Facile synthesis of wormlike quantum dots-encapsulated nanoparticles and their controlled surface functionalization for effective bioapplications

Semiconductor quantum dots (QDs) are considered as ideal fluorescent probes owing to their intrinsic optical properties. It has been demonstrated that the size and shape of nanoparticles significantly influence their behaviors in biological systems. In particular, one-dimensional (1D) nanoparticles with larger aspect ratios are desirable for cellular uptake. Here, we explore a facile and green method to prepare novel 1D wormlike QDs@SiO₂ nanoparticles with controlled aspect ratios, wherein multiple QDs are arranged in the centerline of the nanoparticles. Then, an excellent cationic gene carrier, ethanolamine-functionalized poly(glycidyl methacrylate) (denoted by BUCT-PGEA), was in-situ produced via atom transfer radical polymerization on the surface of the QDs@SiO₂ nanoparticles to achieve stable surfaces (QDs@SiO₂-PGEA) for effective bioapplications. We found that the wormlike QDs@SiO₂-PGEA nanoparticles demonstrated much higher gene transfection performance than ordinary spherical counterparts. In addition, the wormlike nanoparticles with larger aspect ratio performed better than those with smaller ratio. Furthermore, the gene delivery processes including cell entry and plasmid DNA (pDNA) escape and transport were also tracked in real time by the QDs@SiO₂-PGEA/pDNA complexes. This work realized the integration of efficient gene delivery and real-time imaging within one controlled 1D nanostructure. These constructs will likely provide useful information regarding the interaction of nanoparticles with biological systems.

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Template-free synthesis of titania architectures with controlled morphology evolution

Template-free synthesis of TiO₂ architectures with controlled morphology evolution has been developed through solvothermal reaction in 1,4-dioxane. By simply varying the molar ratio of the concentrated HCl over Titanium isopropoxide (TTIP) from 0 to 5.0, series of morphologies including nanoparticle-built microspheres, nanoparticle-built microspheres decorated with nanorods, nanorod cauliflowers, and nanorod dendrites have been obtained. The influence of several key factors on the morphology control of TiO₂ has been systematically investigated. These parameters include the mass (molar) ratio of HCl/TTIP, solvothermal reaction temperature and time, acid species (concentrated nitric acid), and solvent type (tetrahydrofuran and 1,3-dioxane). The mechanism for the formation of the TiO₂ architectures with controlled morphology evolution has been discussed. The application of the TiO₂ architectures as water splitting photocatalyst and lithium–ion battery anode has been demonstrated. And the corresponding structure–property correlation has been discussed.     

Facile and controlled synthesis of FeCo nanoparticles via a hydrothermal method

Magnetic FeCo alloy nanoparticles have been synthesized by reduction of FeSO₄ and CoCl₂ with hydrazine in concentrated alkaline media via a hydrothermal route. The size could be controlled by synthetic conditions such as reaction time and temperature, respectively. The obtained samples were characterized by XRD, SEM, TEM, and VSM techniques. Magnetic investigations show the ferromagnetic behavior with saturation magnetization higher than 148.2 emu/g and maximum coercivity up to 411.0 Oe at room temperature. The present method is simple, inexpensive, surfactant-free, and may stimulate technological interests. Such FeCo alloy nanoparticles may have potential applications in biomedical field and magnetic storage devices.     

Phase and morphology controlled synthesis of high-quality ZnS nanocrystals

Through a facile solvothermal method, the controlled preparation of ZnS nanocrystals with different phases and morphologies was achieved only by changing the organic additives. By adding the surfactant of sodium dodecyl benzene sulfonate (SDBS) into the reaction, the cubic heart-like ZnS nanoparticles with uniform size were obtained in a large scale. While, with the assistance of the biomolecule of alginic acid, the pure phase of hexagonal ZnS nanospheres assembled from small ZnS nanoparticles were synthesized. The optical properties of the obtained ZnS nanocrystals were investigated by ultraviolet-visible (UV-vis) absorption and photoluminescence (PL) spectra. The quantum confinement effect could be observed clearly in ZnS nanoparticles.     

Synthesis and characterisation of large chlorapatite single-crystals with controlled morphology and surface roughness

This work describes the synthesis of chlorapatite single crystals using the molten salt method with CaCl₂ as a flux. By manipulating the processing conditions (amount of flux, firing time and temperature, and cooling rates) it is possible to manipulate the crystal morphology from microscopic fibres to large crystals (up to few millimetre long and ~100?μm thick). The crystal roughness can be controlled to achieve very flat surfaces by changing the melt composition “in situ” at high temperature. The Young modulus and hardness of the crystals are 110?±?15 and 6.6?±?1.5?GPa respectively as measured by nanoindentation. Crystal dissolution in Hanks solution starts around the defects. Several in vitro assays were performed; ClAp crystals with different size and shape are biocompatible. Cell apoptosis was very low at 5, 10, and 15?days (Caspase-3) for all the samples. Proliferation (MTT) showed to be influenced by surface roughness and size of the crystals.     

Facile synthesis of highly faceted multioctahedral Pt nanocrystals through controlled overgrowth

Highly faceted Pt nanocrystals with a large number of interconnected arms in a quasi-octahedral shape were synthesized simply by reducing H2PtCl6 precursor with poly(vinyl pyrrolidone) in aqueous solutions containing a trace amount of FeCl3. The iron species (Fe(3+) or Fe(2+)) play a key role in inducing the formation of the multioctahedral structure by decreasing the concentration of Pt atoms and keeping a low concentration for the Pt seeds during the reaction. This condition favors the overgrowth of Pt seeds along their corners and thus the formation of multiarmed nanocrystals. Electron microscopy studies revealed that the multioctahedral Pt nanocrystals exhibit a large number of edge, corner, and surface step atoms. The size of the multioctahedral Pt nanocrystals can be controlled by varying the concentration of FeCl3 added to the reaction and/or the reaction temperature. These multioctahedral Pt nanocrystals were tested as electrocatalysts for the oxygen reduction reaction in a proton exchange membrane fuel cell and exhibited improved specific activity and durability compared to commercial Pt/C catalyst.     

Facile synthesis of fully ordered L10-FePt nanoparticles with controlled Pt-shell thicknesses for electrocatalysis

We report a simple one-step approach for the synthesis of ～4 nm uniform and fully L10-ordered face-centered tetragonal (fct) FePt nanopartides (NPs) embedded in ～60 nm MCM-41 (fct-FePt NPs@MCM-41).We controlled the Pt-shell thickness of the fct-FePt NPs by treating the fct-FePt NPs@MCM-41 with acetic acid (HOAc) or hydrochloric acid (HC1) under sonication,thereby etching the surface Fe atoms of the NPs.The fct-FePt NPs deposited onto the carbon support (fct-FePt NP/C) were prepared by mixing the fct-FePt NPs@MCM-41 with carbon and subsequently removing the MCM-41 using NaOH.We also developed a facile method to synthesize acid-treated fct-FePt NP/C by using a HF solution for simultaneous surface-Fe etching and MCM-41 removal.We studied the effects of both surface-Fe etching and Pt-shell thickness on the electrocatalytic properties of fct-FePt NPs for the methanol oxidation reaction (MOR).Compared with the non-treated fct-FePt NP/C catalyst,the HOAc-treated and HCl-treated catalysts exhibit up to 34％ larger electrochemically active surface areas (ECASAs);in addition,the HCl-treated fct-FePt NP (with ～1.0 nm Pt shell)/C catalyst exhibits the highest specific activity.The HF-treated fct-FePt NP/C exhibits an ECASA almost 2 times larger than those of the other acid-treated fct-FePt NP/C catalysts and shows the highest mass activity (1,435 mA.mg~,2.3 times higher than that of the commercial Pt/C catalyst) and stability among the catalysts tested.Our findings demonstrate that the surface-Fe etching for the generation of the Pt shell on fct-FePt NPs and the Pt-shell thickness can be factors for optimizing the electrocatalysis of the MOR.     

Facile synthesis of MnV2O6 nanostructures with controlled morphologies

MnV₂O₆ nanostructures including nanorods, nanobelts, and nanosheets, have been synthesized by a facile hydrothermal reaction between Mn(CH₃COO)₂·4H₂O and commercial V₂O₅. The synthesized products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The influences of synthetic parameters, such as, reaction time, temperature and medium, on the morphologies of the resulting products have been investigated. As the reaction temperatures increase from 120 °C to 180 °C, MnV₂O₆ nanorods and nanobelts are obtained, respectively. The time-dependent experimental results at 180 °C reveal that the sizes of MnV₂O₆ nanobelts increase gradually with the reaction proceeding. Interestingly, as the reaction is carried out with the aid of H₂O₂ solution, flower-like MnV₂O₆ nanosheets are formed.     

Facile synthesis of MOF-5 structure with large surface area in the presence of benzoyl peroxide by room temperature synthesis

In this study, for the first time, the uniform cylindrical MOF-5-BPO (Zn₄O(BDC)₃(H₂O)·0.5ZnO, BDC = 1,4-benzenedicarboxylate, BPO = benzoyl peroxide) crystals with large Brunauer–Emmett–Teller (BET) surface area (3210.2 m² g⁻¹) was successfully synthesized by room temperature synthesis in the presence of BPO using zinc nitrate hexahydrate (Zn(NO₃)₂·6H₂O) as the zinc source. The pore volumes of MOF-5-BPO materials prepared with different concentrations of BPO were 0.84–1.07 cm³ g⁻¹, higher than that of MOF-5-NP (0.68 cm³ g⁻¹, Zn₄O(BDC)₃(H₂O)₃·2ZnO) and MOF-5-H₂O₂ (0.84 cm³ g⁻¹, Zn₄O(BDC)₃(H₂O)₂·2ZnO, H₂O₂ = hydrogen peroxide). The addition of the peroxides created new pores, which possessed the same diameters as the existing ones, thus increased the pore volume of the product. The concentration of BPO was critical for the pore texture of MOF-5-BPO. Moreover, MOF-5-BPO could store 1.24 wt% hydrogen at 77 K and 100 kPa. Thus, this study points out some information for one to realize the influence of the peroxides over MOF-5 structure and promises the potentiality of large-scale production of MOF-5 structure with large surface area.     

Facile synthesis of carbon supported copper nanoparticles from alginate precursor with controlled metal content and catalytic NO reduction properties

A copper-nanoparticle-doped carbon was prepared from an alginate based precursor in a one step carbonisation-reduction procedure based on the modified polyol process. The ion exchange capacity of the precursor as well as the porosity, metal content, thermal properties, of the final product, were investigated. The preparation route leads to a porous carbon/copper composite with predefined metal loading reaching up to over 30% (w/w) of finely dispersed Cu nanoparticles of fairly uniform size. NO catalytic abatement evaluation showed high efficiency even at low temperatures compared to other recently reported carbon supported catalysts.     

Facile synthesis and characterization of hydrophobic vaterite CaCO3 with novel spike-like morphology via a solution route

Hydrophobic spike-like vaterite CaCO₃ composed of nanoparticles with an average size of 100 nm has been successfully synthesized via a simple synthetic method. The crystallization of vaterite CaCO₃ was fabricated by the reaction of CaCl₂ with Na₂CO₃ in ethanol-water solvents in the presence of oleic acid. The as-prepared products were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and contact angle analysis. The characterization results revealed that oleic acid played an important role in determining the phase and morphology of the sample. In addition, the surface properties of the vaterite CaCO₃ changed from hydrophilic to hydrophobic. The contact angle of the modified CaCO₃ reached 95.8°.     

Conducting polymers with controlled fibrillar morphology

Electrically conducting polymers have been prepared from pyrrole by electrodeposition through two types of isoporous membranes. When pyrrole is polymerized through isoporous polycarbonate membranes, with the polycarbonate subsequently removed with chloroform, a relatively low density of short filaments is produced. Membranes of large pore diameter gave few, rough filaments, but as the pore size decreased the number of filaments increased and their walls were much smoother. A method in which the filaments are contiguous with a supporting sheet is described. When honeycomb structured -alumina membrane is employed, a quite different product is possible. A very high density polymer of long, hexagonal filaments appear after the -alumina is leached using sodium hydroxide. This material has a very high surface area and structural regularity. It has potential as an electrode material in which switching from conducting to non-conducting states could be efficiently achieved by rapid expulsion of counter-ion.     

A perspective on morphology controlled synthesis of powder by tuning chemical diffusion and reaction

This paper is a review of the progress and perspective of an approach for morphology controlled synthesis of particles by tuning chemical diffusion and reaction. Rational synthesis of materials with designed structures is a long term dream of scientists and engineers. The challenges of this dream lie in the poor understanding on the formation mechanism of diverse structures and the insufficient ability to program structure evolutions. From a view of chemical engineering, a shape-controlled synthesis of particles by regulating chemical diffusion and reaction was developed, which was experimentally confirmed by synthesizing diverse morphologies of silver particles at different diffusion and reaction and synthesizing similar dendritic structures of various materials at diffusion limitation. Diffusion and reaction determines the chemical distribution in the growth front of particles, which drives the anisotropic growth of particles, forming diverse morphologies. Ongoing study focuses on the dynamic stability of structure evolution, to establish a general model for structure design and rational synthesis by considering both the local environment and the nature of materials under the concept of mesoscience.     

Mesoporous silica with controlled porous structure and regular morphology

A new procedure for the synthesis of mesoporous silica with controlled porous structure and regular morphology was developed. It is based on the precipitation from a homogeneous environment using cetyltrimethylammonium bromide as a structure directing agent. The decrease in pH, which causes the formation of solid particles, is achieved by the hydrolysis of ethyl acetate. The procedure enables to obtain not only the MCM-41 mesoporous molecular sieve with a very high degree of pore ordering and phase purity, but also materials of a new type, viz. bimodal silicas containing both the MCM-41 mesopore system with a pore size of about 3 nm and a system of larger mesopores with sizes ranging from 10 to 30 nm. Owing to their structural properties and regular worm-like morphology, bimodal silicas are promising materials for applications in separation processes or as supports for bulky molecules or nanoparticles.     

Facile synthesis of ZnO hollow fibres

In this paper, cotton fibres were used as bio-template to successfully synthesize new ceramic materials, ZnO hollow fibres and in an effort to explore the synthesis condition, and simplify the synthesis procedure. In this synthesis, a direct thermal decomposition of zinc acetate dihydrate coated on the surface of cotton fibres was explored. The wall porosity of the ZnO hollow fibres was controlled by changing the concentration of zinc acetate aqueous solution.     

Facile synthesis of prickly CoNi microwires

Novel prickly CoNi microwires have been successfully synthesized via a hydrothermal synthetic route. The samples prepared at 120 °C for 6 h were made up of large-scale wire-like assemblies with the diameter of about 3 μm and length up to several dozens microns. These wires exhibited hierarchical structure, which was constructed by thornlike crystals with the length of 300-500 nm. The morphology of the wires could be adjusted by the NaOH contents in the system. The magnetic hysteresis measurement revealed that the CoNi microwires displayed ferromagnetic behaviors with a saturation magnetization (Ms) of 83.90 emu/g and a coercivity (Hc) of 119.1 Oe.     

Facile synthesis of self-stabilized polyphenol nanoparticles

We describe here the facile synthesis (in two-steps) of green light emitting phenol polymer with an azomethine side group. For this purpose, hydroxy functionalized-Schiff base monomer, HPMBT, was obtained by condensation of 2,3,4-trihydroxybenzaldehyde with 2-aminophenol. Subsequent oxidation of the monomer in alkaline medium by NaOCl yielded to corresponding phenol polymer (PHPMBT) with molecular weight ca. 34,500 Da. The characterizations were performed by NMR, FT-IR, UV–vis, gel permeation chromatography (GPC), thermogravimetry (TG), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), cyclic voltammetry (CV), photoluminescence (PL), dynamic light scattering (DLS) and scanning electron microscope (SEM) analysis. PL analysis indicated that HPMBT was non-fluorescent whereas PHPMBT was a green light emitter. In addition, the redox behaviors of the polymer were explored by cyclic voltammetry (CV), assigned it's electroactive nature. The formation of nano-sized polyphenol particles was revealed by the SEM and DLS analyses. A possible mechanism for the formation and self-stabilization of the polyphenol nanoparticles was also suggested.