Polysaccharide Beads Research Articles

Carrageenan gel beads for echinochrome inclusion: Influence of structural features of carrageenan

Carrageenan (CRG) and carrageenan/chitosan (CH) gel beads (CRG/CH) were prepared as a release delivery system for echinochrome A (Ech). According to spectral data, the Ech was dispersed in the polymer matrix, interacted with CRG, was not oxidised, and remained stable after encapsulation in CRG beads. Carrageenan beads containing Ech were coated with CH by layering. The influence of the structural features of CRG on the formation of beads and the beads morphology, swelling behaviour, mucoadhesive properties and drug release were evaluated. The polysaccharide matrices with Ech showed different swelling characteristics depending on the pH of the medium and the structure of the CRG used. The slow drug release from polysaccharide matrixes was observed for κ- and κ/β-CRG beads, that contained 3,6-anhydro-α-d-galactopyranose units and had high molecular weight. The obtained results showed the prospects of using polysaccharide beads to include Ech.

Immobilized galactose oxidase in alginate gel (GO-Bead): a versatile and efficient biocatalyst for the regioselective synthesis of 1,4-disubstitued-1,2,3-triazoles: click reaction

Galactose oxidase (E.C. 1.1.3.9) is an extracellular oxidoreductase enzyme containing Cu(I) which is produced by some fungi like Fusarium species. The enzyme catalyzes the selective oxidation of primary alcohols like galactose. In this study, a heterogeneous enzymatic system for click reaction was prepared. The most important advantage of the heterogeneous catalyst is the ease of separation and their possible reusability. Therefore, galactose oxidase was immobilized by entrapment; for this purpose, alginate polysaccharide beads with different diameters were synthesized and galactose oxidase was immobilized into them to obtain galactose oxidase-bead (GO-Bead). Next, the catalytic activity of galactose oxidase-beads was examined in the one-pot synthesis of 1,4-disubstituted 1,2,3-triazoles via click reaction comprising diversely benzyl halides, sodium azide and different alkynes in aqueous medium which need Cu(I) for their performance. The catalyst was conventionally recovered and effectively reused in several runs with no appreciable decrease in its catalytic activity.

Digestion of animal- and plant-based proteins encapsulated in κ-carrageenan/protein beads under simulated gastrointestinal conditions

In this study, we encapsulated both animal-derived (whey) and plant-derived (soy and pea) proteins within polysaccharide/protein beads and measured the digestion of these beads under simulated gastrointestinal tract (GIT) conditions. Bead dimensions were measured using a digital caliper and found to increase as the shear thinning behavior of the protein/polysaccharide solutions used to form them increased. The hydrolysis of the plant and animal proteins trapped inside the protein/polysaccharide beads was studied using the pH-stat automatic titration method under simulated static GIT conditions. The encapsulated proteins were relatively resistant to digestion under gastric conditions, with only about 10 to 13% of the protein being digested by the end of the stomach phase. Conversely, they were almost fully digested under small intestinal conditions, with around 87 to 97% of the protein being hydrolyzed by the end. Indeed, by the completion of the small intestine phase, only “ghost” beads remained that contained cross-linked polysaccharides. The soy and pea proteins were digested slightly faster than the whey proteins in the stomach phase (p < 0.05), whereas the pea proteins were digested slightly faster than the soy and whey proteins under intestinal conditions (p < 0.05). Raman spectroscopy and scanning electron microscopy showed that there were changes in the composition and structure of the beads throughout the simulated GIT. Our results indicate that the gastrointestinal behavior of proteins can be modulated by encapsulating them in polysaccharide beads, which may be useful for the design of certain types of functional foods. Even so, the beads formed from the plant-based and animal-based proteins behaved fairly similarly, suggesting that animal proteins could be replaced by plant-based ones for this purpose.

Silica coating of carboxymethyl tamarind kernel polysaccharide beads to modify the release characteristics

In present study, the release characteristics of ibuprofen-loaded carboxymethyl tamarind kernel polysaccharide beads were modified by coating with silica. The influence of concentrations of carboxymethyl tamarind kernel polysaccharide, calcium chloride and tetraethoxysilane on the % entrapment and in vitro release of ibuprofen was optimized using response surface methodology. The coating of beads with silica restricted the drug release from the beads but at the same time the ethanol formed as by-product of the sol gel process leached out the drug. The optimized batch of beads were prepared using carboxymethyl tamarind kernel powder-12.5 (%, w/v), calcium chloride-10.12 (%, w/v) and coated with tetraethoxysilane-0.25 M, entrapped 89.2% and released 92% of drug over 24 h. Energy dispersive X-ray analysis confirmed the coating of silica on the beads. The coating with silica shielded the crevices on the surface of beads but it did not elicit any significant change in thermal stability of beads. Further, in vitro release was found to be in good agreement with the swelling study. Modeling analysis revealed that ibuprofen was released from the beads following zero-order kinetics with erosion of the matrix as the main mechanism of drug release. Thus, silica coating provides a facile strategy to formulate sustained release formulations.

Mineralized Polysaccharide Transplantation Modules Supporting Human MSC Conversion into Osteogenic Cells and Osteoid Tissue in a Non-Union Defect.

Regenerative orthopedics needs significant devices to transplant human stem cells into damaged tissue and encourage automatic growth into replacements suitable for the human skeleton. Soft biomaterials have similarities in mechanical, structural and architectural properties to natural extracellular matrix (ECM), but often lack essential ECM molecules and signals. Here we engineer mineralized polysaccharide beads to transform MSCs into osteogenic cells and osteoid tissue for transplantation. Bone morphogenic proteins (BMP-2) and indispensable ECM proteins both directed differentiation inside alginate beads. Laminin and collagen IV basement membrane matrix proteins fixed and organized MSCs onto the alginate matrix, and BMP-2 drove differentiation, osteoid tissue self-assembly, and small-scale mineralization. Augmentation of alginate is necessary, and we showed that a few rationally selected small proteins from the basement membrane (BM) compartment of the ECM were sufficient to upregulate cell expression of Runx-2 and osteocalcin for osteoid formation, resulting in Alizarin red-positive mineral nodules. More significantly, nested BMP-2 and BM beads added to a non-union skull defect, self-generated osteoid expressing osteopontin (OPN) and osteocalcin (OCN) in a chain along the defect, at only four weeks, establishing a framework for complete regeneration expected in 6 and 12 weeks. Alginate beads are beneficial surgical devices for transplanting therapeutic cells in programmed (by the ECM components and alginate-chitosan properties) reaction environments ideal for promoting bone tissue.

Mineralized Polysaccharide Transplantation Modules Supporting Human MSC Conversion into Osteogenic Cells and Osteoid Tissue in a Non-Union Defect.

Regenerative orthopedics needs significant devices to transplant human stem cells into damaged tissue and encourage automatic growth into replacements suitable for the human skeleton. Soft biomaterials have similarities in mechanical, structural and architectural properties to natural extracellular matrix (ECM), but often lack essential ECM molecules and signals. Here we engineer mineralized polysaccharide beads to transform MSCs into osteogenic cells and osteoid tissue for transplantation. Bone morphogenic proteins (BMP-2) and indispensable ECM proteins both directed differentiation inside alginate beads. Laminin and collagen IV basement membrane matrix proteins fixed and organized MSCs onto the alginate matrix, and BMP-2 drove differentiation, osteoid tissue self-assembly, and small-scale mineralization. Augmentation of alginate is necessary, and we showed that a few rationally selected small proteins from the basement membrane (BM) compartment of the ECM were sufficient to upregulate cell expression of Runx-2 and osteocalcin for osteoid formation, resulting in Alizarin red-positive mineral nodules. More significantly, nested BMP-2 and BM beads added to a non-union skull defect, self-generated osteoid expressing osteopontin (OPN) and osteocalcin (OCN) in a chain along the defect, at only four weeks, establishing a framework for complete regeneration expected in 6 and 12 weeks. Alginate beads are beneficial surgical devices for transplanting therapeutic cells in programmed (by the ECM components and alginate-chitosan properties) reaction environments ideal for promoting bone tissue.

Hybrid polysaccharide beads for enhancing adsorption of Cr(VI) ions

Alginate (Alg) beads were modified by the adsorption of poly(4-vinyl-N-pentyl pyridinium bromide (QVPV) polycation, aiming towards the adsorption of Cr(VI) ions from aqueous solution. The adsorption isotherm of QPVP onto Alg beads fitted well the Langmuir adsorption model, yielding maximum adsorption capacity (qmax) of 91 mg g−1 and high constant affinity of 7.53 × 107 L mol−1. X-ray photoelectron spectroscopy and elemental analysis indicated that the QPVP chains were mainly on the Alg beads surface. The adsorption of Cr(VI) in the dilute range (0.5 mg L−1 to 10 mg L−1) on Alg-QPVP beads in batch system was investigated by means of flame atomic absorption spectrometry. Under optimal adsorption conditions (HNO3, pH 2, 6 mg of dried beads, 15 mL of solution, 30 min contact time) the nonlinear fitting with Langmuir model yielded qmax of 18 mg g−1 and constant affinity of 124 L mol−1, whereas the qmax of 156 mg g−1 and adsorption energy of 9.8 kJ mol−1 were obtained from linear fitting with Dubinin-Radushkevitch model. The breakthrough curves obtained for Cr(VI) at 100 mg L−1 in the fixed bed column system were fitted to the Adams-Bohart and Thomas models. Fitting parameters indicated a fast dynamic adsorption process, which takes place mainly on the beads surface. The reduction of adsorbed Cr(VI) ions to Cr(III) by ascorbic acid, a non-toxic biological reductant, allowed the fast and complete recycling of the Alg-QPVP beads for at least 20 times without losing performance. Novel Alg-QPVP beads presented attractive features for dynamic process, such as quickness (k > 1 × 10−3 L mg−1 min−1) and high adsorption capacity in the dilute range, low cost and recycling possibility.

Protein‐loaded sodium alginate and carboxymethyl cellulose beads for controlled release under simulated gastrointestinal conditions

AbstractNetwork characteristics of sodium alginate and carboxymethyl cellulose, in relation to the controlled release of bovine serum albumin under simulated gastrointestinal conditions, have been examined. Small‐deformation dynamic oscillation in‐shear, compression testing and optical microscopy were employed to monitor the structural characteristics of polysaccharide beads as excipients for protein entrapment. Work focused on gastrointestinal functionality and controlled release utilising variable acidity and counterion addition in preparations. Beads were found to shrink in gastric and swell in intestinal conditions, thus emphasising the disparate effect of experimental conditions. Changes in mechanical properties reflected alterations in gel microstructure, with beads becoming relatively strong in the gastric environment. In contrast, networks were weakened in the intestinal environment resulting in bead disintegration towards the end of digestion time. This type of structural behaviour allows the controlled delivery of the protein, as a model bioactive, in a particular part of the gastrointestinal tract.

Alginate-based polysaccharide beads for cationic contaminant sorption from water

Massive amounts of agricultural and industrial water worldwide are polluted by different types of contaminants that harm the environment and impact human health. Removing the contaminants from effluents by adsorbent materials made from abundant, inexpensive polysaccharides is a feasible approach to deal with this problem. In this research, alginate beads combined with two types of cellulose, starch or xylan were synthesized. Their average diameters in air- and freeze-dried conditions were assessed by optical microscopy. Differences in morphology were observed by scanning electron microscopy. Their capacity for water uptake, their sorption capabilities for a model cationic pollutant and their charge density was investigated in relationship to their composition and their surface characteristics. Their interaction with water was evaluated using low-field NMR spectroscopy. It was found that nanocrystalline cellulose added the most to the beads’ sorption capacity for cationic contaminants while xylan admixture created the beads with the highest water sorption after lyophilization.

Formulation and characterization of polysaccharide beads for controlled release of plant growth regulators

Owing to their chemical, physical, and functional characteristics, polysaccharides are considered to be the most versatile natural polymers. As a result, their properties have been exploited in various fields of research in the biomedical, pharmaceutical, cosmetic, food, and agricultural industries. A property of special interest is their ability to form systems or materials with unique physicochemical characteristics, such as hydrogels and micro- and nanoparticles for controlled release of active compounds. In the present study, polysaccharide beads formulated from alginate, cellulose powder, cellulose nanocrystals, starch, and xylan were reinforced with kaolin and surface-modified with polyethylenimine (PEI), a positively charged polyelectrolyte. Addition of kaolin improved the mechanical strength of the beads. Modification of the surface of the beads with PEI facilitated better control of the release rate of the plant growth regulator, phenylacetic acid (PAA). The physical properties of the beads were characterized by optical and scanning electron microscopy, and their mechanical strength was determined by an Instron 5565 Tensile Testing Machine. Cumulative release of PAA was measured by UV–Vis spectroscopy.

Polysaccharide-layered double hydroxide–aldolase biohybrid beads for biocatalysed CC bond formation

This study describes the design a novel microbioreactor for the biocatalysed asymmetric synthesis of polyhydroxylated compounds. The bioreactor was elaborated by a hierarchical assembly of a recombinant fructose-6-phosphate aldolase (FSAwt), layered double hydroxides (LDH) nanoplatelets and polysaccharide beads. Various polysaccharides were tested to encapsulate FSAwt and pre-immobilised FSAwt in LDH (FSAwt@Mg2Al-LDH). ι-Carrageenan appears as the most suitable candidate to prepare biohybrid beads. The retained activities in ι-carrageenan beads were measured for both free FSAwt and immobilised FSAwt revealing a 3 fold higher activity in favour of the pre-immobilised FSA. This result was probably due to a positive interaction between the negatively charged polysaccharide and the positively charged LDH layers. The catalytic activity, the recyclability and the storage of the beads were studied in addition to the leakage of FSAwt activity from beads. Nanostructuration of both FSAwt/ι-carr and FSAwt@Mg2Al-LDH/ι-carr was investigated by structural and textural characterization techniques.

Post-crosslinking towards stimuli-responsive sodium alginate beads for the removal of dye and heavy metals

Post-crosslinking as a new strategy to prepare sodium alginate (SA) beads with controllable swelling behavior, pH sensitivity and adsorption capacity was developed by using the solution of glutaraldehyde (GA), acetic acid and hydrochloric acid as the coagulating agent, for which could be used to fabricate polysaccharide beads in a large scale. Fourier transform infrared spectroscopy and thermogravimetric analysis convinced the successful cross-linking of SA by GA. The macro-porous structures of the beads were observed by scanning electron microscopy. Both acetic acid and hydrochloric acid had great effects on the swelling behavior and pH sensitivity of the SA beads. The SA beads could adsorb cationic dye (methylene blue) as high as 572mg/g and other metal ions (Cu2+, Ag+ and Fe3+). The adsorption processes fitted well with the pseudo-second-order kinetic model and the Freundlich isotherm. The large-scale production of SA beads with tunable properties opens a new route to industrially utilize polysaccharide beads in wastewater treatments, intelligent separation and so on.

Development of Enteric-Coated Polysaccharide Beads Intended for Colonic Drug Delivery

Crohn's disease is a type of inflammatory bowel disease (IBD) that frequently affects the ileo-cecal region. For effective treatment, a site-targeting delivery system in the ileo-cecal region is essential. Ciprofloxacin, a broad spectrum antibiotic is widely used for the treatment of Crohn's disease. The present study is an attempt to develop enteric coated polysaccharide beads which targets the drug to the colon. Polysaccharide beads were prepared using different polymers like sodium alginate, gellan gum and chitosan by dispersing the drug loaded solution into calcium chloride and sodium tripolyphosphate solution respectively. The prepared beads were then coated with Eudragit S 100 using pan coating method. Characterization done using SEM revealed that, eudragit coated beads had uniform surface texture. Swelling study suggested that, alginate beads alone or in combination with gellan gum showed good swelling behavior in phosphate buffer (pH 7.4), whereas chitosan beads showed better swelling in pH 1.2. The drug release showed up to 10 % in acidic environment and sustained under neutral condition for a period of 10 h. Release kinetics indicated non-Fickian transport controlled by diffusion and relaxation of the polymer. In-vivo studies in rabbits indicated that the formulation was targeted to the colon region.

Debridement of diabetic foot ulcers.

Foot ulceration is thought to affect 15% of people with diabetes at some time in their lives. Debridement is widely regarded as an effective intervention to speed up ulcer healing. The most effective method is unclear. To assess the effects of debridement interventions on the healing of diabetic foot ulcers. For this third update we searched the Cochrane Wounds Group Specialised Register (June 2009); The Cochrane Central Register of Controlled Trials (CENTRAL) - The Cochrane Library 2009, Issue 2; Ovid MEDLINE - 1950 to June Week 3 2009; Ovid EMBASE - 1980 to 2009 Week 25 and Ovid CINAHL - 1982 to June Week 3 2009. Randomised controlled trials (RCTs) evaluating any method of debriding diabetic foot ulcers and measuring complete healing or rate of healing. There was no restriction on articles/trials based on language or publication status. Data extraction and assessment of study quality were undertaken by one review author and checked by an Editor of the Wounds Group. Six RCTs of debridement were identified: four assessed hydrogels, with an additional study evaluating larval therapy against hydrogel and one evaluated surgical debridement. Pooling the three RCTs which compared hydrogel with gauze or standard care suggested that hydrogels are significantly more effective in healing diabetic foot ulcers (Relative Risk 1.84, 95% Confidence Interval (CI)1.3 to 2.61). Surgical debridement showed no significant benefit over standard treatment. One small trial suggested that larvae resulted in a more than 50% reduction in wound area compared with hydrogel. Other debridement methods such as enzyme preparations or polysaccharide beads have not been evaluated in diabetic foot ulcers. There is evidence to suggest that hydrogel increases the healing rate of diabetic foot ulcers compared with gauze dressings or standard care and larval therapy resulted in significantly greater reduction in wound area than hydrogel. More research is needed to evaluate the effects of a range of widely used debridement methods and of debridement per se.

Inorganic–organic hybrid alginate beads with LCST near human body temperature for sustained dual‐sensitive drug delivery

AbstractIn order to obtain dual‐stimuli‐responsive (temperature/pH) alginate beads that exhibit LCST close to human body temperature for sustained drug release applications, poly (NIPAAm‐co‐AAm) hydrogel (with LCST 37.5°C) were selected and associated with calcium alginate to prepare inorganic–organic hybrid biomineralized polysaccharide alginate beads via a one‐step method in this paper. Scanning electron microscopy (SEM) and energy dispersive X‐ray spectrometer (EDS) results demonstrated that calcium phosphate could not only be found in the surface but also in the cross‐section of biomineralized polysaccharide beads. Both equilibrium swelling and indomethacin release behavior were found to be pH‐ and thermo‐responsive. In addition, indomethacin release profile could be sustained with a inorganic–organic hybrid membrane: the release amount reached 96% within 4 hr for the unmineralized beads, while a drug release of only 64% obtained after subjecting the biomineralized polysaccharide beads to the same treatment. These results indicate that the biomineralized polysaccharide membrane could prevent the permeability of the encapsulated drug and reduce the drug release rate effectively. The studied system has the potential to be used as an effective smart sustainable delivery system for biomedical applications. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Biomineralized Polysaccharide Beads for Dual‐Stimuli‐Responsive Drug Delivery

Biomineralized polysaccharide-coated alginate beads containing PNIPAAM were prepared. The resulting beads can be used as carriers for sustained pH/temperature-sensitive drug delivery. Characterizations using SEM, EDS, FTIR, and POM revealed that the beads were covered by the calcium-phosphate-mineralized alginate/chitosan membrane. The drug-release behavior was examined using indomethacin as a model drug, and the release profile of the developed materials was found to be responsive to pH and temperature. The release profile could be sustained under neutral conditions, indicating that the mineralized polysaccharide membrane could prevent the permeability of the encapsulated drug and reduce the drug release rate.

The value of debridement and Vacuum-Assisted Closure (V.A.C.) Therapy in diabetic foot ulcers

Treatment of diabetic foot ulcers includes a number of different regimes such as glycaemic control, re-vascularization, surgical, local wound treatment, offloading and other non-surgical treatments. Although considered the standard of care, the scientific evidence behind the various debridements used is scarce. This presentation will focus on debridement and V.A.C. Therapy, two treatments widely used in patients with diabetes and foot ulcers. A review of existing literature on these treatments in diabetic foot ulcers, with focus on description of the various types of debridements used, the principles behind negative pressure wound therapy (NPWT) using the V.A.C. Therapy system and level of evidence. Five randomized controlled trials (RCT) of debridement were identified; three assessed the effectiveness of a hydrogel as a debridement method, one evaluated surgical debridement and one evaluated larval therapy. Pooling the three hydrogel RCTs suggested that hydrogels are significantly more effective than gauze or standard care in healing diabetic foot ulcers. Surgical debridement and larval therapy showed no significant benefit. Other debridement methods such as enzyme preparations or polysaccharide beads have not been evaluated in RCTs of people with diabetes. More than 300 articles have been published on negative pressure wound therapy, including several small RCTs and a larger multi-centre RCT of diabetic foot ulcers. Negative pressure wound therapy seems to be a safe and effective treatment for complex diabetic foot wounds, and could lead to a higher proportion of healed wounds, faster healing rates, and potentially fewer re-amputations than standard care. Although debridement of the ulcer is considered a prerequisite for healing of diabetic foot ulcers, the grade of evidence is quite low. This may be due to a lack of studies rather than lack of effect. Negative pressure wound therapy seems to be safe and effective in the treatment of some diabetic foot ulcers, although there is still only one well-performed trial that evaluates the effect.

Shape optimization and characterization of polysaccharide beads prepared by ionotropic gelation

The shape of drug loaded polysaccharide beads produced by ionotropic gelation has been optimized, with the aim of producing spherical beads suitable for further technological operations, such as coating. The optimization was performed on a model system sodium alginate/theophylline by inclusion of various fillers. Incorporation of excipients markedly influenced the morphological characteristics of the beads. The undesired irregular shape of beads caused by incorporation of the drug could only be improved by incorporating a combination of polycarbophil (PK) and polyvinylpyrrolidone (PVP). The spherical shape of these beads was stabilized mechanically by numerous air bubbles trapped inside the beads, which prevented the collapse of the beads during drying. The optimized method was shown to be applicable to a target system of pectin and an anti-inflammatory drug, LK-423.

Selective biosorption of mixed heavy metal ions using polysaccharides

Although much research has been conducted on the separation of single species of heavy metal, the selective adsorption of two or more heavy metals in mixture is relatively little known. In this study, polysaccharide beads were prepared to selectively remove the targeted heavy metal ion from mixture. Among the biomasses, polysaccharide was examined due to its low cost and easy accessibility. In a single metal ion system, chitosan, λ-carrageenan, and alginic acid showed high affinity to mercury, copper, and lead, respectively. In the ion mixture, the same trend shown in the single metal ion solution was observed. The optimum electrolyte concentraion was investigated to adsorb the metal ion selectively, and it was possible to remove the targeted metal ion selectively with chitosan, alginic acid and λ-carrageenan at 1 mmol concentration of electrolyte. In order to demonstrate the feasibility of selective biosorption, two packed-bed reactors in series containing chitosan and alginic acid beads in each were studied and selective adsorption to Hg2+ and Pb2+, respectively, was observed.

Debridement of diabetic foot ulcers.

Foot ulceration is thought to affect 15% of people with diabetes at some time in their lives. The aim of this review is to assess the evidence for the effectiveness of debridement as a treatment for diabetic foot ulcers. Searches of electronic databases, hand searching journals, bibliographies and identification of unpublished work by written communication with recognised experts in the diabetic foot. Randomised controlled trials evaluating a method of debridement in the treatment of diabetic foot ulcers. The outcome had to include either complete healing or rate of healing. There was no restriction on articles/trials based on language or publication status. Data extraction and assessment of study quality were undertaken by one reviewer and checked by an Editor of the Wounds Group. 5 RCTs of debridement were identified; 3 RCTs assessed the effectiveness of a hydrogel as a debridement method, 1 RCT evaluated surgical debridement and 1 RCT evaluated larval therapy. Pooling the 3 hydrogel RCTs suggested that hydrogels are significantly more effective than gauze or standard care in healing diabetic foot ulcers (absolute risk difference 0.23; 95% CI: 0.10,0.36). Surgical debridement and larval therapy showed no significant benefit in these small trials. Other debridement methods such as enzyme preparations or polysaccharide beads have not been evaluated in RCTs of people with diabetes. There is evidence to suggest that hydrogel increases the healing rate of diabetic foot ulcers. More research is needed to evaluate the effects of a range of widely used debridement methods and of debridement per se.