Molecular Weight Alginate Research Articles

Ultrasonic degradation of alginate: A matrix for iron encapsulation using gelation

Alginate has various biological, physical, and chemical properties that can be modified to fulfill a specific purpose. Ultrasonic degradation is a safe and simple method used for alginate modification. This study studied the effect of ultrasonic treatment on the viscosity, molecular weight, solubility and degree of swelling of degraded alginate. Furthermore, performance of these degraded alginates as a matrix for iron encapsulation was also determined using a gelation method. Ethanol concentration and duration of the degradation were negatively correlated with viscosity and molecular weight of alginate, whereas alginate concentration had the opposite effect. Encapsulation using 10% alginate that was degraded using 75% ethanol for 60 min showed the highest encapsulation efficiency. This degraded alginate formed soft, fragile and loose beads when trapping and protecting the iron. The degradation induced the release of iron from the beads at pH 1.2 and 6.8. The iron release from the beads followed the semi-empirical Korsmeyer–Peppas model (R2 > 0.92). The lower molecular weight alginate was not as good as the native alginate in encapsulating iron using gelation.

Inhaled dry powder alginate oligosaccharide in cystic fibrosis: a randomised, double-blind, placebo-controlled, crossover phase 2b study.

BackgroundOligoG is a low molecular-weight alginate oligosaccharide that improves the viscoelastic properties of cystic fibrosis (CF) mucus and disrupts biofilms, thereby potentiating the activity of antimicrobial agents. The efficacy of inhaled OligoG was evaluated in adult patients with CF.MethodsA randomised, double-blind, placebo-controlled multicentre crossover study was used to demonstrate safety and efficacy of inhaled dry powder OligoG. Subjects were randomly allocated to receive OligoG 1050 mg per day (10 capsules three times daily) or matching placebo for 28 days, with 28-day washout periods following each treatment period. The primary end-point was absolute change in percentage predicted forced expiratory volume in 1 s (FEV1) at the end of 28-day treatment. The intention-to-treat (ITT) population (n=65) was defined as randomised to treatment with at least one administration of study medication and post-dosing evaluation.ResultsIn this study, 90 adult subjects were screened and 65 were randomised. Statistically significant improvement in FEV1 was not observed in the ITT population. Adverse events included nasopharyngitis, cough and pulmonary exacerbation. The number and proportions of patients with adverse events and serious adverse events were similar between OligoG and placebo group.ConclusionsInhalation of OligoG-dry powder over 28 days was safe in adult CF subjects. Statistically significant improvement of FEV1 was not reached. The planned analyses did not indicate a significant treatment benefit with OligoG compared to placebo. Post hoc exploratory analyses showed subgroup results that indicate that further studies of OligoG in this patient population are justified.

Enzyme-Assisted Fucoidan Extraction from Brown Macroalgae Fucus distichus subsp. evanescens and Saccharina latissima.

Fucoidans from brown macroalgae (brown seaweeds) have different structures and many interesting bioactivities. Fucoidans are classically extracted from brown seaweeds by hot acidic extraction. Here, we report a new targeted enzyme-assisted methodology for fucoidan extraction from brown seaweeds. This enzyme-assisted extraction protocol involves a one-step combined use of a commercial cellulase preparation (Cellic®CTec2) and an alginate lyase from Sphingomonas sp. (SALy), reaction at pH 6.0, 40 °C, removal of non-fucoidan polysaccharides by Ca2+ precipitation, and ethanol-precipitation of crude fucoidan. The workability of this method is demonstrated for fucoidan extraction from Fucus distichus subsp. evanescens (basionym Fucus evanescens) and Saccharina latissima as compared with mild acidic extraction. The crude fucoidans resulting directly from the enzyme-assisted method contained considerable amounts of low molecular weight alginate, but this residual alginate was effectively removed by an additional ion-exchange chromatographic step to yield pure fucoidans (as confirmed by 1H NMR). The fucoidan yields that were obtained by the enzymatic method were comparable to the chemically extracted yields for both F. evanescens and S. latissima, but the molecular sizes of the fucoidans were significantly larger with enzyme-assisted extraction. The molecular weight distribution of the fucoidan fractions was 400 to 800 kDa for F. evanescens and 300 to 800 kDa for S. latissima, whereas the molecular weights of the corresponding chemically extracted fucoidans from these seaweeds were 10–100 kDa and 50–100 kDa, respectively. Enzyme-assisted extraction represents a new gentle strategy for fucoidan extraction and it provides new opportunities for obtaining high yields of native fucoidan structures from brown macroalgae.

Role of particle clusters on the rheology of magneto-polymer fluids and gels.

Even in the absence of cross-linking, at large enough concentration, long polymer strands have a strong influence on the rheology of aqueous systems. In this work, we show that solutions of medium molecular weight (120 000-190 000 g mol-1) alginate polymer retained a liquid-like behaviour even for concentrations as large as 20% w/v. On the contrary, solutions of alginate polymer of larger (and also polydisperse) molecular weight (up to 600 000 g mol-1) presented a gel-like behaviour already at concentrations of 7% w/v. We dispersed micrometre-sized iron particles at a concentration of 5% v/v in these solutions, which resulted in either stable magnetic fluids or gels, depending on the type of alginate polymer employed (medium or large molecular weight, respectively). These magneto-polymer composites presented a shear-thinning behaviour that allowed injection through a syringe and recovery of the original properties afterwards. More interestingly, application of a magnetic field resulted in the formation of particle clusters elongated along the field direction. The presence of these clusters intensely affected the rheology of the systems, allowing a reversible control of their stiffness. We finally developed theoretical modelling for the prediction of the magnetic-sensitive rheological properties of these magneto-polymer colloids. This article is part of the theme issue 'Patterns in soft and biological matters'.

Detection and isolation of low molecular weight alginate- and laminaran-susceptible gut indigenous bacteria from ICR mice

Alginate and laminaran are the main water-soluble polysaccharides in edible brown algae such as arame Eisenia bicyclis. To determine the alginate- and/or laminaran-susceptible indigenous bacteria (SIB) in the gut, the caecal microbiomes of ICR mice fed a diet containing 2% low molecular weight (LMW ≒50 kDa) alginate or laminaran were analysed by 16S rRNA gene (V4) amplicon sequencing. At the phylum level abundances, compared to those in mice fed a no-fibre diet, Firmicutes was lower and Bacteroidetes was higher in both LMW alginate- or laminaran-fed mouse groups. At the operational taxonomic unit level, Bacteroides acidifaciens- and Bacteroides intestinalis-like bacteria were considered alginate- and laminaran-SIB, respectively. B. acidifaciens PS-4 isolated from the ICR mice fermented LMW alginate and laminaran and mainly produced succinate. B. intestinalis ALB-11 also isolated from these mice fermented laminaran and mainly produced lactate. These SIB might exert interactive effects with edible brown algal consumption and affect host health.

The inhibitory activity of alginate against allergic reactions in an ovalbumin-induced mouse model.

Marine seaweed polysaccharides have been considered as a potential resource for antiallergic therapy. Alginate is an acidic linear polysaccharide and soluble dietary fiber that was extracted from brown algae, Laminaria japonica. The molecular weight of alginate was 108 kDa, and its water solution exhibited non-Newtonian characteristics, including viscoelasticity and shear-thinning behavior. The ability of alginate to inhibit allergic reactions was investigated in ovalbumin (OVA)-induced BALB/c mice, which have been widely used as a mouse model of egg allergy. The results showed that alginate could effectively attenuate the occurrence of allergic reactions, including improving the integrity of the intestinal epithelial villi and inhibition of mast cell degranulation in the jejunum, in OVA-induced mice. Moreover, after treatment with alginate, the levels of IgE, histamine and IL-4 in OVA-induced mice were remarkably decreased, and the levels of IFN-γ were markedly increased. In addition, the number of Treg cells in spleen tissues in OVA-induced mice was increased by alginate, and the OVA-induced differentiation of Th0 cells into Th2 cells was significantly inhibited. These results demonstrate that alginate possesses potential antiallergic activities in a mouse model of egg allergy, which might provide important evidence that alginate, extracted from Laminaria japonica, can be developed into a novel functional food for inhibiting egg allergy.

A simple method to calculate the degree of polymerization of alginate oligosaccharides and low molecular weight alginates

This study presents a quick, simple and accurate method to calculate the degree of polymerization (DP) of alginate oligosaccharides (AOS) and low molecular weight alginates from the concentration of reducing sugar determined by 3,5-dinitrosalicylic acid (DNS) assay. 1H NMR spectroscopy, mass spectroscopy (MS) and certified standards were used to verify the accuracy of this method, and the results showed DP calculated from DNS assay agreed with the actual DP. This method has great potential to simplify the process of measuring DP of alginate in lab and thus could be incorporated into various researches on alginates in the future. Moreover, similar method could be applied when studying the DP of other oligosaccharides.

Alginate Oligosaccharides: Production, Biological Activities, and Potential Applications

Alginate, a group of polyuronic saccharides, has been widely used in both pharmaceutical and food industries due to its unique physicochemical properties as well as beneficial health effects. However, the potential applications of alginate are restricted because of its low water solubility and high solution viscosity when significant concentrations are needed, particularly in food products. Alginate oligosaccharides (AOS), oligomers containing 2 to 25 monomers, can be obtained via hydrolysis of glycosidic bonds, organic synthesis, or through biosynthesis. Generally, AOS have shorter chain lengths and thus improved water solubility when compared with higher molecular weight alginates of the same monomers. These oligosaccharides have attracted interest from both basic and applied researchers. AOS have unique bioactivity and can impart health benefits. They have shown immunomodulatory, antimicrobial, antioxidant, prebiotic, antihypertensive, antidiabetic, antitumor, anticoagulant, and other activities. As examples, they have been utilized as prebiotics, feed supplements for aquaculture, poultry, and swine, elicitors for plants and microorganisms, cryoprotectors for frozen foods, and postharvest treatments. This review comprehensively covers methods for AOS production from alginate, such as physical/chemical methods, enzymatic methods, fermentation, organic synthesis, and biosynthesis. Moreover, current progress in structural characterization, potential health benefits, and AOS metabolism after ingestion are summarized in this review. This review will discuss methods for producing and modified AOS with desirable structures that are suited for novel applications.

Enhancing the Thermo-Stability and Anti-Biofilm Activity of Alginate Lyase by Immobilization on Low Molecular Weight Chitosan Nanoparticles.

Bacterial biofilm causes severe antibiotic resistance. An extracellular polymeric substance (EPS) is the main component in the bacterial biofilm. Alginate is a key EPS component in the biofilm of Pseudomonas aeruginosa and responsible for surface adhesion and stabilization of biofilm. Alginate lyase has emerged as an efficient therapeutic strategy targeting to degrade the alginate in the biofilm of P. aeruginosa. However, the application of this enzyme is limited by its poor stability. In this study, chitosan nanoparticles (CS-NPs) were synthesized using low molecular weight chitosan and alginate lyase Aly08 was immobilized on low molecular weight chitosan nanoparticles (AL-LMW-CS-NPs). As a result, the immobilization significantly enhanced the thermal stability and reusability of Aly08. In addition, compared with free Aly08, the immobilized AL-LMW-CS-NPs exhibited higher efficiency in inhibiting biofilm formation and interrupting the established mature biofilm of P. aeruginosa, which could reduce its biomass and thickness confirmed by confocal microscopy. Moreover, the biofilm disruption greatly increased the antibiotic sensitivity of P. aeruginosa. This research will contribute to the further development of alginate lyase as an anti-biofilm agent.

Mucin structural interactions with an alginate oligomer mucolytic in cystic fibrosis sputum

Cystic fibrosis (CF) is an autosomal recessive, life-limiting condition characterized by progressive lung disease, which is a major cause of morbidity and mortality for these patients. The inhalation therapy, OligoG CF-5/20, is a low molecular weight (mean Mn 3200 g/mol) alginate oligomer, with a high guluronic acid content (>85%). The ability of OligoG CF-5/20 to enhance the activity of antimicrobial/antibiotic therapies, modify the rheological properties of CF sputum and interact with mucin, has previously been shown. To further characterize the physicochemical interactions of OligoG CF-5/20 with CF sputum, Fourier-transform infrared (FTIR) spectroscopy was used to analyze ex vivo sputum samples from adolescent CF patients (n = 13) following treatment with 0.2% OligoG CF-5/20. FTIR analysis confirmed the interaction of OligoG CF-5/20 with mucin glycans in CF sputum, which showed a shift in wavenumber from 1078 cm−1 to 1070 cm-1 and subsequent loss of the 1053 cm−1 peak in the OligoG CF-5/20 treated samples. OligoG CF-5/20 interaction with key terminal moieties in mucin were also evident, with a significant change in sulphation at wavenumber 1116 cm−1, suggesting a link with sulphated Lewis x antigen. There were also significant shifts at wavenumber 1637 cm-1 indicative of β-sheet conformational changes in the mucin peptide caused by action of OligoG. The alterations in charge of glycan and mucin structures support previous observations wherein OligoG CF-5/20 modifies the viscoelastic properties of CF sputum. These findings suggest a possible mechanism of action for the rheological changes observed with this novel therapy.

Nitric oxide-releasing alginates as mucolytic agents.

The excessive production of thick, viscous mucus in severe respiratory diseases leads to obstruction of the airways and provides a suitable environment for the colonization of pathogenic bacteria. The effect of nitric oxide (NO)-releasing alginates with varying NO release kinetics on the viscoelastic properties of human bronchial epithelial (HBE) mucus was evaluated as a function of the NO-release kinetics using parallel plate rheology. Low molecular weight (~5 kDa) alginates with high NO flux (~4000 ppb/mg) and sustained release (half-life ~0.3 h) proved to be most effective in reducing both mucus elasticity and viscosity (≥60% reduction for both). The efficacy of the NO-releasing alginates was shown to be dose-dependent, with high concentrations of NO-releasing alginates (~80 mg•mL-1) resulting in greater reduction of the viscosity and elasticity of the mucus samples. Greater reduction in mucus rheology was also achieved with NO-releasing alginates at lower concentrations when compared to both NO-releasing chitosan, a similarly biocompatible cationic polymer, and N-acetyl cysteine (NAC), a conventional mucolytic agent.

The Prevention of Hepatectomy-Induced Adhesions by Bilayer Sponge Composed of Ultrapure Alginate

BackgroundAdhesion formation is a critical issue in surgery, particularly in hepatectomy. The present study aimed to develop a bilayer adhesion barrier comprising alginate (Alg) of different molecular weight (Mw). It was expected that a slowly dissolving layer remains on the cut surface, functioning as a physical barrier, whereas a rapidly dissolving layer widely distributes in the peritoneal cavity to prevent de novo adhesions. MethodsBilayer Alg sponges were fabricated using low Mw Alg for the upper layer and high Mw Alg for the bottom layer. The dissolution behavior of each layer was evaluated in vitro in peritoneum-like environments. We constructed a Pean crush hepatectomy-induced adhesion model in rats. The effects of the bilayer sponge on cut surface and de novo adhesions were separately evaluated in terms of their extent and grade. ResultsThe Alg sponge layer with low Mw dissolved faster than that with high Mw in vitro. One week after the hepatectomy, although no significant decrease in adhesion extent on the cut surface was observed in rats that received Seprafilm and Interceed, treatment with Alg bilayer sponge significantly decreased the adhesion extent to 38% of that without treatment. Moreover, a significant decrease in de novo adhesion extent was observed in the Alg bilayer sponge compared with the Interceed group. ConclusionsThe Alg bilayer sponge was effective for preventing both cut surface and de novo adhesions in the rat Pean crush hepatectomy model. The simple yet functional design of the Alg bilayer sponge can facilitate its use in future clinical practice.

Design of Aerogels, Cryogels and Xerogels of Alginate: Effect of Molecular Weight, Gelation Conditions and Drying Method on Particles' Micromeritics.

Processing and shaping of dried gels are of interest in several fields like alginate aerogel beads used as highly porous and nanostructured particles in biomedical applications. The physicochemical properties of the alginate source, the solvent used in the gelation solution and the gel drying method are key parameters influencing the characteristics of the resulting dried gels. In this work, dried gel beads in the form of xerogels, cryogels or aerogels were prepared from alginates of different molecular weights (120 and 180 kDa) and concentrations (1.25, 1.50, 2.0 and 2.25% (w/v)) using different gelation conditions (aqueous and ethanolic CaCl2 solutions) and drying methods (supercritical drying, freeze-drying and oven drying) to obtain particles with a broad range of physicochemical and textural properties. The stability of physicochemical properties of alginate aerogels under storage conditions of 25 °C and 65% relative humidity (ICH-climatic zone II) during 1 and 3 months was studied. Results showed significant effects of the studied processing parameters on the resulting alginate dried gel properties. Stability studies showed small variations in aerogels weight and specific surface area after 3 months of storage, especially, in the case of aerogels produced with medium molecular weight alginate.

Injectable cell-encapsulating composite alginate-collagen platform with inducible termination switch for safer ocular drug delivery

Effective retinal drug delivery remains a challenge for treating vision-threatening diseases. Encapsulated-cell therapy (ECT) can provide local drug delivery without repeated invasive injections but is plagued by unsteady performance and biosafety issues. Here, an injectable composite alginate-collagen (CAC) ECT gel with a Tet-on inducible pro-caspase 8 mechanism that acted as an orally-inducible biosafety switch was developed for safer drug delivery. The optimised gels (2 mg/ml collagen, 1.5% high molecular weight alginate and 50,000 cells/gel) could be effectively terminated in vitro (≥20 pg/ml Doxycycline) and in vivo (1 mg/ml oral Doxycycline after 48 h). Also, they displayed effective proliferation control and continuous delivery of bioactive glial-cell derived neurotrophic factor (GDNF) with no significant gel degradation in vitro and in rat vitreous. Most importantly, intravitreally injected gels demonstrated therapeutic efficacy in Royal College of Surgeons rats with degenerating retina in reducing photoreceptor apoptosis and retina function loss. Furthermore, double gel injections into the same eye yielded better outcomes without compromising gel viability. Retrieved gels showed no host-tissue attachment or cell-protrusion 6 months post-implantation. The CAC ECT system exhibited mechanical stability, good encapsulation power, cell viability support, multiplexed GDNF dosage, and compatibility with different cell types (HEK293 and ARPE-19) without immunosuppressant, making it an attractive, safe and well-controlled platform for treating various eye diseases.

Upgrading the antioxidant properties of fucoidan and alginate from Cystoseira trinodis by fungal fermentation or enzymatic pretreatment of the seaweed biomass

The seaweed Cystoseira trinodis was fermented by different fungi prior to extraction of fucoidan and alginate to enhance their antioxidative potential. All the investigated fungi were able to produce fucoidanase (1.05–3.41 U/ml) and alginate lyase (7.27–18.59 U/mL). Different fungal species induced a reduction in the molecular weight (MW) of fucoidan and alginate in comparison to the unfermented control. The MW of fucoidan reduced by 41–81.5%, while the MW of alginate was reduced by 28–75%, depending on the fungal species. Significant increases in the fucose and sulphate contents of fucoidan and mannuronic/guluronic acid ratio of alginate were induced by fungal fermentation. Fungal pretreatment enhanced the ferric reducing antioxidant power, total antioxidant capacity and hydroxyl radical scavenging activity of both fucoidan and alginate. Additionally, enzymatic pretreatment of the macroalgal biomass assisted in the recovery of fucoidan and alginate with low molecular weight and enhanced antioxidative potential.

Nitric Oxide-Releasing Alginates.

Low and high molecular weight alginate biopolymers were chemically modified to store and release potentially therapeutic levels of nitric oxide (NO). Carbodiimide chemistry was first used to modify carboxylic acid functional groups with a series of small molecule alkyl amines. The resulting secondary amines were subsequently converted to N-diazeniumdiolate NO donors via reaction with NO gas under basic conditions. NO donor-modified alginates stored between 0.4-0.6 μmol NO·mg-1. In aqueous solution, the NO-release kinetics were diverse (0.3-13 h half-lives), dependent on the precursor amine structure. The liberated NO showed bactericidal activity against Pseudomonas aeruginosa and Staphylococcus aureus with pathogen eradication efficiency dependent on both molecular weight and NO-release kinetics. The combination of lower molecular weight (∼5 kDa) alginates with moderate NO-release durations (half-life of ∼4 h) resulted in enhanced killing of both planktonic and biofilm-based bacteria. Toxicity against human respiratory epithelial (A549) cells proved negligible at NO-releasing alginate concentrations required to achieve a 5-log reduction in viability in the biofilm eradication assay.

Effect of alginate molecular weight and M/G ratio in beads properties foreseeing the protection of probiotics

Probiotics are live microorganisms that when administered in adequate amounts confer a health benefit to the host. However, to accomplish this positive influence on Human health, probiotics should survive to the passage through the upper digestive tract in large numbers to unsure a desired beneficial effect in the host. Several encapsulation methods have been used to protect probiotics. Alginate is the most used biopolymer in the production of these systems, although its performance is totally dependent of its structure and chemical characteristics. In this work, alginates with different molecular weights and different mannuronic and guluronic acid residues ratio (M/G ratio) were used in the encapsulation of Lactococcus lactis spp. cremoris (LLC) aiming the protection of this probiotic bacteria against the harsh conditions of digestion. Alginate-based beads were produced using an external gelation process (extrusion technique) where variables regarding the processing conditions and alginate chemical characteristics were studied to assess their relevance in this process aiming the most efficient encapsulation system. The most important variables influencing the size of alginate beads were the alginate concentration, alginate type (M/G ratio and molecular weight) and the nozzle diameter. Beads with sizes ranged between 1.9 and 3.0 mm were produced using different alginates. Fourier transform infrared (FTIR) spectroscopy showed relevant differences between beads produced proving the impact of different M/G ratios in the beads’ chemical structure. In general, low molecular weight and low M/G ratio alginate (Protanal LFR5/60) proved to produce the most well organized (according to SEM analyses), less permeable (pore diameter of 2.52 nm) and stronger alginate beads, moreover molecular weight and M/G ratio proved to be an important variable on the protection of probiotics against the harsh conditions of digestion. Produced beads proved to be efficient in the protection of probiotics (i.e. high viability), with the best performance presented by the medium and low molecular weight alginates.

Influence of alginate backbone on efficacy of thermo-responsive alginate-g-P(NIPAAm) hydrogel as a vehicle for sustained and controlled gene delivery

Alginate grafted poly(N-isopropylacrylamide) hydrogels (Alg-g-P(NIPAAm)) form three-dimensional networks in mild conditions, making them suitable for incorporation of labile macromolecules, such as DNA. The impact of P(NIPAAm) on copolymer characteristics has been well studied, however the impact of alginate backbone characteristics on copolymer properties has to-date not been investigated. Six different Alg-g-P(NIPAAm) hydrogels were synthesised with 10% alginate, which varied in terms of molecular weight (MW) and mannuronate/guluronate (M/G) monomer ratio, and with 90% NIPAAm in order to develop an injectable and thermo-responsive hydrogel formulation for localised gene delivery. Hydrogel stiffness was directly proportional to MW and the M/G ratio of the alginate backbone. Hydrogels with a high MW or low M/G ratio alginate backbone demonstrated a greater stiffness than those hydrogels comprising low MW alginates and high M/G ratio. Hydrogels with a high M/G ratio also produced a complexed and meshed hydrogel network while hydrogels with a low M/G ratio produced a simplified structure with the superposition of Alg-g-P(NIPAAm) sheets.This study was designed to produce the optimal Alg-g-P(NIPAAm) hydrogel with respect to localised delivery of DNA nanoparticles as a potential medical device for those with castrate resistant prostate cancer (CRPC). Given that CRPC typically disseminates to bone causing pain, morbidity and a plethora of skeletal related events, a copolymer based hydrogel was designed to for long term release of therapeutic DNA nanoparticles.The nanoparticles were comprised of plasmid DNA (pDNA), complexed with an amphipathic cell penetrating peptide termed RALA that is designed to enter cells with high efficiency. Alginate MW and M/G ratio affected stiffness, structure, injectability and degradation of the Alg-g-P(NIPAAm) hydrogel. Algogel 3001, had the optimal characteristics for long-term application and was loaded with RALA/pDNA NPs. From the release profiles, it was evident that RALA protected the pDNA from degradation over a 30-day period and conferred a sustained and controlled release profile from the hydrogels compared to pDNA only.Taken together, we have designed a slowly degrading hydrogel suitable for sustained delivery of nucleic acids when incorporated with the RALA delivery peptide. This now opens up several opportunities for the delivery of therapeutic pDNA from this thermo-responsive hydrogel with numerous medical applications.

Recent advances in polysaccharides for osteoarthritis therapy

The polysaccharides used in the treatment of osteoarthritis (OA) mainly include sodium hyaluronate, chondroitin sulfate, chitosan, xanthan gum, Low molecular weight heparin, alginate and other polysaccharides. This review summarizes the recent advances in the chemistry and biological activities of polysaccharides for the treatment of OA.

Optimisation of a novel glass-alginate hydrogel for the treatment of intracranial aneurysms

The current gold standard for aneurysm treatment is endovascular coiling. However, recurrence is observed in over 20% of cases. A novel hydrogel has been developed to treat aneurysms. This hydrogel is composed of a polymeric alginate, a novel ion releasing glass and glucono-delta-lactone. This is an internally setting alginate hydrogel, wherein the setting rate can be controlled by both the glass and the alginate chemistry. The aim of this work is to examine the effect of each component of the hydrogel and optimise the composition of the hydrogel, specifically the alginate molecular weight, M/G ratio and concentration. The effects of gamma sterilisation will also be examined. The results show that alginate concentration, chemical composition and molecular weight affect the compressive strength, working time, hardening time and deliverability of the hydrogel. Gamma irradiation of the alginate reduces the molecular weight, which has a negative effect on the usability of this hydrogel.