Calcium Alginate Microparticles Research Articles

Effect of phage vB_EcoM_FJ1 on the reduction of ETEC O9:H9 infection in a neonatal pig cell line

Enterotoxigenic Escherichia coli (ETEC) colonizes the intestine of young pigs causing severe diarrhoea and consequently bringing high production costs. The rise of antibiotic selective pressure together with ongoing limitations on their use, demands new strategies to tackle this pathology. The pertinence of using bacteriophages as an alternative is being explored, and in this work, the efficacy of phage vB_EcoM_FJ1 (FJ1) in reducing the load of ETEC EC43-Ph (serotype O9:H9 expressing the enterotoxin STa and two adhesins F5 and F41) was assessed. Foreseeing the oral application on piglets, FJ1 was encapsulated on calcium carbonate and alginate microparticles, thus preventing phage release under adverse conditions of the simulated gastric fluid (pH 3.0) and allowing phage availability in simulated intestinal fluid (pH 6.5). A single dose of encapsulated FJ1, provided to IPEC-1 cultured cells (from intestinal epithelium of piglets) previously infected by EC43, provided bacterial reductions of about 99.9% after 6 h. Although bacteriophage-insensitive mutants (BIMs) have emerged from treatment, the consequent fitness costs associated with this new phenotype were demonstrated, comparatively to the originating strain. The higher competence of the pig complement system to decrease BIMs’ viability, the lower level of colonization of IPEC-1 cells observed with these mutants, and the increased survival rates and health index recorded in infected Galleria mellonella larvae supported this observation. Most of all, FJ1 established a proof-of-concept of the efficiency of phages to fight against ETEC in piglet intestinal cells.

Double T-junction microfluidic and conventional dripping systems for Bacillus subtilis immobilization in calcium alginate microparticles for lipase production

Bacillus subtilis immobilization in calcium alginate microparticles was investigated using two techniques: droplet microfluidics-based in T-junction geometry composed with a double droplet generation system and conventional dripping system. Alginate microparticles produced by microfluidic technology presented an average size of 68.35 µm with low polydispersity and immobilization efficiency around 86%. The cell response was evaluated in batch cultivation for 24 h, viewing lipase production compared to free cells. In this study, the batch cultivation with immobilized cells in alginate microparticles presented lipase production about 2.4 and 1.7 times higher than cultivation with cells immobilized cells by conventional technique and free cells cultivations. According to the results, this main novelty of the double T junction technique is an innovative contribution as a tool for cell immobilization on a laboratory scale, since the cultivation of immobilized cells in microparticles of small size and low polydispersity favors cell growth and increases the productivity of important metabolites of industrial biotechnology.

Use of Poly(vinyl alcohol)-Malic Acid (CLHPMA) Hydrogels and Chitosan Coated Calcium Alginate (CCCA) Microparticles as Potential Sorbent Phases for the Extraction and Quantitative Determination of Pesticides from Aqueous Solutions.

Pesticides are used worldwide to increase crop yields in agriculture. However, their toxicity and accumulation capacity can make them toxic to the environment, animals and humans. In the case of workers chronically exposed to these substances, they must be sampled continuously, so urine is an excellent option. In this sense, this study proposes to use poly(vinyl alcohol)-malic acid hydrogels, and chitosan-coated calcium alginate as new sorbent phases to be used in pesticide determination processes in urine. To better understand the behavior of these materials in the capture and desorption process, molecular dynamics simulations (MDS) were used, and desorption experiments were performed, using mechanical agitation, ultrasound, and pH variation in the desorption process, in order to optimize the parameters to obtain better recoveries. Under the optimal experimental conditions, the maximum recoveries were of the order of 11% (CFN), 3% (KCF), 53% (DMT), 18% (MTD) and 35% (MTL). Although the recoveries were not exhaustive, they are a first approximation for the use of these new sorbent phases in the determination of this type of compound in aqueous solutions and urine.

The design and green nanofabrication of noble hydrogel systems with encapsulation of doped bioactive hydroxyapatite toward sustained drug delivery

Finding a bioactive hybrid material with the potential for a controlled drug release has been one of the major targets of tissue engineering in the recent years. In this line, the present work describes a new approach for producing singular hydrogel microparticles (HMPs) with different morphologies and compositions by combining experimental and computational methods. Calcium-Alginate microparticles (Ca-ALG) and core–shell Alginate-Chitosan microspheres (Ca-ALG-CHI) were synthesized with the presence of drug-doped Hydroxyapatite (HA) in their inner matrix. The methodology relies on the use of a microfluidic system to obtain crosslinked HMPs with homogeneous sizes and morphologies, integrating external and internal gelation. The impact of the water-to-oil volume ratio, as well as variations in the collecting baths, morphology, and dispersion, were considered. The drug models chosen were Propranolol hydrochloride and Cloxacillin sodium salt monohydrate. Avrami's parameters were used to study and address the adsorption kinetics of each drug onto the bioactive HA, and the Korsmeyer-Peppas model was used to analyze the posterior desorption profiles. The conception and development of this type of hydrogel microparticles with improved functionalities are essential for the creation of granular hydrogels, which are an innovative, green, sustained and highly promising solution for different therapies in regenerative medicine areas.

Food additive based on the encapsulated pot marigold ( Calendula officinalis L.) flowers extract in calcium alginate microparticles

The aim of this paper was to prepare a natural food additive based on the encapsulated aqueous extract of pot marigold flowers in the calcium alginate microparticles. The prepared extract had an antioxidants content of 5.59 g GAE/100 g of dry weight. Its antioxidant activity was expressed based on a half-maximal inhibitory concentration which was found to be 0.096 mg/ml. The average particle sizes of control and encapsulated alginate microparticles prepared using extrusion-assisted by a secondary airflow were 643.7 and 789.3 µm, respectively. The encapsulation efficiency of 87.4% was determined. The study has shown that the chemical interactions between bioactive compounds and alginate did not occur. The release of antioxidants from alginate microparticles was monitored in the conditions of the simulated gastrointestinal tract at 37°C. The higher release of antioxidants by about 70% was noticed in the simulated intestinal fluid. The application of alginate microparticles can ensure the safety of foodstuffs and increase their nutritional value in a way acceptable to the final consumers. Novelty Impact Statement Studies on the encapsulation of pot marigold flowers into the calcium alginate microparticles using extrusion-assisted by a secondary airflow have important research value. The prepared system can be used as an additive of foodstuffs for the improvement of nutritional value and enhancement of their stability. The prolonged delivery system can enable the safe storage of products based on the long-lasting release of antioxidants.

Synthesis and application of hydrogel calcium alginate microparticles as a biomaterial to remove heavy metals from aqueous media

Microfluidic systems are an emerging technology to fabricate uniform spherical microparticles. This study employed a flow-focusing microfluidic device (MFFD) to produce uniform sodium alginate microdroplets by controlling the continuous (soybean oil) and dispersed (sodium alginate solution) flow rates. The resultant hydrogel particles were spherical in shape with diameters ranging from 70 to 100 μ m , and a size distribution under 10%, depending on the experimental conditions. Observations of dried calcium alginate microparticles using scanning electron microscopy showed a surface characterized by the uniform distribution of regular nodules. The resultant biomaterials were further examined and evaluated in terms of the removal of toxic metals (Cu 2 + and Ni 2 + ions); they demonstrated excellent removal performance. The highest adsorption capacities of the prepared calcium alginate microparticles toward Cu 2 + and Ni 2 + ions were 0.36 and 0.81 mg/mg alginate microparticles, respectively. Thus, calcium alginate microparticles prepared by MFFD demonstrated the potential for toxic metal treatment at different concentrations with short duration and stability. This approach may also be controlled to prepare microparticles that are narrow in size distribution and exhibit uniform morphology. • Synthesis of hydrogel calcium alginate microparticles using a microfluidic device. • The toxic metal adsorption behavior of the microparticles was investigated. • Flow rates (ml/h) of 0.1 (alginate) & 6 (soybean oil) yielded uniform particles. • The adsorption capacities (mg/mg) for Cu & Ni ions were 0.36 & 0.81, respectively.

New trends for controlled-release of TBH herbicide in the field by using a biodegradable polymer fashion

The herbicide Tebuthiuron (TBH) is widely used to weed control in sugar cane and cotton crops. However, TBH when applied to the soil is prone to the leaching process due to its high solubility, reaching soil layers below the required control zone. Here, we present a new insight for controlled-release of TBH herbicide by using a microparticulate system on the weed plants of difficult control. For this purpose, calcium alginate (Ca-ALG) microparticles containing the TBH herbicide were developed as a strategy to reduce the groundwater contamination, caused by the mobility of the herbicide element. The obtained results are innovative since demonstrates potential application in controlled-release as well as efficiency on the weed species control of Digitaria horizontalis (Willd) and Ipomoea grandifolia (Dammer) O'Donell weed species in pre-emergence. DOI: http://dx.doi.org/10.17807/orbital.v12i4.1552

Polyphenol-Based Microencapsulated Extracts as Novel Green Insecticides for Sustainable Management of Polyphagous Brown Marmorated Stink Bug (Halyomorpha halys Stål, 1855)

The brown marmorated stink bug (Halyomorpha halys Stål, 1855) is an invasive polyphagous species that threatens fruit growing both in the United States and Europe. Many pesticide active ingredients have been studied in H. halys management, but for sustainable fruit growing, which implies the reduction of chemical harm to the environment, new safe insecticides should be implemented into the practice. For this purpose, novel green insecticide based on natural polyphenols of species Stevia rebaudiana (Bertoni) Bertoni and Aronia melanocarpa (Michx.) Elliott 1821 was developed. Stevia leaves (SLE) and Aronia pomace (APE) aqueous extracts were prepared using the ultrasound-assisted extraction method. Optimal extraction conditions for bioactive compounds (total polyphenols, flavonoids, anthocyanins, and flavan-3-ols, respectively) and antioxidant activity were determined using response surface methodology. Bioactive compounds rich SLE and APE were encapsulated in calcium alginate microparticles by the ionic gelation method. Physicochemical characteristics (morphology, size, encapsulation efficiency, loading capacity, and swelling) of microparticles showed very good properties with especially high encapsulation efficiency. Fitting to simple Korsmeyer–Peppa’s empirical model revealed that the underlying release mechanism of polyphenols is Fickian diffusion. SLE loaded microparticles showed very good pesticidal efficiency against Halyomorpha halys, especially on younger larval stages after both contact and digestive treatment. Microparticles loaded with APE did not achieve satisfactory digestive efficiency, but a certain toxic impact has been observed at contact application on all H. halys growth stages. Microparticles loaded with SLS exhibited prolonged insecticidal action against H. halys and could be a potential candidate as a green insecticide whose application could increase fruit growing safety.

Preparation of internally-crosslinked alginate microspheres: Optimization of process parameters and study of pH-responsive behaviors

In this study, the effects of various parameters of the water-in-oil emulsification/internal gelation method on the properties of calcium-alginate microparticles were evaluated and optimized. Results showed that the spherical-shaped microparticles with the highest circularity and high production yield can be produced by alginate solution with a concentration of 2 wt.%, calcium carbonate/alginate ratio of 10/1 (w/w), water/oil volume ratio of 1/20, emulsifier concentration of 5 % (v/v), and emulsification speed of 1000 rpm. Two model drugs including simvastatin lactone and simvastatin β-hydroxyacid were loaded into the microspheres with promising encapsulation efficiencies of 73 % and 69 %, respectively. The microspheres showed a pH-responsive swelling behavior with a percentage of 10.60 %, 352.65 %, 690.03 %, and 1211.46 % at the pH values of 2.0, 4.5, 7.4, and 8.5, respectively. The microspheres showed an increasing trend of release rate in direct proportion to pH. These findings would be useful for therapeutic applications which need pH-responsive drug carriers.

Optimization of gallic acid encapsulation in calcium alginate microbeads using Box-Behnken Experimental Design

The aim of this study was the optimization of the gallic acid (GA) encapsulation efficiency within calcium alginate microparticles by the ionotropic gelation technique, using Box-Behnken design for the surface methodology response. For this purpose, three independent variables were selected: sodium alginate concentration (X1), calcium chloride concentration (X2), and gallic acid concentrations (X3). The influence of each variable on the encapsulation efficiency was evaluated. The optimum conditions to reach maximum encapsulation efficiency were found to be: X1 = 30 g/l (3%, w/v), X2 = 21.63 g/l (2.163%, w/v) and X3 = 15 g/l (1.5%, w/v), respectively. The encapsulation efficiency was determined to be 42.8%. The obtained microbeads were further examined using differential scanning calorimetry (DSC) and Fourier transform infrared (ATR-FTIR), and the inclusion of gallic acid was confirmed. The gallic acid concentration (X3) is the statistically significant factor in the optimization process. In addition, no autoxidation of the gallic acid compound was observed in the formulated calcium alginate microbeads. Scanning electron microscope (SEM) analysis showed that the shape of the particle was spherical for all formulations and their surface is wrinkled. The release study of the gallic acid carried out in an aqueous medium at pH value 6.8, showed that the GA release pattern was fast for all systems studied (85% at 20 min), and the profile of the release was influenced by the size of the calcium alginate microbeads. The obtained results reveal that the calcium alginate microbeads prepared through the ionotropic gelation technique possess great prominent for gallic acid encapsulation as well as its liberation.

Preparation of hydrogel calcium-alginate microparticles via microfluidic device for Cu<sup>2+</sup> treatment

Alginate-based hydrogels are attracted much attention in biomedical and chemical field, and their size and shape are significant to their applications like drug delivery and cell encapsulation. Monodisperse sodium alginate microdroplets are produced using a flow-focusing microfluidic device (MFFD) by adjusting the flow rate on the continuous phase (soybean oil) and the dispersed phase (sodium alginate solution). The external gelation process of sodium alginate microdroplets occurs outside the chanel in a calcium chloride solution to form calcium alginate hydrogel particales. The shape, size and size distribution of these calcium alginate hydrogel particles depend strongly on the flow rate inside the MFFD. By optimizing the parameters, the hydrogel microparticles were obtained with diameters ranging from 70 µm to 100 µm with size distribution under 10%, depending on experimental conditions. The removal of Cu2+ ions by the absorption of hydrogel microparticles was also demonstrated.

Controlled Release of TBH Herbicide Encapsulated on Ca-ALG Microparticles: Leaching and Phytointoxication Plants

ABSTRACT: The aim of this work was to demonstrate a detailed study of the controlled release of the herbicide Tebuthiuron (TBH) encapsulated in microparticles of calcium alginate (Ca-ALG), to evaluate the phytotoxicity in different concentrations of herbicide (4, 6 and 8 g L-1), and their correlation with the depth of leaching using bioindicator plants. The Ca-ALG microparticles were prepared from the crosslinking of sodium alginate by Ca++ containing varied amounts of TBH supplied in calcium chloride (CaCl2) aqueous solution. The results showed that TBH herbicide, when encapsulated, leached to shallow depths relative to the conventional, non-encapsulated herbicide (which moved to a depth of 40-50 cm). The concentration of 4 g L-1 was the one that leached most in the PVC columns, but its mobility did not exceed 30 cm of depth. The results of the dry mass corroborated with the phytotoxicity results of the bioindicator plants, evidencing the mobility of the conventional herbicide in the soil at depths around 40 and 50 cm, while the herbicide encapsulated in the Ca-ALG microparticles did not show leaching beyond 20 -30 cm deep. The encapsulation of TBH in Ca-ALG microparticles can thus be considered as a more eco-friendly technology, reducing the leaching process and consequently soil contamination.

Developing a Mathematical Model for the Controlled Release Over Time of Sulfentrazone Herbicide from Biodegradable Polymer

In our research group, controlled release systems for the sulfentrazone herbicide has been accomplished by encapsulating this bioactive compound into calcium alginate (Ca-ALG) biodegradable polymer fashion and the release mechanisms were verified by using Korsmeyer-Peppas model (KP). However, the KP model does not allow to evaluate all the phenomena involved in the (Mt/M∞ versus t) curves. Thus, the aim of this work is the development of a new mathematical model to interpret the distinct regions of the controlled release assays of the Sulfentrazone herbicide encapsulated in Ca-ALG microparticles and that can be used for other systems with a similar release profile. The proposed model is based on the herbicide diffusion, dissolution and polymer surface erosion. The results show that the proposed model is closest to the experimental curve when compared to the KP. The new mathematical model allows not just to describe the behavior of the system in terms of Fick’s law, but to know what type of mechanism act in the herbicide release process.

Evaluation of calcium alginate microparticles for copper preconcentration prior to F AAS measurements in fresh water

Evaluation of calcium alginate microparticles for copper preconcentration prior to F AAS measurements in fresh water

Recombinant ferritin-H induces immunosuppression in European sea bass larvae (Dicentrarchus labrax) rather than immunostimulation and protection against a Vibrio anguillarum infection

Vibrio anguillarum causes high mortality in European sea bass (Dicentrarchus labrax) larviculture. In this study, we evaluated if the recombinant sea bass ferritin-H could stimulate the innate immune system of gnotobiotic European sea bass larvae resulting in protection against a V. anguillarum challenge. We also evaluated the effect of a V. anguillarum infection on the transcription of immune-related genes in gnotobiotic European sea bass larvae. Recombinant sea bass ferritin-H was produced, encapsulated in calcium alginate microparticles and orally delivered to sea bass larvae at seven days after hatching. Our results showed V. anguillarum caused an acute infection, resulting in high mortality. The infection significantly upregulated the expression of tlr3, tlr5, cas1, il1β, tnfα, mif, il10, cc1, cxcl8 at 18, 24 and 36 h post infection, but not of the chemokine receptor genes cxcr4 and ccr9. There was no protective effect of ferritin-H. Remarkably, ferritin-H caused significantly higher transcript levels for cxcr4 and ccr9. Sea bass ferritin-H was more likely involved in immune-suppression and results point in the direction of a negative regulation of CXCR4 resulting in inhibition of cell proliferation, differentiation and migration which is detrimental to innate immunity and might explain the non-protective effect of ferritin-H in fish larvae.

Calcium alginate microparticles for rare earth elements preconcentration prior to ICP-MS measurements in fresh water

Calcium alginate microparticles were used for the preconcentration of rare earth elements for ICP-MS analysis of fresh waters.

Controlled release behavior of sulfentrazone herbicide encapsulated in Ca-ALG microparticles: preparation, characterization, mathematical modeling and release tests in field trial weed control

The use of herbicides is important to eliminate losses of weed interference on crops. However, excessive and inappropriate employment of these substances can cause serious consequences to the environment. In this way, the release system is very attractive for the weed control in the agriculture area. The aim of this work was to study a new delivery system for sulfentrazone herbicide encapsulated into the calcium alginate (Ca-ALG) microparticles for the weed control. The alginate microparticles were prepared via ionotropic gelation method and characterized by using optical microscopy, scanning electron microscopy, and thermogravimetric and differential thermal analysis. The controlled release (M t /M ∞ vs. time) of the sulfentrazone herbicide was also analyzed using UV–Vis spectroscopy where we proposed different mathematical models to understand the mechanisms of controlled release of the herbicide. Furthermore, the release tests in field trial weed control were conducted using bioindicator species (Cucumis Sativus—Cucumber) to study the phytotoxicity evaluation caused by the Ca-ALG microparticles at different concentrations and their relationship with leaching depth. The results showed that the Ca-ALG microparticles exhibited good encapsulation efficiency (%EE): 76.11, 78.62, and 80.42% for the 4, 5 and 6 g L−1 concentration of herbicide. The release rates in the region I were 39.2, 46.5, and 35.5 mg s−1 for the 4, 5, and 6 g L−1 of herbicide concentration, respectively. The Ca-ALG microparticles containing sulfentrazone herbicide demonstrated potential application in controlled release platforms in agricultural as well as for controlling of weeds and minimization of leaching processes.

3D-printed air-blast microfluidic nozzles for preparing calcium alginate microparticles

Uniform calcium alginate microparticles were prepared through 3D-printed coaxial air-blast microfluidic nozzles.

Development and Evaluation of a Controlled Release System of TBH Herbicide Using Alginate Microparticles

The development of controlled delivery system formulations has received increasing interest in the agriculture area. Tebuthiuron (TBH) is the most commonly used herbicide for weed control in sugar cane and cotton crops. The TBH and some of its metabolites are detected in surface water by leaching process, evidencing contamination and the need for an efficient process to decrease pesticide residues. The development of a controlled system release appears as a good solution. The present investigation aimed to study the development and evaluation of alginate microparticles as a delivery system for the TBH. The calcium alginate microparticles were prepared from the crosslinking of sodium alginate by Ca++ containing varied amounts of TBH supplied in CaCl2 aqueous solution. The particle size and morphological analysis of microparticles were determined by optical microscopy (OM) and by field emission gun scanning electron microscopy (FEG-SEM). The encapsulation efficiency and release of TBH studies was accessed by UV-vis spectroscopy. The results show that the polymeric microparticles containing TBH can be obtained successfully through a simple method and is suitable as a controlled release carrier system for herbicides and can be effective for controlling weeds.

Calcium-alginate microparticles for sustained release of catechin prepared via an emulsion gelation technique

Catechin-loaded Ca-alginate beads and microparticles were prepared by an emulsion gelation method using sunflower oil for efficient sustained release of catechin. The emulsion was prepared by sequential mixing of alginate, oil, and oleic acid ester as an emulsifier. Encapsulation efficiency (EE) and inhibition of catechin release of the beads were significantly increased approximately to 453.83 and 148.71% by the emulsion gelation technique, respectively (p<0.05). For the microparticles, the highest inhibition of catechin release after 1 h of incubation (78.82%) was observed at the microparticles prepared by 5% (w/w) oil, 3% (w/w) alginate, 4% (w/v) CaCl2, and 200 mg catechin with the most hydrophilic emulsifier, decaglycerol mono-ester. Moreover, the catechin release was sustained at acidic conditions and increased with increase in pH of release medium. These results suggest that catechin encapsulation within Ca-alginate particles by emulsion gelation method can be an effective delivery system for catechin.