Excellent Monodispersity Research Articles

Rational design of polymeric core shell ratiometric oxygen-sensing nanostructures.

A new approach for the fabrication of luminescent ratiometric sensing nanosensors is described using core-shell nanoparticles in which the probe and reference are spatially separated into the shell and core of the nanostructure respectively. The isolation of the reference in the core of the particle ensures a stable emission reference signal unaffected by the external environment. The core shell structure was prepared by engineering structurally well-defined Ru-conjugated block copolymers which acted as emulsifiers in the miniemulsion polymerisation of BODIPY loaded styrene nanoparticles. The resulting particles are highly stable and show excellent size monodispersity. The nanosensors exhibit dual emission under a single excitation wavelength with a reversible and quantitative ratiometric response to the O2 content in aqueous media. In the presence of a low concentration of CTAB, the particles cross the cell membrane and the particles show negligible cytotoxicity. Such an approach to sensor nanoparticles should be of value across a range of applications where a stable ratiometric signal in diverse environments is required.

Synthesis and optical properties of water-soluble CdTe1−xSex quantum dots with ultra-long fluorescence lifetime

Water-soluble ternary-alloyed CdTe1−xSex quantum dots (QDs) have been synthesized via a simple one-pot approach in aqueous phase. The as-prepared CdTe1−xSex QDs show good crystallinity, excellent monodispersity, and a narrow size distribution with average size of 3.0 nm. Lattice parameters and band gaps of the ternary-alloyed CdTe1−xSex (0 ≤ x < 1) QDs are regulated respectively in linear and quadratic relationships with the Se content (x). By tuning composition, the photoluminescence (PL) emission wavelength of CdTe1−xSex can cover from 528.9 to 689.3 nm, and gradually moved to longer wavelengths with a decrease content of Se (x). The lifetime of CdTe1−xSex QDs is decreased gradually with the Se content (x) augment, attributing to the decreasing lattice spacing resulting from substitution of the larger Te atoms with the smaller Se atoms, bringing about a incremental plasmonic coupling effect at smaller inter-lattice fluorophore distance. However, the as-prepared CdTe1−xSex QDs (0 ≤ x < 1) have significantly longer fluorescence lifetimes of >80 ns with the maximum lifetime up to 174.64 ns. The longer life is good for the application of photoelectric conversion, fluorescent biomedical imaging and detecting.

In situ synthesis and visible-light photocatalytic application of CdTeSe@TiO2 nanotube composites with high electron transfer rate

High quality ternary-alloyed CdTeSe quantum dots (QDs) have been synthesized via a simple one-pot approach in aqueous phase. CdTeSe QDs show an average size of 3.0nm with good crystallinity, excellent monodispersity and relatively narrow size distribution. TiO2 nanotubes (TNTs) were prepared by hydrothermal method with larger specific surface area (364.2m2g−1), and CdTeSe@TNTs were synthesized by in situ process. The absorption edge of CdTeSe@TNTs is red shifted significantly toward 697nm. After sensitized with CdTeSe, the photoluminescence (PL) emission of CdTeSe@TNTs is significantly quenched, and the fluorescence lifetime of the composites is drastically decayed from 105.82ns to 0.13ns with a high photoinduced electron transfer rate (ket=7.98×109s−1) because of their high matchable lattice constant. In addition, under visible-light irradiation, the photocatalytic efficiency of rhodamine B (RhB) with CdTeSe@TNTs reaches 90% for 80min. And the photocatalytic reaction rate constant for CdTeSe@TNTs is 0.0272min−1, which is 5.4 and 3.4 times larger than that of pure TNTs and CdTeSe QDs, respectively. It is due to the broad visible absorption of CdTeSe@TNTs and the faster photoinduced electron transfer from CdTeSe QDs to TNTs.

A facile “polystyrene-dissolving” strategy to hollow periodic mesoporous organosilica with flexible structure-tailorability

A facile “template dissolving” strategy has been developed for the fabrication of hollow periodic mesoporous organosilica (HPMO) particles with perpendicularly ordered mesopores, where polystyrene (PS) is used as sacrifice template for the generation of hollow cavity. Systematic characterizations including transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and N2 adsorption/desorption analysis clearly reveal that the HPMO particles have an excellent monodispersity with a high specific surface area of 1246.7 m2 g−1, large pore volume of 1.38 cm3 g−1 and uniformly ordered mesopores of 2.48 nm. The pre-encapsulation of a core into PS (SiO2, Fe3O4@SiO2) results in a yolk-shell (Y-S) particle with high tunable shell thickness (30–60 nm) and cavity size (230–450 nm). The magnetically recyclable Fe3O4-YS-PMO was further utilized to adsorb 2, 4-dichlorophenol (2, 4-DCP) and the controlled release of camptothecin (CPT). Up to 81 mg of CPT was loaded per gram of the Fe3O4-YS-PMO particles, followed with a continuously release of 76% within 5 days.

Acid-Responsive Polymeric Doxorubicin Prodrug Nanoparticles Encapsulating a Near-Infrared Dye for Combined Photothermal-Chemotherapy

Combination therapy with high spatial and temporal resolution is highly promising for efficient medical treatment of cancer. In this study, doxorubicin (DOX) conjugated amphiphilic block copolymer with a terminal folic acid moiety was prepared, which could self-assemble into nanoparticles by encapsulating organic near-infrared (NIR) absorbing dye IR825 for combined photothermal-chemotherapy. The resulting PDOX/IR825 nanoparticles showed excellent colloidal stability and monodispersity in aqueous solution. Specifically, the conjugated DOX could be released quickly in weak acidic environment for chemotherapy due to the cleavage of acid-labile hydrazone bond. Meanwhile, the encapsulated dye could convert the NIR light energy into heat with high efficiency, which makes the self-assembled nanoparticles an effective platform for photothermal therapy. Confocal microscopy observations and flow cytometry analysis confirmed that the PDOX/IR825 nanoparticles could be efficiently endocytosed by HeLa cells and deliver...

Generation and Characterization of an IgG4 Monomeric Fc Platform.

The immunoglobulin Fc region is a homodimer consisted of two sets of CH2 and CH3 domains and has been exploited to generate two-arm protein fusions with high expression yields, simplified purification processes and extended serum half-life. However, attempts to generate one-arm fusion proteins with monomeric Fc, with one set of CH2 and CH3 domains, are often plagued with challenges such as weakened binding to FcRn or partial monomer formation. Here, we demonstrate the generation of a stable IgG4 Fc monomer with a unique combination of mutations at the CH3-CH3 interface using rational design combined with in vitro evolution methodologies. In addition to size-exclusion chromatography and analytical ultracentrifugation, we used multi-angle light scattering (MALS) to show that the engineered Fc monomer exhibits excellent monodispersity. Furthermore, crystal structure analysis (PDB ID: 5HVW) reveals monomeric properties supported by disrupted interactions at the CH3-CH3 interface. Monomeric Fc fusions with Fab or scFv achieved FcRn binding and serum half-life comparable to wildtype IgG. These results demonstrate that this monomeric IgG4 Fc is a promising therapeutic platform to extend the serum half-life of proteins in a monovalent format.

Room-temperature homogeneous precipitation of highly uniform BaCO3 dumbbells in a mixed solvent of ethylene glycol and water

We describe the successful synthesis of highly uniform BaCO3 dumbbells by using different carbonate esters (namely (CH3)2CO3 and (CH3CH2)2CO3) as the precipitating agent in a mixed solvent of ethylene glycol (EG) and water. The products were obtained at room temperature without any extra additives. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic studies identified orthorhombic BaCO3 structure of the prepared samples. The effects of reactant concentration and solvent composition on the morphology of BaCO3 were investigated. In spite of the different carbonate esters used, uniform BaCO3 dumbbells with excellent monodispersity can be generated by adjusting the reactant concentration and volume ratio of EG to water at appropriate values. The synergic effect of carbonate ester and EG modified the acicular habit of BaCO3 and facilitated the formation of dumbbells.

Preparation of highly monodispersed porous-channeled poly(caprolactone) microspheres by a microfluidic system

Microspheres with a porous structure are promising cell carriers for tissue engineering. Here we explored monodisperse porous poly(caprolactone) (PCL) microspheres produced by a microfluidic system. The microfluidic device could generate homogeneous structured microspheres with excellent monodispersity. The microsphere size was tunable from 210 to 330µm by adjusting the sheath flow rate from 170 to 330µm. Camphene, used as a pore-generating material, was effective in creating open-channels, and the channel structure was significantly influenced by the solidification temperature and content of camphene. The size-tunable, monodisperse, and channeled-microspheres developed by using camphene and microfluidic device may be a potential platform in many areas, including biomolecule separation, drug delivery, and cell culture.

Facile Synthesis of Uniform-Sized Bismuth Nanoparticles for CT Visualization of Gastrointestinal Tract in Vivo.

High-performance and biocompatible contrast agents are the key to accurate diagnosis of various diseases in vivo via CT imaging. Fabrication of pure Bi nanoparticles is the best way to maximize X-ray absorption efficiency due to the ultrahigh X-ray attenuation ability of Bi and 100% content of Bi element. However, high-quality Bi nanoparticles prepared through a facile strategy are still lacking. Herein, we report a simple noninjection method to fabricate uniformly sized pure Bi nanoparticles using only two commercial reagents by simply heating the mixture of raw materials in a short time. The obtained Bi nanoparticles owned highly uniform size, excellent monodispersity, and impressive antioxidant capacity. After being modified with oligosaccharide, the "sweet" Bi nanoprobe with comfortable patient experience and favorable biocompatibility was successfully used in CT visualization of gastrointestinal tract in detail.

Hydrophilic Fe3O4@C for High‐­Capacity Adsorption of 2,4‐Dichloro­phenol

AbstractA core–shell‐structured magnetic Fe3O4@C composite has been prepared from Fe3O4@RF (RF = resorcinol‐formaldehyde) through pyrolysis at 600 °C under a N2 atmosphere. The resultant products were characterized by transmission electron microscopy (TEM), powder X‐ray powder diffraction (PXRD), X‐ray photoelectron spectroscopy (XPS), Raman spectroscopy, and thermogravimetric analysis (TGA). The Fe3O4@C composite has excellent particle monodispersity, a uniform particle diameter of ca. 200 nm, a magnetic saturation of 41.2 emu g–1, and a high specific surface area of 247.3 m2 g–1 owing to the existence of a bimodal micro‐macroporous system. Moreover, the carbon shell is graphitized but has good hydrophilicity, which is attributed to the existence of remnant oxygen‐containing groups. When applied as an adsorbent for the removal of 2,4‐dichlorophenol from water, Fe3O4@C shows a good dispersivity (0.2 g L–1) and an average maximum adsorption capacity of 131.83 mg g–1 with a fluctuation of less than 17 % over a wide pH range from 1 to 11 and can be quickly recovered within 30 s by the application of an external magnetic field (800 G). The adsorption performance of Fe3O4@C is revealed to be attributed to π–π electron donor–acceptor interactions between the electron‐rich conjugated aromatic groups of Fe3O4@C and electron‐deficient 2,4‐dichlorophenol. The high adsorption capacity and facile magnetic separation performance make our hydrophilic Fe3O4@C an ideal adsorbent for the removal of 2,4‐dichlorophenol from wastewater.

Microfluidic synthesis of QD-encoded PEGDA microspheres for suspension assay.

Uniform and size-controllable QD-encoded poly(ethylene glycol) diacrylate (PEGDA) microbeads were produced using a microfluidic device followed by in situ photopolymerization. An S-shaped and gradually widening channel was designed to allow optimized UV exposure for photopolymerization and to prevent coalescence. The as-obtained PEGDA microbeads exhibited well-defined sphericity and excellent monodispersity with a coefficient of variation (CV) below 5%. The size varied from 7 μm to 120 μm and can be selectively achieved by simply adjusting the experimental parameters. The fluorescence performance of the QDs was well preserved without significant peak broadening or distortion. Seven barcode libraries were realized with bright fluorescence and distinguishing coding signals which could be conveniently decoded by a flow cytometer. Furthermore, a very facile strategy to conjugate biomolecules on the bead surfaces was developed using polydopamine (PDA). A sandwich immunoassay of rabbit IgG was performed and the applicability of the QD-encoded microbeads for suspension assay was demonstrated.

Bright and Stable Near-Infrared Pluronic-Silica Nanoparticles as a Contrast Agent for in vivo Optical Imaging.

Near-infrared (NIR) fluorescent nanostructured materials have emerged as novel contrast agents for non-invasive bioimaging. Here we report a class of polymer-silica nanoparticles doped with a NIR fluorescent dye prepared through a facile one-pot strategy. Hydrophobic NIR fluorescent dyes such as IR 780 iodide could be easily encapsulated into the micellar core by self-assembly of amphiphilic triblock copolymer Pluronic F127. When subsequently adding silane in aqueous solution, nanoparticles with a cross-linked core and a hydrophilic PEG shell were formed. The structure of the as-obtained nanoparticles was confirmed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The nanoparticles exhibited a well-defined spherical structure with a mean diameter of approximately 30 nm, and excellent monodispersity and stability in aqueous solution. In addition, the photo-stability of IR 780 was significantly improved by encapsulation into the nanoparticles. In vitro MTT assay with cell lines HEK293 and A431 demonstrated that the IR 780 loaded nanoparticles (termed as IR780@NPs) were biocompatible. In vivo sentinel lymph node imaging revealed that the fluorescent intensity and retention time of the IR780@NPs were clearly superior to its constituent free dye, making it amenable to in vivo bioimaging. Further in vivo tumor imaging indicated that IR780@NPs have a longer retention time and much higher accumulation on the tumor site compared to free dye after intravenous administration. Overall this hydrophilic NIR fluorescent contrast agent exhibits excellent photophysical characteristics and low cytotoxicity, and holds a strong promise for a variety of applications including bioimaging and therapy.

Gold Nanooctahedra with Tunable Size and Microfluidic-Induced 3D Assembly for Highly Uniform SERS-Active Supercrystals

Shape-controlled synthesis of uniform noble metal nanoparticles (NPs) is crucial for the development of future plasmonic devices. The use of nanocrystals with well-defined morphologies and crystallinity as seed particles is expected to provide excellent shape control and monodispersity. We report the aqueous-based seed-mediated growth of monodisperse gold octahedra with wide range of sizes (50–150 nm in side length) by reducing different amounts of HAuCl4 on preformed single crystalline gold nanorods using butenoic acid as reducing agent. Butenoic acid plays a key role as a mild reducing agent as well as favoring the thermodynamic control of the reaction. The uniformity of the as-prepared Au octahedra combined with the use of a microfluidic technique based on microevaporation will allow the self-assembly of octahedra into uniform 3D supercrystals. Additionally, these plasmonic substrates exhibit high and uniform SERS signals over extended areas with intensities increasing with the Au nanoparticle size.

Florescent silica PVA hybrids via sol–gel processing

A cost-effective, one-pot synthesis approach is reported to fabricate Rhodamine 6G (R6G) silica hybrid xerogels. Polyvinyl alcohol (PVA) is used as a non-ionic surfactant to homogeneously trap the dye in silica matrix. Presence of R6G in silica matrix is confirmed through Fourier Transform Infrared (FTIR) spectroscopy and Thermo Gravimetric Analysis (TGA) studies. Hybrids containing larger amount of PVA are found to exhibit better thermal stability than the hybrids with lesser PVA content. Optical properties of the hybrids are analyzed via UV–visible spectroscopy, and it is discovered that hybrids containing larger amounts of PVA do not form aggregates. Uniform distribution of fluorophores in silica matrix helps to minimize formation of J-aggregates in the hybrids, therefore making them ideal candidates for use in dye lasers. The resultant hybrids can be ascribed as stable multicomponent systems that exhibit excellent monodispersity and brightness.

Facile synthesis of monodisperse functional magnetic dialdehyde starch nano-composite and used for highly effective recovery of Hg(II)

By covalently linking dialdehyde starch and amine functionalized Fe3O4 nanoparticle, and modifying with aminothiourea functional group, the novel monodisperse nano-composite has been successfully synthesized without any toxic crosslinking agent. The resulting nano-composite was characterized by means of the Fourier transform infrared spectra (FT-IR), transmission electron microscope (TEM), X-ray diffraction (XRD), elemental analysis and vibrating sample magnetometer (VSM). As the new kind of low-cost and environmentally friendly adsorbent with the excellent monodispersity in aqueous phase, the obtained nano-composite has shown not only the good adsorption capacity for Hg(II) on high initial concentration, but also the strong removal ability on low concentration. Moreover, the unique selectivity for Hg(II) among the mixed metal ions solution and good regeneration performance of nano-composite has also been demonstrated by batch experiments.

Monodisperse water-soluble -Fe2O3/polyvinylpyrrolidone nanoparticles for a magnetic resonance imaging contrast agent

Water-soluble γ-Fe2O3/polyvinylpyrrolidone (PVP) nanoparticles were obtained by transferring oleic acid (OA) coated iron-oxide nanocrystals from hexane to water. The particle size of the γ-Fe2O3/PVP nanoparticles with excellent monodispersity is about 14 nm. Fourier transform-infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) results indicate that PVP anchors on the γ-Fe2O3 nanoparticles through its carbonyl group and provided sufficient hydrophilicity. The maghemite content in the γ-Fe2O3/PVP nanoparticles was about 81 wt-%. The saturation magnetisation of the superparamagnetic γ-Fe2O3/PVP nanoparticles is 57·7 emu g− 1 at 295 K. For in vivo magnetic resonance imaging (MRI) studies, the γ-Fe2O3/PVP nanoparticles can be guided to the target area by a permanent magnet and show negative contrast enhancement on the target area of laboratory mice.

Monodisperse microporous carbon nanospheres: An efficient and stable solid phase microextraction coating material

The monodisperse microporous carbon nanospheres (MMCNSs) were applied in solid phase microextraction for the first time. The MMCNSs-fiber was prepared by sol–gel technique and good repeatability and reproducibility were obtained, due to the excellent monodispersity of the MMCNSs. The sol–gel-MMCNSs fiber exhibited superior extraction ability for polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs), compared with the commercial polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber and the fiber prepared with its precursor, the monodisperse microporous polystyrene nanospheres (MMPNSs). Moreover, the fiber has good thermostability and strong acid/base durability. The sol–gel-MMCNSs fiber was then employed to detect PAHs and OCPs in aqueous samples by combining with gas chromatography–mass spectrometer (GC–MS). Under the optimized conditions, the detection limits of the proposed method ranged from 0.10 to 5.5ngL−1. Furthermore, the method was successfully utilized for the analysis of PAHs and OCPs in real samples, with satisfactory recoveries in the range of 81.0–120% for the Pearl River water samples and 72.8–118% for the coking wastewater samples.

Biotemplate-directed fabrication of size-controlled monodisperse magnetic silica microspheres

Biotemplating is an effective strategy to obtain morphology-controllable materials with structural specificity, complexity, and corresponding unique functions. Herein we take advantage of the unique heavy-metal-ion biosorption behavior of cyanobacteria cells to fabricate Fe3O4/cell composites. Meanwhile, cyanobacteria cells served as a biotemplate for fabricating solid and hollow magnetic silica microspheres (MSMs). The obtained MSMs retained the original morphology of the cells, and exhibited excellent monodispersity and uniform spherical shape with narrow size distribution. Furthermore, they demonstrated ferromagnetic behavior at room temperature when measured using a vibrating sample magnetometer.

CPT Encapsulated Silica-titania Hollow Nanoparticle Targeting SK-BR-3 Cells for efficient Anticancer treatment

ABSTRACTHER-conjugated hollow nanoparticles (HER–HNP, ca. 50 nm in diameter) are fabricated using a dissolution and re-deposition method and used to encapsulate camptothecin (CPT). The HER-HNP-CPT is used as an anti-cancer agent for human breast cancer SK-BR-3. It has excellent mono-dispersity and a high loading efficiency for CPT. Two kind of cell lines are used in this study; SK-BR-3 and RAW 264.7. SK-BR-3 and RAW 264.7 are used as targeting and controlling cell line, respectively. When SK-BR-3 cells are treated with HER-HNP-CPT, the viability decreased to 55%, which is ca. 1.5 times higher anti-cancer efficiency in comparison to RAW 264.7. The HER-HNP-CPT system offers a new opportunity to facilitate implementation of a hydrophobic drug for effective anti-cancer treatment of SK-BR-3 cells.

A rapid green strategy for the synthesis of Au “meatball”-like nanoparticles using green tea for SERS applications

We report a simple and rapid biological approach to synthesize water-soluble and highly roughened “meatball”-like Au nanoparticles using green tea extract under microwave irradiation. The synthesized Au meatball-like nanoparticles possess excellent monodispersity and uniform size (250 nm in diameter). Raman measurements show that these tea-generated meatball-like gold nanostructures with high active surface areas exhibit a high enhancement of surface-enhanced Raman scattering. In addition, the Au meatball-like nanoparticles demonstrate good biocompatibility and remarkable in vitro stability at the biological temperature. Meanwhile, the factors that influence the Au meatball-like nanoparticles morphology are investigated, and the mechanisms behind the nonspherical shape evolution are discussed.