Polysaccharide Molecules Research Articles

Comparative analysis of silicon nanostructures by x-ray diffraction technique

Silicon nanoparticles and nanowires prepared by using different methods were investigated by means of x-ray diffraction (XRD) technique. Broadening of the XRD lines of crystalline Si lattice allows us to estimate the mean size of nanoparticles. Silicon nanoparticles stored in aqueous suspensions for several days were found to decrease their sizes due to dissolution process. The kinetics of dissolution for different kinds of nanoparticles were found to be different. It was also shown that the most unstable nanoparticles (microporous silicon ones) could be protected from dissolution via interaction with the polysaccharide molecules (dextrane) into the solution.

Glucose-holmium for radiotherapy: Characterization and in vitro assays

BackgroundThe existence of saccharide-holmium complexes, containing mono or polysaccharide molecules, is an attractive hypothesis toward a radiation therapy (RT) with beta-emitters targeting high glucose metabolic human sites. To exam such hypothesis, the aim of this study was to investigate the possible chemical interactions of Ho and glucose molecules and if glucose may be a facilitator to holmium cell internalization based on in vitro uptake assays and mass spectrometry analyses. MethodsThe ionic-solution preparations were based on glucose-anhydrous and holmium-nitrate hydrated in aqueous solution, in non-radioactive condition. The uptakes in MDAMB231 cell lineage were evaluated, at 0 and 50 µg mL−1 holmium solution, in incubation times of 10, 30 and 50 min. The measurements of the holmium mass into the dried cell were evaluated by Neutron Activation Analysis – NAA method. Also, the ionic solution was tested in Electrospray Ionization Mass Spectrometry (ESI-MS) in order to identify Ho and glucose interactions. ResultsThere were intracellular holmium-uptake in MDAMB-231 of 3.6 ± 0.1, 6.8 ± 0.2 and 9.7 ± 0.3 μg increasing linearly with incubation time. The m/z ions at 523, 586, 649, 991 and 1054 were attributed to the positively loaded species containing Ho+3, glucose (GLU) and NO3-, making up the possible molecular compound formulae, involving Ho, GLU, and anions. ConclusionsThe findings of the in vitro assay and the ESI-MS suggested a suitable holmium cell uptake, increased in function of incubation time, due to the presence of glucose and holmium chemical interactions in solution.

Molecular epidemiology of infections caused by group B Streptococcus in pregnant women and newborns, and development of preventive vaccines

Hypothesis/aims of study. The present analysis was undertaken to summarize current knowledge about molecular properties of group B streptococci (GBS), emphasizing potential targets of vaccines against neonatal GBS infection.
 Study design, materials, and methods. This review is based on articles published mainly in the last ten years.
 Results. Epidemiological data on serotypes, multilocus sequence types, clonal complexes of GBS and their relationship are presented. Genetic events in GBS populations indicate significant obstacles to vaccine development. We described key properties of major GBS virulence factors, such as capsular polysaccharide, pili, and cell adhesion molecules, as well as results of experimental immunization on their basis.
 Conclusion. The population of invasive GBS strains is molecularly and genetically heterogeneous, which complicates selection of vaccine targets. Capsular switching, a low level of immunogenicity and variability of population composition are the most important factors that necessitate the accumulation and monitoring of molecular epidemiological data.

Molecular Weight Determination of Aloe Polysaccharides Using Size Exclusion Chromatography Coupled with Multi-Angle Laser Light Scattering and Refractive Index Detectors

Background: Size exclusion chromatography (SEC)/refractive index (RI) were used to determine molecular weight (MW) and molecular weight distributions (MWD) of polysaccharides. In aloe product research and quality control, commercially available pullulan and dextran are most commonly employed as calibration standards. Significant difference in the MW and MWD were found in literature when different methods were used. Objectives: This study was to investigate the traditional methods and more recent technologies used to determine the MW and MWD of Aloe vera polysaccharides. Methods: In this study, multi-angle laser light scattering (MALS) detection was studied on three polysaccharides, 1, 2, and 3, that were isolated and purified from A. vera leaf. The chemical structures of 1-3 were characterized as 1, 4-β-linked glucomannans by monosaccharide composition and glycosidic linkage analysis. Absolute MW and root-mean-square radius were determined by MALS on the isolated aloe polysaccharides. The conditions to obtain reliable results from MALS measurement were examined. Results: MALS analysis demonstrates that the 1, 4-β-linked glucomannan adopt the conformation of random coils or hard spheres in the analytical environment of a 0.1 M NaCl solution. Non-size exclusion effects and interactions between polysaccharide molecules were also observed in some aloe polysaccharides in the current analysis. The weight-average MW obtained by MALS measurement for 1, 2, and 3 are 55, 129, and 962 kDa, respectively. Comparing the results with SEC/RI calibrated by pullulan and dextran standards, marked differences in the MWD are found. Both overestimated the MW of 1 and 2 by factors of 4.4 and 4.2, and 2.4 and 1.6, when using dextran and pullulan calibration, respectively. Using pullulan calibration underestimated the MW of 3 by a factor of 3.1, but a similar result was obtained from dextran calibration compared to MALS measurement. The two isolated aloe polysaccharides were employed to be broad calibration standards or to be combined with narrow polydispersity pullulan calibration standards. Several aloe samples were tested using the different calibration curves, and the determined MWs were compared with the results obtained by MALS measurement. Conclusions: The results clearly indicated that until true polysaccharide standards become available MW and MWD's will be simply relative to the standards employed and the technologies used.

Microalga-Powered Microswimmers toward Active Cargo Delivery.

Nature presents intriguing biological swimmers with innate energy harvesting abilities from their local environments. Use of natural swimmers as cargo delivery agents presents an alternative strategy to transport therapeutics inside the body to locations otherwise difficult to access by traditional delivery strategies. Herein, a biocompatible biohybrid microswimmer powered by a unicellular freshwater green microalga, Chlamydomonas reinhardtii, is reported. Polyelectrolyte-functionalized magnetic spherical cargoes (1 µm in diameter) are attached to surface of the microalgae via noncovalent interactions without the requirement for any chemical reaction. The 3D swimming motility of the constructed biohybrid algal microswimmers is characterized in the presence and absence of a uniform magnetic fields. In addition, motility of both microalgae and biohybrid algal microswimmers is investigated in various physiologically relevant conditions, including cell culture medium, human tubal fluid, plasma, and blood. Furthermore, it is demonstrated that the algal microswimmers are cytocompatible when co-cultured with healthy and cancerous cells. Finally, fluorescent isothiocyanate-dextran (a water-soluble polysaccharide) molecules are effectively delivered to mammalian cells using the biohybrid algal microswimmers as a proof-of-concept active cargo delivery demonstration. The microswimmer design described here presents a new class of biohybrid microswimmers with greater biocompatibility and motility for targeted delivery applications in medicine.

3D electron tomographic and biochemical analysis of ER, Golgi and trans Golgi network membrane systems in stimulated Venus flytrap (Dionaea muscipula) glandular cells

BackgroundThe insect-trapping leaves of Dionaea muscipula provide a model for studying the secretory pathway of an inducible plant secretory system. The leaf glands were induced with bovine serum albumin to secrete proteases that were characterized via zymogram activity gels over a 6-day period. The accompanying morphological changes of the endoplasmic reticulum (ER) and Golgi were analyzed using 3D electron tomography of glands preserved by high-pressure freezing/freeze substitution methods.ResultsSecretion of multiple cysteine and aspartic proteases occurred biphasically. The majority of the Golgi was organized in clusters consisting of 3–6 stacks surrounded by a cage-like system of ER cisternae. In these clusters, all Golgi stacks were oriented with their cis-most C1 cisterna facing an ER export site. The C1 Golgi cisternae varied in size and shape consistent with the hypothesis that they form de novo. Following induction, the number of ER-bound polysomes doubled, but no increase in COPII vesicles was observed. Golgi changes included a reduction in the number of cisternae per stack and a doubling of cisternal volume without increased surface area. Polysaccharide molecules that form the sticky slime cause swelling of the trans and trans Golgi network (TGN) cisternae. Peeling of the trans-most cisternae gives rise to free TGN cisternae. One day after gland stimulation, the free TGNs were frequently associated with loose groups of oriented actin-like filaments which were not seen in any other samples.ConclusionsThese findings suggest that the secretory apparatus of resting gland cells is “overbuilt” to enable the cells to rapidly up-regulate lytic enzyme production and secretion in response to prey trapping.

Isolation and chemical characterization of a novel immunostimulating galactofucan from freshwater Azolla filiculoides

Water-soluble polysaccharides were isolated from Azolla filiculoides to determine their chemical and structural characteristics as well as anticancer and immunostimulatory activities. Crude and fractions (F1 and F2) were mainly composed of neutral sugars (70.0–80.1%), proteins (2.1–14.2%) and uronic acids (1.2–10.8%). The polysaccharides were mostly formed of different levels of fucose (23.8–61.2%), galactose (28.5–38.7%), mannose (7.5–16.7%), xylose (13.3–13.6%), glucose (12.7–13.3%), arabinose (5.5–11.6%) and rhamnose (8.0–9.5%) units. The polysaccharide molecules contained one or more sub-fractions with average molecular weight ranging from 992 to 2162 × 103 g/mol. Crude and fractionated polysaccharides induced RAW264.7 macrophages to release pro-inflammatory mediators and cytokines including nitric oxide, IL-1β, TNF-α, IL-6, IL-10 and IL-12 through NF-κB and MAPKs signaling pathways as confirmed by the presence of p-NK-κB, p-JNK, p-ERK and p-38 proteins in the cell cytoplasm. The most immunostimulating polysaccharide, F2, consisted of alternating →3)-Fuc-(1→ and →4)-Fuc-(1 → residues.

Effect of Beta Cyclodextrin on the Reduction of Cholesterol in Ewe's Milk Manchego Cheese.

Beta-cyclodextrin (β-CD) is a cyclic oligosaccharide consisting of seven glucose units and is produced from starch using cyclodextrin glycotransferase enzymes to break the polysaccharide chain and forming a cyclic polysaccharide molecule. The use of β-CD in food research for reduction of cholesterol is increasing due to its affinity for non-polar molecules such as cholesterol. The aim of this study was to evaluate the feasibility of using β-CD in cholesterol removal from pasteurized ewe’s milk Manchego cheese and evaluate the effect on the main components of the milk, lipids, and flavor characteristics. Approximately 97.6% cholesterol reduction was observed in the cheese that was treated using β-CD. Physicochemical properties (fat, moisture and protein) were not changed by the β-CD treatment, except the soluble nitrogen and non-protein nitrogen that showed slight differences after the treatment. The amount of the different components of the lipid fraction (fatty acids, triglycerides and phospholipids) were similar in cheeses treated and not treated with β-CD. Flavor compound and short chain free fatty acids were not mostly significantly influenced by the effect of the β-CD. β-CD molecules are edible and nontoxic and as a result they can be used safely for cholesterol removal processing in cheese manufacturing. Therefore, the present study suggests that β-CD treatment is an effective process for cholesterol removal from Manchego cheese while preserving its properties.

Selenized polysaccharides – Biosynthesis and structural analysis

The main objective of our research was to analyze the structure of the Se-containing polysaccharides and to examine how the selenium is bound to the polysaccharide molecule. During investigation of the biosynthesis of new immunomodulators, we isolated a selenium (Se)-containing polysaccharide-protein fraction containing proteoglycans of molecular weights of 3.9 × 106 Da and 2.6 × 105 Da, composed of glucose or mannose, nearly 8% of protein and 190 μg Se/g dry weight. X-ray absorption spectroscopy (XAS) data analysis in the near edge region (XANES) confirmed that selenium in the Se-polysaccharides structure is present at the –II oxidation state and that Se is organically bound. The simulation analysis in the EXAFS (extended X-ray absorption fine structure) region suggested that selenium is most likely bound by a glycosidic-link in a β-1,3 or α-1,4-glycosidic bond or substituted for oxygen in a pyranosidic ring. Calculations performed with Gaussian 03 software predicted deformations in the polysaccharide structure caused by the incorporation of the selenium atom including change in bond lengths and torsion angles and, as a result, disappearance of hydrogen bonds in the vicinity of the selenium atoms.

Intermolecular interactions of polysaccharides in membrane fouling during microfiltration

Membrane technology has been widely employed for seawater desalination, water and wastewater reclamation, while membrane fouling still remains as a major challenge. The polysaccharides in extracellular polymeric substances (EPS) have been recognized as an important foulant that causes serious membrane fouling, while the detailed structure of polysaccharides and the intermolecular interactions between them have not been adequately disclosed. In this study, two different polysaccharides and their mixtures were used to study the intermolecular cross-linking of polysaccharides as well as its effects on membrane fouling. Results demonstrated that the fouling propensities of distinct polysaccharides were completely different, which was attributed to the different intermolecular interactions lying in polysaccharides. The cross-linking among molecules of polysaccharide, regardless of the homogeneity, was found to form complex networks and determine the effective dimension of polysaccharides. Depending on the effective dimension of foulants, pore blocking and cake layer occurred subsequently during filtration processes. In light of this, it potentially gives new insights into the fouling behaviours by combining the structure-function knowledge of polysaccharides with their fouling propensity. In addition, transparent exopolymeric particles (TEP) measurement was found to provide an intuitionistic evaluation of the complex networks formed from polysaccharides, so that may act as a good indicator of fouling during membrane filtration.

Advanced anaerobic digested sludge dewaterability enhancement using sludge based activated carbon (SBAC) in combination with organic polymers

Wastewater sludge is difficult to dewater because the extracellular polymeric substances (EPS) it contains are highly hydrated and sticky. Anaerobic digestion generally results in further deterioration of sludge dewaterability due to the release of large quantities of biopolymers and fine particles. Chemical conditioning is required prior to mechanical dewatering and is of great importance in the operation of the dewatering process. In this work, a novel anaerobically digested (AD) sludge conditioning process that combines sludge based activated carbon (SBAC) as a skeleton builder with organic polymers (cationic polyacrylamide, CPAM, and chitosan, CTS) for flocculation is proposed to simultaneously remove soluble biopolymers and improve sludge dewaterability. Results indicate that the specific resistance to filtration (SRF) of AD sludge was decreased and that tryptophan-like proteins and humic substances in soluble EPS and loosely-bound EPS were effectively removed by SBAC adsorption through hydrophobic interaction. Flocs formed through CTS conditioning were smaller but aggregated more strongly and formed less compressible cake than those formed through CPAM conditioning. SBAC and cationic organic polymers showed a significant synergistic effect in improving sludge dewatering. The incorporation of SBAC into conditioning with organic polymers increased the strength of sludge floc aggregation and improved recover ability from mechanical shearing. Confocal laser scanning microscopy showed that conditioning with SBAC in combination with organic polymers resulted in protein molecules forming large aggregates, while polysaccharide molecules were uniformly distributed in sludge floc. This work provides a green and promising strategy for improved AD biosolid dewatering using sludge based activated carbon in combination with CTS.

Physical-Chemical Properties of Edible Film Made from Soybean Residue and Citric Acid

The effect of citric acid on the properties of soybean enzyme-assisted aqueous extraction processing (EAEP) residue edible film was studied. The washed soybean EAEP residue was produced by the process of EAEP. It was determined that the washed soybean EAEP residue is rich in fibers (76.10 ± 1.03%) and has lower oil and protein contents (7.74 ± 0.11% and 3.50 ± 0.20%, resp.). Edible films intended for food packaging have been produced from the washed EAEP residue combined with glycerol, different concentrations of citric acid (0%, 10%, 15%, 20%, 25%, and 30%), and sodium hypophosphite. The spectra have evidenced that the cross-linking reaction of citric acid and fibers has taken place in the residue. 30-CA films showed the highest tensile strength (17.52 MPa) and the lowest water vapor permeability (7.21 g·cm−1·s−1·Pa−1). Also, it indicated that citric acid can cross-link with the hydroxyls of polysaccharide and improve the compatibilization between the polymeric molecules to improve the intermolecular interaction between polysaccharide molecules, so that the water uptake is reduced. The smooth surface and better translucency of the films suggest that the EAEP residue films treated with citric acid are suitable for application in food packaging.

Extraction, characterization and immunomodulatory property of pectic polysaccharide from pomegranate peels: Enzymatic vs conventional approach

Molecular characteristics, structural properties and immunostimulatory activities of polysaccharides from pomegranate peel were evaluated after 0.1 M HCl, Cellic CTec2 and buffer extractions. The isolated polysaccharides were mainly formed of neutral sugars (32.1%–51.1%) and uronic acids (19.9%–30.8%) as well as varying levels of proteins (15.0%–39.5%). Different levels of sugars including glucose (44.9%–68.1%), galactose (14.6%–19.4%), mannose (3.4%–18.1%), arabinose (3.1%–18.1%) and rhamnose (3.5–6.0%) constructed the structure of isolated polysaccharides. The average molecular weight (Mw) of polysaccharides differed notably and ranged from 422.5 × 103 to 18,631.8 × 103 g/mol. Polysaccharide molecules obtained using Cellic CTec2 enzyme induced RAW264.7 murine macrophage cells to release considerable amount of inflammatory mediators including nitric oxide, IL-1β, TNF-α, IL-6 and IL-10. The polysaccharide stimulation of macrophage cells initiated through NF-κB and MAPKs signaling pathways and activation of p-NF-κB, p-JNK, p-ERK and p-p38 proteins. The most potent immunostimulatory polysaccharides were consisted of (1 → 3)-linked glucose, (1 → 6)-linked galactose, (1 → 4)-linked mannose and (1 → 4)-linked arabinose residues with branching points at C6 and C3. These results indicated that the lower molecular weight of polysaccharides isolated with Cellic CTec2 enzyme could be one of the major determinant structural characteristics in stimulating macrophage cells.

Polysaccharide Transglycosylases: A Survey of Assay Methods

Polysaccharide transglycosylases (PTGs) are a unique group of glycoside hydrolases playing important roles in the formation and modification of plant and fungal cell walls. Their action involves cutting the molecule of the polysaccharide substrate at the glycosidic bond, followed by transfer of the newly formed reducing-end fragment to the non-reducing end of another polysaccharide molecule, with the formation of a new glycosidic bond. As there is no net increase in the number of reducing ends in the system, conventional reductometric methods used to assess the activity of glycoside hydrolases are ineffective. Since the PTGs participate in vital processes, such as the elaboration of cell walls in plants and fungi, and are not present in animal cells, they are considered as possible targets for future specific fungicides and herbicides. Biochemical studies of PTGs, as well as the search for their inhibitors, require the availability of convenient and efficient methods for their assay. In this review we briefly describe the principles of methods used to detect and to determine the activity of this important group of enzymes.

Influence of oat components on lipid digestion using an in vitro model: Impact of viscosity and depletion flocculation mechanism

Depletion flocculation is a well-known instability mechanism that can occur in oil-in-water emulsions when the concentration of non-adsorbed polysaccharide exceeds a certain level. This critical flocculation concentration depends on the molecular characteristics of the polysaccharide molecules, such as their molecular weight and hydrodynamic radius. In this study, a range of analytical methods (dynamic shear rheology, optical microscopy, and static light-scattering) were used to investigate the interaction between lipid droplets and polysaccharides (guar gum and β-glucans) of varying weight-average molecular weight and hydrodynamic radius, and concentration. The aim of this work was to see if the health benefits of soluble fibers like β-glucans could be explained by their influence on the structure and digestibility of lipid emulsions. The apparent viscosity of the emulsions increased with increasing polysaccharide concentration, molecular weight, and hydrodynamic radius. Droplet flocculation was observed in the emulsions only at certain polysaccharide concentrations, which was attributed to a depletion effect. In addition, the water-soluble components in oat flakes, flour, and bran were extracted using aqueous solutions, to examine their impact on emulsion stability and properties. Then, the rate and extent of lipolysis of a sunflower oil-in-water emulsion in the presence of these oat extracts were monitored using the pH-stat method. However, the inhibition of lipolysis was not linearly related to the viscosity of the oat solutions. The water-soluble extracts of β-glucan collected from oat flakes had a significant inhibitory effect on lipolysis. The results of this study increase our understanding of the possible mechanisms influencing the impact of oat constituents on lipid digestion. This work also highlights the importance of considering the molecular properties of polysaccharides, and not just their impact on solution viscosity.

Maghemite Nanoparticles with Enhanced Magnetic Properties: One-Pot Preparation and Ultrastable Dextran Shell.

In the field of nanomedicine, superparamagnetic nanoparticles are one of the most studied nanomaterials for theranostics. In this study, a one-pot synthesis of magnetic nanoparticles is presented, with an increased control on particle size from 10 to 40 nm. Monitoring of vacuum level is introduced here as a crucial parameter for achieving a fine particle morphology. The magnetic properties of these nanoparticles are highly affected by disorders or mismatches in crystal structure. A prolonged oxidation step is applied to the obtained nanoparticles to transform the magnetic phases into a pure maghemite one, confirmed by high-resolution X-ray photoelectron spectroscopy analysis, by Mössbauer spectrometry and, indirectly, by increased performances in magnetization curves and in relaxation times. Afterward, the attained nanoparticles are transferred into water by a nonderivatized dextran coating. Thermogravimetric analysis confirms that polysaccharide molecules replace oleic acid on the surface by stabilizing the particles in the aqueous phase and culture media. Preliminary in vitro test reveals that the dextran-coated nanoparticles are not passively internalized from the cells. As a proof of concept, a secondary layer of chitosan assures a positive charge to the nanoparticle surface, thus enhancing cellular internalization.

Structural and conformational characterization of arabinoxylans from flaxseed mucilage

The structure of neutral fraction gum from flaxseed mucilage (FM-NFG) was studied for better understanding of the relationship between primary structure and conformation. Based on methylation/GC–MS, nuclear magnetic resonance (NMR) spectroscopy, the structure of FM-NFG was proposed as arabinoxylans. Flaxseed mucilage arabinoxylans contained β-1,4-linked xylose backbones, which were mainly substituted at O-2 and/or O-3 positions by 1–3 sugar residues. The possible branches included → 5)-α-l-Araf-(1 → (17.3 mol%), → 3)-α-l-Araf-(1 → (4.9 mol%), and → 4)-α-d-Glcp-(1 → (3.5 mol%), which were ended with three terminal sugar units: T-β-d-Xylp-(1 → (15.5 mol%), T-α-d-Glap-(1 → (4.5 mol%), and T-α-l-Araf-(1 → (2.6 mol%). The weight average molecular weight (Mw) of flaxseed mucilage arabinoxylans was calculated to be 1747 kDa by static light scattering (SLS), and it exhibited random coil conformation. The proposed structure and conformational models confirmed that different backbone sugar units especially substitution positions directly contributed to the conformational diversity and rigidity of polysaccharide molecules.

Morphology and Thermal Characteristics of Polysaccharide Extracted by Ultrasound from <i>Ophiopogon japonicas</i>

The crude polysaccharide UPOJ was extracted by ultrasound from Ophiopogon japonicas and purified by DEAE-cellulose52 column and Sephadex G-150 gel column. Purified polysaccharide UPOJ-DS was obtained. The thermal characteristics of UPOJ-DS were studied by using the thermal analysis system Q1000DSC LNCS FACS Q600SDT. The heating rate was 10°C/min and the test temperature was 20°C ~ 800°C. The results showed that there were three large mass losses in the process of heating, in which the maximum weight loss rate was 66.68% at 220°C ~ 330°C and the decomposition reaction took place in the polysaccharide itself, which indicated that the composition, water content, intermolecular interaction and aggregation behavior of UPOJ-DS were affected by temperature. The surface morphology of UPOJ-DS was observed by environmental scanning electron microscope (ESEM). The results indicated that the polysaccharide molecules were lamellar or clastic, with smooth surface, strong intermolecular interaction and close binding.

Crystallization of Calcium Carbonate in Alginate and Xanthan Hydrogels

Calcium carbonate polymorphs were crystallized in alginate and xanthan hydrogels in which a degree of entanglement was altered by the polysaccharide concentration. Both hydrogels contain functional groups (COOH and OH) attached at diverse proportions on saccharide units. In all systems, the precipitation process was initiated simultaneously with gelation, by the fast mixing of the calcium and carbonate solutions, which contain the polysaccharide molecules at respective concentrations. The initial supersaturation was adjusted to be relatively high in order to ensure the conditions suitable for nucleation of all CaCO3 polymorphs and amorphous phase(s). In the model systems (no polysaccharide), a mixture of calcite, vaterite and amorphous calcium carbonate initially precipitated, but after short time only calcite remained. In the presence of xanthan hydrogels, precipitation of either, calcite single crystals, porous polyhedral aggregates, or calcite/vaterite mixtures were observed after five days of ageing, because of different degrees of gel entanglement. At the highest xanthan concentrations applied, the vaterite content was significantly higher. In the alginate hydrogels, calcite microcrystalline aggregates, rosette-like and/or stuck-like monocrystals and vaterite/calcite mixtures precipitated as well. Time resolved crystallization experiments performed in alginate hydrogels indicated the initial formation of a mixture of calcite, vaterite and amorphous calcium carbonate, which transformed to calcite after 24 h of ageing.

Effect of Laminaria japonica polysaccharides on lipids monolayers at the air-water surface

In this paper, we examined the effect of Laminaria japonica polysaccharides (LJP) on cationic 1,2-Dioleoyl-3-Trimethylammonium-Propane (DOTAP) and anionic 1,2-dipalmitoyl-sn-glycero-3-[phospho-rac-1-glycerol] (DPPG) monolayers at the air-water interface by the pressure-area isotherms (π-A), adsorption curves (π-t) and morphology measurements with atomic force microscopy (AFM) technique. The π-A curves revealed that the isotherms shifted to larger mean molecular area with progressive addition of LJP into subphase for both DOTAP and DPPG monolayers. And the compression modulus Cs−1 obtained from π-A curves showed that the elasticity of the films decreased with the addition of LJP. Adsorption curves were measured at the surface pressure of 10 and 20mN/m, which were fitted by the adsorption kinetics equation. It revealed that DOTAP monolayer changed into a mixed film with the insertion of polysaccharides molecules. However, there was no significant effect on the surface pressure for DPPG monolayer. Besides, surface morphology was observed by AFM, which was consistent with the results of fitted adsorption curves.