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PubMed2003

Oral colon-specific drug delivery for bee venom peptide: development of a coated calcium alginate gel beads-entrapped liposome.

Colon-specific drug delivery systems (CDDSs) can be used to improve the bioavailability of protein and peptide drugs through the oral route. A novel formulation for oral administration using coated calcium alginate gel beads-entrapped liposome and bee venom peptide as a model drug has been investigated for colon-specific drug delivery in vitro. Drug release studies under conditions mimicking stomach to colon transit have shown that the drug was protected from being released completely in the physiological environment of the stomach and small intestine. The release rate of bee venom from the coated calcium alginate gel beads-entrapped liposome was dependent on the concentration of calcium and sodium alginate, the amount of bee venom in the liposome, as well as the coating. Furthermore, a human gamma-scintigraphy technique was used in vivo to determine drug delivery more precisely. The colonic arrival time of the tablets was found to be 4-5 h. The results clearly demonstrated that the coated calcium alginate gel beads-entrapped liposome is a potential system for colon-specific drug delivery.

Administration, Oral↗
PubMed2006

Uptake studies in rat Peyer's patches, cytotoxicity and release studies of alginate coated chitosan nanoparticles for mucosal vaccination.

The design of particulate vaccine delivery systems, particularly for mucosal surfaces, has been a focus of interest in recent years. In this context, we have previously described the development and the characterization of a new nanosized delivery system, consisting of a model antigen adsorbed to chitosan particles and coated with sodium alginate. In the present work the ovalbumin release profiles from these coated nanoparticles in different pH buffers were investigated and compared to those of the uncoated particles. Cytotoxicity of the polymers and nanoparticles was assessed using the MTT assay. Finally, particle uptake studies in rat Peyer's patches were performed. It was demonstrated that the coating of the nanoparticles with sodium alginate not only avoided a burst release observed with uncoated particles but also increased the stability of the particles at pH 6.8 and 7.4 at 37 degrees C. At neutral pH, the release was lower than 5% after 3.5 h incubation in a low ionic strength buffer. For both, chitosan and alginate polymers, and for the nanoparticles, comparable cell viability data close to 100%, were obtained. Additionally, based on confocal laser scanning microscopy observations, it was shown that alginate coated nanoparticles were able to be taken up by rat Peyer's patches, rendering them suitable carriers for intestinal mucosal vaccination.

Alginates↗
PubMed2006

Effects of alginate inclusion on the vector properties of chitosan-based nanoparticles.

Chitosan nanoparticles have shown considerable promise as gene vectors but do not mediate transfection with satisfactory efficiency. To improve upon the transfection efficiency of chitosan, we approached the development of alginate-chitosan nanoparticles with the goals of maintaining low toxicity and biocompatibility. Through ionic gelation, particles were formed with a mean Z-average diameter of 157 nm and a zeta potential of +32 mV. Competition binding assays indicated that the presence of alginate reduces the strength of interaction between chitosan and DNA, contributing to improved transfection. Cell viability assays indicated that nanoparticles exhibit the same low toxicity as chitosan, and significantly reduced toxicity compared to a commercial liposome formulation. As well, complexation with nanoparticles maintained DNA integrity and protected it from nuclease degradation better than chitosan alone. Alginate-chitosan nanoparticles were able to mediate transfection of 293T cells four times that achieved by chitosan nanoparticles; at 48 h, the transfection efficiency was as high as with Lipofectamine, with significantly reduced cytotoxicity. Overall, alginate inclusion improved the vector properties of chitosan-based nanoparticles, demonstrating superior transfection ability while maintaining biocompatibility and low toxicity.

Alginates↗
PubMed2006

Influences of buffer systems on chondrocyte growth during long-term culture in alginate.

OBJECTIVE: Chondrocyte behavior is very sensitive to culture environment such as physical and biochemical conditions. As extracellular pH (pHo) and the existence of bicarbonate could affect the chondrocyte fate, hence, the purpose of this study is to investigate the buffer system effect on chondrocyte fate during relatively long-term culture. METHODS: In order to examine whether effects seen were due to bicarbonate or to pHo, we had to devise a system which could differentiate between the two effects. Culture media buffered by N-2-hydroxyethyl piperazine-N'-2-ethanesulfonic acid (HEPES) only and the combination of HEPES and bicarbonate were used. Bovine articular chondrocytes were cultured in alginate beads for up to 12 days. pHo was kept constant by culture of 3 beads in 2 ml culture medium. Cell density, intracellular pH (pHi) and glycosaminoglycan (GAG) were measured at day 5 and day 12. Cell morphology, distribution and viability in alginate beads were monitored over 12 days of culture. RESULTS: Compared to culture in the absence of bicarbonate, a higher proliferation rate of chondrocytes was observed in the presence of bicarbonate. pHi was more alkaline, about 0.2 pH unit, in the presence of bicarbonate than that in the absence of bicarbonate. About 50% more GAG was deposited in alginate beads when chondrocytes were cultured in the combination of HEPES and bicarbonate, compared to chondrocytes cultured in the absence of NaHCO3 at the end of 12 days of culture. CONCLUSION: The presence of bicarbonate results in more alkaline in the pHi of bovine chondrocytes after long-term culture. The combination of bicarbonate and HEPES in culture medium improves cell growth, matrix production in three-dimensional alginate beads.

Alginates↗
PubMed2004

Affinity precipitation of Aspergillus niger pectinase by microwave-treated alginate.

Affinity precipitation is a simple, single plate separation process in which the complex of a smart macroaffinity ligand with the target protein (from a crude broth) can be selectively precipitated by application of a suitable stimulus. Alginate is a copolymer of guluronic acid and mannuronic acid residues and precipitates with Ca(2+) ions. It was found to bind to pectinase present in a commercial preparation of Aspergillus niger, Pectinex Ultra-SPL. Microwave pretreatment of alginate at 75 degrees C was found to enhance the selectivity of the affinity precipitation. Using microwave-treated alginate, 83% of the enzyme activity with 20-fold purification could be recovered. SDS-PAGE upon silver staining confirmed the enhanced selectivity of affinity precipitation when microwave-treated alginate was used.

Alginates↗
PubMed2005

Treatment of experimental immune complex glomerulonephritis by sodium alginate.

We have studied the therapeutic efficacy of the sodium alginate in experimental immune complex glomerulonephritis. Bovine serum albumin (BSA) nephritis was induced in rats by a subcutaneous immunization and daily intravenous administration of BSA. Sodium alginate at two different doses (25 and 50 mg/kg) was administered intraperitoneally at regular 72-h intervals for 6 weeks. Onset of treatment was day 42. Urinary protein was measured weekly and serum anti-BSA antibody was assessed by ELISA method at different intervals. Animals were euthanized at the 12th experimental week and blood samples and kidney specimens were obtained. BUN, serum creatinine and serum cholesterol and triglyceride were measured at the time of sacrifice. Kidney specimens were processed for light and immunofluorescent microscopic examination. The tolerability and inhibitory effect of LVA on matrix metalloproteinase 2 (MMP-2) were tested using WEHI-164 cell line and zymography method. Results of this experiment showed that treatment with sodium alginate could significantly reduce the urinary protein excretion and serum creatinine in treated rats vs. nontreated controls. Anti-BSA antibody titers were lower in treated rats than in controls at the 12th week post-immunization. There was no significant difference in the level of BUN and serum lipids between two groups. Whereas, glomerular hypercellularity, PMN infiltration and glomerular deposition of BSA were less intense in treated rats vs. controls. Moreover, in vitro examinations revealed that treatment with LVA, as a very safe agent could diminish MMP-2 activity. These results suggest that treatment with sodium alginate as a new immunosuppressive agent can reduce proteinuria, inhibit MMP-2 activity and suppress the antibody production as well as the development of glomerular lesions in a rat model of immune complex glomerulonephritis.

Alginates↗
PubMed2002

Age-related differences in the accumulation and size of hyaluronan in alginate culture.

The alginate bead culture system has unique properties that make it possible to study the accumulation and turnover of macromolecules in two distinct matrix compartments of the cartilage matrix: the cell-associated matrix (CM) and the further removed matrix (FRM). Taking advantage of this culture system, the purpose of this study was to examine age-related changes in the metabolism of hyaluronan (HA) in these two compartments. Bovine chondrocytes, isolated from fetal, young adult, and old adult articular cartilage, were cultured in alginate beads. On Days 7 and 14 of culture, the alginate gel was solubilized, the CM and FRM were separated and macromolecules in both compartments were analyzed. When compared to the cells from fetal and old adult animals, the young adult cells proliferated at the fastest rate. Fetal cells produced a more abundant CM that was richer in proteoglycans (PGs) than the CM of young or old adult cells. With increasing age, there was an increased tendency for PG, collagen, and HA to escape incorporation into the CM and to become immobilized in the FRM. Very striking changes also were observed in the ratio of HA to PG, which increased markedly with age, and in the size of the HA molecules, which decreased markedly with age. The results suggest that the metabolism of HA in cartilage undergoes pronounced age-related changes, some of which are retained during culture in alginate gel. The findings also suggest that the previously documented age-related decrease in the size of HA in native bovine cartilage reflects, at least in part, a biochemical process occurring at the time or at least soon after the glycosaminoglycan chain is synthesized. It does not appear to simply be the result of age-related changes occurring slowly with time after synthesis, as was previously suggested to be the case for human articular cartilage.

Age Factors↗
PubMed1996

HPLC analysis of saturated or unsaturated oligoguluronates and oligomannuronates. Application to the determination of the action pattern of Haliotis tuberculata alginate lyase.

The chromatographic behaviour of various saturated and unsaturated oligouronates obtained by acid or enzymatic degradation of homopolymeric blocks of alginates was investigated by isocratic anion exchange liquid chromatography. This approach was then applied to the determination of the catalytic properties of Haliotis tuberculata alginate lyase. This enzyme presents a high affinity for poly-beta-D-mannuronate blocks, leading to the release of O-(4-deoxy-alpha-L-erythro-hex-4-enopyranosyluronic acid)-(1-->4)-O-(beta-D-mannopyranosyluronic acid)-(1-->4)-O-beta-D-mannopyranuronic acid as the main end reaction product. Kinetic analysis with oligomannuronates of various sizes indicate that the catalytic site of Haliotis tuberculata lyase (abalone) best accommodates an oligomannuronate pentamer. The abalone lyase, however, is also capable of cleaving the G-M linkages of alginate heteropolymeric sequences. In contrast, it does not degrade the G-G nor the M-G diads. This lyase should therefore be referred to as a mannuronate beta-eliminase, indicating that the enzyme performs beta-elimination on mannuronate residues only, from both the M-M and G-M diads of alginates.

Alginates↗
PubMed1997

Novel alginate lyases from marine bacterium Alteromonas sp. strain H-4.

A bacterium Alteromonas sp. strain H-4 isolated from Laminaria fronds produced extra- and intra-cellular alginate lyases and utilized alginate as its sole carbon source. An extracellular alginate lyase was purified from the culture supernatant of the strain and its substrate specificity was characterized. The estimated molecular mass of the enzyme was 32 kDa and the isoelectric point was 4.7. Both polyM and polyG block degrading activities were observed using the substrate-containing gel overlay technique after isoelectric focusing of the enzyme. By analyzing the reaction products from the polyM block, polyG block, MG random block and intact alginate, three major peaks containing unsaturated tri-uronide through octa-uronide were detected for each substrate. The results indicate that the enzyme of Alteromonas sp. H-4 can degrade both polyM and polyG blocks with a K(m) in mg/mL 20-times higher for the polyM block.

Alginates↗
PubMed1993

Injectable alginate seeded with chondrocytes as a potential treatment for vesicoureteral reflux.

Injection of polytetrafluoroethylene (Teflon) or collagen has been used in the endoscopic treatment of vesicoureteral reflux. Although the principle of an endoscopic treatment is valid, there are concerns regarding the long-term safety and effectiveness of these substances. The goal of several investigators has been to find alternate implant materials that would be safe for human use. Toward this goal we conducted a study to determine the effect of chondrocytes using a biodegradable polymer solution as a template. Hyaline cartilage was obtained from the articular surfaces of calf shoulders and chondrocytes were harvested. Chondrocyte suspensions were concentrated to 20, 30 and 40 x 10(6) cells per cc and mixed with dry alginate powder (a biodegradable polymer) to form a gel. Twelve athymic mice were injected subcutaneously with a chondrocyte-alginate solution. Each mouse had 4 injection sites, consisting of control, 10, 15 and 20 x 10(6) chondrocyte cells (48 injection sites). Mice were sacrificed at 2, 4, 6 and 12 weeks after injection. Histological examination of the injection sites demonstrated evidence of cartilage formation in 34 of the 36 experimental injection sites. Gross examination of the injection sites with increasing time showed that the polymer gels were progressively replaced by cartilage. The ultimate size of the cartilage formed was related to the initial chondrocyte concentration injected, and appeared to be uniform and stable within each category. There was no evidence of cartilage formation in the 12 controls. Histological analyses of distant organs showed no evidence of cartilage or alginate gel migration, or granuloma formation. In conclusion, chondrocyte-alginate gel suspensions are injectable, appear to be nonmigratory and are able to conserve their volume. In addition, the use of autologous cartilage cells would preclude an immunological reaction. These preliminary studies indicate that autologous cartilage-polymer gel solutions may be potentially useful in the endoscopic treatment of reflux.

Alginates↗
PubMed2000

Mobility of isoproturon from an alginate-bentonite controlled release formulation in layered soil.

The mobility of isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea] from an alginate-based controlled release (CR) formulation was investigated by using soil columns. A layered bed system simulating the typical arrangement under a plastic greenhouse, which is composed of sand, peat, amended soil and native soil was used. The CR formulation was based on sodium alginate (1.87%), isoproturon (1.19%), natural bentonite (3.28%), and water (93.66%), and was compared to technical grade isoproturon. The use of the alginate-bentonite CR formulation produced less vertical mobility of the active ingredient as compared to the technical product. There was no presence of herbicide in the leachate when the alginate-bentonite CR formulation was used. However, 0.90% of isoproturon appeared when the treatment was carried out with technical grade material. Isoproturon mobility was modelled using the programme CMLS, which showed the peat layer to retard pesticide leaching. Analysis of the soil columns showed the highest isoproturon concentration in the peat layer.

Adsorption↗
PubMed1997

DNA-alginate complex recognized by autoantibodies against DNA.

Double-stranded DNA was effectively complexed with alginic acid and immobilized on a surface of polystyrene microtiter plate. Dose-dependent binding of anti-DNA autoantibodies was finely observed to the solid phase DNA-alginate complex in enzyme-linked immunosorbent assay (ELISA). In contrast, non-specific binding of antibodies to alginate was scarcely detected rather than to poly-L-lysine. These results shown an availability of the solid phase DNA-alginate complex as an antigen in ELISA for detection of anti-DNA antibodies.

Alginates↗
PubMed2000

Porous carriers for biomedical applications based on alginate hydrogels.

Macroporous scaffolds are typically utilized in tissue engineering applications to allow for the migration of cells throughout the scaffold and integration of the engineered tissue with the surrounding host tissue. A method to form macroporous beads with an interconnected pore structure from alginate has been developed by incorporating gas pockets within alginate beads, stabilizing the gas bubbles with surfactants, and subsequently removing the gas. Macroporous scaffolds could be formed from alginate with different average molecular weights (5-200 kDa) and various surfactants. The gross morphology, amount of interconnected pores, and total void volume was investigated both qualitatively and quantitatively. Importantly, macroporous alginate beads supported cell invasion in vitro and in vivo.

Alginates↗
PubMed2002

Galactosylated alginate as a scaffold for hepatocytes entrapment.

Galactose moieties were covalently coupled with alginate through ethylenediamine as the spacer for enhancing the interaction of hepatocytes with alginate. Adhesion of hepatocytes onto the galactosylated alginate (GA)-coated polystyrene (PS) surface showed an 18-fold increase as compared with that of the alginate-coated surface and it increased with an increase in the concentration of GA. The morphologies of attached hepatocytes were observed to spread out at the 0.15 wt% GA-coated PS surface while round cells were observed at the 0.5 wt% GA-coated PS surface. Inhibition of hepatocytes attachment onto the galactose-carrying PS-coated surface occurred with the addition of the GA into the hepatocyte suspension, indicating the binding of GA with hepatocytes via the patch of asialoglycoprotein receptors. Primary hepatocytes were entrapped in the GA/Ca2+ capsules (GAC). Higher cell viability and more spheroid formation of hepatocytes were obtained in the GAC than in the alginate/Ca2+ capsules (AC). Moreover, liver functions of the hepatocytes such as albumin secretion and urea synthesis in the GAC were improved in comparison with those in the AC.

Alginates↗
PubMed2003

Preparation of alginic acid layers on stainless-steel substrates for biomedical applications.

This study is concerned with the blood compatibility of alginic acid layers immobilized on gamma-aminopropyltriethoxysilane (gamma-APS)-grafted stainless-steel (SUS316L). The surfaces were characterized with contact angle measurement and X-ray photoelectron spectroscopy (XPS). The blood compatibility was evaluated in terms of platelet adhesion and blood clotting time. An in vitro platelet adhesion assay indicated that only a small number of platelets adhered to substrate surfaces modified with gamma-APS and subsequently with alginic acid. Moreover, alginic-acid-immobilized SUS316L substrates had little effect on the blood clotting time. This indicated that alginic-acid-immobilized SUS316L substrates do not adsorb some blood-clotting proteins or factors, or stimulate them.

Alginates↗
PubMed1999

Study on gelatin-containing artificial skin: I. Preparation and characteristics of novel gelatin-alginate sponge.

An absorbable sponge, composed of gelatin and alginate, was prepared by new crosslinking method that improved the efficiency of crosslinking. The crosslinking degree was characterized by trinitrobenzenesulfonic acid (TNBS) assay. A water uptake ability test, in vitro drug release and collagenase degradation tests, and an in vivo animal test were employed to confirm the applicability of this gelatin-alginate sponge as a wound dressing material. As the alginate content in the sponge increased, the porosity increased, resulting in an enhanced water uptake ability. Sponges loaded with silver sulfadiazine or gentamicin sulfate slowly released drugs for up to four days. The crosslinked sponge resisted in vitro collagenase digestion for up to three days. An in vivo animal test using witar rat showed rather good wound healing effect of gelatin-alginate sponge containing AgSD than vaseline gauze in our full-thickness skin defect model.

Alginates↗
PubMed1999

Serum albumin-alginate coated beads: mechanical properties and stability.

According to a previously described method, alginate beads were prepared from a Na-alginate solution containing propylene glycol alginate (PGA) and human serum albumin (HSA). The solution was added dropwise to a CaCl2 solution. The beads were treated with NaOH, which started the formation of amide bonds between HSA and PGA at the periphery, giving a membrane. Batches of beads with increasingly thick membranes were prepared using growing concentrations of NaOH, and studied with a texture analyser. When raising NaOH concentration, the rupture strength progressively increased, and the resistance strength to a deformation of 50% of total height also increased before slightly decreasing for the highest NaOH concentration. Variations of bead elasticity were also observed. When the beads were prepared with saline reducing gelation time from 10 to 5 min, and reaction time from 15 to 5 min, mechanical properties varied more progressively with the NaOH concentration, while the results became more reproducible. A series of assays conducted with 0.01 M NaOH confirmed the importance of using a short gelation time, and saline rather than water. Stability assays were also performed. The results were compared to those of alginate-polylysine coated beads and showed the interest of the transacylation method.

Alginates↗
PubMed1998

Induction of pulmonary immunity in cattle by oral administration of ovalbumin in alginate microspheres.

Respiratory infectious diseases are an important cause of economic losses to the cattle industry. There is a need for an effective, easy to administer vaccine to the critical bacterial pathogens that cause pneumonia in cattle. An orally administered vaccine could be given to a large number of animals without significant stress to the animals and with minimal labor. The purpose of this study was to determine whether the oral administration of a model antigen (ovalbumin) in alginate microspheres could induce pulmonary immunity in cattle. Calves were vaccinated orally with ovalbumin (OVA) following either a subcutaneous (s.c.) or oral priming dose of OVA. Calves primed and boostered by oral administration (oral/oral) of OVA encapsulated in alginate microparticles had increased numbers of antigen-specific IgA ASCs (ASCs) in bronchoalveolar lavage (BAL) fluids. Calves that received a s.c. priming followed by an oral booster inoculation (s.c./oral) of OVA in alginate microspheres had a greater number of anti-OVA IgA, IgG1 and IgG2 ASCs in BALF. S.c./oral calves also had increased numbers of anti-OVA IgG1 ASCs in peripheral blood whereas oral/oral calves had none. S.c./oral calves had increased anti-OVA IgG1, IgG2, and IgA titers in BALF, and IgG1 and IgG2 in serum compared to both oral/oral and sham vaccinated calves. These results indicate that oral administration of antigen encapsulated in alginate microspheres results in a mucosal immune response in the respiratory tract of cattle. Furthermore, s.c. priming both enhanced the IgA response and stimulated an IgG1 and IgG2 response not seen in oral/oral calves. The difference in antibody isotype results suggest that design of the vaccination protocol can direct antibody responses as needed for a specific immunization program.

Administration, Oral↗