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In this present work, we developed a phenol grafted polyglucuronic acid (PGU) and investigated the usefulness in tissue engineering field by using this derivative as a bioink component allowing gelation in extrusion-based 3D bioprinting. The PGU derivative was obtained by conjugating with tyramine, and the aqueous solution of the derivative was curable through a horseradish peroxidase (HRP)-catalyzed reaction. From 2.0 w/v% solution of the derivative containing 5 U/mL HRP, hydrogel constructs were successfully obtained with a good shape fidelity to blueprints. Mouse fibroblasts and human hepatoma cells enclosed in the printed constructs showed about 95% viability the day after printing and survived for 11 days of study without a remarkable decrease in viability. These results demonstrate the great potential of the PGU derivative in tissue engineering field especially as an ink component of extrusion-based 3D bioprinting., (Copyright © 2021 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Carbohydrates are involved in many important pathological processes, such as bacterial and viral infections, by means of carbohydrate-protein interactions. Glycoconjugates with multiple carbohydrates are involved in multivalent interactions, thus increasing their binding strengths to proteins. In this work, we report the efficient synthesis of novel muramic and glucuronic acid glycodendrimers as potential Dengue virus antagonists. Aromatic scaffolds functionalized with a terminal ethynyl groups were coupled to muramic and glucuronic acid azides by click chemistry through optimized synthetic strategies to afford the desired glycodendrimers with high yields. Surface Plasmon Resonance studies have demonstrated that the compounds reported bind efficiently to the Dengue virus envelope protein. Molecular modelling studies were carried out to simulate and explain the binding observed. These studies confirm that efficient chemical synthesis of glycodendrimers can be brought about easily offering a versatile strategy to find new active compounds against Dengue virus., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Degradation of the articular cartilage and structural remodeling of the subchondral bone are regarded as the two major pathological characteristics of osteoarthritis. This study aimed to investigate the effect of an interpenetrating polymer network (IPN) of a sodium hyaluronate and sodium alginate (HA/SA) scaffold combined with berberine (BER) on osteochondral repair. We first developed an IPN scaffold of HA/SA and evaluated its characteristics. Then, we analyzed the effect of the HA/SA scaffold combined with BER on the healing of osteochondral defects in vivo. Finally, we explored the mechanism of this system in osteochondral repair. The results showed that the system could simultaneously regenerate not only the cartilage but also the subchondral bone. Our results also revealed that the subchondral bone was partially repaired by activating the Wnt signaling pathway and the cartilage was protected from degeneration by the upregulation of autophagy. This study demonstrated that the combination of the IPN scaffold of HA/SA and BER is a promising strategy for the osteochondral defect regeneration., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Hollow multilayered capsules have shown massive potential for being used in the biomedical and biotechnology fields, in applications such as cellular internalization, intracellular trafficking, drug delivery, or tissue engineering. In particular, hollow microcapsules, developed by resorting to porous calcium carbonate sacrificial templates, natural-origin building blocks and the prominent Layer-by-Layer (LbL) technology, have attracted increasing attention owing to their key features. However, these microcapsules revealed a great tendency to aggregate, which represents a major hurdle when aiming for cellular internalization and intracellular therapeutics delivery. Herein, we report the preparation of well-dispersed polysaccharide-based hollow multilayered microcapsules by combining the LbL technique with an optimized purification process. Cationic chitosan (CHT) and anionic alginate (ALG) were chosen as the marine origin polysaccharides due to their biocompatibility and structural similarity to the extracellular matrices of living tissues. Moreover, the inexpensive and highly versatile LbL technology was used to fabricate core-shell microparticles and hollow multilayered microcapsules, with precise control over their composition and physicochemical properties, by repeating the alternate deposition of both materials. The microcapsules' synthesis procedure was optimized to extensively reduce their natural aggregation tendency, as shown by the morphological analysis monitored by advanced microscopy techniques. The well-dispersed microcapsules showed an enhanced uptake by fibroblasts, opening new perspectives for cellular internalization., Competing Interests: The authors declare no conflict of interest.

Sodium alginate (SA) was oxidized using periodate and amphotericin B (AmB) was conjugated via imine and amine linkages to the oxidized alginate. Oxidization drastically reduced the molecular weight (MW) of the alginate. The conjugates were highly water-soluble to the extent of 1000mg/mL making them useful for therapeutic applications. SA-AmB conjugates derived from 20 and 50% oxidized alginate were non-toxic to HEK 293T and RAW 264.7 cell line at 100μg/mL and was also non-hemolytic to human blood at 100μg/mL. In vitro release of AmB into phosphate buffer from the imine conjugates was negligible with less than 0.2% of the drug released in 48h. Capping of residual aldehyde handles using 2-ethanolamine or glycine resulted in increased release of the drug in vitro. Injectable gels of gelatin crosslinked with oxidized alginate incorporating the SA-AmB conjugates as well as AmB were also fabricated and drug release was examined. In vitro release from the gel discs showed that AmB was released to the extent of 15-20% in 2days. The SA-AmB conjugates showed potent anti-fungal activity against C. albicans, C. neoformans and C. parapsilosis. The injectable gels seem to have potential for prolonged release of AmB when implanted., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Islet transplantation has the potential of reestablishing naturally-regulated insulin production in Type 1 diabetic patients. Nevertheless, this procedure is limited due to the low islet survival after transplantation and the lifelong immunosuppression to avoid rejection. Islet embedding within a biocompatible matrix provides mechanical protection and a physical barrier against the immune system thus, increasing islet survival. Alginate is the preferred biomaterial used for embedding insulin-producing cells because of its biocompatibility, low toxicity and ease of gelation. However, alginate gelation is poorly controlled, affecting its physicochemical properties as an injectable biomaterial. Including different concentrations of the phosphate salt Na 2 HPO 4 in alginate hydrogels, we can modulate their gelation time, tuning their physicochemical properties like stiffness and porosity while maintaining an appropriate injectability. Moreover, these hydrogels showed good biocompatibility when embedding a rat insulinoma cell line, especially at low Na 2 HPO 4 concentrations, indicating that these hydrogels have potential as injectable biomaterials for Type 1 Diabetes Mellitus treatment., (Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.)

The successful treatment of multi-drug resistant microbial pathogens represents a major challenge for public health management. Here, chitosan-alginate (CS/ALG) microspheres with narrow size distribution were fabricated by ionically cross linking method using Ca 2+ ions as agents for polymer solidification. The physicochemical properties of CS/ALG microspheres, such as surface morphology and size, were studied by SEM. The functional group interactions were confirmed by Fourier transform infrared (FTIR) spectroscopy. SEM revealed that the CS/ALG microspheres were spherical in shape with smooth surfaces, size was 50-100 μm. The synthesized CS/ALG microspheres showed antibacterial and antibiofilm activity on bacteria of public health relevance. CS/ALG microspheres exhibited antibacterial activity at the concentration of 5-20 μg, with significant inhibitory zones on multiple antibiotic resistant pathogens, including Gram positive Staphylococcus aureus, Enterococcus faecalis, and Gram negative Pseudomonas aeruginosa and Proteus vulgaris. Furthermore, in situ light microscopy and confocal laser scanning microscopy (CLSM) showed that CS/ALG microspheres inhibited the bacterial biofilm formation in S. aureus, E. faecalis P. aeruginosa and P. vulgaris after a single treatment with 40 μg. Overall, our findings underlined that chemically synthesized CS/ALG biomaterial has high antibacterial and antibiofilm activity against a number of microbial pathogens of interest for human health, thus this synthesis route can be further exploited for drug development in current biomedical science., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

This paper describes a centrifuge-based device for oil-free and mass production of calcium-alginate (Ca-alginate) particles. The device is composed of four components: a tank with a glass capillary for forming sodium alginate droplets, a collecting bath with calcium chloride (CaCl 2 ) solution, a waste liquid box, and a bypass channel bridged between the collecting bath and the waste liquid box. When the device is centrifuged, extra CaCl 2 solution in the collecting bath is delivered to the waste liquid box to maintain the appropriate liquid level of CaCl 2 solution for the production of monodisperse Ca-alginate particles. The proposed device enables oil-free production of over 45 000 uniformly sized Ca-alginate particles in a single 240 s process, whereas using the conventional method with only a glass capillary, ≈1000 particles are formed within the same processing time. Because of the high biocompatibility of the oil-free process, the device is applicable to cell encapsulation in Ca-alginate particles with high cell viability, as well as the formation of a macroscopic 3D cellular structure using Ca-alginate particles covered with cells as assembly modules. These results suggest that the device can be a useful tool for preparing experimental platforms in biomedical and tissue engineering fields., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

In the study reported here, two glucuronic acid-conjugated metabolites of 4-bromo-2,5-dimethoxyphenethylamine (2C-B)-a ring-substituted psychoactive phenethylamine-were chemically synthesized for the first time and a method for analyzing them in urine was developed. β-D-Glucuronide of 4-bromo-2,5-dimethoxyphenylethylalcohol was successfully synthesized using methyl 2,3,4-tri-Ο-acetyl-1-O-(trichloroacetimidoyl)-α-D-glucuronate as a glucuronyl donor and boron trifluoride diethylether complex as a Lewis acid catalyst. β-D-Glucuronide of 4-bromo-2,5-dimethoxyphenylacetic acid was synthesized by condensing 4-bromo-2,5-dimethoxyphenylacetic acid and benzyl D-glucuronate followed by benzyl group deprotection based on catalytic hydrogenation. Two glucuronic acid-conjugated metabolites of 2C-B in urine were qualitatively and semiquantitatively evaluated via direct liquid chromatography/mass spectrometry (LC/MS) analysis of a diluted urine sample. The simple method proposed is expected to be useful for studying the metabolic fate of 2C-B., (© 2016 American Academy of Forensic Sciences.)

Scaffolds made by biomaterials offer favorite environment for cell grow and show a wide potential application in tissue engineering. Novel biocompatibility materials polylatic acid (PLA) nanofiber membranes with favorable biocompatibility and good mechanical strength could serve as an innovative tissue engineering scaffold. Sodium alginate (SA) could be used in biomedical areas because of its anti-bacterial property, hydrophilicity and biocompatibility. In this article, we chose PLA as continuous phase and SA as dispersion phase to prepare a W/O emulsion and then electrospun it to get a SA/PLA composite nanofiber membranes. The CLSM images illustrated that the existence of SA was located on the surface of composite fibers and the FTIR results confirmed the result. A calcium ion replacement step was used as an after-treatment for SA/PLA nanofiber membranes in order to anchor the alginic ion in a form of gelated calcium alginate (CA). The single fiber tensile test shows a good mechanical property of CA/PLA nanofiber membranes, and the nanofiber membranes are beneficial for cell proliferation and differentiation owing to MTT array as well as Alizarin red S (ARS) staining test., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

An in situ formed hydrogel was synthesized by sodium alginate and cysteine methyl ester, which turned the sodium alginate into thiolated alginate (SA-SH). SA-SH can in situ formed into hydrogel (SA-SS-SA) with a large amount of water through covalent bond in less than 20 s. The structure characterization showed that the mechanism of SA-SH gelation was thiol-disulfide transformation. The rheology and cytotoxicity experiments of SA-SS-SA hydrogel were also investigated, which indicated that SA-SS-SA hydrogel had an appropriate mechanical strength as well as an excellent biocompatibility. The SA-SS-SA hydrogel would degrade under certain conditions after a few days and its mechanism was disulfide alkaline reduction. Finally, the hemostatic property of SA-SH was tested by rat tail amputation experiment. The time to hemostasis of rat reduced from 8.26 min to 3.24 min, which proved that SA-SH had an excellent hemostatic property., (© The Author(s) 2016.)

Unlabelled: An emerging strategy to improve adhesiveness of biomaterials in wet conditions takes inspiration from the adhesive features of marine mussel, which reside in the chemical reactivity of catechols. In this work, a catechol-bearing molecule (dopamine) was chemically grafted onto alginate to develop a polysaccharide-based membrane with improved adhesive properties. The dopamine-modified alginates were characterized by NMR, UV spectroscopy and in vitro biocompatibility. Mechanical tests and in vitro adhesion studies pointed out the effects of the grafted dopamine within the membranes. The release of HA from these resorbable membranes was shown to stimulate fibroblasts activities (in vitro). Finally, a preliminary in vivo test was performed to evaluate the adhesiveness of the membrane on porcine intestine (serosa). Overall, this functionalized membrane was shown to be biocompatible and to possess considerable adhesive properties owing to the presence of dopamine residues grafted on the alginate backbone., Statement of Significance: This article describes the development of a mussels-inspired strategy for the development of an adhesive polysaccharide-based membrane for wound healing applications. Bioadhesion was achieved by grafting dopamine moieties on the structural component on the membrane (alginate): this novel biomaterial showed improved adhesiveness to the intestinal tissue, which was demonstrated by both in vitro and in vivo studies. Overall, this study points out how this nature-inspired strategy may be successfully exploited for the development of novel engineered biomaterials with enhanced bioadhesion, thus opening for novel applications in the field of general surgery., (Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Unlabelled: Carbon quantum dots (CQDs), unlike semiconductor quantum dots, possess fine biocompatibility, excellent upconversion properties, high photostability and low toxicity. Here, we report multifunctional CQDs which were developed using alginate, 3% hydrogen peroxide and double distilled water through a facile, eco-friendly and inexpensive one-step hydrothermal carbonization route. In this reaction, the alginate served as both the carbon source and the cationization agent. The resulting CQDs exhibited strong and stable fluorescence with water-dispersible and positively-charged properties which could serve as an excellent DNA condensation. As non-viral gene vector being used for the first time, the CQDs showed considerably high transfection efficiency (comparable to Lipofectamine2000 and significantly higher than PEI, p<0.05) and negligible toxicity. The photoluminescence properties of CQDs also permitted easy tracking of the cellular-uptake. The findings showed that both caveolae- and clathrin-mediated endocytosis pathways were involved in the internalization process of CQDs/pDNA complexes. Taken together, the alginate-derived photoluminescent CQDs hold great potential in biomedical applications due to their dual role as efficient non-viral gene vectors and bioimaging probes., Statement of Significance: This manuscript describes a facile and simple one-step hydrothermal carbonization route for preparing optically tunable photoluminescent carbon quantum dots (CQDs) from a novel raw material, alginate. These CQDs enjoy low cytotoxicity, positive zeta potential, excellent ability to condense macromolecular DNA, and most importantly, notably high transfection efficiency. The interesting finding is that the negatively-charged alginate can convert into positively charged CQDs without adding any cationic reagents. The significance of this study is that the cationic carbon quantum dots play dual roles as both non-viral gene vectors and bioimaging probes at the same time, which are most desirable in many fields of applications such as gene therapy, drug delivery, and bioimaging., (Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

The aim of our research activity was to obtain a biocompatible nanostructured composite based on naturally derived biopolymers (chitin and sodium alginate) loaded with commercial antibiotics (either Cefuroxime or Cefepime) with dual functions, namely promoting wound healing and assuring the local delivery of the loaded antibiotic. Compositional, structural, and morphological evaluations were performed by using the thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and fourier transform infrared spectroscopy (FTIR) analytical techniques. In order to quantitatively and qualitatively evaluate the biocompatibility of the obtained composites, we performed the tetrazolium-salt (MTT) and agar diffusion in vitro assays on the L929 cell line. The evaluation of antimicrobial potential was evaluated by the viable cell count assay on strains belonging to two clinically relevant bacterial species (i.e., Escherichia coli and Staphylococcus aureus).

A facile and flexible approach is developed for controllable fabrication of novel multiple-compartmental calcium alginate capsules from all-aqueous droplet templates with combined coextrusion minifluidic devices for isolated coencapsulation and synergistic release of diverse incompatible components. The multicompartmental capsules exhibit distinct compartments, each of which is covered by a distinct part of a heterogeneous shell. The volume and number of multiple compartments can be well-controlled by adjusting flow rates and device numbers for isolated and optimized encapsulation of different components, while the composition of different part of the heterogeneous shell can be individually tailored by changing the composition of droplet template for flexibly tuning the release behavior of each component. Two combined devices are first used to fabricate dual-compartmental capsules and then scaled up to fabricate more complex triple-compartmental capsules for coencapsulation. The synergistic release properties are demonstrated by using dual-compartmental capsules, which contain one-half shell with a constant release rate and the other half shell with a temperature-dependent release rate. Such a heterogeneous shell provides more flexibilities for synergistic release with controllable release sequence and release rates to achieve advanced and optimized synergistic efficacy. The multicompartmental capsules show high potential for applications such as drug codelivery, confined reactions, enzyme immobilizations, and cell cultures.

Alginate-based supramolecular ionic polyurethanes (ASPUs) as mechanically tunable biomaterials with high strength and toughness in both dry and hydrated states are developed under metal-free conditions. The Young's modulus and tensile strength of ASPUs are tuned from 30 to 100 MPa, and 20 to 50 MPa, respectively. Interestingly, the ASPUs exhibit a small hysteresis loop, minimal loss of tensile strength and minimal creep deformation after 100 repetitive cycles which makes them of use for engineering of load-bearing tissues. This is the first report that describes a linear PU can resist a large number of cyclic stresses without significant stretching. These bio-based elastomers engineered by ionic interactions are biocompatible and biodegradable. The ASPUs demonstrate a similar in vivo degradation rate compared to polycaprolactone (PCL). These biomaterials also demonstrate a rapid self-healing and recovery after rupture, and have a linear biodegradation profile. Furthermore, histological examination of subcutaneous transplanted ASPUs after five months reveals low immunological response and low fibrosis., (Copyright © 2016. Published by Elsevier Ltd.)

Extracellular matrix provides both mechanistic and chemical cues that can influence cellular behaviors such as adhesion, migration, proliferation, and differentiation. In this study, a new material, HA-L-Alg, was synthesized by linking developmentally essential ECM constituents hyaluronic acid (HA) and laminin(L) to alginate (Alg). The fabrication of HA-L-Alg was confirmed by FTIR spectroscopy, and it was used to form 3D cell-carrying beads. HA-L-Alg beads had a steady rate of degradation and retained 63.25% of mass after 9 weeks. HA-L-Alg beads showed biocompatibility comparable to beads formed by Alg-only with no obvious cytotoxic effect on the embedded 3T3-L1 preadipocytes. HA-L-Alg encapsulated 3T3-L1 cells were found to have a higher proliferation rate over those in Alg-only beads. These cells also showed better differentiation capacity after 2 weeks of adipogenic induction within HA-L-Alg beads. These results support that HA-L-Alg facilitated cell survival and proliferation, as well as stimulated and maintained cell differentiation. Our results suggest that HA-L-Alg has a great clinical potential to be used as stem cell carrier for adipose tissue engineering. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 669-677, 2016., (© 2015 Wiley Periodicals, Inc.)

Biopolymers are widely used for the removal of chromium from aqueous medium but it possesses limitations like poor sorption capacity and low stability. To overcome the limitations of biopolymers and to improve their properties, the present study was designed in such a way to develop a novel sorbent with enhanced chromium sorption capacity and better stability by synthesizing metal ion cross-linked binary biocomposites using biopolymers like alginate and gelatin cross-linked with Ca2+, Ce3+ and Zr4+ ions namely Ca@AlgGel, Ce@AlgGel and Zr@AlgGel composites. The functional groups, agglomeration, surface area, surface morphology, elemental analysis and thermal stability of the composites were investigated by FTIR, TEM, BET, SEM with EDAX and TGA analysis. The chromium removal studies of the biocomposites were carried out in batch mode. The sorption process was optimized by varying the influencing aspects like contact time, dosage, presence of common ions, pH, initial chromium concentration and temperature. The maximum sorption capacity of Ca@AlgGel, Ce@AlgGel and Zr@AlgGel composites were found to be 19.40, 24.50 and 25.40 mg/g, respectively. The sorption data was fitted by using Freundlich, Langmuir and Dubinin-Radushkevich (D-R) isotherms. Thermodynamic parameters indicate the nature of chromium sorption. The suitability of the composite materials was also tested under the field conditions., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: Chitosan and alginate are two natural and accessible polymers that are known to be biocompatible, biodegradable and possesses good antimicrobial activity. When combined, they exhibit desirable characteristics and can be created into a scaffold for cell culture., Objective: In this study interaction of chitosan-alginate scaffolds with mesenchymal stem cells are studied., Methods: Mesenchymal stem cells were derived from human umbilical cord tissues, characterized by flow cytometry and other growth parameters studied as well. Proliferation and viability of cultured cells were studied by MTT Assay and Trypan Blue dye exclusion assay., Results: Besides chitosan-alginate scaffold was prepared by freeze-drying method and characterized by FTIR, SEM and Rheological properties. The obtained 3D porous structure allowed very efficient seeding of hUMSCs that are able to inhabit the whole volume of the scaffold, showing good adhesion and proliferation. These materials showed desirable rheological properties for facile injection as tissue scaffolds., Conclusion: The results of this study demonstrated that chitosan-alginate scaffold may be promising biomaterial in the field of tissue engineering, which is currently under a great deal of examination for the development and/or restoration of tissue and organs. It combines the stem cell therapy and biomaterials.

Oxymatrine (OM) can be metabolized to matrine in gastrointestinal ileocecal valve after oral administration, which affects pharmacological activity and reduce bioavailability of OM. A type of multiple-unit alginate-chitosan (Alg-Cs) floating beads was prepared by the ionotropic gelation method for gastroretention delivery of OM. A solid dispersion technique was applied and incorporated into beads to enhance the OM encapsulation efficiency (EE) and sustain the drug release. The surface morphology and internal hollow structure of beads were evaluated using optical microscopy and scanning electron microscopy (SEM). The developed Alg-Cs beads were spherical in shape with hollow internal structure and had particle size of 3.49 ± 0.09 mm and 1.33 ± 0.09 mm for wet and dried beads. Over 84% of the optimized OM solid dispersion-loaded Alg-Cs beads were able to continuously float over the simulated gastric fluid for 12 h in vitro. The OM solid dispersion-loaded Alg-Cs beads showed drug EE of 67.07%, which was much higher than that of beads loading with pure OM. Compared with the immediate release of OM capsules and pure OM-loaded beads, the release of OM from solid dispersion-loaded Alg-Cs beads was in a sustained-release manner for 12 h. Prolonged gastric retention time of over 8.5 h was achieved for OM solid dispersion-loaded Alg-Cs floating beads in healthy rabbit in in vivo floating ability evaluated by X-ray imaging. The developed Alg-Cs beads loading with OM solid dispersion displayed excellent performance features characterized by excellent gastric floating ability, high drug EE and sustained-release pattern. The study illustrated the potential use of Alg-Cs floating beads combined with the solid dispersion technique for prolonging gastric retention and sustaining release of OM, which could provide a promising drug delivery system for gastric-specific delivery of OM for bioavailability enhancement.

Dipeptides and their derivatives have attracted tremendous attention owning to their excellent abilities of self-assemble assembling into various structures which have great potentials for applications in biology and/or nanotechnology. In the present study, we dedicate to fabricate a rigid and structure controllable Fmoc-FF/SA composite hydrogel. We found that the modified dipeptide, fluorenyl-9-methoxycarbonyl (Fmoc)-diphenylalanine (Phe-Phe) can self-assemble into rigid hydrogels with structures of nanowires, layered thin films or honeycombs as the change of sodium alginate (SA) concentration. Meanwhile, CD-spectroscopy demonstrated that SA appeared to control the process, but it did not change the arrangement of the Fmoc-FF peptide. Our results demonstrated that the formed hydrogel showed physical and chemical stability as well as possessing good biocompatibility. Rheological measurements showed that the addition of SA could improve the stability of the hydrogel. Cell viability assay revealed that the Fmoc-FF and Fmoc-FF/SA hydrogels are both beneficial for cell proliferation in-vitro. Our results indicated that the fabricated Fmoc-FF/SA composite hydrogels could be used in tissue engineering and drug delivery in the future., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Alginate-degrading enzyme, alginate lyase, catalyzes the cleavage of glycosidic 1-4 O-linkages between uronic acid residues of alginate by a β-elimination reaction leaving a 4-deoxy-l-erythro-hex-4-ene pyranosyluronate as nonreducing terminal end. The enzymes from a wide variety of sources such as marine molluscs, seaweeds, and marine bacteria have been discovered and studied not only from a point of view of enzymological interest of enzyme itself but also for elucidation of fine chemical structure of alginate, structure-activity relationship of alginate, and biological activities and physicochemical features of the enzymatic digestion products. Based on the substrate specificities, alginate lyases are classified into three groups: poly(β-d-mannuronate) lyase, poly(α-l-guluronate) lyase, and bifunctional alginate lyase, which are specific to mannuronate, guluronate, and both uronic acid residues, respectively. We have studied enzymological aspects of these three types of alginate lyases, and bioactivities of enzymatically digested alginate oligomers. In this chapter, we described the purification and characterization of three types of alginate lyases from different marine origins and overviewed the bioactivities of alginate oligomers., (© 2016 Elsevier Inc. All rights reserved.)

Cross-linked calcium alginate gels are too viscous to be efficaciously incorporated into spray dried formulations. Thus, viscosity reduction is essential to ensure the processability of calcium alginate gels to be sprayed. Viscosity reduction by high pressure homogenization can open new formulation possibilities. Presently, testing of microcapsule integrity is also limited because either single particle tests neglect collective particle behaviours in bulk or bulk testing methods are often associated with single compressions which may not fully characterize individual particle strengths. The aim of this study was sub-divided into three objectives. First objective was to evaluate the impact of high pressure homogenization on gel viscosity. Second objective was to explore the use of the homogenized gels with modified starch for microencapsulation by spray drying. The final objective was to develop a stamping system as microcapsule strength tester that can assess microcapsules in bulk and evaluate the impact of multiple compressions. Collectively, this study would lead towards developing a pressure-activated patch of microcapsules with encapsulated volatiles and the method to assess the patch efficacy. The alginate gels largely experienced an exponential decay in viscosity when homogenized. Furthermore, the homogenized gels were successfully incorporated in spray drying formulations for microencapsulation. The custom-designed microcapsule strength tester was successfully used and shown to possess the required sensitivity to discern batches of microcapsules containing volatiles to have different release profiles. Addition of homogenized gels strengthened the microcapsules only at high wall to core ratios with low mass-load alginate gels. High mass-load gels weaken the microcapsules, exhibiting a higher release at low stamping pressures and wrinkling on the microcapsules surface., (Copyright © 2015 Elsevier B.V. All rights reserved.)

The spatial positioning of 3D tumor-mimetic microenvironments, containing multiple cell types, is controlled with a simple concentric flow device in a single step. A range of geometric architectures are demonstrated, and the migration of segregated tumor cells and macrophages is explored using drugs that inhibit heterotypic interactions., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Polysaccharide-based nanoparticles can be formed, under the right conditions, when a counterion is added to a dilute polysaccharide solution. In this study, the possibility of preparing stable alginate nanoparticles cross-linked with zinc was investigated. The effects of the ionic strength of the solvent and the concentration of zinc were studied. The nanoparticles were characterized by dynamic light scattering, zeta potential and pH measurements. The results showed that an increase in the ionic strength of the solvent provided nanoparticles with considerably narrower size distributions compared to pure water, and a small size. The zinc content was shown to be an important factor for the formation of the nanoparticles. In fact, a critical zinc concentration was needed to obtain nanoparticles, and below this concentration particles were not formed. A stepwise increase in the amount of zinc revealed the process of formation of the nanoparticles. The stages of the nanoparticle formation process were identified, and differences according to the ionic strength of the solvent were also reported. Furthermore, the stability test of the most promising formulation showed a stability of over ten weeks.

The total synthesis of mixed-sequence alginate oligosaccharides, featuring both β-D-mannuronic acid (M) and α-L-guluronic acid (G), is reported for the first time. A set of GM, GMG, GMGM, GMGMG, GMGMGM, GMGMGMG, and GMGGMG alginates was assembled using GM building blocks, having a guluronic acid acceptor part and a mannuronic acid donor side to allow the fully stereoselective construction of the cis-glycosidic linkages. It was found that the nature of the reducing-end anomeric center, which is ten atoms away from the reacting alcohol group in the key disaccharide acceptor, had a tremendous effect on the efficiency with which the building blocks were united. This chiral center determines the overall shape of the acceptor and it is revealed that the conformational flexibility of the acceptor is an all-important factor in determining the outcome of a glycosylation reaction., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

An efficient one-step process to synthesize highly porous (Ca-alginate-SiO2-polycation) shell: (Na-alginate-SiO2) core hybrid beads for cell encapsulation, yielding a reusable long-life photosynthetically active material for a sustainable manufacture of high-value metabolites is presented. Bead formation is based on crosslinking of an alginate biopolymer and mineralisation of silicic acid in combination with a coacervation process between a polycation and the silica sol, forming a semi-permeable external membrane. The excellent mechanical strength and durability of the monodispersed beads and the control of their porosity and textural properties is achieved by tailoring the silica and alginate loading, polycation concentration and incubation time during coacervation. This process has led to the formation of a remarkably robust hybrid material that confers exceptional protection to live cells against sheer stresses and contamination in a diverse range of applications. Dunaliella tertiolecta encapsulated within this hybrid core-shell system display high photosynthetic activity over a long duration (>1 year). This sustainable biotechnology could find use in high value chemical harvests and biofuel cells to photosynthetic solar cells (energy transformation, electricity production, water splitting technologies). Furthermore the material can be engineered into various forms from spheres to variable thickness films, broadening its potential applications., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Alginate hydrogels are well-characterized, biologically inert materials that are used in many biomedical applications for the delivery of drugs, proteins, and cells. Unfortunately, canonical covalently crosslinked alginate hydrogels are formed using chemical strategies that can be biologically harmful due to their lack of chemoselectivity. In this work we introduce tetrazine and norbornene groups to alginate polymer chains and subsequently form covalently crosslinked click alginate hydrogels capable of encapsulating cells without damaging them. The rapid, bioorthogonal, and specific click reaction is irreversible and allows for easy incorporation of cells with high post-encapsulation viability. The swelling and mechanical properties of the click alginate hydrogel can be tuned via the total polymer concentration and the stoichiometric ratio of the complementary click functional groups. The click alginate hydrogel can be modified after gelation to display cell adhesion peptides for 2D cell culture using thiol-ene chemistry. Furthermore, click alginate hydrogels are minimally inflammatory, maintain structural integrity over several months, and reject cell infiltration when injected subcutaneously in mice. Click alginate hydrogels combine the numerous benefits of alginate hydrogels with powerful bioorthogonal click chemistry for use in tissue engineering applications involving the stable encapsulation or delivery of cells or bioactive molecules., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

A photoresponsive hybrid alginate hydrogel was successfully prepared by Ca(2+)-mediated crosslinking reaction with a mixture of β-cyclodextrin-grafted alginate (β-CD-Alg) and diazobenzene-modified poly(ethylene glycol) (Az2-PEG). The water-soluble Az2-PEG exhibits efficient trans-to-cis isomerization of the terminal azobenzene moieties under UV-light irradiation and readily switched back to the initial trans state under visible light. Because of low affinity between β-CD and cis-Az, the host-guest inclusion complex formed by β-CD and trans-Az gradually dissociates under UV-light exposure. Accordingly, the bulk gel exhibits substantial photo-induced transformation in gel morphology by the appearance of significant comb-like cavities. This photosensitive behavior accompanied by the structural degradation enables the rapid release of entrapped dye molecules under UV light stimulus. Moreover, an incident light with higher power and mild acidic environment are capable of accelerating the photo-triggered release, thus allowing the potential applications toward acute wound healing., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

In this study, Pasteurella multocida-loaded alginate microparticles (MPs) for subcutaneous vaccination was developed by emulsification-cross-linking technique. Formulation parameter was varied as a ratio of polymer and bacterin. Optical microscopy revealed spherical particles with uniformly distribution. A mean particle size of approximately 6 µm has been successfully constructed using simple mixer and ultrasonic probe. The zeta potential of the MPs showed negatively charge of approximately -23 mV determined by Zeta Pals® analyzer. The entrapment efficiency and the in vitro bacterin released profile could be controlled by varying the amount of alginate. The high entrapment efficiency up to 69% was achieved with low concentration of alginate. The MPs possessed a slow bacterin release profile, up to 30 days. In vivo safety and potency tests were proved that the alginate MPs were safe and induced protective immunity in mice. In addition, after storage for 6 months at either 4 °C or room temperature, the protective immunity in mice was maintained.

Commercial lipid emulsion of propofol (CLE) has several drawbacks including pain on injection and emulsion instability. In this paper, a novel nanocarrier system is introduced to improve stability and solubility of the poorly soluble anesthetic drug, propofol, for intravenous administration. In this paper, alginate is modified using a facile method in which the carboxylic group of alginate is grafted to octanol. The octanol-grafted alginate (Alg-C8) is then employed to prepare nanoparticles which are subsequently used for encapsulation of propofol. The nanoparticles are analyzed for their pH, osmolarity, particle size, stability, morphology and sleep recovery and the results are compared with CLE as control. It is revealed that nanoparticles have the average particle size of 180 nm ± 1.2 and spherical morphology which is less than CLE while their pH, osmolarity and profile of release of formulated nanoparticles are similar to those of CLE. In addition, the results show good chemical and physical storage stability for the nanoparticles at room temperature for at least 6 months compared to CLE as control. The animal sleep recovery test on rats shows no significant difference in time of unconsciousness and recovery of the righting reflex between nanoparticles and CLE. It is concluded that encapsulated nanoparticles introduced here could be a promising clinical intravenous system for delivery of poorly soluble anesthetic propofol. In addition, this study provides an efficient and facile method for preparing a carrier system for water insoluble drugs.

In the present study, sodium alginate-polyaniline (SAP) nanofibers are evaluated as an adsorbent for the removal of Cr(VI) ion from aqueous solution by batch mode. The SAP nanofibers are characterized using FTIR, SEM, EDX and XRD techniques. The influences of various parameters such as pH, dosage, co-anions, contact time and concentration on Cr(VI) removal efficiency are investigated. The results of FTIR, SEM and EDX analysis reveals the removal of Cr(VI) ions by SAP nanofibers. Also, the existence of the electrostatic interaction between the Cr(VI) ions and SAP nanofibers is further proved by FTIR analysis. The equilibrium data obtained from the experiments are well fitted to the Freundlich isotherm than Langmuir isotherm. The values of Q°, k(F) and thermodynamic parameters reveal the endothermic nature of the Cr(VI) removal process. The Langmuir maximum sorption capacity of SAP nanofibers for Cr(VI) ion at 303 K is calculated to be 73.34 mg g(-1). The kinetic data are well expressed by pseudo-second-order model. Desorption and regeneration experiment shows that the SAP nanofibers can be reused for more than three successive cycles., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Present communication reports on the synthesis and characterization of Hg(II) sorbing millimeter sized porous titania spheres (TSP). The synthesis utilizes guar gum-alginate hybrid beads as sacrificial template to polymerize titanium(IV) isopropoxide. The hybrid beads are crafted by pouring guar-alginate mixed solution to calcium bath. The mechanical strength of the beads depended on guar to alginate ratio in the mixed solution. The equal weight ratio of the two polysaccharides is appropriate for adequate mechanical strength beads. The unique performance of the templating beads is attributed to the synergistic interaction between guar gum and sodium alginate. FTIR, BET, SEM, TEM, XRD, TGA, and DTG analyses have been used for the characterization of the optimum performance TSP (TSPAG2). TSPAG2 is a mesoporous material that has higher surface area and narrower pore size distribution than pure alginate derived titania spheres (TSPA). TEM study demonstrated that TSPAG2 spheres are constituted of aggregated TiO2 nanoparticles of ∼ 10 nm size. TSPAG2 is able to capture >95% Hg(II) from synthetic Hg(II) solution in 10h at pH 5 as opposed to only 68% removal by TSPA., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The present work is an agreement with simple and efficient method of improving the therapeutic efficacy of ibuprofen by masking its acidic moiety. It aims to reduce gastrointestinal side effects by controlling the rate, duration and site of release. This is achieved by synthesis and evaluation of polymeric prodrug of ibuprofen with natural polymer sodium alginate. The synthesis was supported by N-protected serine as spacer due to chemical incompatibility of drug and polymer. Synthesized prodrug was characterized for confirmation of said structures. The in-vitro dissolution profile of ibuprofen-alginate prodrug showed that the release of the drug is significantly higher in case of pH 7.2 buffer as compared to ibuprofen, which might be due to ester group adjacent to drug get hydrolyzed. The hydrolysis was found to be with faster rate in alkaline media than that of in acidic media.

Context: The excellent gelling and safety profiles of alginic acid combined, however, with drawbacks of its ionotropically crosslinked beads (i.e. their quick release of loaded drugs) prompted us to chemically modify alginic acid., Objective: Alginic acid was chemically conjugated with four amines of varying hydrophilic-hydrophobic properties (i.e. tris(hydroxymethyl)methyl-, allyl-, benzyl- or pentyl-amines) in an attempt to enhance the drug release profiles from respective metal crosslinked beads., Materials and Methods: Chemical conjugation procedures were performed using dicyclohexylcarbodiimide as a coupling agent and the resulting new derivatives were characterized using proton nuclear magnetic resonance ((1)H NMR), infrared (IR) spectroscopy and differential scanning calorimetry (DSC). These modified polymers were used to prepare iron (III)-crosslinked beads loaded with folic acid as model drug, which were tested in vitro to assess their folic acid release profiles., Results and Discussion: Interestingly, the resulting beads accessed enteric release kinetics, with tris(hydroxymethyl)methyl-amide alginic conjugate producing most pronounced enteric profile., Conclusion: The results suggest the possibility of achieving controlled drug release from alginate-based beads via facile chemical modification of alginic acid.

Oxygen-releasing alginate beads (ORABs), a new concept of oxygen-releasing compounds (ORCs) designed to overcome some limitations regarding the fast oxygen release rate and the high pH equilibrium of ORCs, were fabricated to promote the stimulation of aerobic biodegradation in anaerobic groundwater. Slow oxygen-releasing rate and maintenance of constant pH were achieved by changing the parameters (ionic radius and valence) related to the cross-linking ions composing ORABs, and the best results were obtained for ORABs cross-linked with Al (Al-ORABs). Furthermore, the mechanism of the improved aerobic biodegradation using Al-ORABs under oxygen-limiting groundwater conditions was elucidated in batch and column studies with 1,4-dioxane and Mycrobacterium sp. PH-06 as a model contaminant and aerobic microbes, respectively. Maximum 1,4-dioxane degradations of 99% and 68.1% were achieved when Al-ORABs were applied in batch and column conditions, respectively, whereas 34.3% and 18% of 1,4-dioxane were degraded without Al-ORABs in batch and column conditions, respectively., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Multifunctional injectable thermo-/pH-responsive hydrogels as release systems for the oral delivery of small molecule drugs and the local delivery of protein are presented. The injectable interpenetrating polymer network (IPN) hydrogels based on poly(ethylene glycol) methacrylate, N-isopropylacrylamide, and methacrylated alginate were prepared by using ammonium persulfate (APS) and N,N,N',N'-tetramethylethylenediamine (TEMED) as a redox initiator system at body temperature, and the obtained hydrogels overcame the instability of calcium cross-linked alginate hydrogels under physiological conditions. The hydrogels showed good mechanical strength by rheometer and exhibited temperature and pH sensitivity by a swelling test. Diclofenac sodium (DCS) as a model for small molecule water-soluble anti-inflammatory drugs and bovine serum albumin (BSA) as a model for protein drugs were encapsulated in situ in the hydrogel. The DCS and BSA release results indicated that these hydrogels, as carriers, have great potential for use in the oral delivery of small molecule drugs and for long-term localized protein release. Furthermore, the cytotoxicity of these hydrogels was studied via live/dead viability and alamarBlue assays using adipose tissue-derived mesenchymal stem cells.

Niosomes are vesicular systems composed of surfactant molecules, claimed to be used as drug delivery carriers thanks to their physico-chemical and biological properties. The aim of this work was to design niosomes obtained with a surfactant synthesized from glucuronic acid. Doxorubicin and 5FU were used as model drugs. Niosomes were prepared with different ratios between surfactant and cholesterol, and characterized in terms of size, morphology, drugs entrapment efficiency and in vitro releases, to identify the optimal formulation to be used in pharmaceutical fields. In addition, the hemolytic activity of all formulations have been also evaluated. Results showed that dodecylglucuronamide surfactant was able to produce vesicular systems with or without the presence of cholesterol. Niosomes resulted regular in size and shape and they have been found to encapsulate and release in a controlled manner both doxorubicin and 5-fluorouracil. Hemolytic tests showed that the capability of disrupting erythrocyte only depend on the size of colloidal aggregates. Finally, our formulations could be potentially used as antitumoral delivery systems in anticancer therapy., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Sodium alginate/Na(+)rectorite-graft-itaconic acid/acrylamide (SA/Na(+)REC-g-IA/AM) hydrogel film was prepared via solution polymerization. The effect of Na(+)REC, KPS, and NMBA content and the ratio of IA to AM on graft ratio, graft efficiency and absorption of liquids were investigated. The structure and morphology were analyzed by FTIR, XRD, TEM and SEM. Results revealed that the optimal Na(+)REC, KPS, and NMBA content and the ratio of IA to AM were 2wt%, 0.8wt%, 0.38wt% and 4, respectively. The hydrogel film was found to exhibit an intercalative structure and coarse surface. The mechanism of graft copolymerization was discussed. A slower and more continuous release of salicylic acid for SA/Na(+)REC-g-IA/AM composite hydrogel film was shown in vitro drug-controlled release studies, in comparison with SA film. The salicylic acid release mechanism of SA/Na(+)REC-g-IA/AM hydrogel film followed Fickian diffusion., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The semi-interpenetrating networks (semi-IPNs) of acrylamide grafted sodium alginate (AAm-g-NaAlg) microspheres (MPs) were prepared by emulsion-crosslinking method using glutaraldehyde (GA) as a crosslinking agent. The grafting of acrylamide onto sodium alginate was prepared by free-radical graft polymerization using ceric ammonium nitrate (CAN) as initiator at three acrylamide concentrations with monomer to polymer ratio of 1:1, 2:1 and 3:1, respectively. The grafting efficiency was found to be 91%. The produced MPs are almost spherical in nature with smooth surfaces. Diclofenac sodium (DS), an anti-inflammatory drug was successfully encapsulated into the MPs. The encapsulation efficiency was found to vary between 83% and 95%. The MPs were characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The diffusion coefficient (D) was dependent upon the amount of crosslinking agent (GA) and amount of grafting ratio in the matrix. The rate of release was found to be dependent on the amount of GA, AAm:NaAlg grafting ratio and % drug loading in the MPs. The release data have been fitted to an empirical equation to investigate the diffusional exponent (n), which indicated that the release mechanism from MPs follows the super Case II transport., (Copyright © 2013 Elsevier B.V. All rights reserved.)

This study reports the synthesis of mesoporous silica nanoparticle-encapsulated alginate microparticles (MSN@Alg) for sustained release and targeting therapy. The MSN@Alg was synthesized by air dynamical atomization, and the effects of several critical factors including concentration of alginate solution, flow rate of alginate solution, flow rate of air, the distance between nozzle and calcium bath, and stirring rate of calcium on the particle size of the synthesized MSN@Alg were investigated. For studying the sustained release properties of the MSN@Alg, rhodamine 6G (R6G) was used as a model drug, and we compared the release properties of R6G/MSN and R6G/MSN@Alg using different concentrations of alginate, concentrations and volumes of phosphate-buffered saline (PBS) buffer solutions. The sustained release behavior of the R6G/MSN@Alg system can be prolonged to 20 days with an optimal condition of 1 mg R6G/MSN@Alg to 2 mL PBS (10 mM). To achieve targeting therapy, an anticancer drug, doxorubicin (Dox), was loaded into MSN@Alg, and a arginine, glycine, and aspartic acid (RGD)-based peptide was functionalized onto the surface of MSN@Alg for the purpose of specific targeting. The results showed that the intracellular drug delivery efficiency was greatly enhanced (i.e., 3.5-folds) for the Dox/MSN@Alg-RGD drug delivery system., (Copyright © 2013 Wiley Periodicals, Inc.)

The scarcity and expense of access to L-sugars and other rare sugars have prevented the exploitation of their biological potential; for example D-psicose, only recently available, has been recognized as an important new food. Here we give the definitive and cheap synthesis of 99.4% pure L-glucose from D-glucose which requires purification of neither intermediates nor final product other than extraction into and removal of solvents; a simple crystallization will raise the purity to >99.8%., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Alginic acid was converted to a variety of ammonium alginate derivatives carrying diverse chemical cargo such as analgesics, antibiotics, and enzymes. These functional polymers could be fashioned into nanofibrous mats by electrostatic spinning. The therapeutic payload could be released in functional form by a simple ion exchange mechanism. Prospects in wound healing are discussed.

A degradable, cytocompatible bioadhesive can facilitate surgical procedures and minimize patient pain and post-surgical complications. In this study a bioadhesive hydrogel system based on oxidized methacrylated alginate/8-arm poly(ethylene glycol) amine (OMA/PEG) has been developed, and the bioadhesive characteristics of the crosslinked OMA/PEG hydrogels evaluated. Here we demonstrate that the swelling behavior, degradation profiles, and storage moduli of crosslinked OMA/PEG hydrogels are tunable by varying the degree of alginate oxidation. The crosslinked OMA/PEG hydrogels exhibit cytocompatibility when cultured with human bone marrow-derived mesenchymal stem cells. In addition, the adhesion strength of these hydrogels, controllable by varying the alginate oxidation level and measured using a porcine skin model, is superior to commercially available fibrin glue. This OMA/PEG hydrogel system with controllable biodegradation and mechanical properties and adhesion strength may be a promising bioadhesive for clinical use in biomedical applications, such as drug delivery, wound closure and healing, biomedical device implantation, and tissue engineering., (Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Alginate has been commonly used as a model foulant in studies of membrane organic fouling. As a complex polymer, alginate is composed of two different monomers, namely M ((1 → 4) linked β-D-mannopyranuronic acid) and G ((1 → 4) linked α-L-gulopyranuronic acid) which are randomly arranged into MG-, MM- and GG-blocks. So far, little information is available about fouling propensity of each block in microfiltration. In this study, microfiltration experiments were conducted respectively with MG-, MM- and GG-blocks separated from alginate under defined conditions. Results showed the severest fouling in the filtration of MG-block, and the least flux decline in the filtration of MM-block. The initial pore blocking was found to be responsible for the fouling observed in MG-block filtration, while the cake layer formed on membrane surface during the MM-block filtration could serve as a pre-filter that prevented membrane from further pore blocking. In order to look into fouling mechanisms, the effects of transparent exopolymeric particles (TEP) on membrane fouling were also studied. TEP were found to form through aggregation or cross-link of alginate blocks. As TEP were bigger than original alginate blocks, they could facilitate the formation of cake layer on membrane surface. It was observed that more TEP were produced from MM-blocks than from MG-blocks in solutions. This in turn explained why cake resistance was dominant in the filtration of MM-blocks as compared to MG-blocks. The analysis by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory further revealed that MM-blocks had lowest cohesive interaction energy among all three alginate blocks, which favoured aggregation of MM-blocks, and ultimately leading to the formation of more TEP. This study provided insights into the roles of different alginate blocks in development of membrane fouling, and suggested that the membrane fouling would be related to molecular structure of alginate., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Anion receptors containing glucuronic acid were synthesized, and their anion binding ability studied. Chirality of anionic guests derived from mandelic acid and amino acids can be distinguished not only in terms of stability constants but also by significant differences in chemical shift changes for sugar moiety protons.

Microbubble particles have been extensively utilized as temporal templates for various biomedical applications. This study proposes a facile strategy to obtain microbubble-containing alginate particles (i.e., microbubbles inside alginate gel particles, called alginate microbubbles). The chemical reaction of sodium bicarbonate and hydrogen peroxide to produce gaseous carbon dioxide and oxygen was utilized to form microbubbles within alginate particles. Uniform alginate particles were obtained by a stable needle-based droplet formation process. Kinetic reaction of gas formation was monitored for 2% alginate particles. The gas formation increased with the concentrations of sodium bicarbonate (1-5 wt%) and hydrogen peroxide (0-36.5 wt%).

Silk fibroin (SF)/sodium alginate (SA) hydrogels can be used as drug injection materials. Homogenate was prepared by centrifugation of the pig myocardial extracellular matrix (PMM) and its modification of SF gel material. This paper observes and compares the different components SF, SF/SA, SF/SA/PMM to illustrate the SF/SA/PMM ternary material as a drug delivery composition material. This ternary material can shorten the gel time, and can make the gel form to be maintained better. Meanwhile, it makes the internal structure of the gel looser so that the hole wall becomes thinner and more conducive to the drug release. In addition, it has good biocompatibility proved by pathological analysis, and is able to enhance the mesenchymal stem cells growth activity, which has great significance in carrying out drug control release.

N-trimethyl chitosan of two quaternization degrees, DQ=20 and 80mol% and labeled as TMC20 and TMC80, were synthesized and characterized by (1)H NMR. Polyelectrolyte complexes (PECs) of TMC/alginate (TMC/ALG) were prepared at pHs 2, 7 and 10 by mixing the aqueous solutions of unlike polymers. The PECs were characterized through infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTG) and wide-angle X-ray scattering (WAXS). Using the TMC of DQ=20 mol% and following the same methodology for preparing the PECs, beads of TMC20/ALG were obtained at pH 2 and loaded with curcumin (CUR) at pH 6.0-6.5. The morphology of the beads was evaluated by scanning electron microscopy (SEM). Studies in vitro of the controlled release of CUR from beads were investigated in simulated intestinal fluid (SIF) and simulated gastric fluid (SGF) and treated using conventional and partition-diffusion models. Results indicated that the beads based on TMC20 and ALG presented potential as drug-carrier to improve the solubility and biological activity of CUR at pH close to physiological one., (Copyright © 2013 Elsevier B.V. All rights reserved.)