One-Pot Synthesis of Fe3O4@PS@P(AEMH-FITC) Magnetic Fluorescent Nanocomposites for Bimodal Imaging.

Magnetic fluorescent nanocomposites have attracted much attention because of their merging magnetic and fluorescent properties for biomedical application. However, the procedure of synthesis of magnetic fluorescent nanocomposites is always complicated. In addition, the properties of fluorescent component could be easily influenced by magnetic component, retaining both of the magnetic and fluorescent properties into one single nanoparticle considered to be a significant challenge. Herein, we report one-pot method to synthesize multifunctional magnetic fluorescent Fe3O4@PS@P(AEMH-FITC) nanocomposites for bimodal imaging. The asprepared Fe3O4@PS@P(AEMH-FITC) nanocomposites with well-define spherical core/shell structure were stable properties. Moreover, the Fe3O4@PS@P(AEMH-FITC) nanocomposites displayed efficient fluorescent and magnetic properties, respectively. Meanwhile, the magnetic resonance imaging (MRI) and HePG2 cancer cell fluorescent images experiment results suggested that Fe3O4@PS@P(AEMH-FITC) nanocomposites could be used as MRI contrast agents and Fluorescence Imaging (FLI) agents for bioimaging application. Our investigation paves a facile avenue for synthesized magnetic fluorescent nanostructures with well biocompatibility for potential bioimaging application in MRI and FLI.

Fatigue damage to pig erythrocytes during repeated swelling and shrinkage.

During the removal of cryoprotectants from cryopreserved-thawed blood with the dialysis-based or dilution-filtration method, due to the change in the extracellular osmolality, erythrocytes usually undergo repeated swelling and shrinkage. However, the erythrocyte fatigue damage induced by this repeated volume change has not yet been studied. In this work, by successively loading hypotonic and hypertonic solutions, we mimicked the repeated swelling and shrinkage of pig erythrocytes and then examined the effect of the number of cycle loops on the steady-state volume and the mortality of the pig erythrocytes. The results suggest that because of cell leakage in the swelling process, the steady-state volume of the pig erythrocytes after one cycle is smaller than the volume before the cycle, even though the cell performs a self-protective regulatory procedure. If the number of cycle loops is increased, the repeated swelling and shrinkage will cause a continuous decrease in the steady-state volume, and the ability of the pig erythrocytes to resist osmotic damage will decrease; as a result, the mortality of the pig erythrocytes increases as the number of cycle loops increases. The viability of the cells is also affected by the hypotonic and isotonic processing times: a short processing time may contribute to a decrease in the mortality of the pig erythrocytes. This work is of significance to optimizing the process of removing cryoprotectants.

A novel platform for enhanced biosensing based on the synergy effects of electrospun polymer nanofibers and graphene oxides.

A novel biosensing platform was developed by combining the advantages of electrospun poly(vinyl alcohol) (PVA)/chitosan nanofibers and graphene oxides (GO). Glucose oxidase (GOD) was employed as a model enzyme. By co-electrospinning the solution of PVA, chitosan, GOD and GO, the PVA/chitosan/GOD/GO nanofibers were directly modified on the platinum (Pt) electrode. The UV-vis spectra and the FTIR spectra were used to characterize the GO nanosheets. The morphologies of fabricated electrospun nanofibers were characterized by high resolution scanning electron microscopy. After a thin layer of nafion was modified on the surface of matrix, the as-prepared electrode was used to detect glucose. The electrode exhibited great advantages in high sensitivity, low detection limit and wide linear range. In the meantime, the electrode showed good stability, acceptable reproducibility, and excellent anti-interference capability for ascorbic acid, uric acid, lactose and sucrose. Moreover, the novel biosensor was successfully applied for the glucose determination in human serum samples. The mechanism of efficient biosensing of the nafion/PVA/chitosan/GOD/GO/Pt electrode was analyzed in detail and the results show that it can be due to the synergy effects of electrospun nanofibers and GO nanosheets.

Smaller silica nanorattles reabsorbed by intestinal aggravate multiple organs damage.

Recent advances in design and controllable synthesis of rattle-type silica nanoparticles have led to a dramatic expansion of their potential drug delivery application. However, the relationship between physico-chemical parameters and bio-effects of silica nanoparticles is still unclear. In the present study, we investigated the effect of particle size on acute toxicity caused by intravenously administered silica nanorattles (SNs) in vivo. Above all, we found that SNs with smaller size may have higher toxicity potency. SNs sized 60 nm but not the others induced multi-organs structural damages, such as necrosis, congestion and haemorrhage. Interestingly, the different feeding mode after the fasted treatment induced the divarication of toxicity of 60 nm SNs. Smaller particles induced mortality even at 100 mg/kg dose injection when mice fasted for 12 hours and instantly replenish food. But no death had happened when mice received food with gradually recovery after the same treatment. The results indicate that smaller SNs drained into the intestinal tract with the bile liquids from liver may be reabsorbed into the blood through the impaired intestinal barriers and induce worse re-injure. These findings may provide useful information for the further toxicity and biodistribution research of nanoparticles.

Novel fluorescence method for detection of α-L-fucosidase based on CdTe quantum dots.

The enzyme α-L-fucosidase (AFu) plays an important role in the diagnosis of hepatocellular carcinoma (HCC) and fucosidosis. In this paper, a simple, sensitive and precise method based upon measuring the fluorescence quenching of CdTe semiconductor quantum dots (QDs) was developed for detecting the enzymatic activity of AFu. The detection limit of AFu was 0.01 U/L (n = 3) and the linear relationship was 0.01-4 U/L. The selectivity experiment indicated excellent selectivity for AFu over a number of interfering species. We have also studied the detection mechanism of AFu by X-ray photoelectron spectroscopy (XPS) and found that the quenching effect was caused by the oxidation of tellurium by 2-chloro-4-nitrophenol (2-CNP) which produced in AFu catalytic reaction. Moreover, the AFu sensor based on QDs was used satisfactorily for the assessment of AFu activity in serum samples. It will most probably be applicable in assembling diagnostic microdevice to realize the rapid clinic analysis of AFu.

Alkylaminosilane-assisted simultaneous etching and growth route to synthesise metal nanoparticles encapsulated by silica nanorattles.

An efficient and facile method to synthesise silica nanorattles with multiple noble metal (Au and Pd) cores by a simultaneous etching and growth route has been developed. In this strategy, a dual-functional alkylaminosilane was adopted to form the middle layer of solid organic-inorganic hybrid solid-silica spheres (HSSSs), which enabled the selective etching of the middle hybrid layer of the HSSSs and the in situ growth of metal nanoparticles (NPs) inside the cavity in a one-step hydrothermal reaction. By adjusting the pH values of the reaction system, the metal NPs could be grown exclusively inside the silica nanorattles, resulting in a high atomic utilisation of the noble metals. The size and number of Au cores were tunable by manipulating the initial concentration of HAuCl(4). The prepared silica nanorattles with Au cores were successfully applied to the catalytic reduction of 4-nitrophenol and showed high catalytic activity and cycle stability. Catalysts with multiple gold cores exhibited superior catalytic activity to those with a single gold core, probably because they possess smaller Au cores with greater surface area.

In vitro degradation behavior of silica nanoparticles under physiological conditions.

Understanding the degradability of silica nanoparticles is significant for the rational design of desired nanomaterials for various biomedical applications. However, the effect of the intrinsic properties of silica nanoparticles, such as particle shape, surface chemistry, and porosity, on kinetic degradation process under different extrinsic conditions has still received little attention. Herein, mesoporous silica nanoparticles (MSNs) with different aspect ratios (ARs, 1, 2, and 4), the corresponding PEG-functionalized MSNs, and amorphous Stöber spherical silica nanoparticles were specially designed and their degradation was evaluated in in vitro simulated physiological media. The results show that shape, surface properties and porosity of nanoparticles, as well as the component of simulated physiological media, play important roles in tuning the degradation kinetics and behaviors. Sphere-shaped MSNs have a faster degradation rate than rod-shaped counterparts. Naked MSNs are eroded from particle external surface, while PEGylated MSNs from interior of particles. And spherical MSNs display more extensive degradation than amorphous silica nanoparticles. The presence of fetal bovine serum (FBS) in Dulbecco's Modified Eagle's Medium (DMEM) can accelerate the degradation process. These results can provide useful guidelines for the rational design of silica nanoparticles for biomedical applications.

Overcoming multidrug resistance with mesoporous silica nanorods as nanocarrier of doxorubicin.

Multidrug resistance (MDR) is a major obstacle to the effective chemotherapy in many human malignancies. Nanoparticulate drug delivery systems (NDDSs) have been reported to be able to bypass MDR, but the cancer therapeutic efficacy is still limited. In this study, we firstly designed the nonspherical mesoporous silica nanorods (MSNRs) with aspect ratio (AR) of 1.5 and 5 as drug delivery systems of doxorubicin to overcome multidrug resistance. For drug loading, the long-rod MSNRs (NLR, AR = 5) showed higher drug loading capacity of doxorubicin (DOX) than the short-rod MSNRs (NSR, AR = 1.5). NLR encapsulated DOX had increased intracellular DOX accumulation in drug-resistant Chinese hamster ovary (CHO) cells compared with free DOX by observablly increased cellular uptake and significantly prolonged intracellular drug retention. It further exhibited increased cytotoxicity compared with free DOX under different drug concentrations. These findings may provide a new perspective for designing high-performance nanoparticulate drug delivery systems for bypassing multidrug resistance of cancer therapy.

Fabrication of fluoroalkylsilane modified ZnO nanorod films for electrode protection of electrophoretic displays.

The electrode protection has gained importance because of its positive robust role for the long term display quality of electrophoretic displays. A simple method of zinc oxide nanorod films prepared by electrochemical deposition and coupling with fluoroalkylsilane (FAS) is introduced to fabricate electrode protection films for Indium Tin Oxide (ITO) electrodes. The surface microstructures of zinc oxide films were characterized by scanning electron microscopy, showing a regular nanorods array. After treated by FAS the surface showed extremely low surface free energy with a water contact angle of 148.0 +/- 2.0 degrees. The settlement of pigments was considerably reduced according to the reflectance measurement by ultraviolet spectrophotometer. A weight experiment further confirmed that 90% of the pigment conglutination was prevented by the surface modification. This research can provide an economical approach to improve reliability and long-term image quality of the electrophoretic displays.

Surfactant-free self-assembly of nanocrystals into ellipsoidal architectures.

A simple approach to control the self-assembly of ZnS nanocrystals into well-defined, uniform, three-dimensional, micrometer-scale, solid ellipsoidal structures with rattle-type, multishelled, and hollow architectures is presented. There is no surfactant or small molecule to assist the self-assembly of the nanocrystals. A possible mechanism of the controlled self-assembly is proposed. The growth process can be divided into two stages: 1) the formation of ellipsoidal architectures via oriented aggregation, the growth kinetics of which is primarily attributed to the charge-charge, charge-dipole, and dipole-dipole interactions of preformed ZnS nanocrystals; and 2) Ostwald ripening, which results in multishelled, rattle-type, and hollow structures. This self-assembly concept is also applicable to other metal sulfides.

Fabricating superhydrophilic wool fabrics.

A simple method for fabricating environmentally stable superhydrophilic wool fabrics is reported here. An ultrathin silica layer coated on the wool altered both the surface roughness and the surface energy of the fiber and endowed the wool fabrics with excellent water absorption. The process of coating silica sols was dependent on an acid solution of low pH, which influenced the electrostatic interactions between nanoparticles and wool fibers. The morphology and composition of silica-sol-coated wool fabrics were characterized by a combination of SEM, TEM, EDX, FTIR, and XPS measurements. The possible mechanism and size effect of silica nanoparticles on the hydrophilic property of wool fabric were discussed. The washing fastness of the superhydrophilic wool fabrics in perchlorethylene and water was also evaluated. This study shows that wool fabrics modified by optical transparence, chemical stability, and nontoxic silica sols are promising in constructing smart textiles.

A study of the electron transfer and photothermal effect of gold nanorods on a glucose biosensor.

A new glucose biosensor based on the electron transfer and photothermal effect of gold nanorods (GNRs) is reported here. The biosensor was prepared by immobilizing glucose oxidase (GOx) on a platinum (Pt) electrode by a composite film consisting of GNRs, polyvinyl butyral (PVB) and glutaraldehyde. GNRs were synthesized by a gold seed-mediated cetyltrimethylammonium bromide (CTAB) surfactant-assisted approach. The fabrication, characterization and analytical performance of the glucose biosensor based on GNRs are described in this paper. Moreover, the modulation of the biosensor by the photothermal effect based on the unique surface plasma resonance (SPR) property of GNRs was investigated for the first time. The results show that the current response of a glucose biosensor can significantly increase, induced by the electrical conductivity and photothermal effect of GNRs.

Preparation and characterization of quantum dots coated magnetic hollow spheres for magnetic fluorescent multimodal imaging and drug delivery.

Innovative nanocomposites of magnetic and fluorescent multifunctional hollow spheres were developed, which combined magnetic resonance imaging (MRI), magnetic targeting, fluorescent imaging (FI) and drug delivery into one system. Fe3O4 hollow spheres were used as templates for the deposition of polyelectrolyte (PE) multilayers and CdTe quantum dots (QDs) via layer-by-layer (LBL) method. The PE multilayers/QDs coated Fe3O4 hollow spheres showed high magnetization and fluorescence, which can be used as magnetic and fluorescent multimodal imaging agent in vivo. The multifunctional nanomaterials of polyelectrolyte multilayers/QDs coated Fe3O4 hollow spheres were used as controlled drug release system, which showed pH-sensitive drug release over a long time. By combining the multiplexing imaging capability, the magnetic and fluorescent nanocomposites are potential candidates for simultaneous disease diagnosis and therapy.

Green and orange CdTe quantum dots as effective pH-sensitive fluorescent probes for dual simultaneous and independent detection of viruses.

One of the most highlighted and fastest moving interfaces of nanotechnology is the application of quantum dots (QDs) in biology. The unparalleled advantages of the size-tunable fluorescent emission and the simultaneous excitation at a single wavelength make QDs the great possibility for use in optical encoding detection. In this paper, we report that green and orange CdTe QDs as convenient, cheap, reversible, and effective pH-sensitive fluorescent probes could monitor the proton (H+) flux driven by ATP synthesis for dual simultaneous and independent detection of viruses on the basis of antibody-antigen reactions. A new kind of biosensor (consisting of the mixture of green-QDs-labeled chromatophores and orange-QDs-labeled chromatophores) fluorescent measurement system was established for rapid, simultaneous, and independent detection of two different kinds of viruses (i.e., H9 avian influenza virus and MHV68 virus). It is crucial to find that the green and orange QDs labeled biosensors coexisting in the detection system can work independently and do not interfere with each another in the fluorescence assays. In addition, a primary steady electric double layer (EDL) model for the QDs biosensors was proposed to illustrate the mechanism of simultaneous and independent detection of the biosensors. We believe that the pH-sensitive CdTe QDs based detection system, described in this paper, is an important step toward optical encoding and has a great potential for simultaneous and independent qualitative and quantitative multiple detection systems.

Synthesis and self-assembly of monodisperse silver-nanocrystal-doped silica particles.

A simple method based on the Stöber reaction was developed to prepare silver-nanocrystal-doped silica composite particles. The silane coupling agent N-[3-(trimethoxysilyl)dropyl]ethylene diamine (TSD) incorporated Ag+ into a siloxane framework and a further chemical reducer reduced Ag+ to silver nanoparticles. TEM images showed that, in the presence of TSD, silver nanocrystals (fcc) of 2-8 nm were homogeneously doped in the silica particles, which showed a typical surface plasmon resonance (SPR) peak. The as-prepared Ag/SiO2 composite particles can be self-assembled into long-range ordered lattices (or photonic crystals) over large areas.

A Dual-Emission Nanohybrid of Gold Nanoclusters and Carbon Dots for Ratiometric Fluorescence Detection of Reactive Oxygen Species and Glucose.

Detecting reactive oxygen species (ROS) is critical for understanding the mechanisms of diseases. In this work, a convenient ratiometric fluorescent method for determination of ROS was developed basing on a nontoxic nanohybrid system which was constructed by carbon dots (CDs) and gold nanoclusters (Au NCs). The combination was prepared easily basing on self-assembly without any complex process, achieving maximum reservation of the two fluorescent properties. Thus the limit of detection (LOD) for hydrogen peroxide (H2O2) and hypochlorite (ClO-) was lower down to 0.1 µM after the experimental conditions were optimized. Being built to reflect H2O2, the test paper provided a method of convenient visual detection with double fluorescence of CDs/Au NCs. Furthermore, the biosensor was proven to be suitable for the detection of H2O2 and glucose (Glu) in human serum examples. The proportion of CDs and Au NCs was adjusted optionally to different color, while keeping the nanohybrid in high physiological stability and excellent biocompatibility. The excellent performance of this ratiometric biosensor is expected to facilitate further development of rapid and high-throughput detection of ROS.

A simple solution route to single-crystalline Sb2O3 nanowires with rectangular cross sections.

We report a simple solution route to large-scale synthesis of uniform, single-crystalline, and well-faceted orthorhombic antimony trioxide (Sb(2)O(3)) nanowires with rectangular cross sections by direct air oxidation of bulk metal antimony (Sb) in a mixed solution made of ethylenediamine (EDA) and deionized water (DIW). The as-synthesized products were analyzed by range of methods, such as XRD, SEM, EDX, TEM, SAED, HRTEM, FTIR, Raman, UV-vis absorption, and photoluminescence (PL) spectra. The as-synthesized Sb(2)O(3) nanowires with rectangular cross sections are usually hundreds of micrometers in length, typically 80-100 nm in width, and 60-80 nm in thickness. The novel room temperature photoluminescence properties of Sb(2)O(3) nanowires with rectangular cross sections displayed a significant UV luminescence with a strong emission band at 374 nm, which was reported for the first time, indicating the as-synthesized products with an optical band gap E(g) = 3.3 eV. It is expected that as-synthesized Sb(2)O(3) nanowires would be a new member of functional materials and used in the manufacture of advanced nanodevices.

Controlled drug delivery system based on magnetic hollow spheres/polyelectrolyte multilayer core-shell structure.

A novel controlled drug delivery system was fabricated by coating chitosan/PAA multilayer onto magnetic hollow spheres via a "Layer-by-Layer" (LBL) assembly approach. Cefradine was used as a model drug to evaluate the drug release characteristics of this core-shell hollow structure and the results show that it exhibits a sustained release of the drug and the release rate can be regulated by the pH environment of release medium. It is believed that this core-shell hollow structure, which combines the advantage of controlled delivery as well as magnetic targeting, has commendable potential in drug delivery therapeutics.

BSA Protein-Mediated Synthesis of Hollow Mesoporous Silica Nanotubes, and Their Carbohydrate Conjugates for Targeting Cancer Cells and Detecting Mycobacteria.

A straightforward method was developed to synthesize hollow mesoporous silica nanotubes (HMSNTs) using bovine serum protein (BSA) as the protective coating and phosphate buffered saline (PBS) as the etching agent at room temperature. Galactose-grafted HMSNTs significantly reduced phagocytosis by macrophages, and enhanced cellular uptake by A549 cells via caveolae-mediated uptake pathway. Trehalose-conjugated HMSNTs interacted strongly with mycobacteria, showing the linear detection range from 1 × 104 to 1 × 108 bacteria/mL and the detection limit of 1 × 103 bacteria/mL. In all cases, the hollow nanotube structure showed higher cellular uptake, bacterial binding, and detection efficiency than their spherical counterpart.