Microencapsulation by spray drying of nitrogen-fixing bacteria associated with lupin nodules

Plant growth promoting bacteria and nitrogen-fixing bacteria (NFB) used for crop inoculation have important biotechnological potential as a sustainable fertilization tool. However, the main limitation of this technology is the low inoculum survival rate under field conditions. Microencapsulation of bacterial cells in polymer matrices provides a controlled release and greater protection against environmental conditions. In this context, the aim of this study was to isolate and characterize putative NFB associated with lupin nodules and to evaluate their microencapsulation by spray drying. For this purpose, 21 putative NFB were isolated from lupin nodules and characterized (16S rRNA genes). Microencapsulation of bacterial cells by spray drying was studied using a mixture of sodium alginate:maltodextrin at different ratios (0:15, 1:14, 2:13) and concentrations (15 and 30 % solids) as the wall material. The microcapsules were observed under scanning electron microscopy to verify their suitable morphology. Results showed the association between lupin nodules of diverse known NFB and nodule-forming bacteria belonging to Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria and Bacteroidetes. In microencapsulation assays, the 1:14 ratio of sodium alginate:maltodextrin (15 % solids) showed the highest cell survival rate (79 %), with a microcapsule yield of 27 % and spherical microcapsules of 5–50 µm in diameter. In conclusion, diverse putative NFB genera and nodule-forming bacteria are associated with the nodules of lupine plants grown in soils in southern Chile, and their microencapsulation by spray drying using sodium alginate:maltodextrin represents a scalable process to generate a biofertilizer as an alternative to traditional nitrogen fertilization.     

Effect of different dextrose equivalents of maltodextrin on oxidation stability in encapsulated fish oil by spray drying

Encapsulating fish oil by spray drying with an adequate wall material was investigated to determine if stable powders containing emulsified fish-oil-droplets can be formed. In particular, the dextrose equivalent (DE) of maltodextrin (MD) affects the powder structure, surface-oil ratio, and oxidative stability of fish oil. The carrier solution was prepared using MD with different DEs (DE = 11, 19, and 25) and sodium caseinate as the wall material and the emulsifier, respectively. The percentage of microcapsules having a vacuole was 73, 39, and 38% for MD with DE = 11, 19, and 25, respectively. Peroxide values (PVs) were measured for the microcapsules incubated at 60 °C. The microcapsules prepared with MD of DE = 25 and 19 had lower PVs than those prepared with MD of DE = 11. The difference in PV can be ascribed to the difference in the surface-oil ratio of the spray-dried microcapsules.     

Preparation and Characterization of Microcapsules Containing Squalene

Ethylcellulose microcapsules containing squalene were fabricated by a solvent evaporation method. The parameters of core/shell ratio, content of surfactant, encapsulation efficiency, and drug-loading rate of squalene were investigated; the Polysorbate-80 was used as surfactant in the external phase. The results showed that the optimal ethylcellulose microcapsules containing squalene were obtained with a surfactant concentration of 0.5 % and a core/shell ratio of 1:1. Under the optimal conditions, the entrapment efficiency and the drug-loading rate reached to 60.31?±?0.55 % and 32.76?±?0.30 %, respectively. The appearance and size of microcapsules were measured by scanning electron microscope and metallographic microscope. The microcapsules were spherical in shape and have a mean diameter of 103 μm.     

Development of Hydrogels for Entrapment of Vitamin D3: Physicochemical Characterization and Release Study

In this study two carbohydrate biopolymers were used to entrap vitamin D3. In order to optimize the microencapsulation parameters, response surface methodology was applied to evaluate the effects of three independent variables (alginate percentage, vitamin: alginate weight ratio, and ultrasound time) on the efficiency of microencapsulation and loading capacity. According to the results, 0.23% alginate (W/V), 1: 5 weight ratio of vitamin D3: alginate, and 13.7 min ultrasound time were determined as the optimal conditions for obtaining maximum microencapsulation efficiency (92.86%) and loading capacity (30.1%). Then, the optimized carrier was coated by chitosan followed by the examinations of morphological characteristics, mean particle size, Fourier transform infrared (FTIR) spectrometry, in vitro release characteristics, and release modeling. Scanning electron microscopy examinations showed that the alginate and alginate-chitosan microcapsules had irregular and interlacing forms. The average particle sizes of alginate and alginate-chitosan were 11.3 and 23.3, respectively, which decreased to 9.8 and 14.0 μm after drying. Results of FTIR indicated a physical interaction between alginate and vitamin D3. The Weibull II model was found to be the best one to predict vitamin release behavior. The results of this study showed the potential application of developed carriers to encapsulate hydrophobic compounds.     

Influence of Milk Whey on High-Oleic Palm Oil Nanoemulsions: Powder Production,Physical and Release Properties

The milk whey is a by-product of the dairy industry with a relevant protein concentration which can be employed as a wall material in spray drying processes. In this work, milk whey was used to encapsulate high oleic palm oil (HOPO) nanoemulsions. The HOPO/whey ratio and the atomization system (two-fluid nozzle and rotary disc) had a significant influence in the capsule formation. In addition, the release of the oleic acid (AO) from HOPO was evaluated by dialysis bag method for powders obtained by both types of atomizers. Different powders were obtained with good physical properties (particle diameter: 6.1–18.8 μm, a_w: 0.058–0.125, moisture: 0.86–2.39%, bulk density: 390–770 kg/m³, dissolution rate: 55–115s) from stable nanoemulsions with high encapsulation efficiencies (77 to 99%). On the other hand, the release percents of AO were 82.8 and 75.8% for the two-fluid nozzle and the rotary disc, respectively. The release was not completed in the tested time (7 h) due to stable HOPO-whey linkages, and the gradient that must be broken was higher. Aditionally, an inverse relation was found between diameter particle and AO release.     

Microencapsulation of β-Carotene Based on Casein/Guar Gum Blend Using Zeta Potential-Yield Stress Phenomenon: an Approach to Enhance Photo-stability and Retention of Functionality

β-Carotene, abundant majorly in carrot, pink guava yams, spinach, kale, sweet potato, and palm oil, is an important nutrient for human health due to its scavenging action upon reactive free radicals wherever produced in the body. Inclusion of liposoluble β-carotene in foods and food ingredients is a challenging aspect due to its labile nature and low absorption from natural sources. This fact has led to the application of encapsulation of β-carotene to improve stability and bioavailability. The present work was aimed to fabricate microcapsules (MCs) of β-carotene oily dispersion using the complex coacervation technique with casein (CA) and guar gum (GG) blend. The ratio of CA:GG was found to be 1:0.5 (w/v) when optimized on the basis of zeta potential-yield stress phenomenon. These possessed a higher percentage yield (71.34 ± 0.55%), lower particle size (176.47 ± 4.65 μm), higher encapsulation efficiency (65.95 ± 5.33%), and in general, a uniform surface morphology was observed with particles showing optimized release behavior. Prepared MCs manifested effective and controlled release (up to 98%) following zero-order kinetics which was adequately explained by the Korseymer-Peppas model. The stability of the freeze-dried MCs was established in simulated gastrointestinal fluids (SGF, SIF) for 8 h. Antioxidant activity of the MCs was studied and revealed the retention of the functional architecture of β-carotene in freeze-dried MCs. Minimal photolytic degradation upon encapsulation of β-carotene addressed the challenge regarding photo-stability of β-carotene as confirmed via mass spectroscopy.     

A Novel Method for Preparing Surface-Modified Fluocinolone Acetonide Loaded PLGA Nanoparticles for Ocular Use: <Emphasis Type="Italic">In Vitro</Emphasis> and <Emphasis Type="Italic">In Vivo</Emphasis> Evaluations

Our objective was to prepare nanoparticulate system using a simple yet attractive innovated method as an ophthalmic delivery system for fluocinolone acetonide to improve its ocular bioavailability. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles were prepared by adopting thin film hydration method using PLGA/poloxamer 407 in weight ratios of 1:5 and 1:10. PLGA was used in 75/25 and 50/50 copolymer molar ratio of DL-lactide/glycolide. Results revealed that using PLGA with lower glycolic acid monomer ratio exhibited high particle size (PS), zeta potential (ZP) and drug encapsulation efficiency (EE) values with slow drug release pattern. Also, doubling the drug concentration during nanoparticles preparation ameliorated its EE to reach almost 100%. Furthermore, studies for separating the un-entrapped drug in nanoparticles using centrifugation method at 20,000 rpm for 30 min showed that the separated clear supernatant contained nanoparticles encapsulating an important drug amount. Therefore, separation of un-entrapped drug was carried out by filtrating the preparation using 20–25 μm pore size filter paper to avoid drug loss. Aiming to increase the PLGA nanoparticles mucoadhesion ability, surface modification of selected formulation was done using different amount of stearylamine and chitosan HCl. Nanoparticles coated with 0.1% w/v chitosan HCl attained most suitable results of PS, ZP and EE values as well as high drug release properties. Transmission electron microphotographs illustrated the deposition of chitosan molecules on the nanoparticles surfaces. Pharmacokinetic studies on Albino rabbit’s eyes using HPLC indicated that the prepared novel chitosan-coated PLGA nanoparticles subjected to separation by filtration showed rapid and extended drug delivery to the eye.     

Development,Optimization, and Anti-diabetic Activity of Gliclazide-Loaded Alginate–Methyl Cellulose Mucoadhesive Microcapsules

The purpose of this work was to develop and optimize gliclazide-loaded alginate–methyl cellulose mucoadhesive microcapsules by ionotropic gelation using central composite design. The effect of formulation parameters like polymer blend ratio and cross-linker (CaCl₂) concentration on properties of gliclazide-loaded alginate–methyl cellulose microcapsules like drug encapsulation efficiency and drug release were optimized. The optimized microcapsules were subjected to swelling, mucoadhesive, and in vivo studies. The observed responses coincided well with the predicted values from the optimization technique. The optimized microcapsules showed high drug encapsulation efficiency (83.57 ± 2.59% to 85.52 ± 3.07%) with low T _50% (time for 50% drug release, 5.68 ± 0.09 to 5.83 ± 0.11 h). The in vitro drug release pattern from optimized microcapsules was found to be controlled-release pattern (zero order) with case II transport release mechanism. Particle sizes of these optimized microcapsules were 0.767 ± 0.085 to 0.937 ± 0.086 mm. These microcapsules also exhibited good mucoadhesive properties. The in vivo studies on alloxan-induced diabetic rats indicated the significant hypoglycemic effect that was observed 12 h after oral administration of optimized mucoadhesive microcapsules. The developed and optimized alginate–methyl cellulose microcapsules are suitable for prolonged systemic absorption of gliclazide to maintain lower blood glucose level and improved patient compliance.     

Preparation and Characterization of Microcapsules Based on Biodegradable Polymers: Pectin/Casein Complex for Controlled Drug Release Systems

Controlled release of drugs is an important strategy to diminish the drug dose and adverse side effects. Aqueous mixtures of polysaccharides and proteins are usually unstable above a certain biopolymer concentration and phase separation occurs either because of repulsive (segregative) or attractive (associative) interactions. Herein, pectin/casein microcapsules were prepared by complex coacervation aiming at prolonged drug release. The morphological characteristics, particle size, distribution, and release kinetics of microcapsules were studied using as a model the hydrophilic drug acetaminophen. It was detected that complexation of pectin/casein particles occurs at pH values lower than 6, resulting in the formation of spherical particles after spray drying. Microcapsules had a mean diameter of 3.138 and 4.929 μm without drug, and of 4.680 and 5.182 μm with drug using USP and 8003 pectin, respectively. The in vitro release of acetaminophen from microcapsules was slow and the drug release mechanism was controlled by diffusion following first-order kinetics. There was greater release of acetaminophen in simulated gastric fluid than simulated intestinal fluid conditions. Concluding, the polymeric system present herein seemed to be appropriate for a prolonged release of acetaminophen throughout the gastrointestinal tract. Nevertheless, it is likely that it is a promising pectin/casein complex for lipossoluble drugs, which merits further investigation.KEY WORDS: casein, complex coacervation, microcapsules, pectin, release kinetics     

Effects of particle size and drying methods of corn on growth performance,digestibility and haematological and immunological characteristics of weaned piglets

The objective of this study was to evaluate the effects of particle size and drying methods of corn on growth performance of weaned piglets. Crossbreed weaned piglets (n = 192; Duroc × Landrace × Large White) were assigned to one of four treatments (2 × 2 factorial arrangement). All piglets were fed corn–soybean meal diets and treatments were (1) hot air-dried and coarsely ground corn, (2) hot air-dried and finely ground corn, (3) sun-dried and coarsely ground corn and (4) sun-dried and finely ground corn. The results showed that finely ground corn (FGC) improved the performance of piglets. Additionally, the apparent total tract digestibility (ATTD) of gross energy (GE) and ether extract (EE) were increased by FGC, but the drying methods did not affect the performance of piglets or ATTD. Furthermore, smaller particle size significantly decreased the intestinal permeability, which was also not influenced by drying methods. FGC increased the total number of white blood cells, but not other blood parameters. Finally, the level of serum interleukin-1 was decreased by fine grinding and that of serum tumour necrosis factor α was decreased by sun drying. Conversely, these characteristics of weaned piglets can hardly have been affected either by the corn drying method or its interaction with grinding methods.     

Konjac glucomannan hydrolysate: A potential natural coating material for bioactive compounds in spray drying encapsulation

This research aimed to develop a suitable coating material for encapsulating a plant bioactive compound via spray drying. A suitable process for modifying the rheological property of konjac glucomannan (KGM) solution by enzymatic treatment was developed. A plant bioactive compound, andrographolide, was selected to use as core material. Mannanase (1500 units of enzyme) was used in the treatment of KGM solution. The concentration of KGM solution was varied from 9 to 18% (w/w). It was found that 12% (w/w) was the optimum KGM concentration that could be hydrolyzed to a viscosity of <100 mPa·s. HPLC analysis of hydrolyzed solution found a fair amount of DP4–DP7 oligosaccharides (where DP is degree of polymerization) were obtained. The solution was then used as coating material in spray drying with inlet air temperature of 170°C and outlet air temperature of 85°C. It was found that 12% (w/w) konjac glucomannan hydrolysate (KGMH) was suitable for coating 2% (w/w) andrographolide. Its efficiency of encapsulation was also higher than that of KGMH combined with gamma‐cyclodextrin or beta‐cyclodextrin. This study revealed a great potential of using KGMH solution for pharmaceutical and food industries in the spray drying encapsulation process.     

Effects of Formulation Variables on the Particle Size and Drug Encapsulation of Imatinib-Loaded Solid Lipid Nanoparticles

Imatinib (IMT), an anticancer agent, inhibits receptor tyrosine kinases and is characterized by poor aqueous solubility, extensive first-pass metabolism, and rapid clearance. The aims of the current study are to prepare imatinib-loaded solid lipid nanoparticles (IMT-SLN) and study the effects of associated formulation variables on particle size and drug encapsulation on IMT-SLN using an experimental design. IMT-SLN was optimized by use of a “combo” approach involving Plackett-Burman design (PBD) and Box-Behnken design (BBD). PBD screening resulted in the determination of organic-to-aqueous phase ratio (O/A), drug-to-lipid ratio (D/L), and amount of Tween® 20 (Tw20) as three significant variables for particle size (S _z), drug loading (DL), and encapsulation efficiency (EE) of IMT-SLN, which were used for optimization by BBD, yielding an optimized criteria of O/A?=?0.04, D/L?=?0.03, and Tw20?=?2.50%?w/v. The optimized IMT-SLN exhibited monodispersed particles with a size range of 69.0?±?0.9 nm, ζ-potential of ?24.2?±?1.2 mV, and DL and EE of 2.9?±?0.1 and 97.6?±?0.1%?w/w, respectively. Results of in vitro release study showed a sustained release pattern, presumably by diffusion and erosion, with a higher release rate at pH 5.0, compared to pH 7.4. In conclusion, use of the combo experimental design approach enabled clear understanding of the effects of various formulation variables on IMT-SLN and aided in the preparation of a system which exhibited desirable physicochemical and release characteristics.     

Kinetic study of controlled release of flavor compounds from spray-dried encapsulated yeast powder using dynamic vapor sorption–gas chromatography

The release profile of d-limonene and ethyl hexanoate was investigated using a dynamic vapor sorption (DVS) system coupled with gas chromatography. The flavors were encapsulated by spray drying using Saccharomyces cerevisiae cells from which β-glucan had been partially extracted. Relative humidity (RH) was stepped from 20% to 50, 60, 70, and 80% at 30, 40, 50, and 60ºC. The maximum release flux for d-limonene and ethyl hexanoate was around 12 and 28 mg/s?m²?g-powder at 80% RH and 60ºC incubation. The Weibull distribution function was well fitted with the experimental data to analyze release kinetics. The release mechanism parameter was greater than 1.0, which indicates a controlled release with initial induction time. The activation energy for ethyl hexanoate (6 kJ/mol) was lower than d-limonene (41 kJ/mol) at 80% RH, which indicates higher affinition of ethyl hexanoate to migrate from the lipid bilayer membrane towards the water phase.     

Formulation and <Emphasis Type="Italic">In vitro</Emphasis> Characterization of Eudragit® L100 and Eudragit® L100-PLGA Nanoparticles Containing Diclofenac Sodium

The aim of this study was to formulate and characterize Eudragit® L100 and Eudragit® L100-poly(lactic-co-glycolic acid) (PLGA) nanoparticles containing diclofenac sodium. Diclofenac generates severe adverse effects with risks of toxicity. Thus, nanoparticles were prepared to reduce these drawbacks in the present study. These nanoparticles were evaluated for surface morphology, particle size and size distribution, percentage drug entrapment, and in vitro drug release in pH 6.8. The prepared nanoparticles were almost spherical in shape, as determined by atomic force microscopy. The nanoparticles with varied size (241–274 nm) and 25.8–62% of entrapment efficiency were obtained. The nanoparticles formulations produced the release profiles with an initial burst effect in which diclofenac sodium release ranged between 38% and 47% within 4 h. The extent of drug release from Eudragit® L100 nanoparticles was up to 92% at 12 h. However, Eudragit®/PLGA nanoparticles showed an initial burst release followed by a slower sustained release. The cumulative release at 72 h was 56%, 69%, and 81% for Eudragit®/PLGA (20:80), Eudragit®/PLGA (30:70) and Eudragit®/PLGA (50:50) nanoparticles, respectively. The release profiles and encapsulation efficiencies depended on the amount of Eudragit in the blend. These data demonstrated the efficacy of these nanoparticles in sustaining the diclofenac sodium release profile.     

Engineering factors in single-cell protein production. I. Fluid properties and concentration of yeast by evaporation

The processing of fermentor-grown, edible yeast involves the removal of water. This can be accomplished through concentration followed by drum or spray drying. This study presents the essential physical properties of yeast solutions necessary for calculation of production economics. In addition, our initial studies of vacuum concentration show that some of the cell leakage necessary for good drying characteristics occurs. The residence time during concentration is also sufficient, to yield 1-2 log cycles of kill which are mandatory since the final product, should contain no viable cells.     

Formulation and Optimization of Doxorubicin and Biochanin A Combinational Liposomes for Reversal of Chemoresistance

Circumvention of drug resistance still remains a challenge in the development of anticancer therapeutics. Combinational nano-formulations provide many avenues for effective cancer therapy and reversal of drug resistance. In the current study, combination of biochanin A (BioA) and doxorubicin (DOX) in liposomes were prepared and studied for its potential to reverse DOX resistance in COLO205 cells. After development and validation of DOX resistant cells of COLO205 (ColoR), dosing ratio of DOX and BioA for reversal of DOX resistance was determined by co-treatment in ColoR cells. As limited solubility and analytical data available for BioA, therefore solubility was studied for BioA and analytical method was developed for the combination. Combinational liposomes were prepared and optimized for both lipid content and surface charge by evaluating size, polydispersity index, zeta potential, and encapsulation efficiency. The optimized formulation had a size about 125 nm; zeta potential of ?19.5 mV and 70% encapsulation efficiency (EE) for BioA. Thus, prepared combinational liposomes of DOX and BioA were evaluated for its cellular uptake and efficacy to reverse DOX resistance. From the study, increased DOX uptake and promising effect for reversal of DOX resistance was observed.     

Release behavior of allyl sulfide from cyclodextrin inclusion complex of allyl sulfide under different storage conditions

The stability of allyl sulfide, an organosulfur compound present in garlic oil, in its α-, β-, and γ-cyclodextrin inclusion complexes was investigated under various storage conditions. The complexes of cyclodextrins and allyl sulfide were prepared by spray drying. The storage temperature, relative humidity, and initial moisture content of the inclusion complex had different effects on the release rate of allyl sulfide. Allyl sulfide in α-cyclodextrin complexes had a lower release rate than in β- and γ-cyclodextrin complexes at 100 °C and at 50 °C under 6, 40, 54, and 73% relative humidity. The initial moisture content affected only the release rate of allyl sulfide from α-cyclodextrin complexes. The release behavior of allyl sulfide can be correlated with the first-order release rate equation with a normal Gaussian distribution of free energy of activation of release rate constant. The results indicated α-cyclodextrin is a suitable material for controlled release of allyl sulfide.     

Encapsulation of basic fibroblast growth factor by polyelectrolyte multilayer microcapsules and its controlled release for enhancing cell proliferation

Basic fibroblast growth factor (FGF2) is an important protein for cellular activity and highly vulnerable to environmental conditions. FGF2 protected by heparin and bovine serum albumin was loaded into the microcapsules by a coprecipitation-based layer-by-layer encapsulation method. Low cytotoxic and biodegradable polyelectrolytes dextran sulfate and poly-L-arginine were used for capsule shell assembly. The shell thickness-dependent encapsulation efficiency was measured by enzyme-linked immunosorbent assay. A maximum encapsulation efficiency of 42% could be achieved by microcapsules with a shell thickness of 14 layers. The effects of microcapsule concentration and shell thickness on cytotoxicity, FGF2 release kinetics, and L929 cell proliferation were evaluated in vitro. The advantage of using microcapsules as the carrier for FGF2 controlled release for enhancing L929 cell proliferation was analyzed.     

The Combined Usage of β-Cyclodextrin and Milk Proteins in Microencapsulation of Bifidobacterium bifidum BB-12

The present study aimed to determine the effects of combined usage of β-cyclodextrin with whey protein isolate and sodium caseinate on the microencapsulation of Bifidobacterium bifidum-BB12 by spray drying.

From the results, the highest count of B. bifidum was provided by whey protein isolate as 8.62 log CFU/g. The increasing concentration of β-cyclodextrin considerably increases gastric and intestinal resistance to B. bifidum cells. In the gastric and intestinal test, the highest protection was determined in whey protein isolate substituted with 10% β-cyclodextrin with reduction rates of 0.98 and 3.30%, respectively. Moreover, free cells did not survive in the same gastric conditions. The lowest hygroscopicity was determined in whey protein isolate as 8.57%. It must be noted that increasing β-cyclodextrin concentration in carrier material combination led to an increase in hygroscopicity of microcapsules. In general, substitution with β-cyclodextrin increased the particle size of microparticles, and microcapsules produced with whey protein isolate had a smaller size than that of sodium caseinate.

     

膜材与制备过程对血红蛋白微胶囊粒径和包埋率的影响

以单甲氧基聚乙二醇聚乳酸共聚物（PELA）为膜材用复乳溶剂扩散法制备了包含牛血红蛋白（BHb）的微胶囊,微胶囊中BHb的P₅₀和Hill系数分别为3 466 Pa和2.4左右,接近于天然BHb的生物活性。研究发现膜材种类对BHb微胶囊包埋率和粒径的影响最大,使用MPEG2000为亲水性嵌段的PELA共聚物时,包埋率最高,达到90％以上,粒径为3～5 μm左右;随着膜材浓度的增大,微胶囊包埋率和粒径均增加;随着外水相NaCl浓度的增大,微胶囊包埋率升高、粒径减小;随着外水相稳定剂PVA浓度的增大,微胶囊粒径减小,包埋率先升高后降低,在较低浓度下（10 g/L、20 g/L）包埋率较高;初乳化搅拌速率的增大,有利于包埋率的提高,但对粒径影响不大;复乳化搅拌速率的影响较复杂,当复乳液体积较大时,复乳化搅拌速率对微胶囊制备的影响规律性不明显。当固定膜材和初乳化搅拌速率时,包埋率和粒径之间存在着类似抛物线的关系,包埋率随着粒径的减小而降低。