Alginate Nanocomposite Research Articles

Calcium alginate fibers containing metallic nanoadditives

AbstractIn this manuscript two types of nanocomposite alginate fibers containing metallic nanoadditives: silver or Fe3O4 were obtained. The effect of the process parameters and the influence of the amount of nanoadditives in the fibers matrix on the mechanical properties, crystalline structure, porous structure, and sorption properties was investigated. The resulting fibers are characterized by the level of tenacity up to 23 cN/tex, the degree of crystallinity about 30%, and high sorption properties, which are strictly connected with hydrophilic nature of the polymer. On the basis of the images obtained by using an electron microscope linked to an X‐ray microanalysis it was found that the distribution of nanoadditives in the material of calcium alginate fibers is uniform. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40223.

Disposable Immunosensor for Escherichia Coli O157:H7 Based on a Multi-Walled Carbon Nanotube-Sodium Alginate Nanocomposite Film Modified Screen-Printed Carbon Electrode

A disposable immunosensor for the detection of Escherichia coli O157:H7 based on a multiwalled carbon nanotube–sodium alginate nanocomposite film was constructed. The nanocomposite was placed on a screen-printed carbon electrode, and horseradish peroxidase-labeled antibodies were immobilized to E. coli O157:H7 on the modified electrode to construct the immunosensor. The modification procedure was characterized by atomic force microscopy and cyclic voltammetry. Under optimal conditions, the proposed immunosensor exhibited good electrochemical sensitivity to E. coli O157:H7 in a concentration range of 103–1010 cfu/mL, with a relatively low detection limit of 2.94 × 102 cfu/mL (S/N = 3). This immunosensor exhibited satisfactory specificity, reproducibility, stability, and accuracy, making it a potential alternative tool for early assessment of E. coli O157:H7.

Montmorillonite–alginate nanocomposite as a drug delivery system – incorporation and in vitro release of irinotecan

The scope of the present study was the preparation and characterization of irinotecan nanocomposite beads based on montmorillonite (Mt) and sodium alginate (AL) as drug carriers. After irinotecan (I) incorporation into Mt, the resulting hybrid was compounded with alginate, and I-Mt-AL nanocomposite beads were obtained by ionotropic gelation technique. The structure and surface morphology of the hybrid and composite materials were established by means of X-ray diffraction (XRD), IR spectroscopy (FT-IR), thermal analysis (TG-DTA) and scanning electron microscopy (SEM). Irinotecan incorporation efficiency in Mt and in alginate beads was determined both by UV-vis spectroscopy and thermal analysis and was found to be high. The hybrid and composite materials were tested in vitro in simulated intestinal fluid (pH 7.4, at 37 °C) in order to establish if upon administering the beads at the site of a resected colorectal tumor, the delivery of the drug is sustained and can represent an alternative to the existing systemic chemotherapy. The in vitro drug release test results clearly suggested that Mt, and Mt along with AL were able to control the release of irinotecan by making it sustained, without any burst effect, and by reducing the released amount and the release rate. The nanocomposite beads may be a promising drug delivery system in chemotherapy.

Periodic Mesoporous Organosilica‐Based Nanocomposite Hydrogels as Three‐Dimensional Scaffolds

Dye-loaded periodic mesoporous organosilica particles functionalized with bioactive molecules were used for the generation of a nanocomposite alginate hydrogel. The affinity of cells was up to four times higher with the embedded particles than with simple alginate hydrogel, caused by both the nanometer-scale particle itself and its bioactive functionalization.

Controlled production of alginate nanocomposites with incorporated silver nanoparticles aimed for biomedical applications

Production of nanocomposite alginate microbeads with electrochemically synthesized silver nanoparticles (AgNPs) based on electrostatic extrusion technique was investigated with respect to potentials for utilization in pharmaceutical and biomedical applications. It was shown that electrochemical synthesis of AgNPs results in reduction of practically all Ag+ ions present in the initial solution yielding stable Ag/alginate colloid solutions that were demonstrated to be suitable for sterilization, manipulation, and electrostatic extrusion with retention of AgNPs. Presence of AgNPs in alginate colloid solutions had negligible effects on the size of the produced Ag/alginate microbeads, which was chiefly determined by the applied electrostatic potential during the extrusion. On the other hand, incorporation of AgNPs within the alginate hydrogel induced slight changes in biomechanical properties determined in a biomimetic bioreactor, so that packed beds of nanocomposite Ag/alginate microbeads exhibited slightly higher dynamic compression modulus as compared to that of control alginate microbeads (154 ? 4 and 141 ? 2 kPa, respectively). On the other hand, equilibrium unconfined compression modulus was significantly lower for nanocomposite microbeads as compared to that of controls (34 ? 2 and 47 ? 0.5 kPa, respectively).

Fabrication and antibacterial properties of ZnO–alginate nanocomposites

Abstract Alginate was used as a controlled environment for the growth of ZnO nanoparticles. The formation of nanostructured particles was confirmed by a blue shift in the onset of the optical absorption with respect to bulk ZnO. From the XRD measurements it was found that the obtained ZnO nanoparticles have a hexagonal crystal structure. The emission spectrum of the nanocomposite is dominated by a strong band-to-band recombination, while the emission from the ZnO defect states depended on the preparation conditions. Besides showing the presence of Zn 2p, O 1s, Na 1s and C 1s core levels, the XPS analysis also showed that the O 1s spectra can be resolved into two lines that are attributed to the presence of OH groups on the surface of the particles and ZnO, respectively. Antimicrobial tests revealed that the ZnO–alginate nanocomposite exhibits a strong activity against the common pathogens Staphylococcus aureus and Escherichia coli.

Biosorption of chromium(VI) ions from aqueous solutions by iron oxide-impregnated alginate nanocomposites: batch and column studies

This study evaluates the feasibility of using iron-oxide-impregnated nanoparticles of alginate (FeO–Alg) in removing hexavalent chromium ions from aqueous solutions by batch and continuous (fixed bed) column adsorption methods. In the batch mode experiments, the influence of contact time, chromium(VI) concentration, pH, and adsorbent were studied while in the fixed-bed column mode, bed height, flow rate, and initial metal ions concentration on the adsorption profiles of the metal ions employing FeO–Alg as nanoadsorbents (0.02 g 20 mL−1) were investigated. The maximum adsorption was observed at 2.3 pH for an initial metal ion concentration of 10 mg L−1. The results suggest that adsorption is due to electrostatic attraction between chromate ions () and protonated surface () groups. At a bed height of 0.82 cm and a flow rate of 0.5 mL min−1, the metal removal capacity of FeO-alginate for chromium(VI) was found to be 85%. The bed depth service time (BDST) model was used to analyze the data of the column mode experiments. Sorption capacity per unit bed volume and rate constant of adsorption were calculated to be 17 mg L−1 and 0.6 L mg−1 min−1, respectively. In the flow rate experiments, the results confirmed that the metal uptake capacity and the metal removal efficiency decreased with increasing flow rate. The characterization of the prepared nanoparticles has been accomplished by Fourier transform infrared spectrocopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and zeta-potential measurements. The sorption equilibrium and kinetic data could be well fitted to the Freundlich, Langmuir, and Lagergren models. FeO–alginate nanoparticles are effective adsorbent for chromium(VI) removal from water samples.

Effect of the material structure and nanoadditive type on the thermal properties of nanocomposite alginate fibres

Abstract Thermal properties of sodium alginate and calcium alginate fibres containing nanoadditives were analysed. Thermal decomposition of fibres based on sodium alginate, both pure and containing nanoadditive, produces sodium carbonate (for fibres without nanoadditive) or, for modified fibres, a mixture of sodium carbonate with the corresponding nanoadditive, which does not undergo any changes within the range of measured temperatures. The chief gaseous products accompanying the decomposition are carbon (IV) oxide and water. The shape of the DTG curves and values of the ∗T50 coefficient indicate an improvement in the thermal properties of the fibres when ceramic nanoadditives (SiO2 and HAp) are introduced, as compared with pure sodium alginate fibres. When ceramic nanoadditives (MMT, SiO2, bioglass) are added to the material of calcium alginate fibres the nature of the thermal processes is not affected. However, similarly as for sodium alginate fibres modified with nanoadditive, here also it was note th...

The influence of fiber formation conditions on the structure and properties of nanocomposite alginate fibers containing tricalcium phosphate or montmorillonite

AbstractThe authors devised conditions for the formation of nanocomposite calcium alginate fibers containing tricalcium phosphate (TCP) or montmorillonite (MMT). The rheological, sorptive, and strength properties of these fibers, as well as their porous and supramolecular structures were subjected to analysis. It has been concluded that the presence of nanoadditives in the material of alginate fibers decreases their susceptibility to distortion in the drawing stage. The obtained fibers are characterized by an even distribution of the nanoadditive on the fiber surface. POLYM. COMPOS., 31:1321–1331, 2010. © 2009 Society of Plastics Engineers

Effect of formation conditions on the structure and properties of nanocomposite alginate fibers

AbstractThe conditions for producing nanocomposite fibers composed of calcium alginate, containing a hydroxyapatite nanoadditive were devised and the rheological, sorptive, and strength properties of these fibers, as well as their porous and supramolecular structure were subjected to analysis. It has been concluded that the presence of the HAp nanoadditive in the material of alginate fibers decreases their susceptibility to distortion in the drawing stage, which results in their tenacity properties being lower by 2cN/tex than of the fibers with no nanoadditive. The obtained nanocomposite fibers are characterised by a tenacity value exceeding 26 cN/tex, accompanied by high sorptive and water‐retention properties of 90% and the even distribution of the nanoadditive on the fiber surface. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Memory effects and magnetic interactions in a γ-Fe2O3 nanoparticle system

The low-temperature dynamics of a magnetic nanoparticle system (γ-Fe2O3—alginate nanocomposite with average particle size around 4nm) have been studied by superconducting quantum interference device measurements. Using different temperature and field protocols, memory phenomena in the dc magnetization and magnetic relaxation have been observed at temperatures below its blocking temperature TB=37K. However, aging experiments show an absence of any waiting time dependence in the magnetization relaxation. These observations indicate that the dynamics of this nanoparticle system are governed by a wide distribution of particle relaxation times which arise from the distribution of particle sizes and weak interparticle interactions.