequence. The difference of interaction between univalent cations and alginate chains in solution is attributed to the ability of their binding with the polyion, which depends on the properties of ions itself. © 1998 John Wiley & Sons, Inc. Biopoly 46: 395–402, 1998     

Metabolism and calcium antagonism of sodium alginate oligosaccharides

Sodium alginate oligosaccharides (NaAOs) consisting of a mixture of eight oligosaccharides have previously been reported to lower blood pressure. We investigated in this study the excretion of NaAOs into the urine or feces, and attempted to elucidate the mechanism for lowering blood pressure by using isolated mesenteric arteries from the rabbit. The recovery rate of P8, which is the main component of NaAOs, was 5.2% and 58.9% over 48 hours in the urine and feces, respectively. The mechanism for lowering blood pressure appeared to be NaAOs having calcium antagonist activity, especially voltage-operated calcium channels. Our results suggest that NaAOs are substantially excreted into the feces, although some of them may be absorbed internally, exerting antagonist activity towards the calcium channels, especially voltage-operated calcium channels.     

海藻酸钠包埋法制备固定化菠萝蛋白酶

以海藻酸钠为载体,包埋法固定菠萝蛋白酶,对固定化奈件进行优化,同时探讨固定化菠萝蛋白酶的部分酶学性能。结果表明：固定化菠萝蛋白酶的质量受海藻酸钠质量分数、固定化酶量、固定化时间以及CaCl2质量分数的影响,其最佳固定化条件为：海藻酸钠质量分数1．0％,CaCl2质量分数3％,固定化酶液量与海藻酸钠体积之比1：2,固定化时间60min,在此条件下,制备的固定化菠萝蛋白酶的比活力为211．8U／g（湿质量载体）,由此制得的固定化酶的最适pH为7．6,与游离酶相比,升高了0．8个pH单位,同时显示固定化菠萝蛋白酶能耐受较高的碱性环境,固定化酶最适温度与游离酶相同,均为50℃,固定化酶在较高温度范围内,仍能保持较高的相对活力。     

Effect of cross-linking with calcium ions on the physical properties of alginate films

Three films of sodium alginate, with different amounts of guluronic fraction, were investigated with different techniques. On increasing the fraction of guluronic units the chain-to-chain interaction was promoted. The three samples were ionically cross-linked with calcium ions by soaking the films in a solution of calcium chloride. The introduction of the cross-linking points caused an appreciable change in the physical properties, and the results were discussed in terms of different composition of the materials and in terms of the increased free volume during the cross-linking process.