Formation Of Microspheres Research Articles

Effects of a pressurized water treatment on internal gelation sol–gel microspheres

Based on previous observations that a pressurized water treatment (PWT) prevented cracking of sol–gel microspheres, we investigated the effects of a PWT on microsphere crystallinity, density, and specific surface area (SSA). Results were used to determine how a PWT alters the properties of microspheres upon drying and heating. Microspheres with diameters near 100–200 µm were prepared with and without a PWT and measured using x-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption (BET), and pycnometry. Properties of air-dried microspheres processed with and without a PWT are compared. In addition, the properties of microspheres processed using a PWT are reported after heating to 150, 450, 750, 1050, and 1350 °C. XRD measurements indicate that the PWT step improves the crystallinity of air-dried microspheres. XRD data were also used to calculate crystallite size, which increases with higher heat-treatment temperatures. TEM images support crystallite size calculations from XRD data and provide an indication of the range of crystallite sizes, particularly for samples processed at higher temperatures where crystallite sizes are too large for estimation using the Scherrer formula. Density and SSA measurements performed as a function of heat-treatment temperature indicate that a PWT increases the density of air-dried microspheres, creates a pore network, and that significant densification occurs between 450 and 750 °C. These results may be used to inform decisions on internal gelation flowsheet parameters to optimize the microsphere formation and gelation step, prevent microsphere cracking, and produce microspheres suitable for subsequent coating operations or pressing into pellets.

Development of Budesonide Oral Colon Specific Drug Delivery System using Interpolymer Complexation Method

Abstract: Background: Oral bioavailability of Budesonide is 10% due to its extensive first pass metabolism, its high volume of distribution and 85-90% of protein binding. Protection of drug release in stomach and targeting drug to colon which is an absorption site of drug is an attempt to improve therapeutic efficacy. The objective of this study was to develop interpolymer complex microspheres of Budesonide for oral colon specific drug delivery. Methods: Emulsion solvent evaporation method was used in the preparation of microspheres. Microspheres prepared at different polymer ratio and surfactant concentration were analysed for its mean particle size, surface morphology, flow property, drug release, % encapsulation efficiency. Results: Microspheres prepared with 3:5 polymer ratios F4 was optimized with respect to its % EE, in vitro drug release and percentage yield. Drug release from formulated tablets containing microspheres of 3:5 polymer ratios showed an extended release up to 12 h in pH buffer 7.4. Interpolymer complexation was confirmed by FT-IR studies, compatibility of drug with excipients by DSC indicated no significant changes with drug. SEM studies revealed formation of round microspheres with pervious and uneven surface. In vitro release data from microspheres was analysed by kinetic model fitting for mechanism of drug release. Microspheres showed 5-10% of drug release in pH 1.2 which was further prevented by formulating coated tablets of microspheres using cellulose acetate phthalate. Conclusion: Targeted colon specific drug delivery of Budenoside with extended release up to 12 h was successfully achieved by formulation of tablets containing microspheres prepared by interpolymer complexation technique. Key words: Budesonide, Colon Specific Delivery, Interpolymer Complexation, Microspheres, Cellulose Acetate phthalate.

Preparation of NiCo2O4 microspheres employing hydrothermal approach

In this study, nickel cobalt oxide (NiCo2O4) microspheres were prepared by using facile hydrothermal route. The structural confirmation of bimetal oxide formation was acquired by X-ray powder diffraction and Raman studies. The formation of microspheres combined via irregular nanosheets was confirmed by scanning electron microscopy. Highly oriented NiCo2O4 microspheres yielded a high current density (258 mA/g) at 10 mV/s and low overpotential (224 V). The highly active electrode showed efficient electron transportation towards oxygen evolution reaction. Long-term stability over 16 h was achieved by the fabricated high-performance NiCo2O4 electrode. It is recommended that NiCo2O4 microspheres obtained from 3:1 stoichiometry ratio of Ni and Co would lead to new electrocatalysts that give best performance than expensive catalysts used currently in the water oxidation process.

Amphiphilic Peptide P15-encapsulated paclitaxel and analysis of its in vitro antitumor activity

Amphiphilic polypeptide P15 (YIGSRHHHLLLGFLG) was designed and synthesized for the encapsulation of paclitaxel to prepare targeted nano-microspheres (P15-PTX). The self-assembly behavior and drug-loading effect of P15-PTX in aqueous solution were investigated. The micelle-forming ability and in vitro antitumor activity of P15-PTX were also studied. The results showed that the mixing of P15 and PTX at an optimal ratio of 6:1 resulted in the formation of microspheres with regular rounded morphology, small particle size, high drug-loading rate, good drug release effect, high cell inhibition rate, enhanced antitumor activity, and a certain dose–response relationship with the P15-PTX concentration. At a P15-PTX concentration of 400 μg/mL, the proliferation inhibition rate of MCF-7 cells was 70%. The microsphere designed and prepared in this study is expected to provide a targeted drug delivery system with good application prospects for the treatment of tumor cells.

Dry fabrication of poly(dl-lactide-co-glycolide) microspheres incorporating a medium molecular drug by a ball mill method.

Poly(dl-lactide-co-glycolide) acid (PLGA) microspheres is a useful carrier for controlled drug release. However, the organic solvents used in their conventional manufacturing process may affect the chemical structure of a macromolecular drug. Thus, we investigated the applicability of a dry fabrication method for PLGA microspheres. Cyanocobalamin (MW = 1,355) (VB12) was used as a model drug, and it formed agglomerates under mild conditions with powdered PLGA in a generic ball milling system. Light and scanning electron microscopy showed the formation of PLGA microspheres and few agglomerates. The obtained microspheres had the particle size injectable as suspensions, namely smaller than 150 μm specified for subcutaneous and intramuscular injections by the Japanese Pharmacopoeia. The observed and theoretical drug contents were consistent. PLGA microspheres fabricated using a combination of small (ϕ3 mm) and large (ϕ10 mm) balls showed low initial burst of cyanocobalamin release in vitro. The in vitro drug release profile was equivalent with that of the microspheres fabricated by a conventional oil-in-water emulsion solvent evaporation method, while the drug release profile was influenced by the brand of the PLGA used. To prevent drug loss during fabrication, the dry fabrication method using a ball mill should be applied to prepare PLGA microspheres containing a medium macromolecular drug.

Design and Evaluation of Long Acting Biodegradable PLGA Microspheres for Ocular Drug Delivery

Background:: The research work involves the development of PLGA biodegradable microspheres loaded with dexamethasone for intraocular delivery. Objective:: The study aimed to design and evaluate long acting PLGA microspheres for ocular delivery of dexamethasone. Methods:: The present formulation involves the development of long-acting dexamethasone loaded microspheres composed of a biodegradable controlled release polymer, Poly(D,L-lactide-coglycolide) (PLGA), for the treatment of posterior segment eye disorders intravitreally. PLGA with a monomer ratio of 50:50 of lactic acid to glycolic acid was used to achieve a drug release for up to 45 days. Quality by Design approach was utilized for designing the experiments. Single emulsion solvent evaporation technique along with high-pressure homogenization was used to facilitate the formation of microspheres. Results:: Particle size evaluation, drug content and drug entrapment efficiency were determined for the microspheres. Particle size and morphology were observed using Field Emission Gun- Scanning Electron Microscopy (FEG-SEM) and microspheres were in the size range of 1-5 μm. Assessment of drug release was done using in vitro studies and trans retinal permeation was observed by ex vivo studies using goat retinal tissues. Conclusion:: Considering the dire need for prolonged therapeutic effect on diseases of the posterior eye, an intravitreal long-acting formulation was designed. The use of biodegradable polymer with biocompatible degradation products was a rational approach to achieve this aim. The outcome of the present research shows that developed microspheres would provide a long-acting drug profile and reduce the frequency of administration thereby improving patient compliance.

Green and facile synthesis of hierarchical ZnOHF microspheres for rapid and selective adsorption of cationic dyes

Employing DL-Alanine (DL-Ala) as the structure-directing agent, hierarchical microspheres of ZnOHF have been designed with optimized geometric features in a facile one-step hydrothermal approach. Morphological characterizations demonstrated that the obtained hierarchical microspheres were formed by numerous nanotubes with outer diameter of 10 nm and wall thickness about 3.5 nm. A series of controllable experiments proved that DL-Ala and reaction time played vital roles in the formation of nanotubes-assembled hierarchical microspheres. By taking advantage of the optimized geometric features and large specific surface areas (271.06 m2/g), the obtained ZnOHF nanotubes-assembled microspheres were evaluated as adsorbents for the removal of various dyes in aqueous solution. Adsorption behavior conducted by batch mode experiments indicated that the adsorption was well described by Langmuir isotherm and pseudo-second-order model. The obtained hierarchical ZnOHF microspheres exhibited effective adsorption and selectively properties towards cationic dyes. For example, the maximum adsorption capacity of ZnOHF microspheres was 140.4 mg/g for malachite green (MG) at 298 K. Analysis of thermodynamic data suggested that it was an endothermic and spontaneous physical adsorption process. The fabrication strategy may provide new insights for designing other high-performance materials, and the novel hierarchical ZnOHF microspheres are promising adsorbents for wastewater purification.

Synthesis and Characterization of Various Doped TiO2 Nanocrystals for Dye-Sensitized Solar Cells.

Few works are reported on solvothermal preparation of nanoparticles by utilizing acetone alone without a surfactant. This synthesis approach is found to be prominent for producing the mesoporous structure, which is crucial in improving the dye loading of the photoanode. In addition, doping of metal ions is advantageous in order to bring down the excitation energy, which is promising for boosting the performance of the doped oxides. This research aims to synthesize various kinds of doped-TiO2 nanocrystals to serve as photoanode materials in dye-sensitized solar cells (DSSCs). An X-ray diffraction study evidenced the existence of the crystalline phase in pure and doped-TiO2 nanocrystals. Rietveld refinement study showed the mixed phases of crystalline TiO2 in the CrT, CuNT, and ST as compared to a single anatase phase in the samples PT, AgT, BT, CoT, FeT, SnT, ZT, VT, and ZMT. The absorption spectroscopy analysis demonstrated the reduced optical band gap from 3.10 to 2.79 eV. Scanning electron microscopy investigation endorsed the formation of TiO2 mesoporous microspheres with a mean diameter ranging from 200 to 331 nm along with a nanocrystal diameter ranging from 10 to 20 nm. Doping with the different dopants enhanced the conversion efficiency of DSSCs from 1.31 to ∼6%. Furthermore, we have performed the electrochemical impedance spectroscopy of DSSCs, and the findings are presented.

Hydrothermal carbonization of spent mushroom substrate: Physicochemical characterization, combustion behavior, kinetic and thermodynamic study

Hydrothermal carbonization (HTC) was employed for the conversion of the spent mushroom substrate (SMS) into a carbonaceous hydrochar. The effect of operating temperature (180, 200, 220, 240, and 260 °C) on the physicochemical, structural, and combustion properties of the obtained hydrochars was analyzed. The HTC treatment caused the increase of the higher heating value (HHV) and the lower heating value (LHV) of hydrochars for 58 % and 65 % in comparison with SMS, respectively. Analysis of morphology and functional groups showed the formation of microspheres and cracks on the hydrochar surface, which are predominantly dominated by aromatic and oxygen-rich functional groups. Thermal and kinetics analysis showed that HTC treatment improves the combustion behavior of the obtained solids. Combustion kinetic parameters of SMS and hydrochars were determined by the methods of Kissenger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The thermodynamic parameters and pre-exponential factors reveal a complex mechanism of SMS and hydrochars decomposition process.

Effect of surfactant concentration on the formation of Fe2O3@SiO2 NIR-reflective red pigments

High NIR-reflective red pigments were developed by encapsulating Fe2O3 particles in a transparent SiO2 shell layer to form Fe2O3@SiO2 core-shell structures. The pigments were prepared by a sol-gel process and the effect of CTAB surfactant concentration on structural formation and optical properties was investigated. The reaction between CTAB and silica species was found to increase the yield of SiO2 formation, which had a major role to control the SiO2 shell thickness by ranging from 8 to 62 nm when varying CTAB concentration from 0 to 2 mM. After encapsulation, Fe2O3@SiO2 pigments still had the red-brown hue of hematite and the NIR reflectivity improved to 62.7 %–65.3%, or twice that of the uncoated Fe2O3. The pigments prepared using the highest CTAB concertation changed from the original Fe2O3 color (CIE Lab color space coordinates) by only ΔE 8.2% due to the formation of second phase SiO2 microspheres formed from excess CTAB micelles. The NIR-reflective red Fe2O3@SiO2 pigments showed good chemical stability and light resistance, thus they were suitable for use as cool pigments for coating applications.

Synthesis of hollow spherical nickel oxide and its gas-sensing properties

Semiconductor metal oxides have attracted wide attention in the area of gas sensor due to that they have unique advantages in the rapid and accurate detection of harmful gases. A simple strategy is to synthesize porous NiO hollow microspheres via a simple hydrothermal method with trisodium citrate as structure guide agent is presented in this paper, and the shell of the microsphere is composed of porous and lamellar assembly units. The cavity proportion can be adjusted by changing the amount of trisodium citrate. A reasonable mechanism was proposed to explain the formation of porous NiO hollow microspheres. As a gas-sensing material, porous NiO hollow microspheres show excellent gas selectivity and rapid response recovery time for n-butyl alcohol gas. When the content of trisodium citrate was 0.10 g, the synthesized hollow sphere NiO had the highest response value (25.6) to 100 × 10–6 of n-butyl alcohol at 300 °C and the response and recovery times were only 68 and 10 s.

Effect of Accumulative Recycling of Aqueous Phase on the Properties of Hydrothermal Degradation of Dry Biomass and Bio-Crude Oil Formation

For hydrothermal liquefaction of dry biomass to produce liquid fuels, water needs to be added or the aqueous phase products can be recycled. This paper focuses on understanding the relationship between hydrothermal degradation of the dry biomass and oil formation under the condition of accumulative recycling of the aqueous phase. Completely dried corn stalk and deionized water were used for the hydrothermal liquefaction (HTL) experiment. The aqueous products for subsequent recycling were not diluted. It was demonstrated that the recycling of the aqueous can promote the enrichment of organic acids and the conversion of ketones and phenols in the aqueous, improving the yield and quality of Bio-crude oil. After recycling, the yield of Bio-crude oil increased from 20.42% to 24.31% continuously, and the oxygen content decreased from 13.34% to 9.90%. Although the process was accompanied by solid deposition and had a negative impact on the hydrothermal degradation efficiency, the formation of carbon microspheres during the deposition enhanced the utilization of nondegradable solids, while the formation of metal salt particles had a positive impact on oil production. After three rounds of recycling, the solid deposition effect was weakened. At this time, oil production and solids degradation can be promoted simultaneously.

Tert-butylamine/oleic acid-assisted morphology tailoring of hierarchical Bi4Ti3O12 architectures and their application for photodegradation of simulated dye wastewater

Herein we report the morphology tailoring of hierarchical Bi4Ti3O12 architectures by using tert-butylamine (TB) and oleic acid (OA). It is demonstrated that the content of TB and OA has an important effect on the morphologies of as-derived Bi4Ti3O12 samples. When adding 12 mmol TB and 6 mmol OA (with respect to 1 mmol Bi4Ti3O12) to the precursor solution, rod-like hierarchical architectures (length 2–15 μm, diameter 0.5–1.7 μm) are obtained. The hierarchical microrods are composed of nanosheets of 20–50 nm in thickness and 300–1700 nm in diameter. The addition of other amounts of TB and OA results in the formation of nanoflake-assembled hierarchical hollow microspheres with size of several micrometres; however the sizes of the microspheres and their sub-nanoflakes depend on the TB/OA amounts. Rhodamine B (RhB), methyl orange (MO) and methylene blue (MB) aqueous solutions, as well as RhB/MO/MB mixture solution (simulated dye wastewater), were used to evaluate the photodegradation performances of the as-prepared Bi4Ti3O12 samples under simulated sunlight irradiation. It is demonstrated that the nanosheet-assembled hierarchical microrods possess a photodegradation activity preponderating over the other morphologies. Moreover, the photocatalytic experiments reveal an interesting photodegradation process of RhB/MO/MB in the mixture solution, which is different from the photodegradation of single dye solution. The photodegradation mechanism of the Bi4Ti3O12 photocatalysts was investigated and discussed.

Targeted Inhibition of LPL/FABP4/CPT1 fatty acid metabolic axis can effectively prevent the progression of nonalcoholic steatohepatitis to liver cancer.

Rationale: Nonalcoholic steatohepatitis (NASH), as one of the key stages in the development of nonalcoholic fatty liver disease (NAFLD), can directly progress to HCC, but the underlying mechanism is not fully understood.Methods: Differentially expressed genes (DEGs) in each stage of disease development were studied through a GEO dataset deriving from a Stelic Animal Model (STAM), which can simulate the evolution of NAFLD/NASH to HCC in humans. GSVA analysis was performed to analyze the differentially expressed oncogenic signatures in each stage. A human NAFLD-related dataset from GEO database was utilized for gene expression verification and further validated in the protein level in STAM mice. Small molecule inhibitors were applied to STAM mice for investigating whether inhibition of the LPL/FABP4/CPT1 axis could prevent the occurrence of NASH-related HCC in vivo. Microsphere formation and clonal formation assays in vitro were applied to study if inhibition of the LPL/FABP4/CPT1 axis can reduce the viability of liver cancer stem cells (LCSCs).Results: We found that upregulation of the LPL/FABP4/CPT1 molecular axis, as a fatty acid metabolic reprogramming process, occurred specifically during the NASH phase. GSVA analysis showed widespread activation of a large number of oncogenic signals, which may contribute to malignant transformation during NASH. Furthermore, inhibition of the LPL/FABP4/CPT1 axis could effectively delay the tumor growth in STAM mice. Cell assays revealed inhibitors targeting this axis can significantly reduce the sphere-forming, proliferation, and clonality of LCSCs.Conclusion: These results suggest that activation of the LPL/FABP4/CPT1 axis is essential for LCSCs maintenance, which acts synergistically with a variety of up-regulated oncogenic signals that drive the hepatocyte-LCSCs transdifferentiation during NASH to HCC progression. Thus, targeting the LPL/FABP4/CPT1 axis may provide a potential direction for NASH-related HCC prevention.

Cationic peptidomimetics derived from CAP-18 cathelicidin shown activity in vitro against mycobacterium tuberculosis H37RA and synergy combined with isoniazid

Aims & objectives: Tuberculosis (TB) is the infectious disease that results in the largest number of deaths around the world caused by a bacterial infectious agent. According to the World Health Organization (WHO), there were 10 million new cases and 1.2 million deaths caused by TB in 2018. The problem increases due to drug resistance and HIV/AIDS coinfection, which is why it is necessary to develop new anti-TB compounds with different mechanisms of action. Antimicrobial peptides are molecules gener42ated in the innate immune response of the host with an effect on pathogens. This is the case of the cathelicidins present in mammals involved in the formation of channels in the bacterial cell membrane that leads to cell lysis. Methods: In this study, the antimycobacterial activity and the possible mechanism of action of peptides derived from CAP-18 with unnatural amino acids were evaluated. Using bioinformatic tools, the epitope of the native sequence with the best characteristics of helical structure, amphipathicity and antibacterial value was determined. The corresponding peptides, CAP18-B and CAP18-C, had changes from L-Lys to D-Lys and from L-Gly to N-methyl-Gly in the sequence, generating the peptides CAP18-BD, CAP18-CD and the peptoid CAP18-BP. Peptides and peptoids were synthesized using the Fmoc strategy, purified by RP-HPLC and characterized by ESI-MS, circular dichroism and H1 -NMR. The in vitro assesament of the designed sequences was carried out in Mycobacterium smegmatis mc2 155 and Results: Mycobacterium tuberculosis H37Ra, obtaining a minimum inhibitory concentration increase from 2 to 6 times in the ranges from 1200 to 60 μg/mL, less than 10% hemolytic activity and no cytotoxic activity on U937 monocytes with LC50 values at least 10 times higher than the MIC and synergy combined with isoniazid. Confocal microscopy showed the insertion of peptides and peptoids in Mycobacterium smegmatis mc2 155 and transmission electron microscopy showed alterations in the cell membrane of Mycobacterium smegmatis mc2 155 evidenced in the formation of blisters, microspheres, channels and cell lysis. Conclusions: The results suggest that analogous sequences derived from CAP-18 can be considered as potential antimycobacterial compounds.

Cross-linked polyelectrolyte microspheres: preparation and new insights into electro-surface properties.

Polyelectrolyte microspheres find applications in many fields such as ion exchange columns, fuel cell membranes, and catalysis, to name a few. Synthesis of these microspheres by inverse emulsion polymerization offers various advantages due to the increased specific surface area and high surface charge density. The surface charge density of the obtained polyelectrolyte microspheres is a hundred times higher than that of either particles obtained by dispersion copolymerization of styrene and styrenesulfonic acid or sulfonated microspheres. The morphology, chemical structure, and electro-surface properties of the synthesized microspheres were studied by transmission and scanning electron microscopy, FTIR-spectroscopy, and conductometric and potentiometric titrations, respectively. Using the potentiometric titration it is possible to characterize the structure of the surface layer of polyelectrolyte microspheres as entirely as possible. The study of the ion-exchange capacity of polyelectrolyte microspheres shows that ion-exchange capacity is 2.1 meq g-1 in this case, which is more than 2 times higher than that of sulfonated microspheres, and 20 times higher than that of particles obtained by dispersion copolymerization.

Formation of alginate microspheres prepared by optimized microfluidics parameters for high encapsulation of bioactive molecules

Drug delivery systems such as microspheres have shown potential in releasing biologicals effectively for tissue engineering applications. Microfluidic systems are especially attractive for generating microspheres as they produce microspheres of controlled-size and in low volumes, using micro-emulsion processes. However, the flow rate dependency on the encapsulation of molecules at a microscale is poorly understood. In particular, the flow rate and pressure parameters might influence the droplet formation and drug encapsulation efficiency. We evaluated the parameters within a two-reagent flow focusing microfluidic chip under continuous formation of hydrogel particles using a flourinated oil and an ionic crosslinkable alginate hydrogel. Fluorescein isothiocyanate-dextran sulfate (FITC-dextran sulfate MW: 40 kDa) was used to evaluate the variation of the encapsulation efficiency with the flow parameters, optimizing droplets and microsphere formation. The ideal flow rates allowing for maximum encapsulation efficiency, were utilised to form bioactive microspheres by delivering transforming growth factor beta-3 (TGFβ-3) in cell culture media. Finally, we evaluated the potential of microfluidic-formed microspheres to be included within biological environments. The biocompatibility of the microspheres was tested over 28 days using adult human mesenchymal stem cells (hMSCs). The release profile of the growth factors from microspheres showed a sustained release in media, after an initial burst, up to 30 days. The metabolic activity of the cells cultured in the presence of the microspheres was similar to controls, supporting the biocompatibility of this approach. The fine-tuned parameters for alginate hydrogel to form microspheres have potential in encapsulating and preserving functional structure of bioactive agents for future tissue engineering applications.

LINC00261/microRNA-550a-3p/SDPR axis affects the biological characteristics of breast cancer stem cells.

Long non-coding RNAs (lncRNAs) have been shown to play key roles in the pathogenesis of breast cancer (BC). The study was to explore the effect of long non-coding RNA LINC00261/microRNA (miR)-550a-3p/serum deprivation response (SDPR) axis on the biological characteristics of BC stem cells (BCSCs). BC and adjacent normal tissues of patients were collected. LINC00261, miR-550a-3p and SDPR expression in BC tissues and cell lines and CD24 and CD44 expression in BC tissues was detected. CD44+ /CD24-/low BCSCs were sorted. CD44+ /CD24-/low MDA-MB-231 and MCF-7 cells were screened and transfected with altered expression of LINC00261 or miR-550a-3p to explore their roles in cell viability, microsphere (MS) formation ability, migration and invasion of CD44+ /CD24-/low BCSCs. The targeting relationships of LINC00261, miR-550a-3p and SDPR were detected. Reduced LINC00261, decreased SDPR and elevated miR-550a-3p exhibited in BC tissues of patients and cell lines. Elevated CD44+/ CD24- were present in BC tissues. LINC00261 up-regulated SDPR expression as a sponge of miR-550a-3p. Elevated LINC00261 suppressed BC cell viability, MS formation ability, migration and invasion of CD44+ /CD24-/low BCSCs. Moreover, up-regulated miR-550a-3p reversed the inhibitive effect of elevated LINC00261 on BCSCs, and reduced SDPR reversed the promotive effect of decreased miR-550a-3p on BCSCs. The study highlights that LINC00261 can adsorb miR-550a-3p to modulate SDPR, thus inhibiting the viability and MS formation of BC cells, reducing migration and invasion of CD44+ /CD24-/low BCSCs, exerting a potential effect on therapy.

Bactericidal activity of Moringa oleifera leaf extract assisted green synthesis of hierarchical copper oxide microspheres against pathogenic bacterial strains

Hierarchical copper oxide (CuO) microspheres were prepared by Moringa oleifera (M. oleifera) leaf extract assisted green synthesis method. The structural, chemical, and morphological features of the hierarchical CuO microspheres were inspected by XRD, FTIR, SEM, and EDAX techniques. The XRD pattern unveiled the formation of monoclinic crystal structured CuO, which confirmed the conversion of Cu(NO3)2.3H2O to Cu2+ ions by phytochemicals present in the M. oleifera leaf extract. The SEM micrographs demonstrated that small CuO nanostructures have interacted with adjacent CuO nanostructures leading to the formation of cluster-like morphologies that resemble hierarchical CuO microspheres. The asymmetric stretching deformation vibration bands observed in the FTIR spectrum of the hierarchical CuO microspheres correspond to Cu–O bond along the (−2 0 2) direction that conveyed monoclinic unit crystal formation of the CuO. The detected Cu and O elements through the EDAX analysis reveal the pristine nature of the hierarchical CuO microspheres. The rich phytochemicals in the M. oleifera leaf extract played crucial roles towards the formation and stabilization of hierarchical CuO microspheres. The highest bactericidal activity was noticed against the Staphylococcus aureus strain with zone of inhibition (ZOI) of 30 and 32 mm for the hierarchical CuO microspheres dosage of 50 and 100 μL, respectively, followed by Klebsiella pneumoniae, Escherichia coli and Bacillus cereus strains. The better bactericidal activity observed against the selected bacterial strains could be credited to ideal interaction of the hierarchical CuO microspheres/small nanostructures with cell walls of the bacterial strains, favorable deliverance of copper ions inside the cells and subsequent production of reactive oxygen species.

Time-resolved investigation of mesoporous silica microsphere formation using in situ heating optical microscopy

A fundamental understanding of the drying behavior of droplets containing solids or solutes is important for various industrial applications. However, droplets are typically highly polydisperse and time-resolved imaging data of the process dynamics are often lacking, which makes it difficult to interpret the effects of different drying parameters. Here, the controlled drying of monodisperse emulsion droplets containing colloidal silica nanoparticles and their subsequent assembly into mesoporous silica microspheres (MSMs) is investigated using an optical microscope outfitted with a heating and vacuum stage. Quantitative imaging results on droplet shrinkage and observed contrast are compared with a theoretical mass-transfer model that is based on the droplet number density, solvent characteristics and temperature. The results presented here provide key insights in the time-resolved formation of MSMs and will enable an optimized direct synthesis of monodisperse MSMs for separation applications and beyond.