Zinc Alginate Research Articles

Porous chitosan microspheres containing zinc ion for enhanced thrombosis and hemostasis

Quick hemostats for non-lethal massive traumatic bleeding in battlefield and civilian accidents are important for reducing mortality and medical costs. Chitosan (CS) has been widely used as a clinic hemostat. To enhance its hemostatic efficiency, Zn2+ in the form of zinc alginate (ZnAlg) was introduced to CS to make porous CS@ZnAlg microspheres with ZnAlg component on the surface. Such microspheres were prepared by successive steps of micro-emulsion, polyelectrolyte adhesion, and thermally induced phase separation. Their structure and hemostatic performance were analyzed by SEM, FT-IR, XPS and a series of in vitro hemostatic experiments including thromboelastography analysis. The composite microspheres had an outer and internal interconnected porous structure. Their size, surface area, and water absorption ratio were ca. 70μm, 48m2/g, and 1850%, respectively. Compared to the neat chitosan microspheres, the CS@ZnAlg microspheres showed shorter onset of clot formation, much faster in vitro and in vivo whole blood clotting, bigger clot, less blood loss, and shorter hemostatic time in the rat liver laceration and tail amputation models. The synergetic hemostatic effects from (1) the electrostatic attraction between chitosan component and red blood cells, (2) the activation of coagulation factor XII by Zn2+ of zinc alginate component, and (3) physical blocking by microsphere matrix, contributed to the enhanced hemostatic performance of CS@ZnAlg microspheres.

Effect of reactive time on flame retardancy and thermal degradation behavior of bio-based zinc alginate film

A bio-based zinc alginate film was prepared via a facile ionic exchange and casting approach. Effects of reactive time on the flame retardancy and thermal stabilities of zinc alginate film were studied systemically; and the pyrolysis mechanism of zinc alginate was investigated. According to the results in vertical burning (UL-94) and thermogravimetric analysis (TGA) tests, the optimized reactive time was 2 h. Microscale combustion calorimetry (MCC) results indicated that the addition of zinc ion significantly increased the flame retardancy of alginate, showing in the reduction of peak heat release rate (PHRR), from 105 to 12.0 W/g; and the reactive time had no obvious effect on the reduction of PHRR for zinc alginate. Thermogravimetric analysis coupled with Fourier transform infrared analysis (TG-FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) results showed that zinc alginate produced much less flammable products than sodium alginate did in whole thermal degradation process. The results implied that zinc ion had the catalysis effect during the pyrolysis process. Finally, the possible thermal degradation mechanism of zinc alginate was proposed.

Novel zinc alginate hydrogels prepared by internal setting method with intrinsic antibacterial activity

In this paper, a controlled gelation of alginate was performed for the first time using ZnCO3 and GDL. Uniform and transparent gels were obtained and investigated as potential wound dressings. Homogeneity, water content, swelling capability, water evaporation rate, stability in normal saline solution, mechanical properties and antibacterial activity were assessed as a function of zinc concentration. Gelation rate increased at increasing zinc content, while a decrease in water uptake and an improvement of stability were found. Release of zinc in physiological environments showed that concentration of zinc released in solution lies below the cytotoxicity level. Hydrogels showed antimicrobial activity against Escherichia coli. The hydrogel with highest zinc content was stabilized with calcium by immersion in a calcium chloride solution. The resulting hydrogel preserved homogeneity and antibacterial activity. Furthermore, it showed even an improvement of stability and mechanical properties, which makes it suitable as long-lasting wound dressing.

Effect of impression valve system on adhesion force of impression materials to edentulous maxillary jaw: a preliminary clinical study

Objective: The purpose of this preliminary clinical study was to evaluate the effect of novel impression valve system (IVS) on adhesion force of different impression materials to edentulous maxilla. Background data: Impression materials and techniques have an important role in complete denture success. During the functional impression with an individual impression tray (IIT), high adhesive forces exist between edentulous ridge and impression material. Removing the IIT from the mouth with minimal force provides the most accurate and non-deformed impression. Materials and methods: This study included twenty maxillary edentulous patients (n = 20). Patients who had palatal torus, anatomic undercut, gagging reflex, and flabby ridges were excluded from the study. The age range of the participants was 55–70. All patients gave written informed consent. Two impression materials – zinc oxide eugenol (ZOE) and alginate – were used as experimental material. The digital dynamometer was used to determine the adhesion force of impression materials with and without IVS to edentulous maxilla. The mean values of the adhesion forces were analyzed using the Wilcoxon signed-ranks test (α = 0.05). Results: The effect of IVS on adhesion force was found to be statistically significant (p < 0.05). There were also statistical differences between the ZOE and alginate groups (p < 0.05). Conclusions: The IVS is useful to remove the functional impression from the mouth without any deformation and detaching in cases which high adhesive force occurs.

농도에 따른 알긴산 아연칼슘 필름의 제조 및 항균성

7 wt% alginate를 용액상태로 제조한 후 필름 메이커를 이용하여 필름 형태로 만든 후 3, 5 wt%의 <TEX>$ZnCl_2$</TEX>, <TEX>$CaCl_2$</TEX> 수용액에 필름을 고화시킨 후 수세하여 상온에서 건조시켜 zinc calcium alginate 복합필름을 제조하였다. 필름의 특성을 조사하기 위하여 항균성, 수용해도, 팽윤도 및 점도, SEM, EDS 분석 등을 측정하였다. Zinc calcium alginate 복합필름은 <TEX>$ZnCl_2$</TEX>, <TEX>$CaCl_2$</TEX> 함량이 증가할수록 용해저항성은 증가하였으며, 항균성 시험 결과, zinc alginate 필름뿐만 아니라 calcium alginate 필름에서도 두 균주(포도상구균, 대장균) 모두 우수한 항균력을 확인하였으며, 본 연구를 통해 복합필름의 물성개선의 가능성을 확인하였다. Composite films of zinc calcium alginate were prepared by a film maker from 7 wt% sodium alginate solution and then they solidified into 3, 5 wt% content <TEX>$ZnCl_2$</TEX>, <TEX>$CaCl_2$</TEX> solution followed by washing and drying at room temperature. The characteristics were measured with several methods (antimicrobial activity, water solubility, swelling ratio and viscosity, SEM, EDS) and the film properties were investigated. Composite films of zinc calcium alginate showed an increase in the water resistance by increasing <TEX>$ZnCl_2$</TEX> and <TEX>$CaCl_2$</TEX> content and the antimicrobial test showed that the calcium alginate as well as zinc alginate films result in excellent antimicrobial activity in the two strains, Staphylococcus and Escherichia coli. The results show the possible improvement of the physical properties of composite films.

The Flame Retardancy, Thermal Properties, and Degradation Mechanism of Zinc Alginate Films

The coordination structure, flame retardancy, thermal stabilities, and degradation mechanism of zinc alginate films were studied by Fourier transform infrared spectroscopy (FTIR), limiting oxygen index (LOI), vertical burning (UL-94), and thermogravimetric analysis (TGA) tests. The FTIR results showed that the structure of zinc alginate was correlated to its bidentate bridging coordination. The LOI (49.3) and UL-94 (V-0 rating) results indicated that zinc alginate was an inherent flame retardant material. The TG results showed that zinc alginate had better thermal stabilities than sodium alginate in the lower temperature zones; however, the thermal stabilities of zinc alginate were worse than those of sodium alginate at higher temperatures because of the decomposition of zinc oxalate formed in the degradation process of zinc alginate. Based on the TG results and FTIR of the residues at different temperatures, the effect of zinc ions on the degradation process of alginate was different from that of sodium ions. The zinc ions can catalyze alginate to form the residues and increase the amount of the residues, finally forming zinc oxide. Further, it could decrease the release of flammable gases and increase the flame retardancy of alginate.

Zinc alginate–hydroxyapatite composite microspheres for bone repair

This paper presents a novel method for producing composite and ceramic microspheres containing zinc for bone regeneration. The microspheres were prepared from a mixture of sodium alginate and hydroxyapatite that was extruded into a zinc nitrate solution. After 24h in the solution, Na+ exchange with Zn2+ ions produced zinc alginate–hydroxyapatite composite microspheres. After calcination, Zn-containing beta-TCP ceramic microspheres were produced.

용액 농도에 따른 항균성 알긴산 아연 필름의 제조 및 그 특성

Alginate를 농도 별로 용액상태로 제조한 후 필름 메이커를 이용하여 필름 형태로 만든 후 3 wt%의 <TEX>$ZnCl_2$</TEX> 수용액에 필름을 고화시킨 후 수세하여 <TEX>$60^{\circ}C$</TEX>의 건조기에서 약 20분 동안 건조시켜 zinc alginate 필름을 제조하였다. 필름의 특성을 조사하기 위하여 항균성 및 점도와 FTIR, TGA, SEM, EDS 및 접촉각, 인장측정, 용해도분석 등을 측정하였다. 항균성 시험 결과, zinc alginate 필름에서는 두 균주(포도상구균, 폐렴간균) 모두 우수한 항균력이 나타나는 것을 확인하였다. 9 wt%의 sodium alginate로 제조한 zinc alginate 필름의 표면은 다른 농도별 필름보다 균일한 형태를 나타내었으며, <TEX>$ZnCl_2$</TEX> 응고액에 잘 고화될 때 단단하고 거친 느낌의 단면 형태를 확인하였다. Zinc alginate 필름의 인장강도는 가교결합에 의해 sodium alginate 용액의 농도가 증가함에 따라 증가하였으며, 초기 열 분해 온도가 점차적으로 높아지고 있는 형태를 보였다. Zinc alginate films were prepared by a film maker from sodium alginate solutions of different weight ratios and then they solidified into 3 wt% content <TEX>$ZnCl_2$</TEX> coagulation solution and washed and dried at a <TEX>$60^{\circ}C$</TEX> oven for 20 min. The characteristics were measured by several methods (antimicrobial activity, viscosity, FTIR, TGA, SEM, EDS, contact angle, tensile strength and solubility) and the film properties were investigated. The antimicrobial test showed that the zinc alginate films result in excellent antimicrobial activity in the two strains (Klebsiella pneumonia, Staphylococcus). The surface of zinc alginate film from the solution of 9 wt% sodium alginate showed more uniform shape than any other films and the cross-section were hard and rough when the films were well-solidified by the <TEX>$ZnCl_2$</TEX> solution. The tensile strength of zinc alginate films increased along with the concentration of sodium alginate solution due to the cross-linking, and the initial thermal decomposition temperature increased gradually.

The effect of zinc ion content on flame retardance and thermal degradation of alginate fibers

The study employs limiting oxygen index (LOI) measurements, cone calorimetry (CONE) and thermogravimetric analysis (TGA) to examine the catalytic effect of zinc ion content on the flame retardance and thermal degradation of alginate fibers. LOI results show that all zinc alginate fibers are intrinsically flame retardant, with LOI values of over 27.0, as compared with about 24.5 for alginic acid fiber. The heat release rate (HRR) and total heat release values of zinc alginate fibers (obtained from CONE) are significantly less than those of alginic acid fiber, and decrease with increasing zinc ion content. TGA indicates that char formation increases and maximum thermal weight-loss rate is reduced when zinc content in the fibers is increased. The residues of zinc alginate fibers keep their shapes better than those of the alginic acid fiber. Further discussion of the combustion process and flame retardant mechanism is presented.

Antifungal Activity and Cytotoxicity of Zinc, Calcium, or Copper Alginate Fibers

The antifungal properties and cytotoxicity of alginate fibers were investigated to widen their application in tissue engineering. Calcium, zinc, and copper alginate fibers were separately prepared by replacing Na(+) with Ca(2+), Zn(2+), or Cu(2+). The antifungal properties of the three alginate fibers were studied after coming into contact with Candida albicans. Then, the fungal inhibitory rates were measured using the plate-count method following shake-flask test. Moreover, an inhibition-zone test and observation by scanning electron microscopy were carried out. The inhibitory rate of the calcium, copper, and zinc alginate fibers were, respectively, 49.1, 68.6, and 92.2 %. The results from inhibition-zone test and shake-flask test show that zinc alginate fibers have the most significant antifungal action and that copper alginate fibers have obvious inhibitory action, but the calcium alginate fibers have weak inhibitory effects. The scanning electron micrographs similarly illustrate that the fungal surfaces show most scraggly after the interaction between C. albicans and zinc alginate fibers. Moreover, the relative growth rates of zinc or calcium alginate fibers in human embryonic kidney cells and human fibroblast cells were more than 100 %. No significant results were obtained (P>0.05). The calcium alginate fibers in human fibroblast cells were not much different from the negative control group (P>0.05). However, zinc alginate fibers had a significant change (P<0.05). Therefore, the excellent antifungal property of zinc alginate fibers demonstrates potential application in skin tissue engineering comparing with calcium or copper alginate fibers.

Zinc–alginate microparticles for controlled pulmonary delivery of proteins prepared by spray-drying

The aim of this study was to prepare novel Zn2+-cross-linked alginate microparticles for controlled pulmonary delivery of protein drugs via a simple one-step spray-drying process and to physicochemically characterize these systems. Microparticles were prepared by spray-drying aqueous alginate solutions, containing the model protein BSA, Zn(NH3)4SO4, and optionally additional excipients. Upon ammonia evaporation, the alginate was cross-linked by Zn2+-ions. The microparticles were characterized by SEM, laser and X-ray diffraction, gel electrophoresis, aerodynamic particle size, and drug release measurements. Particles in a size range suitable for deep lung administration were obtained. Pure alginate microparticles were spherical in shape, whereas the addition of zinc led to a more collapsed geometry. Protein release depended on the (i) alginate:ZnSO4 ratio (minimum release rate at 2:1); (ii) BSA content (decreasing release rate and extent with decreasing BSA content); (iii) type of release medium (increasing release rate with increasing phosphate concentration). The emitted microparticle dose was high for all formulations (∼90%). Fine particle fractions (FPF, depositing in the deep lung) up to 40% could be achieved. The FPF was affected by the BSA content, alginate:ZnSO4 ratio and presence/absence of poloxamer. Thus, novel Zn2+-cross-linked alginate microparticles were prepared via a simple one-step process, providing an interesting potential for controlled pulmonary delivery of proteins.

Photocatalytic degradation of methylene blue using ZnO made by thermal degradation of Zn-alginate fibers

Zinc alginate fibers (Zn-AF) were obtained by wet-spinning of sodium alginate into coagulating bath containing an aqueous zinc chloride solution. ZnO nanostructures consisting of nanofibers on the ZnO matrix were prepared from controlled thermal degradation of the as-obtained Zn-AF at 800 °C in air condition when Zn granules were added for extra ZnO source during calcination. The composition and morphology of ZnO nanostructures were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL). The SEM images show that ZnO nanofibers with diameter about 20 nm were formed on the ZnO matrix. The photocatalytic degradation experiment of methylene blue (MB) dye from aqueous solution show that ZnO nanostructures possess good photo catalytic reactivity. The performance of ZnO nanostructures can be attributed to the ZnO nanofibers which facilitate the photocatalytic degradation reaction.

Cytotoxicity and Antiviral Activity of Calcium Alginate Fibers and Zinc Alginate Fibers

The cytotoxicity and anti-influenza virus (IFV) activity of calcium or zinc alginate fibers were investigated to explore the feasibility of them to be used as biomaterials. African Green Monkey kidney cell (Vero) and human cervical cancer cell (Hela) cultured with alginate fibres were used to screen cytotoxic effects. After 48 h, MTT (3-(4,5-dimethyl-2-thiazol)-2,5-diphenyl-2H tetrazolium bromide) assays were performed. Then cytotoxicity was evaluated with six grades according to cell relative growth rate (RGR). In anti-IFV activity assay, IFV were added to all fibers and the Vero cell survival were detected by MTT assays with calculating the percentage of protection. The cytotoxity of calcium alginate fibers on Vero were grade 0 or 1 in contrast to zinc alginate fibers which was grade 0. The cytotoxity of calcium or zinc alginate fibers on Hela were grade 0. Furthermore, partial calcium or zinc alginate fibers could promote Vero or Hela cell growth. In antiviral assay the highest percentage of protection of calcium alginate fibers was 34.42%, while that of zinc alginate fibers was 59.42%. The results showed that calcium or zinc alginate fibers had a good cellular biocompatibility and the large weight zinc alginate fibers had a better anti-IFV activity than calcium alginate fibers, which is potential for tissue engineering.

Effect of cross-linker and cross-linker concentration on porosity, surface morphology and thermal behavior of metal alginates prepared from algae ( Undaria pinnatifida)

Alginic acid and metal alginates are prepared from fresh algae using extraction method. FTIR spectra indicate that alginic acid is converted into metal alginate. Asymmetric stretching of free carboxyl group of zinc alginate at 1596 cm −1 is shifted to 1582 cm −1 in cadmium alginate, due to the change of charge density, radius and atomic weight of the cation. Surface morphology changes by changing the cross-linker and cross-linker concentration at same magnification. Total intrusion volume, porosity (%) and pore size distribution also changes by changing cross-linker and cross-linker concentration. Thermal degradation results reveals that zinc and cadmium alginates started decomposing at 100 °C, but rapid degradation started around 300 °C and showed a stepwise weight loss during thermal sweep, indicating different types of reactions during degradation. Kinetic analysis was performed to fit with TGA data, where the entire degradation process has been considered as two or three consecutive 1st order reactions.

Immobilization of Alginate-Encapsulated Bacillus thuringiensis var. israelensis Containing Different Multivalent Counterions for Mosquito Control

Immobilized techniques have been used widely for the controlled release formulation of mosquitoes. Among the microbial formulations, polymeric matrices play an important role in the controlled release of microbial pesticide at rates sufficiently effective to kill mosquitoes in the field. The advantage of these matrices is that they enhance the stability of both spores and toxin against pH, temperature variations, and UV irradiation. The disadvantage of using calcium alginate beads is that they are unstable upon contact with phosphate of potassium or sodium ions rich in the mosquito habitats. To overcome these problems, attempts were made to encapsulate Bacillus thuringiensis var. israelensis within alginate by using different multivalent counterions, namely, calcium chloride, zinc sulfate, copper sulfate, cobalt chloride, and ferric chloride, and the beads formed were tested for its mosquito larvicidal activity. Among all the beads tested, zinc alginate beads resulted in maximum larvicidal activity of 98% (+/-1.40 SE) against Culex quinquefasciatus IIIrd instar larvae and maximum spore count of 3.36 x 10(5) (+/-5291.50 SE) CFU/ml. Zinc alginate beads maintained their structure for up to 48 h when shaken vigorously on a rotary shaker at 180 rpm in the presence of 10 mM potassium phosphate buffer (pH 6.8 +/- 0.1). In conclusion, our results suggest that the use of zinc sulfate as counterions to encapsulate B. thuringiensis var. israelensis within alginate may be a potent mosquito control program in the habitats where more phosphate ions are present.

Preparation of ZnO Nanostructures by Thermal Degradation of Zinc Alginate Fibers

Zinc alginate (Alg-Zn) fibers were obtained by wet spinning of sodium alginate (Alg-Na) into a coagulating bath containing an aqueous zinc chloride solution. ZnO nanostructures were prepared by thermal degradation of the as-obtained zinc alginate fibers at different temperatures in air. The compositions, morphologies, and microstructures of products were investigated by thermal gravimetry (TG), X-ray diffraction (XRD), electron energy-loss spectroscopy (EELS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). Annealing time and temperature influenced Final structures and shapes of ZnO nanostructures. ZnO nanorods with diameters of about 120 nm were obtained at 800 degrees C and with a reaction time of more than 24. It in air. A ZnO growth mechanism was proposed by a careful investigation of ZnO nanostructures after different thermal treatment times.

Alginate fibres: an overview of the production processes and applications in wound management

AbstractAlginate fibers are made from sodium alginate, which is a natural polymer extracted from brown seaweeds. Over the last two decades, alginate fibers have become well established in the wound management industry where their ion‐exchange and gel‐forming abilities are particularly useful for the treatment of exuding wounds. In order to deliver functional performances for advanced wound management products, many improvements have been made in recent years to enhance the absorption and gel‐forming capabilities and the anti‐microbial properties of alginate fibers. In addition, attempts have been made to use alginate fibers as a carrier to deliver zinc, silver and other active ingredients that are beneficial to wound healing. This paper reviews the development in the production of various fibers from alginate, and summarizes the production processes for calcium alginate, calcium/sodium alginate, sodium alginate, zinc alginate, silver alginate and other types of alginate fibers containing novel functional ingredients. Copyright © 2007 Society of Chemical Industry

Preparation of ZnO nanoparticles by thermal decomposition of zinc alginate

A new method to produce zinc oxide nanocrystals is presented. The method is based on the thermal decomposition of zinc alginate gels. The gels were produced in the form of beads by ionic gelation between a zinc solution and sodium alginate. The wet beads were heated at 800 and 450 °C for 24 h and the products were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission electron microscopy (TEM) and micro-Raman spectroscopy. XRD analysis showed that all obtained samples are of wurtzite structure. TEM analysis combined with electron diffraction also showed the presence of single crystals indexed as ZnO hexagonal phase. Crystal size was determined by measuring individual crystals from SEM pictures. It was found that heating temperature and the kind of zinc agent influence the crystal size. Raman scattering revealed the existence of defects in the structure of nanoparticles whose cringing was discussed in the context of recent studies in this field.

Removal and recovery of antinutritional factors from soybean flour

An integrated process for removal purification of two antinutritional factors, namely soybean trypsin inhibitor and soybean agglutinin, from soybean flour has been developed. The process is based upon binding of soybean trypsin inhibitor and soybean agglutinin to an immobilized metal affinity chromatography medium, consisting of zinc alginate beads. Both soybean trypsin inhibitor (95%) and soybean agglutinin (94%) could be removed from an aqueous extract of soybean flour. The bound protease inhibitor and lectin could be recovered by washing the zinc alginate beads with 0.05 M imidazole solution and dissolving the beads in 0.01M EDTA, respectively. Recoveries of 89%, in the case of soybean trypsin inhibitor and 81% in case of soybean agglutinin, were possible. Both purified proteins gave single band on SDS–PAGE. Thus, soybean flour, free of these two antinutritional factors, could be obtained. Simultaneously, these two antinutritional factors were purified as value-added products.

Oral Controlled Release Formulation for Highly Water‐Soluble Drugs: Drug–Sodium Alginate–Xanthan Gum–Zinc Acetate Matrix

An oral controlled release formulation matrix for highly water‐soluble drugs was designed and developed to achieve a 24‐hour release profile. Using ranitidine HCl as a model drug, sodium alginate formulation matrices containing xanthan gum or zinc acetate or both were investigated. The caplets for these formulations were prepared by direct compression and the in vitro release tests were carried out in simulated intestinal fluid (SIF, pH7.5) and simulated gastric fluid (SGF, pH1.2). The release of the drug in the sodium alginate formulation containing only xanthan gum completed within 12 hours in the SIF, while the drug release in the sodium alginate formulation containing only zinc acetate finished almost within 2 hours in the same medium. Only the sodium alginate formulation containing both xanthan gum and zinc acetate achieved a 24‐hour release profile, either in the SIF or in the pH change medium. In the latter case, the caplet released in the SGF for 2 hours was immediately transferred into the SIF to continue the release test. The results showed that the presence of both xanthan gum and zinc acetate in sodium alginate matrix played a key role in controlling the drug release for 24 hours. The helical structure and high viscosity of xanthan gum might prevent zinc ions from diffusing out of the ranitidine HCl–sodium alginate–xanthan gum–zinc acetate matrix so that zinc ions could react with sodium alginate to form zinc alginate precipitate with a cross‐linking structure. The cross‐linking structure might control a highly water‐soluble drug to release for 24 hours. Evaluation of the release data showed the release mechanism for the novel formulation might be attributed to the diffusion of the drug.