Low-viscosity Sodium Alginate Research Articles

Production of growth factors, pro – and anti-inflammatory cytokines by postnatal MMSCs from various tissue sources during in vitro co-cultivation with immunoisolated pancreatic β-cells

The article presents the results of evaluating growth factors, pro – and anti-inflammatory cytokine production by multipotent mesenchymal stem cell cultures under the conditions of co-cultivation with immuno-isolated beta-cells of the pancreas. β-cell transplantation is a minimally invasive therapeutic approach (compared to transplantation of entire pancreas), and it provides better metabolic control with respect to insulin administration. However, when transplanting β-cells, there is always a risk of immune rejection of the grafted cells. It is generally recognized that encapsulation is an effective means of immunological protection against the recipient’s immune system during transplantation. Regulation of the autoimmune response to transplanted cells is crucial for the treatment of type I diabetes mellitus. In recent years, along with replacement of islet cells, much attention has been paid to the use of multipotent mesenchymal stem cells with immunomodulatory and/or immunosuppressive properties, aimed for the correction of diabetes mellitus. Either in vitro and in vivo, they impact not only T-lymphocytes, but also B-lymphocytes, dendritic and NK-cells. Mesenchymal stem cells are able to inhibit proliferation of immune cells and reduce their secretion of inflammatory cytokines, acting as auxiliary cells to improve the survival of islets in the early post-transplant phase. Combined transplantation of multipotent mesenchymal stem cells and pancreatic β-cells is a promising approach to the treatment of type I diabetes mellitus. Deeper study of the mechanisms that cause their cytoprotective effect upon the transplant may be helpful for implementation of this therapeutic approach and improve its efficiency. In our study, a 1% solution of low-viscosity sodium alginate with addition of saline solution (0.9% sodium chloride) was used to create immuno-insulating scaffolds, and a 2.2% BaCl2 solution was added for polymerization. Decreased production of proinflammatory cytokines (TNFα, IL-12, IL-5) and growth factor (GM-CSF) was registered in co-cultures of β-cells with mesenchymal stem cells of bone marrow origin, and those obtained from subcutaneous adipose tissue. Anti-inflammatory activity was more pronounced in adipose stem cells and their immunomodulatory effects were shown via changes of their cytokine-producing activity. Hence, the multipotent mesenchymal stem cells obtained from adipose tissue and bone marrow have shown to exert cytoprotective effect upon pancreatic beta-cells by shifting the cytokine-producing activity towards an antiinflammatory profile.

Low-viscosity sodium alginate combined with TiO2 nanoparticles for improving neuroblastoma treatment

Titanium dioxide (TiO2) nanoparticles have been explored to prevent various cancer developments but it may cause oxidation, inflammation and high cytotoxicity. Alginate has nontoxic, anti-inflammatory, and antioxidant effects. We aimed to explore the effects of alginate-TiO2 temozolomide (TMZ) nanoparticles on neuroblastoma. A neuroblastoma model was established with neuroblastoma cells and alginate-TiO2 TMZ nanoparticles were made by spraying low-viscosity sodium alginate (250–360 kDa). The morphology of nanoparticles was observed via scanning electron microscope (SEM). The crystallinity values were analyzed via X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic study. Neuroblastoma mice were treated with saline solution, TMZ, TiO2-TMZ and alginate-TiO2-TMZ nanoparticles. Anti-oxidant, anti-inflammatory, and anti-tumor properties and the mouse survival rates were measured. The spectrometric profiles of alginate-TiO2 were consistent with those of TiO2 and alginate. Alginate-TiO2 TMZ nanoparticles had higher cytotoxicity toward neuroblastoma cells and less inhibitory activity toward normal neuronal cells. The combined nanoparticles increased antioxidant, anti-inflammatory and antitumor activities and prolonged the survival time of the neuroblastoma model (P < 0.05). On the other hand, Alginate-TiO2 TMZ nanoparticles reduced the levels of mitogen-activated protein kinases (MAPKs) and nuclear factor-κB (NF-κB). The combined nanoparticles improved neuroblastoma treatment by affecting NF-κB and MAPK signals.

Monitoring of infection volatile markers using CMOS-based luminescent bioreporters

Over the past two decades, whole-cell biosensors (WCBs) have been widely used in the environmental field, with only few applications proposed for use in agricultural. This study describes the development and optimization of a WCB for the detection of volatile organic compounds (VOCs) that is produced specifically by infected potato tubers. First, the effect of calcium-alginate matrix formation (beads vs. tablets) on the membrane uniformity and sensing efficiency was evaluated. Then, important parameters in the immobilization process were examined for their effect on the sensitivity to the presence of VOCs. The highest sensitivity to the target VOC was obtained by 20 min polymerization of bacterial suspension with optical density of 0.2 at 600 nm, dissolved in low-viscosity sodium alginate (1.5% w/v) and exposure to VOC at 4 °C. After optimization, the lowest limit of detection for three infection-sourced VOCs (nonanal, 3-methyl-1-butanol, and 1-octen-3-ol) was 0.17-, 2.03-, and 2.09-mg/L, respectively, and the sensor sensitivity was improved by 8.9-, 3.1- and 2-fold, respectively. Then, the new optimized immobilization protocol was implemented for the CMOS-based application, which increased the sensor sensitivity to VOC by 3-fold during real-time measurement. This is the first step in creating a sensor for real-time monitoring of crop quality by identifying changes in VOC patterns.

N-Acetylserotonin vs Melatonin: In-Vitro Controlled Release from Hydrophilic Matrix Tablets

Background: N-Acetylserotonin (NAS, N-acetyl-5-hydroxytryptamine) is the immediate precursor of the neurohormone melatonin (MT, N-acetyl-5-methoxytryptamine), which regulates sleep and wake cycles. NAS is produced by the N-acetylation of serotonin and is converted to melatonin via the action of Acetylserotonin O-methyltransferase (ASMT). Like melatonin, NAS acts as an agonist on the melatonin receptors MT1, MT2, and MT3. However, as NAS is abundant in specific brain areas, separate from serotonin and melatonin, it may also have discrete central effects. Indicatively, it has been reported that NAS may play a role in the antidepressant effects of Selective Serotonin Reuptake Inhibitors (SSRIs) and Monoamine Oxidase Inhibitors (MAOIs). &lt;/P&gt;&lt;P&gt; Objective: To decipher the controlled release characteristics of the active substances (NAS and MT) in a quick initial pace, aiming at a satisfactory sleep-onset related anti-depressive profile and prolonged release, thereafter, targeting at coping with poor sleep quality problems. &lt;/P&gt;&lt;P&gt; Methods: A series of hydrophilic matrix tablets involving as excipients, hydroxypropylmethylcellulose (HPMC) K15M, low viscosity sodium alginate, lactose monohydrate, and polyvinylpyrrolidone (PVP) M.W.: 10.000 and 55.000) was developed and tested at two dissolution media (pH 1.2 and 7.4). &lt;/P&gt;&lt;P&gt; Results: The results showed that commonly used excipients with different physicochemical properties govern the controlled release of NAS and MT from solid matrix systems. &lt;/P&gt;&lt;P&gt; Conclusions: We have demonstrated how broadly used excipients affect the in vitro controlled release of NAS and MT from solid pharmaceutical formulations. Currently, we extend our studies on the controlled release of these drugs using various other biopolymers/formulants of different physicochemical characteristics, which will help to highlight the discrete release profiles of NAS and MT.

Hydroxyl radical pretreatment for low-viscosity sodium alginate production from brown seaweed

Formalin pollution and water wastage are two of the main problems in the alginate industry. A novel pre-extraction treatment method based on the Fenton and electro-Fenton reactions is proposed to disrupt the cell wall of Macrocystis pyrifera and reduce the alginate filtrate viscosity, as an environmentally friendly process for alginate extraction. Under optimum Fenton (7.4 mM FeSO4 90 min) and electro-Fenton (EF-Fere 9 V, 90 min at pH 3, stirring) pre-extraction treatment conditions, the filtrate viscosity decreased by 83.99% and 97.79%, respectively. The filtrate viscosity decreased significantly as compared to the traditional approach under suitable operating conditions. Using of electro-Fenton for pre-extraction reduced water consumption by 60% in the filtration step and eliminated the use of formaldehyde during the process, reducing production costs and environmental pollution. Moreover, the yield and the quality of the alginate extracted after the pre-extraction improved.

Nephroprotective Effect of Low Viscosity Sodium Alginate on Lead Acetate-Induced Nephrotoxicity in Rats

Nephroprotective Effect of Low Viscosity Sodium Alginate on Lead Acetate-Induced Nephrotoxicity in Rats

Comparative In Vitro Controlled Release Studies on the Chronobiotic Hormone Melatonin from Cyclodextrins-Containing Matrices and Cyclodextrin: Melatonin Complexes

A series of hydrophilic matrix tablets was prepared and tested with respect to their ability to release the hormone melatonin in a controlled manner, in order to alleviate sleep onset and sleep maintenance dysfunctions. Besides the active ingredient, the tablets were comprised of combinations of the following: HPMC K 15M, low viscosity sodium alginate, microcrystalline cellulose (Avicel PH 102), magnesium stearate, and the cyclodextrins, α-CD, β-CD, γ-CD, HP-β-CD, sulfated β-CD, HP-α-CD and HP-γ-CD, and MLT (guest):CD (host) complexes of the above cyclodextrins, in 1:1 ratio. The controlled release studies were conducted in two aqueous dissolution media at pH 1.2 and 7.4. The stoichiometry of the formed complexes was examined by applying the continuous variation method (Job plot), while the stability constants were calculated by monitoring the spectrophotometric properties of free and CD-encapsulated melatonin (UV-Vis). Host-guest interactions were studied by Nuclear Magnetic Resonance (NMR) spectroscopy. The dissolution data suggest that melatonin is released faster from the MLT:CD complexes than from the rest matrix systems. This enhancement in the dissolution rate and the % release of melatonin from the complexes is due to the increased solubility of the MLT:CD complexes.

Stability of Lactobacillus rhamnosus GG incorporated in edible films: Impact of anionic biopolymers and whey protein concentrate

The incorporation of probiotics and bioactive compounds, via plasticised thin-layered hydrocolloids, within food products has recently shown potential to functionalise and improve the health credentials of processed food. In this study, choice of polymer and the inclusion of whey protein isolate was evaluated for their ability to stabalise live probiotic organisms. Edible films based on low (LSA) and high (HSA) viscosity sodium alginate, low esterified amidated pectin (PEC), kappa-carrageenan/locust bean gum (κ-CAR/LBG) and gelatine (GEL) in the presence or absence of whey protein concentrate (WPC) were shown to be feasible carriers for the delivery of L. rhamnosus GG. Losses of L. rhamnosus GG throughout the drying process ranged from 0.87 to 3.06 log CFU/g for the systems without WPC, losses were significantly reduced to 0 to 1.17 log CFU/g in the presence of WPC. Storage stability (over 25d) of L. rhamnosus GG at both tested temperatures (4 and 25 °C), in descending order, was κ-CAR/LBG > HSA > GEL > LSA = PEC. In addition, supplementation of film forming agents with WPC led to a 1.8- to 6.5-fold increase in shelf-life at 4 °C (calculated on the WHO/FAO minimum requirements of 6 logCFU/g), and 1.6–4.3-fold increase at 25 °C. Furthermore probiotic films based on HSA/WPC and κ-CAR/LBG/WPC blends had both acceptable mechanical and barrier properties.

Characterization of a novel bile acid-based delivery platform for microencapsulated pancreatic β-cells

Introduction In a recent study, we confirmed good chemical and physical compatibility of microencapsulated pancreatic β-cells using a novel formulation of low viscosity sodium alginate (LVSA), Poly-L-Ornithine (PLO), and the tertiary bile acid, ursodeoxycholic acid (UDCA). This study aimed to investigate the effect of UDCA on the morphology, swelling, stability, and size of these new microcapsules. It also aimed to evaluate cell viability in the microcapsules following UDCA addition. Materials and methods Microencapsulation was carried out using a Büchi-based system. Two (LVSA-PLO, control and LVSA-PLO-UDCA, test) pancreatic β-cells microcapsules were prepared at a constant ratio of 10:1:3, respectively. The microcapsules’ morphology, cell viability, swelling characteristics, stability, mechanical strength, Zeta potential, and size analysis were examined. The cell contents in each microcapsule and the microencapsulation efficiency were also examined. Results The addition of UDCA did not affect the microcapsules’ morphology, stability, size, or the microencapsulation efficiency. However, UDCA enhanced cell viability in the microcapsules 24 h after microencapsulation (p < 0.01), reduced swelling (p < 0.05), reduced Zeta potential (− 73 ± 2 to − 54 ± 2 mV, p < 0.01), and increased mechanical strength of the microcapsules (p < 0.05) at the end of the 24-h experimental period. Discussion and conclusion UDCA increased β-cell viability in the microcapsules without affecting the microcapsules’ size, morphology, or stability. It also increased the microcapsules’ resistance to swelling and optimized their mechanical strength. Our findings suggest potential benefits of the bile acid UDCA in β-cell microencapsulation.

Gelucire BasedIn SituGelling Emulsions: A Potential Carrier for Sustained Stomach Specific Delivery of Gastric Irritant Drugs

Non steroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed medications to the geriatric patients for the treatment of arthritis and other painful disorders. The major side effects of NSAIDs are related to their effects on the stomach and bowels. The present study concerns assessment of the potential of liquid in situ gelling emulsion formulations (emulgels) as patient compliant stomach specific sustained release carrier for the delivery of highly gastric irritant drug, Piroxicam. Emulgels were prepared, without using any emulgent, by mixing different concentrations of molten Gelucire 39/01 with low viscosity sodium alginate solution prepared in deionized water at 50°C. CaCO3 was used as buoyancy imparting as well as crosslinking agent. Emulgels so prepared were homogenous, physically stable, and rapidly formed into buoyant gelled mass when exposed to simulated gastric fluid (SGF, pH 1.2). Drug release studies carried out in SGF revealed significant retardation (P < 0.05) of Piroxicam release from emulgels compared to conventional in situ gelling formulations prepared without Gelucire 39/01. Pharmacodynamic studies carried out in albino rats revealed significantly increased analgesic/anti-inflammatory response from in situ emulgels compared to conventional in situ gelling formulations. Further, in vivo toxicity studies carried out in albino rats revealed no signs of gastric ulceration upon prolonged dosing.

Evaluation of hydrophilic matrix tablets based on Carbopol® 971P and low-viscosity sodium alginate for pH-independent controlled drug release

Background: The aim of this study was to evaluate matrix tablets containing different ratios of Carbopol® 971P (CP) to low-viscosity sodium alginate (SA) and assess their suitability for pH-independent controlled drug release. Methods: Two processing methods (physical mixing, PM and spray-drying, SD) were applied before compaction and the release from corresponding matrices was compared. The release from CP-SA PM matrices was also investigated using three model drugs (paracetamol, salicylic acid, and verapamil HCl) and two dissolution media (0.1 N HCl or phosphate buffer, pH = 6.8), and the release rate, mechanism, and pH-dependence were characterized by fitting of Higuchi and Peppas models, and evaluation of similarity factor. Furthermore, swelling behavior of CP-SA matrix tablets was studied for evaluating its impact on drug release. Results: The processing method (SD or PM) markedly affected the drug release from CP-SA matrices. ANOVA tests showed significant effects of the CP:SA ratio and drug type on the release rate (expressed by the constant, KH, from Higuchi model) and of the dissolution medium on the release mechanism (expressed by the exponent, n, from Peppas model). Similarity factor (f2) indicated that the CP:SA ratios ≥ 25:75 and ≥ 50:50 were suitable for pH-independent release of paracetamol and salicylic acid, respectively, although for verapamil HCl, the matrix with low CP:SA ratio (0:100) showed remarkably reduced pH-dependence of release. Swelling parameters (water uptake and mass loss) were significantly changed with experimental variables (CP:SA ratio, medium, and time) and were in good correlation with drug release. Conclusion: Matrix tablets based on CP and SA form a potentially useful versatile system for pH-independent controlled drug release.

Statistical optimization of floating pulsatile drug delivery system for chronotherapy of hypertension

Introduction:A pulsatile drug delivery system is characterized by a lag time that is an interval of no drug release followed by rapid drug release. The purpose of this work was to develop hollow calcium alginate beads for floating pulsatile release of valsartan intended for chronopharmacotherapy. Floating pulsatile concept was applied to increase the gastric residence of the dosage form having lag phase followed by a burst release.Materials and Methods:To overcome the limitations of various approaches for imparting buoyancy, hollow/porous beads were prepared by simple process of acid-base reaction during ionotropic crosslinking by low viscosity sodium alginate and calcium chloride as a crosslinking agent. In this study, investigation of the functionality of the sodium alginate to predict lag time and drug release was statistically analyzed using the response surface methodology (RSM). RSM was employed for designing of the experiment, generation of mathematical models and optimization study. The chosen independent variables, i.e. sodium alginate and potassium bicarbonate were optimized with a 32 full factorial design. Floating time and cumulative percentage drug release in 6 h were selected as responses.Results:Results revealed that both the independent variables are significant factors affecting drug release profile. A second-order polynomial equation fitted to the data was used to predict the responses in the optimal region. The optimized formulation prepared according to computer-determined levels provided a release profile, which was close to the predicted values. The floating beads obtained were porous (21-28% porosity), hollow with bulk density <1 and had Ft70 of 2–11 h. The floating beads provided expected two-phase release pattern with initial lag time during floating in acidic medium followed by rapid pulse release in phosphate buffer.Conclusion:The proposed mathematical model is found to be robust and accurate for optimization of time-lagged formulations for programmable pulsatile release of valsartan.

Effect of Concentration and Substrate Flow Rate on Isomaltulose Production from Sucrose by Erwinia sp. Cells Immobilized in Calcium-Alginate Using Packed Bed Reactor

Isomaltulose was obtained from sucrose solution by immobilized cells of Erwinia sp. D12 using a batch and a continuous process. Parameters for sucrose conversion into isomaltulose were evaluated using both experimental design and response surface methodology. Erwinia sp. D12 cells were immobilized in different alginates, and the influence of substrate flow rate and concentration parameters to produce isomaltulose from sucrose were observed. Response surface methodology demonstrated that packed bed columns containing cells immobilized in low-viscosity sodium alginate (250 cP) presented a mean isomaltulose conversion rate of 47%. In a continuous process, both sucrose substrate concentration and substrate flow rate parameters had a significant effect (p < 0.05) and influenced the conversion of sucrose into isomaltulose. Higher conversion rates of sucrose into isomaltulose, from 53-75% were obtained using 75 g of immobilized cells at a substrate flow rate of 0.6 mL/min.

Some properties of alginate gels derived from algal sodium alginate

Alginic acid in soluble sodium alginate turns to insoluble gel after contact with divalent metal ions, such as calcium ions. The sodium alginate character has an effect on the alginate gel properties. In order to prepare a suitable calcium alginate gel for use in seawater, the effects of sodium alginate viscosity and M/G ratio (the ratio of D-mannuronate to L-guluronate) on the gel strength were investigated. The wet tensile strengths of gel fibers derived from high viscosity sodium alginate were higher than those from low viscosity sodium alginate. The tensile strength increased with diminishing sodium alginate M/G ratio. Among the gel fibers tested, the gel fiber obtained from a sodium alginate I-5G (1% aqueous solution viscosity = 520 mPa·s, M/G ratio = 0.6) had the highest wet tensile strength. After 13 days treatment in seawater, the wet tensile strength of the gel fiber retained 36% of the original untreated gel strength. For sodium alginates with similar viscosities, the seawater tolerance of low M/G ratio alginate was greater than that of the high M/G ratio one. This study enables us to determine a suitable calcium alginate gel for use in seawater.

Therapeutic effect of sodium alginate in experimental chronic ulcerative colitis.

The aim of this study was to test the therapeutic efficacy of sodium alginate in a rat model of trinitrobenzene sulfonic acid (TNBS)-induced inflammatory bowel disease. This experiment was carried out using 77 Sprague-Dawley rats which were divided into six groups; normal, control, prophylactic, therapeutic and two experimental groups. Rats were sacrificed 1, 2, 3 and 6 weeks after colitis induction. Severity of colitis was graded macroscopically and assessed using serum and colonic mucosal cytokines and eicosanoids. Intrarectal TNBS (30 mg) produced a significant chronic ulcerative colitis. The lesions were most severe on day seven after TNBS instillation, and then declined, but lesions were still observed after six weeks. TNBS administration also significantly enhanced the serum and colonic mucosal cytokines (TNF-alpha and IL-6) and eicosanoids (LTB4 and PGE2) levels, which paralleled with the severity of colitis. Low viscosity sodium alginate (LVA) solution as therapeutic agent was administered orally as drinking water at concentration of 0.5% (W/V) for six weeks. Results showed that pre-treatment (in prophylactic group) and treatment with LVA were significantly able to reduce colonic damage score, serum level and colonic mucosal production of TNF-alpha, IL-6, LTB4 and PGE2 in pre-treated and treated animals compared with non-treated controls. LVA therapy is able to suppress chronic ulcerative colitis in experimental model.

Sodium Alginate as a Novel Therapeutic Option in Experimental Colitis

The potential therapeutic effect of low-viscosity sodium alginate (LVA) was studied in a rat model of acute colitis induced by intracolonic administration of acetic acid. This experimental model produced a significant ulcerative colitis. Induction of colitis also significantly enhanced the serum and colonic mucosal cytokine (IL-6 and TNF-alpha) and eicosanoid (LTB4 and PGE2) levels, which paralleled with the severity of colitis. LVA solution was administered orally as drinking water at concentration of 0.5% (W/V) for 1 week. The tolerability and inhibitory effect of LVA on matrix metalloproteinase-2 (MMP-2) were tested using WEHI-164 cell line and zymography method. The results showed that LVA therapy is able to significantly reduce colonic damage score, histological lesion, serum and colonic mucosal IL-6, TNF-alpha, LTB4 and PGE2 levels in treated group compared with nontreated controls. Moreover, in vitro examinations revealed that treatment with LVA could diminish MMP-2 activity. It is concluded that LVA is able to suppress acetic acid-induced colitis in rats. Some of the action of LVA may be associated with its inhibitory effects on cytokine and eicosanoid production and MMP-2 activity. Our data suggest that LVA could potentially be a novel therapeutic option for inflammatory bowel disease.

The Effect of Erosion and Swelling on the Dissolution of Theophylline from Low and High Viscosity Sodium Alginate Matrices

The extent of dissolution of theophylline from sodium alginate matrices has been studied in water and HCl. Surprisingly, it was observed that the dissolution rate was very fast for the low viscosity (LV) material in water and for the high viscosity (HV) in acid, whereas slow release was seen for LV in acid with very slow release for the HV in water. The extent of erosion and swelling of the matrices (with and without drug and with and without stirring) was determined from simple weighing experiments. Based on the extent of erosion and swelling, along with visual observations, it was concluded that the rapid release from LV in water was due to rapid and complete erosion of a weak gel layer. The rapid release of HV in HCl was due to an unexpected lamination of the tablet during swelling, which resulted in exposure of more of the tablet core, and caused increased erosion of the matrix. The slow release seen with the LV in HCl was due to the acid gel being tough and resistant to erosion. The very slow release observed with the HV in water was due to very substantial swelling, with the presence of near zero-order kinetics for this system being due to a balance of swelling and erosion, keeping the diffusion process at a constant rate. Furthermore, an anisotropic swelling behavior is indicated by the preferential expansion in the axial dimension relative to the radial dimension for both LV and HV alginates.

Rheological behavior of sodium alginate solutions with added divalent metal salts and their use as thickeners in cotton printing with reactive dyes

The addition of traces of certain divalent metal ions (Ca2+ and Mg2+) to aqueous solutions of sodium alginate increases their viscosity to a high extent. Further increase in the concentration of the added metal ions causes gelation and precipitation of the metal alginate salt. The effect of adding the divalent metal ions on the viscosity of sodium alginate solutions (before gelation or precipitation stages) was investigated via rheological and viscosity measurements. The optimum concentrations of the divalent metal salts were determined. Calculated traces of divalent metal salts were added to pastes of low-viscosity sodium alginate (5%) to increase its viscosity and subsequently decrease the amount of sodium alginate required for use in screen printing of cotton fabrics with reactive dyes (i.e., decreasing cost). For the sake of comparison, a comparativey was conducted by preparing other series of printing pastes thickened with low-viscosity sodium alginate (8%) and high-viscosity sodium alginate (2.5%). These printing pastes were applied to cotton fabrics by using the same technique. © 2001 John Wiley & Sons, Inc. Adv Polym Techn 20: 58–71, 2001

Method To immobilize the aphid-pathogenic fungus erynia neoaphidis in an alginate matrix for biocontrol

Erynia neoaphidis is an important fungal pathogen of aphid pests worldwide. There have been few reported attempts to formulate this natural agent for use in biocontrol. In the current study, factors involved in the immobilization of E. neoaphidis hyphae in an alginate matrix were investigated. Hyphae of two isolates cultured in liquid medium were 220 to 620 &mgr;m in length and 7 to 19 &mgr;m in diameter with a 74 to 83% cytoplasmic content. The optimal concentration of low-viscosity sodium alginate for production of conidia from entrapped hyphae was 1.5% (wt/vol), and 0.1 and 0.25 M calcium chloride were equally suitable for use as the gelling solution. Alginate beads were rinsed with 10% sucrose after gelling. However, beads should not be left for longer than 40 min in 0.1 M calcium chloride or 10% sucrose to prevent a 10% loss in conidial production. A 40% (vol/vol) concentration of fungal biomass produced significantly more conidia than either 20% or the standard concentration of 10%. This effect persisted even after beads were dried overnight in a laminar flow hood and stored at 4 degreesC for 4 days. Conidia from freshly produced alginate beads caused 27 to 32% infection in Pea aphids as determined by standardized laboratory bioassays. This finding was not significantly different from infections in aphids inoculated with fresh mycelial mats or plugs from Petri dish cultures. In conclusion, algination appears to be a promising technique for utilizing E. neoaphidis in the biocontrol of aphid pests.

Response Surface Methodology To Optimize β-Galactosidase Immobilization Using a Combination of Hydrocolloids as the Supporting Matrix

Response surface methodology (RSM) was applied to optimize the composition of a mixture of hydrocolloids (low-viscosity sodium alginate, high-viscosity sodium alginate, and κ-carrageenan) used in the immobilization of β-galactosidase for application in the hydrolysis of lactose. A five levels, a three-factor design was adopted. The activity and stability of the immobilized enzyme and the strength of the supporting matrix were optimized by using a mathematical model applied in the range of process conditions. Requirements for multifactor response surface designs were satisfied, and the correlation coefficient, R2, was larger than 0.850, ensuring a good adjustment of the model to the experimental values. Best results were obtained for values of 1.00% low-viscosity sodium alginate, 1.40−1.60% high-viscosity sodium alginate, 0.10−0.30% κ-carrageenan, and 10−12% enzyme.