Encapsulation of olive leaf antioxidants in microbeads: Application of alginate and chitosan as wall materials

Edible microcapsule technology has been declared as a newly developed technology in 21st century by some certain authorities in order to preserve food products. Encapsulation of the bioactive materials in edible coatings is a blessing that can eliminate many undesirable situations that might arise when it is used as additive. In this study, olive leaf extract has been evaluated as active material to prepare microcapsules by using alginate as coating. Ionic gelation was used to produce microbeads. The experimental design of the encapsulation system, the effects of the process parameters, the modeling of the experimental data and the optimization of the conditions were carried out with Box-Behnken design of response surface method (Box-Behnken-RSM). Box-Behnken-RSM produced 17 experimental runs. Calcium chloride (2–15%, w/v) and sodium alginate concentrations (1–2%, w/v), and hardening time (15–45 min) were selected as independent variables, while encapsulation efficiency (EE) of the capsules in terms of total phenolic content (TPC) and oleuropein concentration were responses. Impact of chitosan as coating layer was also investigated with three different ratios of chitosan (0.4%, 0.7%, 1% w/v). Accelerated oxidation test was employed to measure the stability of the microcapsules against oxidation by means of Rancimat method. Encapsulation of the olive leaf extract in alginate microbeads was satisfying with >70% and >90% efficiencies with respect to TPC and oleuropein under optimum conditions (2.34% calcium chloride concentration and 2% sodium alginate for 26 min of hardening time).     

Determination of the decay rate constant for hepatocytes immobilized in alginate microcapsules

Primary mouse hepatocytes (between 10–250 cells per capsule) were immobilized within 1.0% w/v alginate microbeads. The textural properties of the alginate matrix were characterized and a full protocol based upon the measurement of the initial rate of Resazurin reduction was studied and standardized. Using this method, the decay rate constant (K_d = 0.45 ± 0.01 days^?1) and the time in which the cell viability decreases in half (VI₅₀ = 37 ± 0.7 h) have been measured. The method was compared with the analysis of cell vitality using Calcein A/M and Ethidium Homodimer I. Differences between the two methods were found in the viability profile due to the significant presence of double stained cells along the culture time. According to the author's knowledge, this is the first report of a systematic study and determination of the K_d value for immobilized hepatocytes, incorporating a wide range of cell concentrations within the alginate matrix.     

A prebiotic matrix for encapsulation of probiotics: physicochemical and microbiological study

This work aims to develop an encapsulated oral-synbiotic supplement by studying the effect of adding inulin in alginate beads and observing its ability to protect three probiotic strains: Pediocucus acidilactici, Lactobacillus reuteri and Lactobacillus salivarius. Beads of different inulin concentrations 0%, 5%, 10%, 15% and 20% (w/v) in 2% (w/v) alginate solution were prepared by the extrusion/ionotropic gelation method. Polymer distribution within beads was characterised using confocal laser scanning microscopy. Interactions between alginate and inulin were monitored by Fourier transform infra-red spectroscopy (FTIR). Effect of encapsulation on viability, antimicrobial ability, acid tolerance and bile tolerance of probiotic strains were investigated. Antimicrobial and probiotic properties of bacterial strains were not affected by encapsulation. Bacterial protection against acidity was increased by adding inulin. Beads with 5% w/v inulin were the most effective in bacterial protection against bile-salts. To our knowledge, this work is the first to use such high concentrations of inulin.     

Formulation and stability evaluation of 3D alginate beads potentially useful for cumulus–oocyte complexes culture

Ovarian follicle encapsulation in synthetic or natural matrixes based on biopolymers is potentially a promising approach to in vitro maturation (IVM) process, since it maintains follicle 3D organisation by preventing its flattening and consequent disruption of gap junctions, preserving the functional relationship between oocyte and companion follicle cells. The aim of the work was to optimise physico-chemical parameters of alginate microcapsules for perspective IVM under 3D environments. On this purpose alginate and cross-linking agent concentrations were investigated. Alginate concentration between 0.75% and 0.125% w/w and Mg²⁺, Ba²⁺, Ca^2+?at concentration between 100 and 20?mM were tested. Follicle encapsulation was obtained by on purpose modified diffusion setting gelation technique, and evaluated together with beads, chemical and mechanical stability in standard and stressing conditions. Beads permeability was tested towards albumin, fetuin, pyruvate, glucose, pullulan. Results demonstrated that 0.25% alginate cross-linked in 100?mM CaCl₂ beads is suitable to follicle encapsulation.     

Improved viability of Lactobacillus acidophilus NRRL-B 4495 during freeze-drying in whey protein-pullulan microcapsules

Abstract

In this research, pullulan was incorporated in protein-based encapsulation matrix in order to assess its cryoprotective effect on the viability of freeze-dried (FD) probiotic Lactobacillus acidophilus NRRL-B 4495. This study demonstrated that pullulan in encapsulation matrix resulted in a 90.4% survival rate as compared to 88.1% for whey protein (WPI) encapsulated cells. The protective effects of pullulan on the survival of FD-encapsulated cells in gastrointestinal conditions were compared. FD WPI-pullulan capsules retained higher survived cell numbers (7.10?log CFU/g) than those of FD WPI capsules (6.03?log CFU/g) after simulated gastric juice exposure. Additionally, use of pullulan resulted in an increased viability after bile exposure. FD-free bacteria exhibited 2.18?log CFU/g reduction, while FD WPI and FD WPI-pullulan encapsulated bacteria showed 0.95 and 0.49?log CFU/g reduction after 24?h exposure to bile solution, respectively. Morphology of the FD microcapsules was visualized by scanning electron microscopy.     

Effect of alginate composition and gelling cation on microbead swelling

Purpose: The purpose of this study was to determine the roles of alginate composition and gelling cations on bead swelling, which affects its durability.

Method: Using a 2-channel droplet generator, microspheres were generated with 1.5% solutions of low viscosity high-mannuronic acid (LVM), medium viscosity high-mannuronic acid (MVM), low viscosity high-guluronic acid (LVG) and medium viscosity high-guluronic acid (MVG) alginate. They were gelled by cross-linking with 1.1% solution of either BaCl₂ or CaCl₂. The diameters of the microbeads were measured and recorded on day 0. The microbeads were subsequently washed and incubated in saline at 37°C for 2 weeks with size assessment every 2 days. The data were normalized by calculation of the percentage change from control (day 0) for all groups of microbeads.

Results: Diameters of all beads were between 550–700 microns on day 0. Viscosity had no effect on swelling of Ba⁺⁺- and Ca⁺⁺-alginate microbeads. Ca⁺⁺-alginate microbeads were more prone to swelling than the corresponding Ba⁺⁺-alginate beads. High G-Ba⁺⁺ beads had only a modest increase in size over time, in contrast to the high M-Ba⁺⁺.

Conclusion: Alginate composition and the gelling cation have significant effects on bead swelling.     

Control of mosquito larvae by encapsulated pathogen Bacillus thuringiensis var. israelensis

Abstract

Bacillus thuringiensis var. israelensis (B.t.i.) containing alginate microcapsules were prepared in order to maintain durable formulations which could resist several effects causing reduced efficiency during applications. B.t.i. spores were harvested through NYSM agar plates and encapsulated in Ca-alginate (0.5–2.0% w/v) gels without any significant loss of sporal or larvicidal activity. The effect of acidic pH on the larvicidal toxin was tested using Culex sp. larvae in the laboratory. The alginate microcapsules pretreated with saturated KH₂PO₄ solution gave larvicidal activity after 24–48h, by bioassay. Suspension and encapsulated forms of the pathogenic bacterium were exposed to pH variations (3.4–10.0), UV light and high temperature (50°C). Durability to Pb ^{+ +}, Cu⁺⁺, Fe^{+ +} compounds and phenol was also examined. As the alginate content increased, stability of B.t.i. drastically increased against the tested effects, but to obtain useful releasing microcapsules, 14–1.5% w/v alginate concentrations were found to be optimum.     

Formulation and optimization of alkaline extracted ispaghula husk microparticles of isoniazid – in vitro and in vivo assessment

Microparticles containing isoniazid were prepared by the emulsification internal ionic gelation method using a novel, alkaline extracted ispaghula husk as a wall forming material. A four-factor three-level Box–Behnken design was employed to study the effect of independent variables on dependent variables. Sodium alginate concentration (X₁), alkaline extraction of ispaghula husk (AEISP) concentration (X₂), concentration of cross-linking agents (X₃) and stirring speed (X₄) were four independent variables considered in the preparation of microparticles, while the particle size (Y₁) and entrapment efficiency (Y₂) were dependent variables. Optimized microparticles exhibited 83.43% drug entrapment and 51.53?µm particle size with 97.80% and 96.37% validity, respectively, at the following conditions – sodium alginate (3.55% w/v), alkaline extracted ispaghula husk (3.60% w/v), cross-linker concentration (7.82% w/v) and stirring speed (1200?rpm). The optimized formulation showed controlled drug release for more than 12?h by following Higuchi kinetics via non-Fickian diffusion. The gamma scintigraphy of the optimized formulation in Wistar rats showed that microparticles could be observed in the intestinal lumen after 1?h and were detectable in the intestine up to 12?h, with decreased percentage of radioactivity (t_1/2 of ^99mTc 4–5?h).     

A Comparative Histological Study of Alginate Beads as a Promising Controlled Release Delivery for Mefenamic Acid

The new mefenamic acid-alginate bead formulation prepared by ionotropic gelation method using 3 × 2² factorial design has shown adequate controlled release properties in vitro. In the present study, the irritation effects of mefenamic acid (MA), a prominent non-steroidal anti-inflammatory (NSAI) drug, were evaluated on rat gastric and duodenal mucosa when suspended in 0.5% (w/v) sodiumcarboxymethylcellulose (NaCMC) solution and loaded in alginate beads. Wistar albino rats weighing 200 ± 50 g were used during in vivo animal studies. In this work, biodegradable controlled release MA beads and free MA were evaluated according to the degree of gastric or duodenal damage following oral administration in rats. The gastric and duodenal mucosa was examined for any haemorrhagic changes. Formulation code A10 showing both Case II transport and zero order drug release and t₅₀ % value of 5.22 h was chosen for in vivo animal studies. For in vivo trials, free MA (100 mgkg^?1), blank and MA (100 mgkg^?1) loaded alginate beads (formulation code A10) were suspended in 0.5% (w/v) NaCMC solution and each group was given to six rats orally by gavage. NaCMC solution was used as a control in experimental studies. In vivo data showed that the administration of MA in alginate beads prevented the gastric lesions.     

Encapsulation of Lactobacillus plantarum ATCC 8014 and Pediococcus acidilactici ATCC 8042 in a freeze-dried alginate-gum arabic system and its in vitro testing under gastrointestinal conditions

Abstract

The aim of this study was to investigate the viability of Pediococcus acidilactici ATCC 8042 and Lactobacillus plantarum ATCC 8014 in a freeze-dried capsules system prepared with sodium alginate and gum arabic using the extrusion technique. The capsules made with alginate 2% (w/v)/gum arabic 2% (w/v) showed higher hardness (7.12?±?0.71?N), with highly cohesive (0.81?±?0.02) and elastic (0.99?±?0.00) features on the Texture Profile Analysis (TPA), as well as higher sphericity with 1.75?±?0.12?mm y 1.73?±?0.13?mm diameter axes and regularity in their surface by Scanning Electron Microscopy (SEM). The use of skimmed milk at 10% as a cryoprotector in the freeze-drying process allowed the obtention of high viability percentages (88% a 96%) for both strains. Best results of viability for P. acidilactici encapsulated was with the use of alginate 2% (w/v)/gum arabic 2% (w/v) (92%±2.65), and L. plantarum with the use of alginate 2% (w/v) (84.71%±10.33) during the gastrointestinal environment challenge.     

Preparation and detection of calcium alginate/bone powder hybrid microbeads for in vitro culture of ADSCs

Abstract

Calcium alginate microbeads have been widely used in tissue engineering application, due to their excellent biocompatibility, biodegradability, enhanced mechanical strength and toughness. Bone powder containing abundant hydroxylapatite, type I collagen and growth factors such as BMP2 and BMP4, possesses good osteoinductive activity. Herein, a hybrid calcium alginate/bone powder microbead was therefore prepared. Afterwards, different seeding density of adipose-derived stem cells (ADSCs) in these hybrid microbeads was discussed systematically for further in vitro expansion. Optimised microbeads suitable for in vitro expansion and differentiation of ADSCs were prepared using the droplet method under overall considering suitable concentrations of calcium alginate and calcium chloride as well as the density of bone powder through an orthogonal experiment. The results showed that the concentration of sodium alginate had the most influence on inside mass transfer and mechanical strength of the hybrid microbeads, secondly the calcium chloride, then the density of bone powder. The hybrid microbeads could be optimally performed while the concentrations of sodium alginate and calcium chloride were 2.5% and 4.5%, as well as 5.0?mg/mL bone powder, respectively. Live/Dead assay showed that the expanded ADSCs differentiated well with an initial embedding density of 5?×?10⁶ cells/mL.     

Novel solvent-based method for preparation of alginate beads with improved roundness and predictable size

Attempts to determine conditions or processes within alginate gel beads often suffer from inaccuracies due to an improper roundness of the analysed beads. Therefore, a novel solvent-based method for the preparation of alginate beads with improved shape was developed: An aqueous solution of 2% (w/v) alginate in water was injected into a solvent layering consisting of hexane, n-butanol, n-butanol with 1% (w/v) CaCl₂ and finally 2% (w/v) CaCl₂ in water. Beads of up to 3.5?mm in diameter obtained with this method had a roundness which was ～5% better than comparable beads prepared by dropping an alginate solution into a CaCl₂-hardening bath. This was determined by a software supported quantitative analysis of bead size and shape. Additionally, the novel solvent-based method allows for highly reproducible preparation of alginate beads with exactly predictable sizes. The biggest beads obtained with this method were 9?mm in diameter. Thus, with the solvent-based preparation of alginate beads it is now possible to easily obtain beads of exactly the type needed for a specific analytical purpose.     

Survival and stability of bifidobacteria loaded in alginate poly-l-lysine microparticles

Bifidobacteria-loaded alginate microparticles were prepared by spraying a mixture of alginate and bifidobacteria culture using an air atomization method. Survival and stability of bifidobacteria loaded in microparticles were then evaluated. Survival of bifidobacteria from alginate poly-l-lysine microparticles was significantly increased when MRS broth or yeast extract was added in simulated intestinal fluid (pH 6.8). The number of bifidobacteria gradually increased for 8 h (10⁸ cfu/g) and then reached about 10⁹–10¹⁰ cfu/g when incubated over 12 h in intestinal fluid containing 0.5% yeast extract and 0.05% -cysteine. The survival of bifidobacteria was highly dependent on the pH of the exposing media. When the bifidobacteria was immobilized with alginate or even poly-l-lysine treatment, the survival of bifidobacteria was highly enhanced in the low pH conditions (ca. >10⁸ vs. <10³ cfu/g). The stability of free flowing bifidobacteria-loaded alginate poly-l-lysine microparticles was significantly improved during storage at 4°C in a refrigerator when compared to bifidobacteria cultures. The bifidobacteria-loaded alginate poly-l-lysine microparticles could be applied to various dairy products.     

Effect of alginate composition and purity on alginate microspheres

Background: Alginate is commonly used to microencapsulate islets in experiments with islet allografts and xenografts for the treatment of Type I diabetes. The purpose of the present study is to determine the effects of alginate composition and purity on the morphology and size of microspheres. Methods: Microcapsules produced with the impure alginate types, medium-viscosity high-guluronic acid (IMVG), low-viscosity high-G (ILVG), low-viscosity high-mannuronic acid (ILVM) and medium-viscosity high-M (IMVM) were compared with one another and others generated with a highly purified LVM (HPLVM) alginate. Droplets of 1.5% alginate from an air-syringe pump were gelled in 1.1% CaCl₂ solution. While leaving the alginate pressure and needle recess constant, the air-jacket pressure was varied between 9.5–10.5 PPSI to enhance stable microcapsule generation and different batches of microbeads were made from each alginate type. Results: The sizes of the high-guluronic acid alginate microbeads were consistently bigger than those of the corresponding high-mannuronic acid alginate beads at all air-jacket settings. At the optimal air-jacket pressure of 9.0 PPSI, the mean+SD diameter of the IMVG microbeads was 780+20?µm, while that of IMVM was 607+44?µm (p<0.0001, n?=?30). Similarly, the mean ILVG microbead diameter was 816+28 µm compared to 656+26?µm for ILVM capsules (p<0.0001, n?=?30). Less polymorphism was found with the HPLVM microspheres than with the ILVM microbeads. Conclusion: Highly purified high-mannuronic acid alginate will provide smaller, spherical microcapsules suitable for islet cell transplantation.     

Biodegradable alginate microparticles developed by electrohydrodynamic spraying techniques for oral delivery of protein

In this study, alginate microparticles were prepared by cross-linking alginate with calcium chloride solution using an electrohydrodynamic spraying technique. The effects of alginate and calcium chloride concentration as well as electrical potential on particle size and shape were investigated. The results showed that 1 mg ml^?1 alginate medium viscosity (AMV), 2.5 mg ml^?1 CaCl₂, electrical potential 18 kV (F1) and 0.5 mg ml^?1 alginate low viscosity (ALV), 2.5 mg ml^?1 CaCl₂, electrical potential 20 kV (F2) yielded the spherical shape and small particles of 937 ± 158 nm and 1556 ± 51 nm, respectively. In bovine serum albumin (BSA) entrapment efficiency study, initial BSA of 5, 10, 20, 40 and 60% w/w to polymer was incorporated into these alginate microparticles. The results revealed that F2 with initial BSA 10% w/w showed the highest entrapment efficiency of 49.70 ± 0.01%. The result of BSA content revealed that F2'with the initial BSA of 20% w/w showed the highest amount of BSA content of 3.92 ± 0.02 mg g^?1 of particles. F1 and F2 with the initial BSA of 5%, 20% and 40% w/w were chosen to evaluate for the release in PBS pH 7.4. It was found that F1 with the initial BSA of 40% w/w showed the slowest release rate and sustained release. The release of F1 in 0.1 N HCl solution (pH 1.2) was slower than that in pH 7.4. This electrohydrodynamic spray technique (EHDA) can be applied to prepare alginate in micro size and can encapsulate BSA. Alginate microparticles can further be optimized for oral delivery of several pharmaceutical peptides and proteins.     

Oil encapsulation in core–shell alginate capsules by inverse gelation. I: dripping methodology

The production of capsules by inverse gelation consists of adding dropwise oil containing calcium dispersion into an alginate bath. A dripping technique to produce capsules from oil-in-water (O/W) emulsions was proposed by Abang. However, little is known about the oil encapsulation using water-in-oil (W/O) emulsions. This work aims to develop a new method of W/O emulsions encapsulation by inverse gelation. The success of the W/O emulsion encapsulation is due to three factors: 1) use of an emulsion with moderate stability (50?min); 2) production of an emulsion with at least 90?g/L of CaCl₂ and 3) addition of ethanol (20% v/v) into the alginate bath. Both wet and dry capsules were obtained with a spherical shape with diameters of 7 and 3.6?mm, respectively. All volume of oil was encapsulated and the oil loading in the wet and dry capsules was of 23 and 68% v/v, respectively.     

Mucoadhesive and floating chitosan-coated alginate beads for the controlled gastric release of amoxicillin

This work focused on the development of mucoadhesive and floating chitosan-coated alginate beads as a gastroretensive delivery vehicle for amoxicillin, towards the effective eradication of Helicobacter pylori, a major causative agent of peptic ulcers. Alginate was used as the core bead core polymer and chitosan as the mucoadhesive polymer coating. Amoxicillin-loaded alginate beads coated with 0.5% (w/v) chitosan (ALG/0.5%CHI) exhibited excellent floating ability, high encapsulation efficiency, high drug loading capacity, and a strong in vitro mucoadhesion to the gastric mucosal layer. In vitro, amoxicillin was released faster in simulated gastric fluid (pH 1.2, HCl) than in simulated intestinal fluid (phosphate buffer, pH 7.4). ALG/0.5%CHI could be prepared with a > 90% drug encapsulation efficiency and exhibited more than 90% muco-adhesiveness, 100% floating ability, and achieved sustained release of amoxicillin for over six hours in SGF.     

Comparative buccal permeability enhancement of didanosine and tenofovir by potential multifunctional polymeric excipients and their effects on porcine buccal histology

Abstract

This study identified and compared the buccal permeability properties of antiretroviral drugs, didanosine (ddI) and tenofovir (TNF), and the permeability effects of polymeric excipients – i.e. carboxymethylcellulose (CMC), sodium alginate (SA), polyacrylic acid (PAA) and polyethylene glycol (PEG) – as potential multifunctional excipients for buccal drug delivery. Permeation studies across porcine buccal mucosa were performed and the drug was quantified using UV spectrophotometry. The mean flux for both ddI (113–181?µg/cm²h) and TNF (40–102?µg/cm²h) increased linearly with increasing donor concentration. All polymeric excipients improved permeability of TNF while only PEG was effective for ddI. Permeability enhancement ratios at 20?mg/mL for ddI and TNF were 1.63 and 1.74, respectively, using PEG (0.5% w/v) and CMC (0.5% w/v), respectively. The maximum enhancement ratio of 2.13 for TNF was achieved with 4% w/v PEG. Light and transmission electron microscopy revealed no significant loss in cellular integrity of mucosa treated with either TNF or ddI alone or when coupled with PEG as a polymeric enhancer. Histomorphological observations correlated with flux values obtained for TNF and ddI alone, as well as with PEG’s effects on drug mass flux. TNF and ddI have demonstrated buccal delivery potential. Selective polymeric excipients provide an effective means to increase their penetration and may serve as potential formulation multifunctional excipients in a delivery system for delivery via the buccal route.     

Bactericidal effects of CaO (scallop-shell powder) on foodborne pathogenic bacteria

This study was investigated the bactericidal effects of calcium oxide (CaO) on three common foodborne pathogenic bacteria: Escherichia coli, Listeria monocytogenes, and Salmonella typhimurium. Each bacteria level was determined in a CaO solution (0.01, 0.03, 0.05, 0.10, 0.15, and 0.20% [w/v]) exposed for either 15 sec, 30 sec, 1 min, 2 min, 3 min, 5 min, 10 min, or 30 min. All three bacteria were not greatly affected by CaO solutions at concentrations of 0.01 and 0.03%, however, the decline of E. coli (99%; 2.78 log10 CFU/mL), L. monocytogens (45%; 1.44 log10 CFU/mL), and S. typhimurium (70%; 2.08 log10 CFU/mL) was greatest when they were exposed to 0.05% CaO solution for 10 min. Moreover, the bactericidal action of CaO was maintained for at least 24 h of storage. The results of this study provide evidence that CaO, as a substitute for synthetic chemical substances has potential for use in the disinfection and sanitization of foods and food processing equipment.     

Investigation of the role of alginate containing high guluronic acid on osteogenic differentiation capacity of human umbilical cord Wharton’s jelly mesenchymal stem cells

Background and aim: Cell encapsulation using biodegradable material has promising results for tissue engineering. Since pressure is an effective factor on stem cell behaviour and various concentrations of alginate create different pressures on the cells, therefore our goal was to evaluate the mechanical effect of 1/2% (w/v) and 1/8% (w/v) alginate containing high guluronic acid on viability and osteogenic capacity of HUCWJ cells.

Methods: Cell viability was evaluated by MTT assay after 1, 7 and 14 days. Alkaline phosphatase activity was evaluated by alkaline phosphatase assay kit after 14 and 21 days. Alizarin red S staining was performed for calcium deposition among histological section.

Results: MTT assay showed significant difference in the mean of viability rates between groups in day 14 (p 相似文献