Interaction Of Alginate Research Articles

A supramolecular catalyst based on sodium alginate and viologen calix[4]resorcinol for the room temperature hydrolysis of paraoxon

Properties of paraoxon, such as poor water solubility, low rate of natural decomposition, ability to accumulate in soil and wastewater, lead to the fact that paraoxon is found in various agricultural products and textiles. In this regard, the search for effective ways of paraoxon degradation becomes an extremely urgent problem, which can be solved by creating catalysts by mimicking paraxonase. In this work, a complex of physicochemical methods was used to study the supramolecular interactions of sodium alginate, which has a calcium-binding ability similar to paraxonase, with viologen calix[4]resorcinol and to reveal the nature of the intermolecular interactions between them resulting in the spontaneous formation of nanoparticles. Before proceeding to the investigation of the binding ability of obtained nanoparticles to paraoxon, the encapsulating effect of nanoparticles on a number of model substrates of different solubility (doxorubicin hydrochloride, quercetin and oleic acid) was studied. The kinetics of paraoxon hydrolysis reaction using these nanoparticles was studied at room temperature in an aqueous medium by spectrophotometric method. The rate of this reaction increases with increasing concentration of stable nanoparticles having hydrophobic domains that ensure paraoxon immobilization. The results obtained allow considering the supramolecular polysaccharide/calixarene system as an effective biomimetic catalyst.

Freeze-gelated sodium alginate incorporated GO hydrogel membrane fabrication, thermal and mechanical studies

In this study, sodium alginate-graphene oxide (SA-GO) hydrogel membrane was prepared by freeze-gelation method and externally crosslinked with CaCl2. The prepared SA, SA-0.5% GO and SA-1% GO were characterized by FTIR analysis for the bonding interaction of sodium alginate and porosity of SA-GO hydrogels was confirmed by analyzing surface morphology through SEM. A further enhancement in porosity was confirmed by swelling studies due to water absorption. Also, GO incorporated hydrogel membranes showed controlled degradation at pH 7.4 in-vitro. Moreover, TGA analysis showed improved thermal stability of SA hydrogel with increasing concentration of GO. The mechanical studies revealed that SA-1% GO hydrogel membrane exhibit a fracture stress and young modulus of 0.30 MPa and 0.016 MPa respectively.

Characterization of Alginate with Natural Polymers Combination for Drug Encapsulation

Alginate is one of the natural biopolymers that is widely used for drug formulations, combination of alginate with other polymers, such as gum acacia, pectin, and carrageenan can increase mechanical strength, therefore, can reduce leakage of the encapsulated active pharmaceutical ingredient from the polymer matrix. Interaction of alginate and these polymers can occur via intermolecular hydrogen bonds causing synergism, which is determined from the viscosity of polymer mixture. Alginate was combined with gum acacia/pectin/carrageenan in different blending ratios (100:0, 75:25, 50:50, 25:75, and 0:100) with and without addition of CaCl2. The synergism effect is obtained from the design of experimental (DoE), and calculation the percentage value of viscosity deviation viscosity synergism index, then the strength of gel was analyzed. The interaction between two polymers was observed using FTIR spectroscopy. In distilled water, the synergistic effect was found in the combination of alginate-carrageenan at ratios 25:75 and 50:50. Otherwise, in CaCl2 solution, synergistic effect appears in alginate-gum acacia (75:25), alginate-pectin (50:50 and 75:25), and alginate-carrageenan (50:50 and 75:25). The synergistic effect and strength of gel polymers increased, with the addition of CaCl2.

Ca2+-Triggered Interaction of Amphiphilic Alginate and Soil to Facilitate Agrochemical Adsorption

Ca2+-Triggered Interaction of Amphiphilic Alginate and Soil to Facilitate Agrochemical Adsorption

Impact of the solvent properties on molecular interactions and phase behaviour of alginate-gelatin systems

Alginate-gelatin systems are used in a wide range of applications, e.g., foods, cosmetics, drugs, and medicine. To target the techno-functionalities of alginate-gelatin systems such as texture, stability, or appearance it is necessary to understand the structure formation of gel systems, which is influenced by the molecular interactions and the phase behaviour. Therefore, the aim of this study was to characterise the molecular interactions and phase behaviour of dilute alginate-gelatin systems. For this purpose, we analysed alginate, gelatin A and their mixtures at pH 7. First, we characterised the effect of the sodium chloride concentration on the single polymer solutions by measuring the critical overlap concentration, the zeta potential, intrinsic viscosity, the Huggins coefficient as well as the molecular weight and the second virial coefficient. To gain a better understanding of the molecular interactions between alginate and gelatin, we determined the Huggins coefficient and the interaction parameter by Wolf as a function of mixing ratio, NaCl and urea concentration. Additionally, we calculated the second cross-virial coefficient. Lastly, we characterised the influence of the interactions on the secondary structure of gelatin by Fourier-transform-infrared-spectroscopy. The attractive interactions between alginate and gelatin potentially enabling the formation of soluble complexes, were demonstrated as deviations from additivity of intrinsic viscosity and negative cross-virial coefficients. Interestingly, the Wolf interaction parameter was affected by the NaCl concentration and the mixing ratio, whereas the presence of urea showed no impact. This indicates that the attractive interactions of alginate and gelatin A at pH 7 is rather caused by electrostatic interactions than hydrogen bonds. The present study clarifies the relevance of hydrogen bonds and electrostatic interactions as well as the impact of mixing ratio and solvent properties on the phase behaviour of alginate-gelatin systems. The insights contribute to a better understanding of the structure formation of concentrated alginate-gelatin systems, levelling the path to specific modifications of functionality.

On the mechanism of the cholesterol lowering ability of soluble dietary fibers: Interaction of some bile salts with pectin, alginate, and chitosan studied by isothermal titration calorimetry.

Reducing high blood cholesterol is an important strategy to decrease the chances of a cardiovascular disease occurrence, the main cause of mortality in western developed countries. Therefore, the search for an alternative therapeutic or preventive approach being natural, biocompatible, and not toxic is still more relevant than ever. This need is particularly felt in Pediatrics for treating childhood hypercholesterolemia, due to statins interference in the production of steroid hormones in prepuberal children. Notwithstanding the general acceptance of the healthy role of the fibers in the diet, the mechanism underlying the cholesterol-lowering ability of soluble fibers is still under discussion. Therefore, we started a systematic study of the binding ability of some soluble dietary fibers (SDF) originated from different natural sources toward selected bile salts (BS) by isothermal titration calorimetry (ITC). Here we report the results of our ITC studies on the interaction of alginate, pectin and chitosan with sodium cholate (NaC), sodium deoxycholate (NaDC), sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC). Thermodynamic data on the micelle formation process of the above bile salts, as a premise to the study of their binding ability to the SDF, are also reported. Alginate does not show specific binding interaction with BS, while pectin shows a strong exothermic bond with NaDC in monomeric form. Chitosan, positively charged and soluble only at low pH, shows strong exothermic interactions with NaTC and NaTDC (soluble at pH = 3 in acetate buffer) with precipitate formation. For NaTC, the exothermic peak starts at about 5 mM. At this concentration NaTC bound on the fiber reaches locally the cmc value and micelles start forming on the fiber inducing its conformational change. For NaTDC the same process occurs at much lower concentrations, due to lower cmc, and with a greater quantity of heat involved. The first set of results here presented shows that for some SDF the binding of BS could be an important mechanism in cholesterol lowering but not the only one. The information here presented could be a starting point for the design of optimized functional foods with high cholesterol lowering ability.

Halloysite nanotubes-based composite material with acid/alkali dual pH response and foliar adhesion for smart delivery of hydrophobic pesticide

Smart pesticide delivery systems with pH response are arousing huge interests recently, but single pH sensitivity may bring about constraint in different agricultural situations. We have developed a novel type of responsive material with acid/alkali dual pH sensitivity to deliver hydrophobic pesticide by the combination of acid-sensitive calcium ion (Ca2+)-ethylenediamine tetraacetate (EDTA2-) complex and base-sensitive calcium alginate. During the loading of chlorpyrifos, assembly occurs spontaneously by mixing Ca2+-modified acid-treated halloysite nanotubes (a-HNTs) with EDTA2-, followed by the functionalization of alginate gel to obtain the foliar-adhesive pesticide, namely HCECA (each letter representing halloysite, Ca2+, EDTA2-, chlorpyrifos and alginate, respectively). With loading capacity and loading efficiency of chlorpyrifos at 130 mg/g and 65 %, this engineered pesticide exhibits characteristic sustained release behavior of chlorpyrifos with dual pH response, displaying the release ratio of 58 % and 83 % in 24 h at pH = 4.0 and pH = 8.5, respectively, which is further demonstrated by prolonged control efficiency of corn borers. Owing to the strong interaction of alginate with plant leaves, the foliar adhesion property of HCECA against rain rinsing was strengthened by 86 % and 45 %, in comparison to pristine chlorpyrifos and HCEC (the control pesticide without alginate). The stability of HCECA was investigated, showing its resistance to high temperature (50 °C) and ultraviolet irradiation. Notably, the carrier material shows excellent biocompatibility by testing toxicity on zebrafish. Featured by green preparation, acid/alkali dual pH response and multifaceted stability, the halloysite nanotubes-based gel material serves as a promising carrier for hydrophobic pesticide to be applied in controlled management of agricultural hazards.

Interaction of alginate with nano-hydroxyapatite-collagen using strontium provides suitable osteogenic platform

BackgroundHydrogels based on organic/inorganic composites have been at the center of attention for the fabrication of engineered bone constructs. The establishment of a straightforward 3D microenvironment is critical to maintaining cell-to-cell interaction and cellular function, leading to appropriate regeneration. Ionic cross-linkers, Ca2+, Ba2+, and Sr2+, were used for the fabrication of Alginate-Nanohydroxyapatite-Collagen (Alg-nHA-Col) microspheres, and osteogenic properties of human osteoblasts were examined in in vitro and in vivo conditions after 21 days.ResultsPhysicochemical properties of hydrogels illustrated that microspheres cross-linked with Sr2+ had reduced swelling, enhanced stability, and mechanical strength, as compared to the other groups. Human MG-63 osteoblasts inside Sr2+ cross-linked microspheres exhibited enhanced viability and osteogenic capacity indicated by mineralization and the increase of relevant proteins related to bone formation. PCR (Polymerase Chain Reaction) array analysis of the Wnt (Wingless-related integration site) signaling pathway revealed that Sr2+ cross-linked microspheres appropriately induced various signaling transduction pathways in human osteoblasts leading to osteogenic activity and dynamic growth. Transplantation of Sr2+ cross-linked microspheres with rat osteoblasts into cranium with critical size defect in the rat model accelerated bone formation analyzed with micro-CT and histological examination.ConclusionSr2+ cross-linked Alg-nHA-Col hydrogel can promote functionality and dynamic growth of osteoblasts.Graphical

Fabrication of aerogel-templated oleogels from alginate-gelatin conjugates for in vitro digestion

In this work, the alginate-gelatin conjugates were developed by Maillard reaction. The aerogel templates were obtained by freeze-drying the conjugates, and they were transformed into oleogels by being immersed in camellia oil. Degree of graft and browning index revealed the occurrence of Maillard reaction. Compared with pure alginate/gelatin samples, the rheology and mechanical properties of mixing samples were improved, indicating the interaction of alginate and gelatin. Aerogel templates formed by Maillard reaction presented the micromorphology of lamellar aggregation, obvious changes of peak intensity in infrared spectrum and better thermal stability. The materials reached a considerable oil adsorption capacity of 23.31 g/g and oil holding capacity of 84.75%. Through Maillard reaction, oleogels showed good in vitro digestion properties. This work suggested that oleogels could be constructed from alginate-gelatin conjugates that formed the aerogel templates for oil adsorption, and Maillard reaction significantly affected the physical structures and oil capacities of alginate-gelatin compound systems.

Effects of alginate and laminaran on the microbiota and antioxidant properties of human faecal cultures

Alginate and laminaran are water soluble dietary fibres in brown algae. In a previous study, pure cultures of Bacteroides xylanisolvens, Bacteroides uniformis, and Erysipelaclostridium ramosum increased antioxidant capacities in the broth with alginate and/or laminaran fermentation. This study was conducted to evaluate the presence of the alginate- and laminaran-responsive human gut indigenous bacteria (RIB) and their functions. Briefly, human stool samples were cultured in media without (control), or with 1% (w/v) alginate or laminaran at 37 °C for 24 h under anaerobic conditions. Results showed that during incubation, the pH of the culture reduced with the polysaccharides. Phenol production was clearly suppressed via laminaran supplementation in the faecal sample cultures. The 16S rRNA (V4) gene amplicon sequencing confirmed that B. xylanisolvens-, B. uniformis and E. ramosum-like bacteria were alginate- and/or laminaran-RIB in human gut, although their read numbers differed among individuals. Additionally, some butyrate-producers, such as Faecalibacterium and Roseburia, were also detected as the RIB in alginate and laminaran cultures, respectively. Fermentation increased 1,1-diphenyl-2-picrylhydrazyl and superoxide anion radical-scavenging capacities and the Fe-reducing power of the culture medium. Additionally, the fermented cultures increased the nitric oxide secretion in macrophage like RAW 264.7 cells culture. These results suggest that the interaction of alginate and laminaran with their RIB may have desirable effects on the host as next generation prebiotics when brown algae are ingested.

Designing a new alginate-fibrinogen biomaterial composite hydrogel for wound healing

Wound healing is a complex process and rapid healing necessitates a proper micro-environment. Therefore, design and fabrication of an efficacious wound dressing is an impressive innovation in the field of wound healing. The fabricated wound dressing in this scenario was designed using a combination of the appropriate coagulating and anti-bacterial materials like fibrinogen (as coagulating agent), nisin (as anti-bacterial agent), ethylenediaminetetraacetic acid (as anti-bacterial agent), and alginate (as wound healing agent). Biophysical characterization showed that the interaction of fibrinogen and alginate was associated with minor changes in the secondary structure of the protein. Conformational studies showed that the protein was structurally stable at 42 °C, is the maximum temperature of the infected wound. The properties of the hydrogel such as swelling, mechanical resistance, nisin release, antibacterial activity, cytotoxicity, gel porosity, and blood coagulation were assessed. The results showed a slow release for the nisin during 48 h. Antibacterial studies showed an inhibitory effect on the growth of Gram-negative and Gram-positive bacteria. The hydrogel was also capable to absorb a considerable amount of water and provide oxygenation as well as incorporation of the drug into its structure due to its sufficient porosity. Scanning electron microscopy showed pore sizes of about 14–198 µm in the hydrogel. Cell viability studies indicated high biocompatibility of the hydrogel. Blood coagulation test also confirmed the effectiveness of the synthesized hydrogel in accelerating the process of blood clot formation. In vivo studies showed higher rates of wound healing, re-epithelialization, and collagen deposition. According to the findings from in vitro as well as in vivo studies, the designed hydrogel can be considered as a novel attractive wound dressing after further prerequisite assessments.

Adventitial injection of HA/SA hydrogel loaded with PLGA rapamycin nanoparticle inhibits neointimal hyperplasia in a rat aortic wire injury model.

Neointimal hyperplasia is a persistent complication after vascular interventions, and it is also the leading cause of vascular graft restenosis and failure after arterial interventions, so novel treatment methods are needed to treat this complication. We hypothesized that adventitial injection of HA/SA hydrogel loaded with PLGA rapamycin nanoparticle (hydrogel-PLGA-rapamycin) could inhibit neointimal hyperplasia in a rat aortic wire injury model.The HA/SA hydrogel was fabricated by the interaction of hyaluronic acid (HA), sodium alginate (SA), and CaCO3; and loaded with PLGA rapamycin nanoparticle or rhodamine uniformly. A SD rat aortic wire injury induced neointimal hyperplasia model was developed, the control group only received wire injury, the adventitial application group received 10 μL hydrogel-PLGA-rapamycin after wire injury, and the adventitial injection group received 10 μL hydrogel-PLGA-rapamycin injected into the aortic adventitia after wire injury. Tissues were harvested at day 21 and analyzed by histology and immunohistochemical staining.Hydrogel loaded with rhodamine can be successfully injected into the aortic adventitia and was encapsuled by the adventitia. The hydrogel could be seen beneath the adventitia after adventitial injection but was almost degraded at day 21. There was a significantly thinner neointima in the adventitial application group and adventitial injection group compared to the control group (p = 0.0009). There were also significantly fewer CD68+ (macrophages) cells (p = 0.0012), CD3+ (lymphocytes) cells (p = 0.0011), p-mTOR+ cells (p = 0.0019), PCNA+ cells (p = 0.0028) in the adventitial application and adventitial injection groups compared to the control group. The endothelial cells expressed arterial identity markers (Ephrin-B2 and dll-4) in all these three groups.Adventitial injection of hydrogel-PLGA-rapamycin can effectively inhibit neointimal hyperplasia after rat aortic wire injury. This may be a promising drug delivery method and therapeutic choice to inhibit neointimal hyperplasia after vascular interventions.

A detailed assessment on the interaction of sodium alginate with a surface-active ionic liquid and a conventional surfactant: a multitechnique approach.

An investigation has been made on the interaction of a biodegradable anionic polyelectrolyte, sodium alginate (NaAlg), with two oppositely charged cationic surfactants, 1-hexadecyl-3-methyl imidazolium chloride (C16MImCl) and 1-hexadecyl triphenylphosphonium bromide (C16TPB), the former is a surface active ionic liquid (SAIL) and the latter a conventional surfactant over a wide concentration regime of the polyelectrolyte. Dual influence of electrostatic and hydrophobic interactions plays in this investigation when mixing surfactants with an oppositely charged polyelectrolyte. A number of different experimental techniques, e.g., conductometry, tensiometry, steady state and time resolved spectrofluorimetry, turbidimetry, isothermal titration calorimetry (ITC), dynamic light scattering (DLS), attenuated total reflection (ATR), high resolution transmission electron microscopy (HR-TEM) and fluorescence microscopy, have been implemented to get comprehensive information about the interaction of the oppositely charged polyelectrolyte and surfactants. Tensiometry study reveals the existence of several conformations of NaAlg influenced by different concentrations of surfactants titrated to it and these are abbreviated as critical aggregation concentration (cac), saturated concentration of polymer-surfactant complex (Cs) and finally extended critical micelle concentration due to the aggregation of the surfactant itself, appearing in chronological order from low to high concentrations of surfactants. Apart from tensiometry, these above concentrations have been well found and the values are well comparable when investigating polyelectrolyte-surfactant interaction by other physicochemical techniques as well. Irreversible phase separation of the oppositely charged polyelectrolyte-surfactant complex (PS-complex) occurs at higher polyelectrolyte concentration investigated here for both the surfactants in the vicinity of cac for C16MImCl and near for C16TPB and finally persists after further addition of surfactants above the formation of free micelles. Several bulk and interfacial parameters, viz., Gibbs free energy of micellization , enthalpy of micellization , entropy of micellization , degree of counterion binding (β), surface excess at cmc (Γmax), area minimum (Amin), surface pressure at cmc (πcmc), pC20, packing parameter (P), hydrodynamic radius (r) and aggregation number (Na) of two surfactants both in the presence and absence of NaAlg, have been calculated for these investigated systems. Characterization of NaAlg, both surfactants and their individual complexes was performed using FTIR-ATR. DLS shows the distribution of size of polymer surfactant complexes over a wide range of surfactant concentrations at a fixed polyelectrolyte concentration, while HR-TEM study reveals not only the size of agglomerated clusters of the PS-complex but also its shapes. Images of NaAlg-surfactant complexes were also captured using fluorescence microscopy in solution phase. A strong PS-complex in the presence of C16MImCl has been reported here over C16TPB.

Reaction heterogeneity in the bridging effect of divalent cations on polysaccharide fouling

Polysaccharide is an important foulant in membrane filtration. Nevertheless, the “bridging effect” of divalent cations on polysaccharide fouling is still not completely understood and thus is the main objective of this study. To reveal the basic underlying mechanism, a wide range of concentrations of Ca2+ and Mg2+ were analysed and alginate sodium was employed as model foulant to generate results. Results showed that the fouling propensities of alginate first increased and then decreased along with the increasing of the concentration of Ca2+. Ca2+ at high concentration acted like coagulant in alleviating alginate fouling. While the membrane fouling caused by alginate continuously aggravated with increasing Mg2+ level in feed water and surprisingly the specific filtration resistances caused by Mg2+ were much higher than those of Ca2+ at all ion concentrations. Transparent exopolymer particles (TEP) measurements revealed that both Ca2+ and Mg2+ increased the molecular interactions of alginate via “bridging effect”, while the binding of Ca2+ to alginate was much greater than that of Mg2+ which resulted with aforementioned fouling phenomenon. This study suggests that the roles of Ca2+ and Mg2+ in polysaccharide fouling are dramatically different and Mg2+ is more important than we thought.

Theoretical study for determining the type of interactions between a GG block of an alginate chain with metals Cu2+, Mn2+, Ca2+ and Mg2+

The alginate interaction with divalent cations has been the subject of extensive study since this biopolymer forms hydrogels in the presence of divalent cations (ionic crosslinking), which exhibit important properties with applications in fields such as medicine. It has been proposed that the properties of the hydrogel formed from the ionic crosslinking process depend, among several factors, on the type of interactions between the polymer and divalent metals. In this work, theoretical calculations based on density functional theory (DFT) were used to determine the chemical stability and the type of interaction between alginate and Cu 2+ , Mn 2+ , Ca 2+ and Mg 2+ cations. For this, the lowest energy geometries were determined at the B3LYP 6-31G (d, p) level of theory for the systems formed with Ca 2+ and Mg 2+ , while those formed with Cu 2+ and Mn 2+ used effective central potential (ECP) with LanL2DZ bases. The following models were used to characterize the bonds between the oxygen atoms of the polymer chain with the different metals; theory of non-covalent interactions (NCI), natural bonding orbitals (NBO) method, and topological analysis of the electronic location function (ELF). Our results showed that the properties such as chemical stability of the systems would be correlated with the degree of covalence of the bonds and the delocalization phenomena charge, where the systems constituted with Cu 2+ and Mn 2+ formed bonds with highly polarized covalent characteristics, while Ca 2+ and Mg 2+ form bonds of the electrostatic type. Nevertheless, our results support the idea proposed by previous studies; regarding the lack of correlation between the alginate for divalent cations affinity with the strength of the interactions between these metals and the polymer.

Biocompatibility of Alginate -Graphene Oxide Film for Tissue Engineering Applications

The present paper indicates promising potential of Sodium Alginate) Alg)/Graphene oxide (Go) films in fields bone tissue engineering (TE). The Sodium Alginate (Alg)/Graphene oxide (Go) films, were fabricated via (solvent casting method). The interaction of Sodium Alginate (Alg) with Graphene oxide (Go) via hydrogen bonding was confirmed by FTIR analysis. The swelling degree of Sodium Alginate (Alg)/Graphene oxid (Go) films was also studied. Furthermore, the biocompatibility of Sodium Alginate (Alg)/Graphene oxide (Go) films disclosed its non-cytotoxic effect on the cell lines (MG-63) in-vitro test, the viability of cell lines on the films, and hence its appropriateness as potent biomaterial for tissue engineering.

A novel intramural TGF β 1 hydrogel delivery method to decrease murine abdominal aortic aneurysm and rat aortic pseudoaneurysm formation and progression

ObjectivesAneurysms are generally the result of dilation of all 3 layers of the vessel wall, and pseudoaneurysms are the result of localized extravasation of blood that is contained by surrounding tissue. Since there is still no recommended protocol to decrease aneurysm formation and progression, we hypothesised that intramural delivery of TGF β1 hydrogel can decrease aneurysm and pseudoaneurysm formation and progression. MaterialsMale C57BL/6 J mice (12–14 wk), SD rats (200 g) and pig abdominal aortas were used, and hydrogels were fabricated by the interaction of sodium alginate (SA), hyaluronic acid (HA) and CaCO3. MethodsA CaCl2 adventitial incubation model in mice and a decellularized human great saphenous vein patch angioplasty model in rats were used. TGF β1 hydrogel was intramurally delivered after CaCl2 incubation in mice; at day 7, the abdomen in some mice was reopened, and TGF β1 hydrogel was injected intramurally into the aorta. In rats, TGF β1 hydrogel was delivered intramurally after patch angioplasty completion. Tissues were harvested at day 14 and analysed by histology and immunohistochemistry staining. The pig aorta was also intramurally injected with hydrogel. ResultsIn mice, rhodamine hydrogel was still found between the medium and adventitia at day 14. In the mouse aneurysm model, there was a thicker wall and smaller amount of elastin breaks in the TGF β1 hydrogel-delivered groups both at day 0 and day 7 after CaCl2 incubation, and there were larger numbers of p-smad2- and TAK1-positive cells in the TGF β1 hydrogel-injected groups. In the rat decellularized human saphenous vein patch pseudoaneurysm model, there was a higher incidence of pseudoaneurysm formation when the patch was decellularized using 3% SDS, and delivery of TGF β1 hydrogel could effectively decrease the formation of pseudoaneurysm formation and increase p-smad2 and TAK1 expression. In pig aortas, hydrogels can be delivered between the medium and adventitia easily and successfully. ConclusionsIntramural delivery of TGF β1 hydrogel can effectively decease aneurysm and pseudoaneurysm formation and progression in both mice and rats, and pig aortas can also be successfully intramurally injected with hydrogel. This technique may be a promising drug delivery method and therapeutic choice to decrease aneurysm and pseudoaneurysm formation and progression in the clinic.

Interaction of sodium alginate with cetyltrimethylammonium bromide in aqua-organic mixed solvents: influence of temperatures and compositions

Herein, the interaction of sodium alginate (SA) with cetyltrimethylammonium bromide (CTAB) has been studied in aqueous solution as well as in aqua-organic mixed solvents at varying temperatures using conductivity measurements. Ethylene glycol (EG), dimethyl formamide (DMF), 1,4-dioxane (DO), and acetonitrile (AN) were used as organic solvents. The CMC values for SA + CTAB system in 10% (v/v) mixed solvents follow the order: CMCwater + DO > CMCwater + DMF > CMCwater + AN > CMC water + EG > CMCwater. The CMC values for the SA + CTAB system in aqueous medium indicate that SA lowers the CMC of pure CTAB. The higher CMC values in all the solvent mixtures may be due to the decrease of the dielectric constant and cohesive energy density of water. The interaction of SA with CTAB is affected significantly by the change in temperature which is attributed to changes in hydration of SA and CTAB. The negative values of free energy of micellization () for the SA + CTAB system imply the spontaneous aggregation phenomenon and the negative values in H2O and 10% (v/v) mixed solvents follow the trend: (H2O) > (water + EG) > (water + DMF) > (water + DO) > (water + AN). The values of free energy changes of transfer () were also evaluated for the shift of SA + CTAB mixture from water to aqua-organic mixed solvents and discussed the results in detail. The binding interactions of SA with CTAB are proposed to be hydrogen bonding, ion-dipole, and hydrophobic interactions. The enthalpy-entropy compensation of SA + CTAB systems was assessed and illustrated in detail.

Graphene oxide enhanced ionic liquid plasticisation of chitosan/alginate bionanocomposites

The effect of graphene oxide (GO) or reduced GO (rGO) on the structure and properties of polyelectrolyte-complexed chitosan/alginate bionanocomposites is highly dependent on plasticiser type (glycerol or 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc])) due to the competing interactions between the components. For the glycerol-plasticised chitosan/alginate matrix, inclusion of GO/rGO enhanced the chitosan crystallinity and increased matrix ductility. While the chitosan/alginate matrix plasticised by [C2mim][OAc] showed dramatically weakened interactions between the two biopolymers, GO was highly effective at counteracting the effect of [C2mim][OAc] by interacting with the biopolymers and the ionic liquid ions, resulting in enhanced mechanical properties and decreased surface hydrophilicity. Compared with GO, rGO was much less effective at promoting chitosan–alginate interactions and even resulted in higher surface hydrophilicity. However, irrespective of the plasticiser type, inclusion of rGO resulted in reduced crystallinity by restricting the interactions between [C2mim][OAc] and the biopolymers, and higher ionic conductivity.

Alginate Calcium Microbeads Containing Chitosan Nanoparticles for Controlled Insulin Release

Effective delivery system for oral insulin administration is a promising way for diabetes therapy. Herein, we prepared alginate microbeads containing chitosan nanoparticles (CNP) for controlled release of insulin. CNP was developed by reaction between tripolyphosphate (TPP) and chitosan. The ratio of TPP to chitosan was optimized aiming with smaller and more unified distributed CNP. TEM and DLS analysis confirmed that CNP has size around 150 nm with low PDI value and strong surface charge. Encapsulate ability for bovine serum albumin, working as model protein, was 11.45%, and the encapsulate efficiency was 23.70%. To modify the release profile of protein suitable for oral insulin delivery, sodium alginate was applied to coat on the surface of CNP by electrostatic interaction. After that, CaCl2 was added to reinforce the alginate coating layer. FTIR analysis confirmed the interaction of alginate with chitosan and reaction with calcium ion. After reaction with Ca2+ ion, size measurement revealed that CNP was incorporated into alginate microbeads with mean diameter about 3.197 μm. Alginate microbeads presented irregular shape with small particles inside as revealed by optical microscope. Meanwhile, the release test demonstrated that protein release was pH-dependent. Acidic pH value retards protein release and neutral pH value promotes protein release. At last, insulin-loaded alginate microbeads were administrated to hyperglycemia model mice and blood glucose profile was monitored afterward. Insulin-loaded microbeads significantly lowered blood glucose level compared with mice treated with alginate microbeads without insulin. It is noted that insulin-loaded alginate microbeads could lower blood glucose level in much prolonged period of 96 h, indicating thatinsulin was released in controlled manner.