Nanoencapsulation Methods Research Articles

Synthesis of nanoencapsulated vitamin E in phase change material (PCM) shell as thermo-sensitive drug delivery purpose

Purpose of this paper is preparation of nanoencapsulated vitamin E (α-tocopherol) in phase change material (PCM) shell for thermo-sensitive drug delivery purpose. This type of enloaded nanoencapsules with vitamin E have not been reported in literature, nor patented. Vitamin E has been successfully nanoencapsulated in stearic acid-lauric acid (SA-LA) eutectic mixture with (1:3) mole ratio in the form of core-shell structure for thermo-sensitive drug delivery purpose. The obtained results from FT-IR spectrum and SEM nanographs indicate the success of encapsulation process to create core-shell structure with spherical shape. The particle size distribution (PSD) measurement shows a 70–550 nm size distribution which is in the range of nanoencapsulated products. The measured zeta potential for the nanoencapsules indicates good stability in suspension during 120 days. Thermogravimetric analysis (TGA) test supply drug to PCM ratio with (65:35) wt% which is in good agreement with that used in the recipe. The obtained results indicate the high efficiency of used method for nanoencapsulation of vitamin E (α-tocopherol) in PCM shell. At last, the result of releasing test for the nanocapsules shows the rapid and easy release of vitamin E from the synthesized nanoencapsules at T = 37 °C.

Transglutaminase-Catalyzed Encapsulation of Individual Mammalian Cells with Biocompatible and Cytoprotective Gelatin Nanoshells.

Mammalian cells are extremely vulnerable to external assaults compared with plant and microbial cells because of the weakness of cell membranes compared with cell walls. Construction of ultrathin and robust artificial shells on mammalian cells with biocompatible materials is a promising strategy for protecting single cells against harsh environmental conditions. Herein, layer-by-layer assembly combined with a transglutaminase-catalyzed cross-linking reaction was employed to prepare cross-linked and biocompatible gelatin nanoshells on individual human cervical carcinoma cell line (HeLa) cells and mouse insulinoma cell line 6 (MIN6) cells. The encapsulated HeLa and MIN6 cells showed high viability and a prolonged encapsulation period. Moreover, the nanoshells can protect encapsulated cells from cytotoxic enzymes (such as trypsin) and polycation (polyethylenimine) attacks and help cells resist high physical stress. We also investigated how nanoshells would affect the cell viability, proliferation, and cell cycle distribution of encapsulated and released cells. The approach presented here may provide a new and versatile method for nanoencapsulation of individual mammalian cells, which would help cells endure various environmental stresses and thereby expand the application field of isolated mammalian cells.

Utilization of various encapsulation methods in proteolytic bacteria to maintain biomass cells during storage

Bacterial isolates used are proteolytic bacteria. Bacterial cell encapsulation aimed to protect cells from some external environmental factors that can interfere with the metabolism of the cell, so as to maintain the viability of bacteria, extending the shelf life and facilitate the distribution and utilization. In this study, the encapsulation of the bacteria was carried out by nanoencapsulation method using a spray dyer and electrospun nanofibers. Encapsulation in nanosize has advantages such as immobilization efficiency because of the increased surface area and volume, providing protection due to the increased flexibility of the encapsulation material. Nanoencapsulation the proteolytic bacteria was using the coating material in the form of skim milk and maltodextrin. Electrospun nanofiber for proteolytic bacteria was using polyvinyl alcohol (PVA) and skim milk as a coating material. The results of the viability of proteolytic nanoencapsulation were higher when encapsulated using skim milk at a concentration of 15% was 44.07%. Results of encapsulation of bacteria using electrospun nanofiber method showed three parameters that affected the process of electrospun nanofiber: the coating material parameters (concentration, viscosity and mixing ratio), the process parameters (voltage, flow rate, and the distance between the collector and needle), and environmental parameters (relative humidity and temperature).

N-Dodecanol nanocapsules with supramolecular lock shell layer for thermal energy storage

It is still a big challenge to obtain shape-stabilized nanoencapsulated core-shell phase change materials (NC-PCMs) with the encapsulation ratio up to 90 wt% via surfactant-free method due to the lack of novel nanoencapsulation method and related mechanism. Herein, we for the first time report a novel supramolecular lock shell layer technique without surfactant to facilely prepare shape-stabilized NC-PCMs with the encapsulation ratio range of 70–90 wt%. To this aim, amphiphilic macromolecular nanoreactors with the particle size of ~15 nm were firstly synthesized. n-Dodecanol as the heat storage core was then self-assembled into the nanoreactors under ultrasonification. A thin layer of crosslinked acrylates copolymers was prepared by in-situ grafting polymerization to further stabilize the potentially leaked n-dodecanol. Crystalline structure, morphology, and thermal behavior of the resulting NC-PCMs were extensively investigated. Relevant results indicate that the obtained NC-PCMs fluids show excellent storage stability in the temperature range of −50 to 50 °C, benefiting from their small particle size (60–90 nm) and intense supramolecular interactions between n-dodecanol and the prepared nanoreactors. Phase change temperature of the produced NC-PCMs is very close to that of neat n-dodecanol, no obvious supercooling phenomena have been detected for the produced NC-PCMs. The maximum encapsulation ratio, latent heat, and thermal conductivity of the shape-stabilized NC-PCMs approximate 90 wt%, 180 J g−1, and 0.1705 W m−1K−1, respectively, implying large potential application in the sectors of solar energy storage, waste heat management etc. The developed supramolecular lock-layer technique probably opens a new avenue in the search for NC-PCMs with ultrahigh mass content of core layer.

SMA-PAGE: A new method to examine complexes of membrane proteins using SMALP nano-encapsulation and native gel electrophoresis

Most membrane proteins function through interactions with other proteins in the phospholipid bilayer, the cytosol or the extracellular milieu. Understanding the molecular basis of these interactions is key to understanding membrane protein function and dysfunction. Here we demonstrate for the first time how a nano-encapsulation method based on styrene maleic acid lipid particles (SMALPs) can be used in combination with native gel electrophoresis to separate membrane protein complexes in their native state. Using four model proteins, we show that this separation method provides an excellent measure of protein quaternary structure, and that the lipid environment surrounding the protein(s) can be probed using mass spectrometry. We also show that the method is complementary to immunoblotting. Finally we show that intact membrane protein-SMALPs extracted from a band on a gel could be visualised using electron microscopy (EM). Taken together these results provide a novel and elegant method for investigating membrane protein complexes in a native state.

Electrospraying as a suitable method for nanoencapsulation of the hydrophilic bioactive dihydrochalcone, aspalathin.

The bioactive hydrophilic dihydrochalcone, aspalathin, has poor stability and bioavailability hampering its use in functional food ingredients with standardised aspalathin content. The aim of the study was to produce nanoparticles with controlled release to overcome these obstacles. Nanoencapsulation was investigated using both natural (chitosan and lecithin) and synthetic (poly(lactide-co-glycolide) and Eudragit S100® (ES100)) polymers by suitable conventional methods and electrospraying for all polymers. All polymer-method combinations produced particles smaller than 1.1 µm. Electrospraying produced more favourable results than conventional methods for the synthetic polymers, resulting in spherical particles with higher (p < 0.05) encapsulation efficiencies (>50%) and loading capacities (>10%). Opposite trends were observed for natural polymers. An in vitro release study revealed biphasic aspalathin release profiles at pH 7.4 with ES100 electrosprayed nanoparticles having the slowest (p < 0.05) release rate (1.67 h-1). Overall, ES100 electrosprayed nanoparticles showed the most favourable combination of parameters.

Antimicrobial Activity of Coleus Ambonicus Herbal Finish on Cotton Fabric

An extract obtained from Coleus Ambonicus was applied on cotton fabric by means of the exhaust, micro encapsulation and nano encapsulation methods, and the antimicrobial activity of the finished fabric assessed quantitatively by the AATCC test method 100 against gram positive (staphylococcus aureus) and gram negative (Escherichia coli) microbes. The finish applied on the the samples using all three methods exhibit a good bacterial reduction percentage. The finish applied on the samples using all three methods possesses a higher bacterial reduction percentage against gram positive microbes than gram negative, even after washing. The method of washing conforms to ISO method 3. The wash durability of the antimicrobial activity was assessed by the bacterial reduction percentage after washing. The wash durability of the samples using the direct exhaust method was very poor and it lost its antimicrobial activity after 10 wash cycles. The wash durability of the samples using the micro encapsulated method shows antimicrobial activity up to 10 wash cycles, dropping gradually to very low levels at 20 wash cycles. The wash durability of the samples using nano encapsulation shows good antimicrobial activity against both gram positive and gram negative microbes even after 30 washes

Characterisation of electrospun gelatine nanofibres encapsulated with Moringa oleifera bioactive extract.

Drumstick (Moringa oleifera) leaves have been used as a folk herbal medicine across many cultures since ancient times. This is most probably due to presence of phytochemicals possessing antioxidant properties, which could retard oxidative stress, and their degenerative effect. The current study deals with nanoencapsulation of Moringa oleifera (MO) leaf ethanolic extract within fish sourced gelatine matrix using electrospinning technique. The total phenolic and flavonoid content, radical scavenging (IC50 ) and metal reducing properties were 67.0 ± 2.5 mg GAE g-1 sample 32.0 ± 0.5 mg QE g-1 extract, 0.08 ± 0.01 mg mL-1 and 510 ± 10 µmol eq Fe(II) g-1 extract, respectively. Morphological and spectroscopic analysis of the fibre mats confirmed successful nanoencapsulation of MO extract within defect free nanofibres via electrospinning process. The percentage encapsulation efficiency (EE) was between 80% and 85%. Furthermore, thermal stability of encapsulated fibres, especially at 3% and 5% of core loading content, was significantly improved. Toxicological analysis revealed that the extract in its original and encapsulated form was safe for oral consumption. Overall, the present study showed the potential of ambient temperature electrospinning process as a safe nanoencapsulation method, where MO extract retained its antioxidative capacities. © 2016 Society of Chemical Industry.

Ultrasound Detection of Regional Oxidative Stress in Deep Tissues Using Novel Enzyme Loaded Nanoparticles.

Oxidative stress is a powerful tool that is critical to immune mediated responses in healthy individuals, yet additionally plays a crucial role in development of cancer, inflammatory pathologies, and tissue ischemia. Despite this, there remain relatively few molecular tools to study oxidative stress, particularly in living mammals. To develop an intravenously injectable probe capable of labeling sites of oxidative stress in vivo, 200 nm catalase synthetic hollow enzyme loaded nanospheres (catSHELS) are designed and fabricated using a versatile enzyme nanoencapsulation method. catSHELS catalyze H2 O2 to water and oxygen producing microbubbles that can be detected and imaged using a clinical ultrasound system. catSHELS are optimized in vitro to maximize ultrasound signal and their functionality is demonstrated in rat ischemic renal injury model. Ischemic oxidative injury is induced in a single kidney of normal rats by clamping the renal artery for 1 h followed by 2 h of reperfusion. Imaging of both kidneys is performed following the intravenous bolus injection of 1012 catSHELS of the optimized formulation. There is significant increase in ultrasound signal of the injured kidney relative to controls. This method offers a novel intravenous approach to detect oxidative stress in deep tissues in living animals.

Physicochemical characterization of chitosan nanoparticles and nanocapsules incorporated with lime essential oil and their antibacterial activity against food-borne pathogens

Lime oil has recognized fungicidal and antibacterial properties. Nanoparticles and nanocapsules are structures that have been developed to overcome the high volatility of essential oils. Chitosan nanoparticles and chitosan nanocapsules incorporated with lime essential oil were synthesized by nanoprecipitation and nanoencapsulation methods, respectively. The samples were characterized by transmission electron microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR), and Z potential was measured. Also, particle size distribution was analyzed by dynamic light scattering (DLS) and the antibacterial activity was studied. According to TEM, the average size of nanocapsules was higher than for nanoparticles. When lime essential oil was incorporated, the particle size increased. Lime essential oil incorporation was evidenced by FTIR. Chitosan nanocapsules showed higher Z potential value compared to chitosan nanoparticles. The antibacterial activity was tested against four food-borne pathogens, being higher for nanoparticles than for nanocapsules. The highest antibacterial activity was observed for chitosan nanoparticles incorporated with lime essential oil applied against Shigella dysenteriae, attaining an inhibition halo (IH) value of 3.5 cm for 40 μL of minimum inhibitory volume (MIV). The novelty of incorporating lime essential oil into chitosan nanoparticles and nanocapsules and the study of their enhancing effect on antibacterial activity are shown in this paper.

Antibacterial Activity of Fructus forsythia Essential Oil and the Application of EO-Loaded Nanoparticles to Food-Borne Pathogens.

Fructus forsythia essential oil (FEO) with excellent antibacterial activity was rarely reported. The objective of the present study was to investigate the antibacterial activity and the antibacterial mechanism of FEO against two food-borne pathogenic bacteria, Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in vitro. When treated FEO, the zones of inhibition (ZOI) of E. coli (20.5 ± 0.25 mm) and S. aureus (24.3 ± 0.21 mm) were much larger than control (p < 0.05). The minimum inhibitory concentrations (MICs) of FEO were 3.13 mg/mL and 1.56 mg/mL for E. coli and S. aureus, respectively. The antibacterial mechanism of FEO against E. coil was due to the changes in permeability and integrity of cell membrane leading to the leakage of nucleic acids and proteins. With the superior antibacterial activity of FEO, the nano-encapsulation method has been applied in FEO. When compared to FEO and blank chitosan nanoparticles, FEO-loaded nanoparticles (chitosan to FEO of 1:1) can effectively inhibit the growth of E. coil above 90% at room temperature. It is necessary to consider that FEO and FEO-loaded nanoparticles will become promising antibacterial additives for food preservative, cosmetic, and pharmaceutical applications.

Chemical approach to solvent removal during nanoencapsulation: its application to preparation of PLGA nanoparticles with non-halogenated solvent

The objective of this study was to develop a new oil-in-water emulsion-based nanoencapsulation method for the preparation of PLGA nanoparticles using a non-halogenated solvent. PLGA (60–150 mg) was dissolved in 3 ml of methyl propionate, which was vortexed with 4 ml of a 0.5–4 % polyvinyl alcohol solution. This premix was sonicated for 2 min, added into 30 ml of the aqueous polyvinyl alcohol solution, and reacted with 3 ml of 10 N NaOH. Solvent removal was achieved by the alkaline hydrolysis of methyl propionate dissolved in an aqueous phase into water-soluble methanol and sodium propionate. It was a simple but effective technique to quickly harden nanoemulsion droplets into nanoparticles. The appearing PLGA nanoparticles were recovered by ultracentrifugation and/or dialysis, lyophilized with trehalose, and redispersed by water. This nanoencapsulation technique permitted a control of their mean diameters over 151.7 ± 3.8 to 440.2 ± 22.2 nm at mild processing conditions. When the aqueous polyvinyl alcohol concentration was set at ≥1 %, nanoparticles showed uniform distributions with polydispersity indices below 0.1. There were no significant changes in their mean diameters and size distribution patterns before and after lyophilization. When mestranol was encapsulated into nanoparticles, the drug was completely nanoencapsulated: depending on experimental conditions, their encapsulation efficiencies were determined to be 99.4 ± 7.2 to 105.8 ± 6.3 %. This simple, facile nanoencapsulation technique might have versatile applications for the preparation of polymeric nanoparticulate dosage forms. Schematic illustration of an innovative chemical approach to solvent removal during nanoencapsulation. Methyl propionate present in the aqueous continuous phase reacts with sodium hydroxide, thereby producing methanol and sodium propionate. Its alkaline hydrolysis allows the continuous extraction of the solvent out of nanoemulsion droplets, eventually solidifying them into nanoparticles. It is a simple but effective nanoencapsulation technique that has advantages over typical solvent evaporation and/or extraction methods.

Recent Trends in Preparation of Poly(lactide‐co‐glycolide) Nanoparticles by Mixing Polymeric Organic Solution with Antisolvent

In recent years, there have been a plethora of nanoengineering approaches for the development of poly(lactide‐co‐glycolide) (PLGA) nanoparticulate carrier systems. However, overlooking the multifaceted issues in the preparation and characterization of PLGA‐based nanoparticles, many reports have been focused on their in vivo behaviors. It is imperative to fully assess technological aspects of a nanoencapsulation method of choice and to carefully evaluate the nanoparticle quality. The selection of a nanoencapsulation technique should consider drug property, nanoparticle quality, scale‐up feasibility, manufacturing costs, personnel safety, environmental impact, waste disposal, and the like. Made in this review are the fundamentals of classical emulsion‐templated nanoencapsulation methods used to prepare PLGA nanoparticles. More specifically, this review provides insight into emulsion solvent evaporation/extraction, salting‐out, nanoprecipitation, membrane emulsification, microfluidic technology, and flow focusing. Innovative nanoencapsulation techniques are being developed to address many challenges existing in the production of PLGA‐based nanoparticles. In addition, there are various out‐of‐the‐box approaches for the development of novel PLGA hybrid systems that could deliver multiple drugs. Latest trends in these areas are also dealt with in this review. Relevant information might be helpful to those who prepare and develop PLGA‐based nanoparticles that meet their specific demands.

Meeting report: the 1st BRG-training school in Asia, a first step in the building of an ASEAN encapsulation network.

The 6th training school on bioencapsulation of the Bioencapsulation Research Group (BRG http://bioencapsulation.net/2014_Nha_Trang/index1.html) took place in Nha Trang, Vietnam, in March 2014. This event, organised by AgroSup Dijon, Nha Trang University and the BRG with the support of the Agency of French‐Speaking Universities (Agence Universitaire de la Francophonie, AUF) and Buchi was the first BRG‐event organised in Asia. The success of this school, which brought together bioencapsulation researchers from eight countries of the Association of Southeast Asian Nations (ASEAN) along with those from Europe, Japan, Australia and many other countries, shows that bioencapsulation is a growing field in Southeast Asia. After a brief presentation of bibliometric data showing the dynamism and the specificities of encapsulation research in Southeast Asia, a presentation of the achievements and needs in some countries is given showing the interest in building a network in this region.

Curcumin-Loaded Nanocapsules: Formulation and Influence of the Nanoencapsulation Processes Variables on the Physico-Chemical Characteristics of the Particles

The aim of this work was to assess the influence of various formulation parameters on the incorporation of Curcumin into nanoparticles. For this purpose, the influence of the aqueous monomer (ethylene diamine, hexamethylene diamine, and 1,4-diaminobutane), as well as the effect of the stirring rate and the influence of the nanoencapsulation method on the encapsulation efficiency were investigated. It was found that variation in the amount of ingredients had profound effects on the curcuminoid loading capacity, the mean particle size, and size distribution. Furthermore, from the thermal results, it is concluded that the reactivity of diamine and the length of flexible methylene chain in diamine determine the thermal properties of resultant polymer wall membrane. The encapsulation yield depends not only on the encapsulation process but also on the chemical structure of the diamine. Whereas, the size and its distribution vary according to the process choice and the emulsification stirring rate.

An ion pairing approach to increase the loading of hydrophilic and lipophilic drugs into PEGylated PLGA nanoparticles

The aim of this study was to enhance the loading of dalargin (enkephalin derivatives) a hydrophilic drug and loperamide HCl (non-opiate antidiarrheal agent) a lipophilic drug candidates within PEGylated nanoparticles. A novel nanoencapsulation method based on the concept of s/o/w and ion pairing followed by solvent diffusion was adopted. The copolymers with three different mPEG densities (5%, 12% and 17%) were employed separately in combination with two different grades of dextran sulphate (DS) 5000 and 500,000 MW in the preparations. Nanoparticles prepared from copolymers with increasing mPEG densities, showed an insignificant ( p > 0.05) increasing trend of drug loading, this was however significantly increased when DS5000 was included in the preparations. The particle size remains unchanged after dalargin loading, with no significant ( p > 0.05) alteration in the neutral zeta potential compared to that of the preparations without DS5000. Considering that a dalargin ion pair could also have a neutral charge, it was not advisable to conclude its incorporation, as the size remain unchanged, which would otherwise increase if an ion pair was incorporated within the core of nanoparticles. Therefore, it was expected that a dalargin ion pair might be located outside the core as a separate particulate entity or reside in the hydrophilic shell of the nanoparticles. A loperamide HCl ion pair showed significant ( p < 0.05) increase in size when incorporated; at the same time it provided a neutral zeta potential despite adding negatively charged DS5000 in the preparation, hence it seemed encapsulated. Inclusion of DS500,000 in the preparation further increased the drug loading of dalargin and loperamide HCl. However, a significant ( p < 0.05) negative zeta potential was noted in both cases which suggested that excess charge was still available on the surface of nanoparticles which could trap further amounts of drug on the surface rather than inside the core of nanoparticles. During in vitro evaluation of drug loaded nanoparticles, dalargin released as quickly as free drug, when loperamide HCl showed almost burst free sustained release profile with respect to the release of their free drug solutions, suggested that ion pairing approach was more pronounced for loperamide HCl formulation.

Preparation of Biodegradable Nanoparticles and Their Use in Transfection

INTRODUCTIONBiodegradable nanoparticles (NPs) are colloidal particles with a gene of interest encapsulated inside a polymeric matrix. They are typically 100 nm in diameter, and are formulated using FDA-approved, biodegradable, biocompatible polymers such as poly(D,L-lactide-co-glycolide) (PLGA) or polylactide (PLA). The NPs are taken up by cells via an endocytic process, and the encapsulated plasmid DNA entrapped in NPs is protected from degradation by both extra- and intracellular nucleases. It is released slowly, sustaining gene delivery and gene expression. In contrast, higher but transient gene expression is observed with lipid- or polymer-based complexes where most of the delivered DNA is available quickly for transfection. Thus, unlike other nonviral gene delivery systems, NPs thus constitute a sustained gene expression vector. Sustained gene expression is advantageous, especially when the half-life of the expressed protein is very low or when chronic gene delivery is required for therapeutic efficacy. This protocol describes a method for nanoencapsulation of DNA and the subsequent use of NPs for transfection.

Sol–gel synthesis at neutral pH in W/O microemulsion: A method for enzyme nanoencapsulation in silica gel nanoparticles

The classical sol–gel synthesis of silica gels has been adapted to a W/O (micro)emulsion process under conditions that minimize denaturing effects on encapsulated enzymes. We have in particular focused on optimizing the purification procedures with the aim to produce water nanoparticles dispersions from W/O emulsions without the use of precipitation/sedimentation steps.A proof of principle of encapsulation has been conducted using horseradish peroxidase (HRP).