Capsule-like Structures Research Articles

One-pot biogenic synthesis of C. limon/TiO2 with dual applications as an advance photocatalyst and antimicrobial agent

The present study portrays a facile, cost-effective, and environmentally benign way for the preparation of TiO2 nanoparticles utilizing C. limon extract, which possesses phytochemicals as reducing and stabilizing agents. Structural characterization by XRD reveals that C. limon/TiO2 NPs exhibit anatase-type tetragonal crystallinity. An average crystallite-size is calculated using Debye Scherrer's method (3.79nm), Williamson-Hall plot (3.60nm), and Modified Debye Scherrer plot (3.68nm), which are very closely intercorrelated. The absorption peak at 274nm (UV-visible spectrum) corresponds to the bandgap (Eg) value of 3.8eV. The existence of different phytochemicals containing organic groups like N-H, C=O, and O-H, has been elucidated from FTIR along with Ti-O bond stretching at wavenumber 780cm-1. Micro-structural investigations of TiO2 NPs using FESEM and TEM display different geometrical configurations involving spherical, pentagonal, hexagonal, heptagonal and capsule-like structures. BET and BJH analysis show mesoporous characteristics of synthesized nanoparticles with specific surface-area (97.6m2g-1), pore-volume (0.018322cm3g-1), and mean pore-diameter (∼7.5nm) values. In adsorption studies, the influence of reaction parameters, i.e., catalyst dosage and contact-time, for removal of Reactive Green dye is explored along with Langmuir and Freundlich models. The highest adsorption capability is ∼219mgg-1 for green dye. TiO2 displays an excellent photocatalytic efficiency of ∼96% towards the degradation of reactive green dye within 180min and excellent reusable performance. C. limon/TiO2 is found to have an outstanding performance with a quantum yield value of 4.68×10-5 molecules photon-1 for Reactive Green dye degradation. Additionally, synthesized nanoparticles have exhibited antimicrobial activity against gram-positive Staphylococcus aureus (S. aureus) and gram-negative Pseudomonas aeruginosa (P. aeruginosa) bacteria.

The impact of osmotic stresses on the biofilm formation, immunodetection, and morphology of Aeromonas hydrophila

Aeromonas hydrophila (Ah) is a zoonotic pathogen of great importance to aquaculture and human health. This study systematically evaluated the impact of salinity, sugar, ammonia nitrogen, and nitric nitrogen levels on the fitness of Ah by using Luria-Bertani (LB) broth supplemented with different concentrations of NaCl, sucrose, NH4Cl, urea, NaNO2 or NaNO3. Results showed that the static biofilm formation of Ah was higher at 28°C compared to 37°C (P<0.05). At 28°C, as the NaCl (>1 %) and sucrose levels increased, the Ah biofilm formation and the binding between Ah cells and monoclonal antibodies (mAbs, for immunodetection) decreased. Elevated ammonia nitrogen and nitric nitrogen levels generated no significant impact on Ah biofilm formation or immunodetection (P>0.05). The expression of mAbs-targeted Omp remained unchanged under high NaCl or sucrose conditions. Further analysis showed that high sucrose conditions led to the over-expression of the extracellular polysaccharides (PS) and promoted the formation of capsule-like structures. These over-expressed PS and capsule structures might be one reason explaining the inhibited immunodetection efficacy. Results generated from this study provide crucial insights for the design of recovery and detection protocols for Ah present in food or environmental samples.

Numerical investigation of the thermal protection mechanisms of phase change capsules with orderly stacked layouts applied to pulse power sources in deep wells

<p indent="0mm">Currently, the reliance of oil and gas consumption on imported resources in China is indicative of a serious energy supply concern. The mainland of China has been found to contain abundant medium- and low-maturity shale oil resources that represent substantial exploitable reserves of energy supply. The exploitation of medium- and low-maturity shale oil resources, which are comparable to conventional oil and gas resources, can alleviate the problem of energy import dependence. However, low-maturity shale oil resources are mainly enriched in the deep crust, with temperatures reaching 150°C at a 2-km depth. This high-temperature environment might severely limit the operation of electronic equipment. This paper focuses on the thermal protection of pulsed power source equipment in the harsh thermal environment of deep wells. The performance of phase change materials (PCMs) with capsule-like structures having various orderly stacked orientations is numerically investigated. By calculating the inner wall temperature and heat flow, the influence of phase change capsule size and stacked layout on the thermal protection efficiency is analyzed, and the evaluation criteria considering the heat flux density as well as the prediction model for the inner wall temperature are proposed. The results show that the case of phase change microcapsule-glass wool composite structures exhibits improved thermal protection performance, with the inner wall temperature rising rate reduced by 13.8% and 2.35% compared to the case of the glass wool material and microcapsule, respectively. However, the small packed volume of PCMs in the microcapsules restricts further improvement of the thermal insulation. Consequently, PCM capsules of larger size are applied, increasing the PCM proportion and natural formation of closed porous material. Compared to the case of microcapsule-glass wool composite structures, for the case of larger PCM capsules, the temperature at the inner wall is further reduced by 19.3%, and the total heat flow during heating is reduced by <sc>373.7 W/m².</sc> By changing the stacked structure of the capsules, the case of single-layer orientation with large-scale PCM capsules illustrates the best thermal protection performance. The temperature rise rate during the heating period decreases by 1.25% and 5.84% compared to that of the staggered and double stacking structures, respectively, and the total inflow heat flux is also 1.09% and 4.19% lower compared to that of the staggered and double stacking structures, respectively. Based on the results, the prediction model for the inner wall temperature is proposed when applying the single-layer stacked PCM capsules. Note that the average deviation between the prediction model and numerical simulations is &lt; 7%. The maximum temperature difference can be controlled to within ±6°C during 84% of the operating time.

Extracellular fibrinogen-binding protein (Efb), a key immune evasion protein of Staphylococcus aureus and a potential therapeutic target

Due to the continued growth of antibiotic-resistant Staphylococcus aureus strains, it is necessary to explore alternative targets for future therapeutic applications. For this reason, is important to understand the staphylococcal immune evasion mechanisms with a special focus on extracellular fibrinogen-binding protein (Efb) and Efb related proteins. Therefore, it was conducted a literature review to compile relevant information on this protein. It was found that Efb has three binding sites with biological relevance that could be used as therapeutic targets with specificity for fibrinogen, platelets, and complements. First, the fibrinogen-binding motifs also found in coagulase block neutrophil αMβ2 adherence to fibrinogen and attract fibrinogen to the bacterial surface, forming capsule-like structures that block phagocytosis. Second, Efb is a potent anti-thrombotic agent, probably related to its P-selectin binding capacity. Efb P-selectin binding blocks the interaction of P-selectin with the PSGL-1 receptor, thereby impairs the mechanisms of platelet-mediated leukocyte recruitment to the site of vascular injury. Third, the Efb complement binding domain, also found in other staphylococcal complement inhibitory proteins like Ecb, Sbi, and SCIN, is responsible for the evasion of the complement-mediated immune response. Efb reduces the formation of C3 convertase and the interaction with neutrophils, affect B-cells activation, and maturation. Efb binding sites have a clear implication on the virulence of Staphylococcus aureus in mastitis, wound infection, staphylococcal pneumonia, and infections related to implanted devices, and contributes to staphylococcal persistence in host tissues and abscess formation in the kidneys. Given the biological relevance of Efb binding sites in staphylococcal infections, they are promising vaccine targets. Additionally, due to the inhibitory effect of Efb on platelets and complements, Efb can be a potential therapeutic agent to treat diseases associated with thrombosis and abnormal complement activity.

Newly characterized bovine mammary stromal region with epithelial properties supports representative epithelial outgrowth development from transplanted stem cells.

Limited outgrowth development of bovine mammary epithelial stem cells transplanted into de-epithelialized mouse fat pads restricts advanced studies on this productive organ's development and renewal. We challenged the mouse-bovine incompatibility by implanting parenchymal adjacent or distant bovine stromal layers (close and far stroma, respectively) into the mouse fat pad to serve as an endogenous niche for transplanted stem cells. The close stroma better supported stem cell take rate and outgrowth development. The diameter of these open duct-like structures represented and occasionally exceeded that of the endogenous ducts and appeared 8.3-fold wider than the capsule-like structures developed in the mouse fat pad after similar cell transplantation. RNA-Seq revealed lower complement activity in this layer, associated with secretion of specific laminins and WNT proteins favoring epithelial outgrowth development. The close stroma appeared genetically more similar to the parenchyma than to the far stroma due to epithelial characteristics, mainly of fibroblasts, including expression of epithelial markers, milk protein genes, and functional mammary claudins. Gene markers and activators of the mesenchymal-to-epithelial transition were highly enriched in the epithelial gene cluster and may contribute to the acquired epithelial properties of this stromal layer.

Microstructural Analysis of Whey/Soy Protein Isolate Mixed Gels Using Confocal Raman Microscopy.

This work explores the potential of confocal Raman microscopy to investigate the microstructure of mixed protein gel systems. Heat-set protein gels were prepared using whey protein isolate (WPI), soy protein isolate (SPI), and mixtures thereof, with a total of five different whey-to-soy protein ratios (100, 75, 50, 25, and 0%). These were analysed using confocal Raman microscopy, and different data analysis approaches were used to maximize the amount of structural and compositional information extracted from the spectral datasets generated, including both univariate and multivariate analysis methods. Small spectral differences were found between pure WPI and SPI gels, mainly attributed to conformational differences (amide bands), but SPI exhibited considerably greater auto-fluorescence than WPI. The univariate analysis method allowed for a rapid microstructural analysis, successfully mapping the distribution of protein and water in the gels. The greater fluorescence of the capsule-like structures found in the mixed gels, compared to other regions rich in proteins, suggested that these may be enriched in soy proteins. Further analysis, using a multivariate approach, allowed us to distinguish proteins with different levels of hydration within the gels and to detect non-proteinaceous compounds. Raman microscopy proved to be particularly useful to detect the presence of residual lipids in protein gels.

Responses to Ecopollutants and Pathogenization Risks of Saprotrophic Rhodococcus Species.

Under conditions of increasing environmental pollution, true saprophytes are capable of changing their survival strategies and demonstrating certain pathogenicity factors. Actinobacteria of the genus Rhodococcus, typical soil and aquatic biotope inhabitants, are characterized by high ecological plasticity and a wide range of oxidized organic substrates, including hydrocarbons and their derivatives. Their cell adaptations, such as the ability of adhering and colonizing surfaces, a complex life cycle, formation of resting cells and capsule-like structures, diauxotrophy, and a rigid cell wall, developed against the negative effects of anthropogenic pollutants are discussed and the risks of possible pathogenization of free-living saprotrophic Rhodococcus species are proposed. Due to universal adaptation features, Rhodococcus species are among the candidates, if further anthropogenic pressure increases, to move into the group of potentially pathogenic organisms with “unprofessional” parasitism, and to join an expanding list of infectious agents as facultative or occasional parasites.

Stimuli-Responsive Proteinosomes Based on Biohybrid Shell Cross-Linked Micelles

A new method of stimuli-responsive proteinosome fabrication with the shell cross-linked micelle as a template is reported in this research. A thermoresponsive diblock copolymer poly[di(ethylene glycol) methyl ether methacrylate]-b-poly[poly(ethylene glycol) methyl ether methacrylate-co-pyridyl disulfide methacrylamide] [PDEGMA-b-P(PEGMA-co-PDSMA)] was synthesized and self-assembled into micelles with PDEGMA cores and P(PEGMA-co-PDSMA) shells at the temperature above its lower critical solution temperature (LCST). Reduced bovine serum albumin (BSA) molecules with six thiol groups were used to cross-link the shells of the micelles by reacting with the pendant pyridyl disulfide groups on the P(PEGMA-co-PDSMA) block. At a temperature below the LCST of the polymer, the PDEGMA cores were dissolved in water, affording proteinosomes with a size of about 50 nm and capsule-like structures. The proteinosome was also thermoresponsive with a phase transition temperature at 35 °C. The fabrication of the proteinosome had no obvious influence on the structure and activity of BSA, and BSA retained most of its secondary structure and esterase-like activity. Because the BSA molecules were connected to the polymer chains through disulfide bonds, they could be released upon addition of dithiothreitol. The in vitro cell viability evaluation and the cellular uptake assay demonstrated that the proteinosome showed low toxicity to NIH 3T3 and 4T1 cells and could be internalized into the 4T1 cells.

Spectroscopic Study of the Interaction of Carboxyl-Modified Gold Nanoparticles with Liposomes of Different Chain Lengths and Controlled Drug Release by Layer-by-Layer Technology.

In this article, we investigate the interactions of carboxyl-modified gold nanoparticles (AuC) with zwitterionic phospholipid liposomes of different chain lengths using a well-known membrane probe PRODAN by steady-state and time-resolved spectroscopy. We use three zwitterionic lipids, namely, dipalmitoylphosphatidylcholine (DPPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), which are widely different in their phase transition temperatures to form liposome-AuC assemblies. The steady-state and time-resolved studies indicate that the AuC brings in stability toward liposomes by local gelation. We observe that the bound AuC detach from the surface of the liposomes under pH ≈ 5 due to protonation of the carboxyl group, thus eliminating the electrostatic interaction between nanoparticles and head groups of liposomes. The detachment rate of AuC from the liposome-AuC assemblies is different for the aforementioned liposomes due to differences in their fluidity. We exploited the phenomena for the controlled release of a prominent anticancer drug Doxorubicin (DOX) under acidic conditions for different zwitterionic liposomes. The drug release rate was further optimized by coating of liposome-AuC assemblies with oppositely charged polymer (P), polydiallyldimethylammonium chloride, followed by a mixture of lipids L (DMPC:DMPG) and again with a polymer in a layer-by-layer fashion to obtain capsule-like structures. This system is highly stable for weeks, as confirmed by field-emission scanning electron microscopy (FE-SEM) and confocal laser scanning microscopy (CLSM) imaging, and inhibits premature release. The layer coating was confirmed by hydrodynamic size and zeta potential measurements of the systems. The capsules obtained are of immense importance as they can control release of the drug from the systems to a large extent.

Nano-structured polymeric microparticles produced via cationic aerosol photopolymerization

Abstract Microparticles with non-full structures are interesting in many applications. In their production, however, issues related to purification are common. To overcome these issues, in this study a continuous polymerization process was developed in order to obtain powdered, nano-structured microparticles using neither surfactants nor a liquid medium. More specifically, a photo-induced cationic polymerization in aerosol was applied. A monomer solution was sprayed and irradiated with UV-light. During the reactor passage, both polymerization and phase separation occurred inside the single droplet. By adjusting the solvents amounts and ratios, different structures could be realized. Nano-structured particles with tunable pore shapes and dimensions were obtained. Capsule-like structures were obtained with the addition of a co-solvent able to get involved in the polymerization. An active ingredient was encapsulated within the particles. Results showed that the addition of the active ingredient did not affect the synthesis; furthermore, the particles structure had an impact on the release kinetics.

ChemInform Abstract: Protein Cages and Synthetic Polymers: A Fruitful Symbiosis for Drug Delivery Applications, Bionanotechnology and Materials Science

AbstractReview: 401 refs.

L-form transformation phenomenon in Mycobacterium tuberculosis associated with drug tolerance to ethambutol

Cell wall-deficient bacterial forms (L-forms) may occur along with resistance to factors that trigger their appearance. It is of interest to study the relationship between the L-form transformation of Mycobacterium tuberculosis and the exhibition of drug tolerance to ethambutol (EMB), an inhibitor of cell wall synthesis. L-form variant was produced from a sensitive EMB strain of M. tuberculosis through a cryogenic stress treatment protocol and was subsequently cultivated in Middlebrook 7H9 semisolid medium, containing EMB in a minimal inhibitory concentration of 2mg/L. Susceptibility to EMB of the parental strain and its L-form variant was evaluated phenotypically and using polymerase chain reaction-restriction fragment length polymorphism assay targeting a mutation in the embB306 gene fragment. In contrast to the sensitivity to EMB of the parental strain, its L-form variant showed phenotypic resistance to high concentrations of EMB (16mg/L), but the mutation in embB306 was not found. Electron microscopy observation of the L-form variant showed a heterogenic population of bacteria, with different degrees of cell wall deficiency, as well as cells of protoplastic type without cell walls. Of special interest were the observed capsule-like structures around the L-form cells and the biofilm-like matrix produced by the L-form population. We suggest that the expression of phenotypic resistance to EMB in M. tuberculosis can be associated with alterations or loss of cell walls in L-form bacteria, respectively, which results in a lack of a specific target for EMB action. In addition, production of capsule-like structures and biofilm matrix by L-forms could contribute to their resistance and survival in the presence of antibacterial agents.

Amorphous silicoboron carbonitride monoliths resistant to flowing air up to 1800 °C

Abstract The oxidation resistance of amorphous Si B C N monolith was investigated at 1500–1800 °C. The oxide products are amorphous SiO2 and cristobalite underlying amorphous oxide scale. The release of gases including CO, CO2, N2 and evaporation of B2O3 result in formation of bubbles and loose, porous oxide scale at 1600 °C. Si B C N monolith exhibits oxidation resistance superior to SiC and Si3N4 above 1600 °C, and retains significant resistance to oxidation up to 1800 °C. The formation of dense, passivating surface layers of N-containing amorphous SiO2, the ternary chemical bonds and capsule-like structures are primarily responsible for the oxidation resistance.

Fabrication and microstructures of functional gradient SiBCN–Nb composite by hot pressing

Abstract A functional gradient material with five layers composed of SiBCN ceramic and niobium (Nb) was prepared successfully by hot pressing. The phase composition, morphology features and microstructures were investigated in each layer of the gradient material. The Nb-containing compounds involving NbC, Nb6C5, Nb4C3, Nb5Si3 and NbN increase with the volume fraction of Nb increasing in the sub-layer. They are randomly scattered (≤ 25 vol.% Nb), then strip-like, and finally distribute continuously (≥ 75 vol.% Nb). The size of BN(C) and SiC grains in Nb-containing layers is larger than in 100% SiBCN layer due to the loss of the capsule-like structures. No distinct interfaces form in the transition regions indicating the gradual changes in phase composition and microstructures.

Oncolytic adenovirus targeting cyclin E overexpression repressed tumor growth in syngeneic immunocompetent mice.

BackgroundClinical trials have indicated that preclinical results obtained with human tumor xenografts in mouse models may overstate the potential of adenovirus (Ad)-mediated oncolytic therapies. We have previously demonstrated that the replication of human Ads depends on cyclin E dysregulation or overexpression in cancer cells. ED-1 cell derived from mouse lung adenocarcinomas triggered by transgenic overexpression of human cyclin E may be applied to investigate the antitumor efficacy of oncolytic Ads.MethodsAd-cycE was used to target cyclin E overexpression in ED-1 cells and repress tumor growth in a syngeneic mouse model for investigation of oncolytic virotherapies.ResultsMurine ED-1 cells were permissive for human Ad replication and Ad-cycE repressed ED-1 tumor growth in immunocompetent FVB mice. ED-1 cells destroyed by oncolytic Ads in tumors were encircled in capsule-like structures, while cells outside the capsules were not infected and survived the treatment.ConclusionAd-cycE can target cyclin E overexpression in cancer cells and repress tumor growth in syngeneic mouse models. The capsule structures formed after Ad intratumoral injection may prevent viral particles from spreading to the entire tumor.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1731-x) contains supplementary material, which is available to authorized users.

Growth of crystalline silicon nanotubes under hydrothermal condition

Abstract Silicon nanotubes (SiNTs) were prepared from silicon monoxide using a hydrothermal method without solid templates. The structure of the products was investigated by transmission electron microscopy, which showed that SiNTs had diamond cubic crystalline structures and capsule-like structures at the tip of them. It was speculated that several hundred nanometer-sized water droplets condensed in the vessel acted as cores for the growth of SiNTs.

Development of novel ultrathin structures based in amaranth (Amaranthus hypochondriacus) protein isolate through electrospinning

Abstract Amaranth protein isolate (API) ultrathin structures have been developed using the electrospinning technique. The effects of pH, type of solvent and surfactant addition on the spinnability, morphology and molecular organization of the obtained structures have been studied. Regarding the effect of pH on API electrospinning, capsule morphologies were only obtained at extreme pH values (i.e. pH 2 and pH 12), which allowed the solubilisation of the proteins, and the process was favoured when the solutions were previously heated to induce protein denaturation. Fibre-like morphologies were only obtained when the solvent used for electrospinning was hexafluoro-2-propanol, as this organic solvent promotes the formation of random coil structures and, thus, an increase in the biopolymer entanglements. Capsule morphologies were obtained from the API-containing formic acid solutions and this solvent was better for electrospraying than the acetic acid, probably due to the higher viscosity and lower surface tension of the solutions thereof. Addition of 20 wt.% of Tween 80 considerably improved the formation of capsule-like structures from the formic acid solution, as this surfactant contributed to the formation of alpha helical structures. Similar results were obtained when combining the surfactant with the reducing agent 2-mercaptoethanol. However, denaturation of the protein structure was not sufficient for fibre formation through electrospinning, as the solution properties play a fundamental role in determining the morphology of the electrospun structures.

A novel lanthanum hydroxide nanostructure prepared by cathodic electrodeposition

A novel and interesting nanostructure of La(OH)3 was prepared by electrochemical method under mild conditions without any hard templates and surfactants. In this method, La(OH)3 was galvanostatically deposited from low-temperature nitrate bath on the steel substrate by electrogeneration of base. X-ray results showed that the obtained deposit has single crystalline hexagonal phase of La(OH)3. Morphological characterization revealed that the product has compact morphology with capsule-like structures having approximately an average diameter of 15 nm and the length of up to 50 nm. The results showed that low-temperature cathodic electrodeposition can be recognized as an easy and facile method for the synthesis of La(OH)3 nanocapsules.

La2O3 Nanoplates Prepared by Heat-Treatment of Electrochemically Grown La(OH)3 Nanocapsules from Nitrate Medium

Cathodic electrodeposition of La(OH)3 was successfully carried out from low-temperature nitrate bath at current density of 1 mA cm−2 without any templates and surfactants. To obtain oxide product, the prepared hydroxide sample heat treated at 700°C for 2 hours in dry air atmosphere. The XRD results showed that the obtained hydroxide and oxide samples have hexagonal phase of La(OH)3 and pure single crystalline of La2O3, respectively. Mechanism of La(OH)3 deposition from nitrate bath at the applied conditions was proposed. CHN and FT-IR analyses showed that nitrate intercalation in the deposit during the electrodeposition process and confirmed the proposed mechanism. Morphological characterization revealed that La(OH)3 has compact morphology with capsule-like structures having approximately an average diameter of 15 nm and the length of up to 50 nm. After heat treatment, formation of plate-like structures of La2O3 with different size at nanoscale was confirmed by SEM and TEM. Mechanism of La(OH)3 cathodic deposition from nitrate bath, and the Mechanism of La(OH)3 nanocapsules formation and growth and their conversation to La2O3 nanoplates during the heat treatment have been proposed and discussed.

Characteristics, morphology, and stabilization mechanism of PAA250K-stabilized bimetal nanoparticles

Injection of bimetal (Pd/Fe) nanoparticles was evidenced as a promising treatment to remediate trichloroethene (TCE) polluted groundwater. However, the particles usually aggregate rapidly and result in a very limited migration distance. This study employed poly acrylic acid (PAA) for the synthesis of stable bimetal nanoparticles (SBN) by selecting appropriate PAA molecular weight and dosage to reduce particle aggregation. In addition, this study elucidated the SBN stabilization mechanism by analyzing morphology and characteristics. The results of TCE dechlorination and SBN stabilization experiments indicate that the bimetal nanoparticles modified with PAA250K exhibit better reactivity and stability characteristics than did other such nanoparticles. The SBN bind chemically onto PAA250K via the carboxylic group and bidentate pattern bridging, which could provide both electrostatic and steric repulsion to prevent particle aggregation. Therefore, the SBN exhibited a higher dechlorination effect than did bare bimetal. The morphology of SBN shown in the transmission electron microscopy (TEM) images exhibits capsule-like and wire-like structures instead of a single particle dispersed in the slurry. The results of this work can preliminarily elucidate the SBN's morphology, dispersion, and size distribution.