Capsule Size Research Articles

Impact of electrostatic potential on microcapsule-formation and physicochemical analysis of surface structure: Implications for therapeutic cell-microencapsulation.

Cell-encapsulation is used for preventing therapeutic cells from being rejected by the host. The technology to encapsulate cells in immunoprotective biomaterials, such as alginate, commonly involves application of an electrostatic droplet generator for reproducible manufacturing droplets of similar size and with similar surface properties. As many factors influencing droplet formation are still unknown, we investigated the impact of several parameters and fitted them to equations to make procedures more reproducible and allow optimal control of capsule size and properties. We demonstrate that droplet size is dependent on an interplay between the critical electric potential (Uc,), the needle size, and the distance between the needle and the gelation bath, and that it can be predicted with the equations proposed. The droplet formation was meticulously studied and followed by a high-speed camera. The X-ray photoelectron analysis demonstrated optimal gelation and substitution of sodium with calcium on alginate surfaces while the atomic force microscopy analysis demonstrated a low but considerable variation in surface roughness and low surface stiffness. Our study shows the importance of documenting critical parameters to guarantee reproducible manufacturing of beads with constant and adequate size and preventing batch-to-batch variations.

Dissolution time and shelf life quality of Ficus deltoidea powder and granule

Lyophilized from plants extract is a process to prolong the amounts of phytochemicals in a solid form. The bioactive compound in Ficus deltoidea (FD), which is isovitexin should be stable and bioavailable during the downstream processing such as drying process to achieve its optimum health benefits. Therefore, this study focuses on the impact of lyophilizing methods such as spray drying followed by a granulator method to determine the stability of the bioactive compound in FD during drying and storage. After the powdered produce, it will test on the model of human digestion (dissolution study) either the amounts of phytochemicals remain stable. Finally, shelf-life quality analysis and the dissolution rate (capsule size 0 and 1) were carried out. The results obtained show the methods employed in this study can be used for the analysis of quality content and dissolution tests of FD capsules. For FD in the shelf-life quality study, parameters for appearance and Total Yeast Microbial Count (TYMC) showed no significant difference after 3 months. For pH, the slight decrease in pH level will increase the number of Total Aerobic Microbial Count (TAMC) in powder form. Compared to granule form, the pH level more consistent and the number of TAMC also in a control condition. The dissolution of capsules containing powder and granulated of FD showed a high percentage of bioactive compound released into the dissolution medium, although the bioactive compound content of herbal products (capsule size 1) was found to be half that of capsules size 0. Through observation for both capsules size content of FD, the maximum dissolution was achieved after 100 min.

Preparation and thermal characterization of n-octadecane/pentafluorostyrene nanocapsules for phase-change energy storage

A novel class of nano-encapsulated phase-change material (NEPCM) was produced using the suspension polymerization method with the core n-octadecane capsulated in the shell of poly(2,3,4,5,6-pentafluorostyrene). The morphology and components of the NEPCM were analyzed by the scanning electron microscopy, the X-ray diffractometer, and the Fourier-transform infrared spectroscopy. The thermal performance of various NEPCM samples was compared based on the measurements of the differential scanning calorimetry, the thermogravimetric analyzer, and the thermal conductivity meter. It is found that the NEPCM4 with shell/core mass ratio 1:2 has the best thermal performance among the tested samples with six different mass ratios. The measured melting enthalpy heat of (171.8 ± 2.2) J•g−1 for the NEPCM4 is the highest among all the tested capsules and the encapsulation efficiency for the NEPCM4 is also maximized at (76.1 ± 1.8)%. Capsule size variation in the prepared samples is small. The average size diameter of the NEPCM4 capsules is measured to be 490 ± 16 nm. The thermogravimetric investigation reveals that the initial weight-loss temperature for the NEPCMs is increased in comparison with that for the pure n-octadecane. The prepared nanocapsules exhibit excellent thermal stability and thermal properties, possessing enormous potentials to enable practical applications in thermal energy storage.

Pleiotropy and epistasis within and between signaling pathways defines the genetic architecture of fungal virulence.

Cryptococcal disease is estimated to affect nearly a quarter of a million people annually. Environmental isolates of Cryptococcus deneoformans, which make up 15 to 30% of clinical infections in temperate climates such as Europe, vary in their pathogenicity, ranging from benign to hyper-virulent. Key traits that contribute to virulence, such as the production of the pigment melanin, an extracellular polysaccharide capsule, and the ability to grow at human body temperature have been identified, yet little is known about the genetic basis of variation in such traits. Here we investigate the genetic basis of melanization, capsule size, thermal tolerance, oxidative stress resistance, and antifungal drug sensitivity using quantitative trait locus (QTL) mapping in progeny derived from a cross between two divergent C. deneoformans strains. Using a “function-valued” QTL analysis framework that exploits both time-series information and growth differences across multiple environments, we identified QTL for each of these virulence traits and drug susceptibility. For three QTL we identified the underlying genes and nucleotide differences that govern variation in virulence traits. One of these genes, RIC8, which encodes a regulator of cAMP-PKA signaling, contributes to variation in four virulence traits: melanization, capsule size, thermal tolerance, and resistance to oxidative stress. Two major effect QTL for amphotericin B resistance map to the genes SSK1 and SSK2, which encode key components of the HOG pathway, a fungal-specific signal transduction network that orchestrates cellular responses to osmotic and other stresses. We also discovered complex epistatic interactions within and between genes in the HOG and cAMP-PKA pathways that regulate antifungal drug resistance and resistance to oxidative stress. Our findings advance the understanding of virulence traits among diverse lineages of Cryptococcus, and highlight the role of genetic variation in key stress-responsive signaling pathways as a major contributor to phenotypic variation.

Investigation of poly(lactic acid) nanocapsules containing the plant extract via coaxial electrospraying method for functional nonwoven applications

This study focuses on the development of functional nanocapsules via the coaxial electrohydrodynamic atomization (electrospraying) method. These nanocapsules can manipulate nonwoven surface functionality in terms of antibacterial characteristics for medical textile purposes. Electrosprayed nanocapsules were produced from Poly(lactic acid) (PLA) polymer and Plumbago europaea plant extract. Here, we employ optimized solution and process parameters (needle to collector distance, electrical field, application time, and needle dimension) for the coaxial electrospraying process. Different Plumbago europaea extract concentrations and co-fluids’ flow rates were investigated as part of the study. Also, the effect of these parameters on capsule morphology and dimension were investigated. After the formation of PLA nanocapsules, morphological and dimensional characteristics were analyzed through SEM, FESEM, TEM images in addition to FTIR and nanosize measurements. According to our findings, a lower co-fluids’ flow rate gives the smaller nanocapsules with narrow-sized distribution and desired spherical morphology. Antibacterial efficiency doesn’t show any significant difference except the lowest plant extract concentrations. After characterizing the nanocapsules’ structures, the core-sheath structure can be clearly identified. Consequently, the desired capsule morphology and size for nanocapsules were accomplished. The antibacterial efficiency of covered surfaces with nanocapsules is up to 80% for Staphylococcus aureus and about 31% for Escherichia coli, even with low pick-up ratios. Even for a very low amount of extract usage, good antibacterial efficiency can be achieved. The application has endless potential in terms of higher concentration and a wide range of chemical usage.

Development of a nanostructured double-layer coated tablet based on polyethylene glycol/gelatin as a platform for hydrophobic molecules delivery

The aim of the current study was to develop a nanostructured double-layer for hydrophobic molecules delivery system. The developed double-layer consisted of polyethylene glycol-based polymeric (PEG) followed by gelatin sub coating of the core hydrophobic molecules containing sodium citrate. The polymeric composition ratio of PEG and the amount of the sub coating gelatin were optimized using the two-level fractional method. The nanoparticles were characterized using AFM and FT-IR techniques. The size of these nano capsules was in the range of 39-76 nm depending on drug loading concentration. The drug was effectively loaded into PEG-Gelatin nanoparticles (≈47%). The hydrophobic molecules-release characteristics in terms of controlled-release duration and dissolution efficiency were examined in various dissolution media, such as physiological pH (7.4) and simulated stomach fluid (3.4). Consequently, the optimized double-layer for hydrophobic molecules delivery system showed a gradual release of hydrophobic molecules in the and in physiological pH, indicating its novelty for using as a platform for hydrophobic molecules delivery.

Differential Interactions of Chiral Nanocapsules with DNA.

(1) Background: Chiral nanoparticular systems have recently emerged as a compelling platform for investigating stereospecific behavior at the nanoscopic level. We describe chiroselective supramolecular interactions that occur between DNA oligonucleotides and chiral polyurea nanocapsules. (2) Methods: We employ interfacial polyaddition reactions between toluene 2,4-diisocyanate and lysine enantiomers that occur in volatile oil-in-water nanoemulsions to synthesize hollow, solvent-free capsules with average sizes of approximately 300 nm and neutral surface potential. (3) Results: The resultant nanocapsules exhibit chiroptical activity and interact differentially with single stranded DNA oligonucleotides despite the lack of surface charge and, thus, the absence of significant electrostatic interactions. Preferential binding of DNA on d-polyurea nanocapsules compared to their l-counterparts is demonstrated by a fourfold increase in capsule size, a 50% higher rise in the absolute value of negative zeta potential (ζ-potential), and a three times lower free DNA concentration after equilibration with the excess of DNA. (4) Conclusions: We infer that the chirality of the novel polymeric nanocapsules affects their supramolecular interactions with DNA, possibly through modification of the surface morphology. These interactions can be exploited when developing carriers for gene therapy and theranostics. The resultant constructs are expected to be highly biocompatible due to their neutral potential and biodegradability of polyurea shells.

In vitro synergistic effects of fluoxetine and paroxetine in combination with amphotericin B against Cryptococcus neoformans.

Cryptococcus neoformans is a yeast that mainly affects immunocompromised individuals and causes meningoencephalitis depending on the immune status of the host. The present study aimed to validate the efficacy of selective serotonin reuptake inhibitors, fluoxetine hydrochloride (FLH) and paroxetine hydrochloride (PAH), alone and in combination with amphotericin B (AmB) against C. neoformans. Susceptibility tests were conducted using the broth microdilution method and synergistic effects of combining FLH and PAH with AmB were analyzed using the checkerboard assay. Effects of minimum inhibitory concentration (MIC) and synergistic concentration were evaluated in biofilms by quantifying the biomass, measuring the viability by counting the colony-forming units (CFU/mL) and examining the size of the induced capsules. Cryptococcus neoformans was susceptible to FLH and PAH and the synergistic effect of FLH and PAH in combination with AmB reduced the MIC of AmB by up to 8-fold. The isolated substances and combination with AmB were able to reduce biofilm biomass and biofilm viability. In addition, FLH and PAH alone or in combination with AmB significantly decreased the size of the yeast capsules. Collectively, our results indicate the use of FLH and PAH as a promising prototype for the development of anti-cryptococcal drugs.

Microencapsulation of pendimethalin with polyurethane-urea and determination of its stability

In this study, pendimethalin (PM) used as an herbicide was encapsulated using interfacial polymerization method. The size, shell thickness, microencapsulation efficiency, the effect of mixing speed on capsule size and active substance release times of the produced microcapsules were investigated. Polyurethane-urea resin, which is the main component of the capsule shell, was synthesized using isocyanate / glycol / amine at different molar ratio at 55°C for 180 min. It was measured that the microencapsulation efficiency was 53.2–89.1% and the microcapsule shell thickness was 399.7–1479.0 nm. The lowest and highest release percentages of microcapsules under alcohol-water and ultraviolet (UV) light for 4 h at 20°C were found to be 30.79% and 40.12%, respectively. It has been found that the microcapsules containing ethyl glycol in the capsule wall composition had the highest stability, and the capsules containing PEG-400 in the capsule wall structure had the highest capsulation efficiency.

Microencapsulation of lambda-cyhalothrin with polyurethane-urea and application on peppermint plant leaves containing a two-spotted red spider mite (tetranychus urticae)

In this study, lambda-cyhalothrin (LC) used as a pesticide was microencapsulated with polyurethaneurea (PUU) at 55°C temperature for 180 min. Wall thickness and dimensions of the microcapsules, the effect of mixing speed on the capsule size, active substance release times of LC-PUU microencapsules under UV rays and alcohol/water medium, microencapsulation yields and the effect of microencapsulated active substance on the red spider on peppermint plant leaves (mentha piperita) were investigated. The microcapsule yield was found 77.4–85.5%, also capsule shell thickness was 512.3–724.5 nm. The highest release percentage of the microcapsules was found to be 35.00% at 20°C for 4 h under UV light. When the LC-PUU microcapsules applied to the peppermint plant leaves (mentha piperita) which contained a two-spotted red spider mites (tetranychus urticae), it remained active for 8 weeks and during this period no insect formation was observed on the peppermint leaves.

Crystal capillary origami capsule with self-assembled nanostructures.

The self-assembling mechanism of elasto-capillaries opens new applications in micro and nanotechnology by providing 3D assembly structures with 2D planar unit cells, so-called capillary origami. To date, the final structure has been designed based on the predetermined shape and size of the unit cell. Here, we show that plate-like salt crystallites grow and cover the emulsion interface, which is driven by Laplace pressure. Eventually, it creates a spherical capsule with self-assembled nanostructures. The capsule and the crystallite are investigated by scanning electron microscopy and X-ray diffraction analysis. To explain the mechanism, we develop a theoretical model to estimate the capsule size, the shell thickness, and the conditions necessary to form the shell based on a thin-walled pressure vessel. The proposed crystal capillary origami can fabricate a three-dimensional self-assembled salt capsule without any complicated procedures. We believe that it can offer a new physicochemical avenue for the spontaneous and facile fabrication of water-soluble carrier particles.

The exploration of size and toddler interaction with liquid laundry detergent capsules.

Liquid laundry capsules have been involved in multiple poisoning incidents with young children in the home. There are a range of contributing factors for these incidents, including influences from industry, culture, home environments, and parenting/supervision. There also are influences from children’s behaviour and decisions in reaction to potential hazards. Previous research examined the influence of capsule product appearance and colour on children’s behaviour around hazardous household items, but little research examines the influence of product size. This research explored if differences in the size of liquid laundry capsules result in different levels of toddler interaction. We compared two commercially available capsule designs that are identical in physical appearance but differ in physical size. Our research was conducted using three studies: Study 1, forced-choice test in an out-of-context laboratory setting; Study 2, an ecologically-valid, simulated real-world setting replicating a home laundry cabinet with a container of capsules left open; and Study 3, a second ecologically-valid study replicating a home laundry cabinet, this time with a capsule left outside its container. Capsule interaction was measured by grasping choice among samples of 156 toddlers ages 9–36 months. The same sample was used for Studies 1 and 2, and a second identically sized sample recruited for Study 3. Results from Study 1 indicated toddlers selected the small (49.8% selection) and large (50.2%) capsule with nearly identical frequency. Study 2 largely replicated Study 1: Toddlers selected the small capsule or container of small capsules 26.8% of the time and the large capsule or container of large capsules 22.3% of the time. Study 3 also replicated previous findings: Toddlers selected the smaller capsule 18.0% of the time and the larger 19.2%. We discuss study results, which suggest no appreciable difference in toddler’s grasping choice to smaller versus larger laundry capsules.

Diffuse approximation for identification of the mechanical properties of microcapsules

A novel data-driven real-time procedure based on diffuse approximation is proposed to characterize the mechanical behavior of liquid-core microcapsules from their deformed shape and identify the mechanical properties of the submicron-thick membrane that protects the inner core through inverse analysis. The method first involves experimentally acquiring the deformed shape that a given microcapsule takes at steady state when it flows through a microfluidic microchannel of comparable cross-sectional size. From the mid-plane capsule profile, we deduce two characteristic geometric quantities that uniquely characterize the shape taken by the microcapsule under external hydrodynamic stresses. To identify the values of the unknown rigidity of the membrane and of the size of the capsule, we compare the geometric quantities with the values predicted numerically using a fluid-structure-interaction model by solving the three-dimensional capsule-flow interactions. The complete numerical data set is obtained off-line by systematically varying the governing parameters of the problem, i.e. the capsule-to-tube confinement ratio, and the capillary number, which is the ratio of the viscous to elastic forces. We show that diffuse approximation efficiently estimates the unknown mechanical resistance of the capsule membrane. We validate the data-driven procedure by applying it to the geometric and mechanical characterization of ovalbumin microcapsules (diameter of the order of a few tens of microns). As soon as the capsule is sufficiently deformed to exhibit a parachute shape at the rear, the capsule size and surface shear modulus are determined with an accuracy of 0.2% and 2.7%, respectively, as compared with 2–3% and 25% without it, in the best cases (Hu et al. Characterizing the membrane properties of capsules flowing in a square-section microfluidic channel: Effects of the membrane constitutive law. Phys Rev E 2013; 87(6): 063008). Diffuse approximation thus allows the capsule size and membrane elastic resistance to be provided quasi-instantly with very high precision. This opens interesting perspectives for industrial applications that require tight control of the capsule mechanical properties in order to secure their behavior when they transport active material.

Formulation of a responsive in vitro digestion wall material, sensory and market analyses for chia seed oil capsules

Spray drying encapsulation of chia seed oil and its subsequent incorporation into powdered chocolate milk was carried out. It was sought to formulate a responsive wall material using three different formulations consisting of maltodextrin:sodium caseinate ratios of 100:0, 95:5 and 90:10. Zeta potential of the emulsion, capsule size, loading capacity, morphology, and oil release into in vitro digestive fluids were evaluated. The formulation which contained more sodium caseinate as wall material, demonstrated the highest oil release rates at simulated intestinal fluid, resistance to simulated salivary fluid, less capsules agglomeration and the highest loading capacity (41.8%). Consequently, product formulation was assured to be harmless, it was incorporated into chocolate milk powder. Product acceptance and consumer tendency was evaluated through a bilateral sensory and market analyses. 46% consumer positive response of this product was obtained, and cereal or vanilla drinks are proposed as future products to incorporate the capsules.

Layer‐by‐Layer‐Assembled Capsule Size Affects the Efficiency of Packaging and Delivery of Different Genetic Cargo

AbstractThe lack of an efficient and versatile intracellular nucleic acids delivery platform impedes the clinical implementation of gene therapy. Advances in layer‐by‐layer (LbL) technology have led to the production of LbL polymer capsules, a promising universal delivery tool. The biocompatibility, sufficient packaging capacity, safety, low cost, and high variability of structure and composition of the LbL capsules make it possible to meet the requirements for clinical‐grade nonviral gene transfer. Here, the possibility of polymeric LbL capsules of different sizes (micrometer and sub‐micrometer‐sized) to serve as universal nonviral carriers for messenger RNA (mRNA) and small interfering RNA (siRNA) is considered. In particular, the internalization of capsules into human mesenchymal stem cells (hMSCs, as an example of adult primary stem cells), capsule uptake, and intracellular delivery of mRNA and siRNA is studied. Importantly, the use of micrometer‐ or sub‐micrometer‐sized polymer capsules (MicCaps and SubCaps) allows the mRNA or siRNA to be packaged and transferred into hMSCs with high efficiency. While the uptake efficiency is comparable between MicCaps and SubCaps, the latter are significantly more efficient than MicCap when transferring siRNAs. These results demonstrate the potential of the LbL capsules as a universal gene delivery platform, which can be tuned according to the properties of genetic cargo.

Temperature-Responsive Pyraclostrobin-Loaded Octadecane Submicrocapsules with Lowered Toxicity.

Pyraclostrobin (Pyr) is one of the most effective fungicides. However, it can degrade via photolysis in water, it is toxic to aquatic life and if inhaled, it has a low solubility in water, that leads to difficulties when applying to plants by spraying. Additionally, the necessity of repeated (weekly) sprays of fungicides when the pathogen growth risk is the highest, such as at the temperature range of 24 to 36 °C and increased humidity of about 95%, leads to loss of efficiency of the fungicide and overdose of chemicals. In the present study, pyraclostrobin was microencapsulated to solve the abovementioned issues. As a core of capsules octadecane (OD) with a melting point of 28 °C was used, thus, the release of pyraclostrobin was controlled via temperature change. Pyraclostrobin-loaded submicrocapsules (PyrSMCs) were characterized using SEM, DLS, TGA/DSC, HPLC, FTIR methods; stimuli-responsivity was tested employing in vitro tests with pathogenic culture (Fungal strain of Pyrenophora teres - CPPF-453) grown in Petri dishes. Toxicity of PyrSMCs to Artemia salina was studied as well. Size of capsules was 200–600 nm along with the presence of bigger capsules with a diameter of 1–4 µm. PyrSMCs showed excellent antifungal effects above the melting point of octadecane. PyrSMCs demonstrated 29 times less toxicity than pyraclostrobin of technical grade. Overall, results show the potential of such capsules to be applied in the agricultural industry for precise agriculture strategies.

Corrosion Protection of Self-Healing Coating Contained Fiber/Spherical Shaped Capsules Formed on Substrate Metal

Coating is one of the most useful techniques for corrosion protection of metallic materials, however, if coating is damaged, local corrosion will occur. It is important to repair the damaged area of coating soon, however it needs much cost. From these, our research group develop the coating with self-healing property, called by self-healing coating. In this coating capsules containing healing-agent of coating are dispersed. If the coating is damaged, capsules will be broken at the same time. The healing-agent containing in capsules will flow out. The healing-agent reacts with the water vapor in the air to form a healing-structure and cover the damaged area of coating. The capsules contained healing-agent are produced as follows. First, the prepolymer, this is precursor of shell of capsules, drip into the aqueous solution dissolved glycerol, it hardly dissolves in the aqueous solution since the prepolymer is the oil phase. A mixture of oil droplets dispersed in the aqueous solution is formed. When this mixture is agitated with high speed, the oil droplets become micro spheres and emulsion forms. Furthermore, the reaction between prepolymer and glycerol occurs only at this interface between oil phase and water phase, spherical shaped capsules contained a healing-agent in a polyurethane shell can be produced. From our previous study, the coating with these spherical capsules has a self-healing property, because healing-structure could be observed at the damaged area of coating, but this structure covered damaged area, incompletely. It is necessary to improve self-healing property of coating. From the self-healing mechanism of the coating, the self-healing property of the coating will be strongly depended on the amount of healing-agent flowing to the damaged area. Therefore, we start the development of the coating with capsules with other shape such as fiber shape are dispersed in order to develop an advanced self-healing coating with higher healing property. Considering the procedure of capsule formation, the shape of capsules can be controlled by the agitation speed and viscosity of prepolymer solution. The shape of capsules will be related to the amount of healing-agent flow from capsules to the damaged area of coating, when coating is damaged. e.g. more amount of healing-agent will flow from fiber shaped capsules than that from spherical shaped capsules, because fiber capsules will be arranged horizontally to the metal substrate due to the flow during the formation of coating, and the more capsules will be broken, when vertical damage was formed in the coating. In this paper, the shape of capsules produced from prepolymer solution with high viscosity and self-healing property of coating dispersed with these capsules were discussed.The procedure synthesizing capsules is follows. The prepolymer prepared by reaction between TDI and glycerol in cyclohexanone as a solvent under 75 ℃, 600 rpm. In order to increase the prepolymer concentration and viscosity of solution, the heat treatment of prepolymer solution were performed under 140 ℃, 8 min. After heat treatment, IPDI as a healing-agent, and xylene as inhibiter solidification inside of capsules were added. First, this prepolymer solution drip into the sodium dodecyl sulfate and glycerol aqueous solution with low agitation speed (200 rpm). The prepolymer solution was not dissolved in the aqueous solution and small oil droplets were dispersed in the aqueous solution. The shape of some of droplets will be changed from spherical to long spheroidal or fiber by agitation of solution. Furthermore, the shell formation reaction take place only at the interface between oil and water phases, the spherical, spheroidal and fiber shaped capsules could be formed. For comparison, the capsules produced under high agitation speed (600 rpm) and those from prepolymer solution without heat treatment were also prepared. These capsules were observed by a scanning electron microscope SEM.Fig. 1-a show the shape of capsules prepared from prepolymer solution without heat treatment under high agitation speed, 600 rpm. From this image, only spherical with 20 - 60 µm of diameter can be observed. The shape of capsules from same prepolymer under low agitation speed, 200 rpm, also only spherical however the size of capsules is bit larger, the maximum diameter is about 80 µm, as shown in Fig. 1-b. The shape of the capsule the produced from prepolymer with heat treatment with high agitation speed, shown in Fig. 1-c, are similar to that without heat treatment. In contrast to these, the capsules produced from prepolymer with heat treatment under low agitation speed have some kinds of shape, such as spherical, spheroidal and long fiber. The coating dispersed with these shaped capsules will be also discussed. Figure 1

Cellulose acetate encapsulated upconversion nanoparticles – A novel theranostic platform

Luminescent upconversion nanoparticles (UCNPs) are of great interest in a wide range of nanotechnological applications, particularly in the biomedical area like imaging and therapy but their biocompatibility and stability pose major challenges hampering progression towards further pharmaceutical applications. Herein, we present a biocompatible theranostic platform enabling simultaneous diagnosis and drug delivery consisting of UCNPs encapsulated with cellulose acetate (CA), a biocompatible polymer. Luminescence properties of UCNPs in the developed theranostic platform remain stable even after encapsulation. The size of the CA capsules, ranging from micro- to nano-sized particles, can easily be tuned by adjusting the stirring rate during encapsulation. Doxorubicin, a well-known chemotherapeutic drug, onto the CA nanocapsules containing UCNPs (UCNP-CA nanocapsules) was loaded with up to ∼63 % efficiency and acid-induced release (∼47 %) obtained at pH 3.6 and 5.5. It was found that encapsulation decreased toxicity of UCNPs as confirmed in a cellular assay (L-929 and MCF-7 cell lines). Taken together, the developed UCNP-CA nanocapsules serve as a highly interesting novel theranostic platform, combining the biocompatible optical properties of UCNP, with reduced cell toxicity and drug encapsulating properties of CA. The proposed system could be subject for further refinement and exploration.

A mutation in C. neoformans mitochondrial NADH dehydrogenase results in increased virulence in mice

ABSTRACT Cryptococcus neoformans: (H99W) was serially passaged in the invertebrate wax moth Galleria mellonella fifteen times to study how fungal virulence evolves under selection and whether those adaptations affect virulence. The G. mellonella passaged strain (P15) and the pre-passage H99W strains were used to infect three different host models of C. neoformans: C. elegans, G. mellonella, and Balb/c mice. While there was no difference in survival in the invertebrate models, P15 killed mice faster than H99W through both intratracheal and intravenous routes of infection and mice infected intravenously with P15 showed higher fungal burden in the brain. Characterization of the major virulence factors of C. neoformans found that P15 had increased capsule size, GXM release, and melanization. Whole genome sequencing of P15 and H99W revealed two mutations in P15, an insertion in the promoter region of NADH dehydrogenase (CNAG_09000) and an insertion in the LMP1 gene (CNAG_06765). Both ATP production and metabolic rate were higher in P15 compared to H99W. Quantitative RT-PCR suggested that the increased ATP was due to increased RNA levels of NADH dehydrogenase. Thus, adaptation to growth in hemocytes resulted in increased production of ATP, increased metabolic rate, and increased virulence in mice. This was likely due to differential expression of virulence factors, which skewed the host immune response to a less efficient Th2 response, with higher levels of IL-4, IL-10, and TNF-α in the brain. Overall, serial passage experiments have increased our understanding of how this yeast evolves under innate immune selection pressure.

Computational study of performance of cascaded multi-layered packed-bed thermal energy storage for high temperature applications

Continued effort towards decarbonizing the power sector has attracted enhanced research interest on the ideas revolving around different Coal-Concentrated Solar Power hybrid plant concepts. A few pre-feasibility studies indicate the importance of high-temperature (> 600 °C) latent heat packed-bed energy storage systems to ensure operational flexibility of the power plants, especially during the peak demand. In this study, a tractable and computationally fast numerical model comprising of two simplified non-equilibrium energy equations for the working fluid and the phase change material (PCM), respectively, is developed to account for the radiation effects at the high temperatures in the cascaded multi-layered packed bed latent heat thermal energy storage (PBLTS). The PBLTS is filled with spherical capsules of different diameters, containing PCMs having different melting temperatures, while air is chosen as the heat transfer fluid (HTF). The arrangement of different capsule diameters is found to affect the thermal performance of the storage significantly during the charging and discharging process. Equal bed heights with the capsule size arrangement of 10, 20, 30 mm from the inlet towards the oulet of the storage tank showed enhanced thermal performance during discharging operation. An aspect ratio between 4 and 4.5 leads to a better discharging performance of the storage, maintaining a stabilized high temperature at the storage outlet for a longer duration. It is found that the radiative heat transfer plays a significant role at high temperature (> 650 °C) in dictating the performance of the thermal energy storage system during the charging operation.