Search

AbstractGiant liposomes, or giant unilamellar vesicles (GUVs), have been utilized as cell-size bioreactors to replicate the physical and chemical properties of biological cells. However, conventional methods for preparing GUVs typically lack precise control over their size. Several research groups have recently developed microfluidic techniques to create monodisperse GUVs by generating water-in-oil-in-water (W/O/W) droplets with a thin oil layer that subsequently transform into GUVs. However, the formation of a thin oil shell requires the intricate control of the flow rate, which can be both challenging and unstable. In this study, we investigated the design of a two-step flow-focusing microfluidic channel to produce stable W/O/W droplets. These droplets underwent substantial oil layer reduction through spontaneous removal by fluidic shear forces. Consequently, the majority of the oil layer in the W/O/W droplets was reduced, improving uniformity of GUVs. [ABSTRACT FROM AUTHOR]

The rapid nucleic acid extraction is essential, particularly the communicable diseases pandemic. In this work, aluminum modified Fe3O4 (Fe3O4@Al3+) particles were successfully synthesized by solvthermal method, epoxidation, covalent binding of iminodiacetic acid and Al3+ ions coordination for DNA extraction. Fe3O4@Al3+ particles could greatly improve the efficiency of DNA extraction and the extraction could be totally completed within 15 minutes at the optimum condition. The simple and rapid method is mainly based on the Fe3O4@Al3+ particles, which have large specific surface area, superparamagnetism, and Al3+ ions affinity to DNA. Additionally, several characterizations were carried out to further investigate the features of Fe3O4@Al3+ particles. According to SEM image, the average dimension of monodispersed Fe3O4@Al3+ spheres was around 200 nm. XPS results showed the existence of Al3+ on the surface of Fe3O4 particles, which further demonstrated the success of metal chelation in this material synthesis. The XRD patterns indicated that the Fe3O4@Al3+ particles were the inverse spinel structure as the bare Fe3O4 particles. Good magnetism of Fe3O4@Al3+ particles determined by VSM indicated that this material could be easily separated from the reaction system. To summarize, Fe3O4@Al3+ particles is expected to play an important role in future DNA extraction due to remarkable performance. The DNA separation media Fe3O4@Al3+ particles were successfully synthesized. DNA adsorption was effectively achieved by Fe3O4@Al3+ particles based on metal chelation. DNA extraction was significantly boosted by Fe3O4@Al3+ particles. [ABSTRACT FROM AUTHOR]

In this research, hydrophilic molecularly imprinted microspheres (HMIPs) for azoxystrobin were successfully synthesized through precipitation polymerization. The adsorption capacities of HMIPs for azoxystrobin in water medium were higher than ordinary molecularly imprinted microspheres (MIPs), and HMIPs exhibited good hydrophilic properties. HMIPs and non-imprinted microspheres (HNIPs) were characterized by FT-IR, SEM, laser particle size analyzer and TGA. Comparing with HNIPs, azoxystrobin had a significant influence on morphologys and sizes of HMIPs. The Langmuir adsorption isotherm illustrated each binding site of HMIPs had the same adsorption capacity. The Lagergran pseudo-second-order kinetic model indicated the adsorption process between azoxystrobin and HMIPs was chemical adsorption. BET test illustrated HMIPs had bigger specific surface areas than HNIPs. Selective adsorption indicated that HMIPs had highly specific recognition of azoxystrobin. HMIPs successfully exhibited high selectivity and high hydrophilicity in water medium. [ABSTRACT FROM AUTHOR]

In this study, monodispersed and re-dispersed poly (methyl methacrylate) (PMMA) particles were prepared by high solid content (50 wt%) macroemulsion polymerization using commercial macromonomer (Emulsogen APS 100) as a reactive surfactant (surfmer). Highly monodispersed, re-dispersed PMMA particles with sizes around 300 nm were obtained using this process. The effect of recipe composition including surfmer content, monomer/water ratio and electrolyte concentration on particle formation and growth were also investigated. Compared to classical macroemulsion polymerization theory, the formation of particles was found different. The number of formed particles firstly increased to a maximum value, then rapidly decreased to reach a constant value stabilized at around 1/5 of the maximum particle number. The particle coagulation theory was used to explain the process of particle formation and growth. The relationship between polymer particle size distribution and particle coagulation was also examined and the results were discussed. The proposed method would probably find applications in industrial production of monodisperse particles. [ABSTRACT FROM AUTHOR]

Letrozole (LTZ) is effective for the treatment of hormone-receptor-positive breast cancer in postmenopausal women. In this work, and for the first time, using vibrating orifice aerosol generator (VOAG) technology, monodisperse poly-e-caprolactone (PCL), and poly (D, L-Lactide) (PDLLA) LTZ-loaded microparticles were prepared and found to elicit selective high cytotoxicity against cancerous breast cells with no apparent toxicity on healthy cells in vitro. Plackett-Burman experimental design was utilized to identify the most significant factors affecting particle size distribution to optimize the prepared particles. The generated microparticles were characterized in terms of microscopic morphology, size, zeta potential, drug entrapment efficiency, and release profile over one-month period. Long-term cytotoxicity of the microparticles was also investigated using MCF-7 human breast cancer cell lines in comparison with primary mammary epithelial cells (MEC). The prepared polymeric particles were monodispersed, spherical, and apparently smooth, regardless of the polymer used or the loaded LTZ concentration. Particle size varied from 15.6 to 91.6 µm and from 22.7 to 99.6 mm with size distribution (expressed as span values) ranging from 0.22 to 1.24 and from 0.29 to 1.48 for PCL and PDLLA based microparticles, respectively. Upon optimizing the manufacture parameters, span was reduced to 0.162-0.195. Drug entrapment reached as high as 96.8%, and drug release from PDLLA and PCL followed a biphasic zero-order release using 5 or 30% w/w drug loading in the formulations. Long-term in vitro cytotoxicity studies indicated that microparticles formulations significantly inhibited the growth of MCF-7 cell line over a prolonged period of time but did not have toxic effects on the normal breast epithelial cells. [ABSTRACT FROM AUTHOR]

Core-shell structure particles are attracting considerable attention because of their applications in drug delivery and catalysis carrier. In this study, SiO2@SiO2 core-shell structure with tunable shell thickness was successfully prepared by using tetraethoxysilane (TEOS) as the silica source. Monodisperse nonporous silica spheres with a diameter of 1.7 μm were synthesized by a modified Stöber method. An template CTAB was first grafted onto the SiO2 microsphere surface. Then TEOS was hydrolyzed with the addition of ammonia. Finally, superficially porous core-shell SiO2@SiO2 microspheres were obtained through calcination to remove the template. [ABSTRACT FROM AUTHOR]

Photocatalytic technology has attracted wide attention in the application of sewage treatment. Core-shell spheres can have better properties of photocatalytic performance because of the interaction between the core and shell layers with stable core materials. TiO2@SiO2 core-shell microspheres belong to inorganic core-shell microspheres which have gained more and more attention. In this paper, diazo-resin (DR) was chosento crosslink shell and core, which can be a novel way in the synthesis of monodisperse TiO2@DR@SiO2 core-shell microspheres. Because of core-shell structures with TiO2 surface, the obtained TiO2@DR@SiO2 microspheres can be used as photocatalysts. [ABSTRACT FROM AUTHOR]

Knowledge of an inverse fluidized-bed fluid hydrodynamics is advantageous in optimal adjustment and designing high-efficiency beds. In the present study, a combination of a single relaxation time collision operator lattice Boltzmann method (LBM) and the smoothed profile method (SPM) is employed to simulate the hydrodynamics of an inverse liquid–solid fluidized bed comprising circular monodisperse and polydisperse particles in a rectangular channel. A numerical instance of inverse fluidization involving 231 particles is illustrated to show the capability of the combined methods. Moreover, comparison of the numerical results is performed with the Ergun equation and the Richardson–Zaki correlation. The comparison demonstrates that the present model can simulate the fluid flow behavior in an inverse fluidized bed. Several different models were also presented to investigate the effect of different fluid properties and size of particles in the bed. Simulations indicate that the more the superficial liquid velocity, the higher the porosity of the bed. The present simulations show that porosity of the bed increases by increasing the particles size, and also the vertical velocity of the bed decreases with an increase in liquid viscosity. Finally, polydisperse particle systems are also simulated. The results show that porosity in an inverse fluidized bed comprising polydisperse particles is more than that of a monodisperse particle bed. [ABSTRACT FROM PUBLISHER]

Composite materials show more superior performance compared with the single-component materials. Core-shell material as a new composite material are more and more widely used. TiO2@SiO2core-shell microspheres belong to inorganic core-shell microspheres, compared with other types of core-shell material, the inorganic core-shell microspheres have advantage of controlled size, structural stability, easy surface modification, and so on. In the present paper, we demonstrated the synthesis of novel monodisperse core-shell microspheres with a TiO2shell using a convenient process. Due to owning core-shell structures with TiO2surface, the obtained TiO2@SiO2microspheres can be used as photocatalysts. [ABSTRACT FROM PUBLISHER]

In this paper, we reported an effective microfluidic-based method for fast continuous synthesis of monodisperse PEG/SiO2hybrid microspheres. The T-junction microfluidic chip equipped with rounded channels and the online photopolymerization system were applied for the microspheres microfabrication. The size of the microspheres was well controlled by the rounded channels and flow rate ratios of immiscrible fluids. We can obtain porous PEG microspheres when the hybrid microspheres were corroded by hydrofluoric acid. What's more, the interpenetrating polymer network structures of SiO2microspheres were obtained after the hybrid microspheres treated via a calcination process. [ABSTRACT FROM PUBLISHER]

Monodisperse microsphere has drawn more and more attention in the past two decades. In order to synthesize it, an efficient procedure was employed by combining dispersion and seeding polymerizations together. The polymerization can be divided into two processes: nucleation and growth. Monodisperse polystyrene seed colloids with a diameter of 2 μm were synthesized in the nucleation process using dispersion polymerization, and then the seed colloids were swollen by monomer and further polymerized in the growth process. Finally, monodisperse polymer microspheres with an average diameter of 10 μm were obtained. [ABSTRACT FROM AUTHOR]

Monodisperse ϵ-caprolactone (CL) oligomers with different end groups (t-butyldimethylsilyl, benzyl, hydroxyl, and carboxylic acid) and different numbers of repeating units (4–64) have been studied by differential scanning calorimetry and small-angle X-ray scattering (SAXS) in order to gather information regarding the melting temperature, long period, and melting enthalpy. Oligomers crystallized at their maximum temperatures (different for the different oligomers) to full crystallinity yielded extended-chain crystals for oligomers with 4, 8, and 16 repeating units with the important exception of the oligomers with four and eight repeating units and hydroxyl and benzyl end groups that showed double-layer crystals. Oligomers with 32 and 64 repeating units exhibited remarkably stable once-folded (32-mer) and thrice-folded (64-mer) crystals. Only the oligomer with 16 repeating units showed two crystallization temperature regimes resulting in once-folded crystals (low temperatures) and extended-chain crystals (high temperatures). The end groups had a profound effect on the structures. Hydrogen-bonding groups promoted the formation of crystal bilayers and led to a very high melting enthalpy (150 J g−1) exceeding the melting enthalpy of 100% crystalline poly (ϵ-caprolactone). The bulky end groups, in particular t-butyldimethylsilyl, reduced the crystallinity and favored chain tilting and probably preventing the unfolding of crystal stems in the oligomers with 32 and 64 repeating units. Melting temperatures of mature crystals obeyed a linear relationship with inverse CL stem length. The intercept (equilibrium melting temperature) was in the range of 350 to 357 K. [ABSTRACT FROM AUTHOR]

Aim: Investigated the self-assembly and characterization of novel antifouling polyethylene glycol (PEG)-coated iron oxide nanoparticles as nanoprobes for magnetic resonance imaging (MRI) contrast agent. Method: Monodisperse oleic acid-coated superparamagnetic iron oxide cores are synthesized by thermal decomposition of iron oleate. The self-assembly behavior between iron oxide cores and PEG-lipid conjugates in water and their characteristics are confirmed by transmission electron microscope, X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, and vibrating sample magnetometer. Result: Dynamic light scattering shows superparamagnetic iron oxide nanoparticles coated with PEG are stable in water for pH of 3–10 and ionic strengths up to 0.3 M NaCl, and are protein resistant in physiological conditions. Additionally, in vitro MRI study demonstrates the efficient magnetic resonance imaging contrast characteristics of the iron oxide nanoparticles. Conclusion: The result indicates that the novel antifouling PEG-coated superparamagnetic iron oxide nanoparticles could potentially be used in a wide range of applications such as biotechnology, MRI, and magnetic fluid hyperthermia. [ABSTRACT FROM AUTHOR]

We investigate the preparation of nearly monodisperse gold nanoparticles by heat treatment in different conditions. The effects of various solvents, heating temperature, and heating time length on the monodispersity of gold nanoparticles were studied systematically and a general route to generate gold nanoparticles with uniform size was determined. The first step was to prepare gold nanoparticles with less than 3 nm and the following operation was to heat the gold nanoparticles in the present of thiolated solvents where monodispersed gold nanoparticles could be obtained easily. Our approach has enriched synthesis of monodisperse gold nanoparticles, and may provide some valuable experimental data about how the heating process affects the size evolution of gold nanoparticles. [ABSTRACT FROM AUTHOR]

The capillarity-driven ascent of liquid through certain elementary assemblies of equal spherical particles held in a neutrally wetted container is considered and the conditions for liquid to flow are established. For flow through the assembly to be possible, critical contact angles of the liquid on the spheres must not be exceeded. These critical angles are considerably lower than the 90° which the Washburn equation predicts. Finally, the effect of sphere size disparity (or polydispersity) is considered in an Appendix. It is shown that wetting of the assembly may be controlled by manipulation of size distributions as well as by change in the contact angle. Experimental evidence in support of these ideas is presented for a two-dimensional array. [ABSTRACT FROM AUTHOR]

Spray drying is a widely used process to produce pharmaceutical powders. In traditional spray drying, the particle size distribution is wide and not well controlled. Using EHD atomization for spray drying offers a possibility to tailor the particle size and morphology. In conventional EHD spray drying, the generated particles are charged and need to be discharged to avoid Rayleigh breakup. Discharging adds complexity to the process and eliminates the possibility to collect the powder using an electric field. The present work describes a novel EHD spray drying setup based on a low-voltage nozzle. The low-voltage nozzle imparts moderate charge to the droplets, which makes discharging unnecessary. The charged particles can be controlled and collected by using an auxiliary electric field. The EHD spray dryer has been characterized in terms of particle size, particle morphology, process output, and yield. The size distribution of the generated particles is very narrow. Both porous and completely spherical particles can be produced. The yield of small-scale bench-top equipment was 20%, which is similar to the yield of a small-scale conventional spray dryer. The effective output with five nozzles was 75 mg/hr of dry powder. Because of the repelling forces associated with the unipolarly charged droplets, the number of nozzles can be increased without risking coalescence. [ABSTRACT FROM AUTHOR]

We develop Well-Deposition Particle Templating (W-DePT), a fast approach for mass-producing monodisperse shape-designed colloids, or LithoParticles. W-DePT is based on a single solid template that has been permanently etched in negative relief to provide one or more wells of desired shapes of particles. This "well-template" is coated with a sacrificial release layer, and the desired particle material, whether organic, inorganic, or metal, or a combination thereof, is deposited into the wells. By simply dissolving the sacrificial layer in a fluid, particles having the desired shapes can be released and the well-template can be re-used. Parallel production of many particles using multiple well templates is an inexpensive alternative to optical-exposure based approaches. The particles are released from the wells with greater than 99% efficiency, and they have less than 5% polydispersity. Using W-DePT, LithoParticles are made without either repeated optical exposure or imprinting, which involves mechanically contacting a patterned template with a second flat plate. [ABSTRACT FROM AUTHOR]