Nano

Malignant primary brain tumors have a very high morbidity and mortality. Even though enormous advances have been made in primary brain tumor management, in the case of malignant primary brain tumors, current diagnostic strategies cannot identify exact infiltrating margins, surgery alone cannot achieve total mass resection, and adjuvant therapies cannot improve survivals. Therefore, there is an urgent need to explore novel strategies to diagnose and treat such infiltrating brain tumors. Nanomaterials, particularly zero-dimensional and one-dimensional platforms, can carry various compounds such as contrast agents, anticancer drugs and genes into brain tumor cells specifically. Thus, contrast agent-based nanomaterials can selectively present infiltrating tumor outlines, while anticancer agent-based nanomaterials can specifically kill malignant tumor cells. In addition, dual-targeting nanomaterials, multifunctional nanocarriers, theranostic nanovehicles as well as convection-enhanced delivery technology hold promise to increase drug accumulation in tumor tissues, which could largely improve anticancer efficacy. In this review, we will mainly focus on the application of nanomaterials in preoperative diagnosis, intraoperative diagnosis and adjuvant treatment for malignant primary brain tumors.

We directly visualized the uptake and intracellular vesicle transport of shortened single walled carbon nanotubes in living cells through a dual-labeling system. With a stable labeling of fluorescein isothiocyanate and a pH-sensitive stacking of doxorubicin on carbon nanotubes, the location of internalized nanotubes inside the cell and the microenvironment especially the pH change of the nanotube-embedded vesicles could be monitored at the same time. Results showed that after internalization through endocytic pathway, carbon nanotubes tended to transport from the early endosomes to later acidic lysosomes and these vesicles moved along the microtubule track toward a perinuclear region where is a microtubule-organizing center. These results might provide a novel understanding for the intracellular interaction of carbon nanotubes and living cells.

By acoustically irradiating pristine, white, electrically insulating h-BN in aqueous environment we were able to invert its material properties. The resulting dark, electrically conductive h-BN (referred to as partially oxidized h-BN or PO-hBN) shows a significant decrease in optical transmission (>60%) and bandgap (from 5.46 eV to 3.97 eV). Besides employing a wide variety of analytical techniques (optical and electrical measurements, Raman spectroscopy, SEM imaging, EDS, X-Ray diffraction, XPS and TOF-SIMS) to study the material properties of pristine and irradiated h-BN, our investigation suggests the basic mechanism leading to the dramatic changes following the acoustic treatment. We find that the degree of inversion arises from the degree of h-BN surface or edge oxidation which heavily depends on the acoustic energy density provided to the pristine h-BN platelets during the solution-based process. This provides a facile avenue for the realization of materials with tuned physical and chemical properties that depart from the intrinsic behavior of pristine h-BN.

CNTs–TiO₂ films with different morphology were fabricated on stainless steel substrates through chemical vapor hydrolysis deposition (CVHD) process and sol–gel process, respectively. Their morphology was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The photocatalytic properties of the films were tested in the degradation of methyl orange by UV light irradiation. The results revealed that TiO₂ nanoparticles could form a continuous layer on the surface of CNTs through CVHD process. While for sol–gel process, most TiO₂ nanoparticles were isolated and only a small amount of TiO₂ nanoparticles attached on the surface of CNTs. And the photocatalytic property of TiO₂/CNTs film synthesized through CVHD process was better than that of TiO₂/CNTs films synthesized through sol–gel process. Electrochemical impedance spectroscopy (EIS) analysis illuminated that TiO₂/CNTs synthesized through CVHD process displayed a smaller resistance than the sample which was synthesized through sol–gel process and certified that the close combination between TiO₂ and CNTs could minimize recombination of photogenerated electrons and holes, and thus promote the photocatalytic property.

Two nanocontact models with different initial contact locations are built to simulate the process of the multiasperity nanocontact for investigating the effect of initial contact location on the nanocontact process by using the quasicontinuum method. The indenter is initially located on the top of the middle wave crest (MWC) of the substrate and the top of the wave trough on the left side (LWT) of the substrate, respectively. The microscopic deformation mechanism, the load–displacement curve and the nanohardness–displacement curve are examined. It is found that the deformation mechanisms in the two multiasperity contact models are different. During the initial contact stage, in the MWC model, the twinning deformation dominates the whole contact process, while in the LMT model many Lomer-Cottrell locks are generated in the copper substrate, which inhibits the occurrence of twinning deformation.

A series of monodisperse Ag nanoparticles (Ag NPs), whose size can be tuned between 2 nm and 34 nm, have been successfully synthesized in one pot by controlling the growth time. The standard deviation of the small-size Ag NPs is 12% while that of the large-size ones is 15%. During the synthesis process, sodium borohydride and sodium dodecyl sulfate were used as reducing agent and surfactant, respectively, and the effect of the synthesis parameters on the size-tuning range and the size distribution of Ag NPs was studied to get the optimum growth condition. Moreover, surface enhanced Raman scattering (SERS) spectra were analyzed to explore the synthesis mechanism of Ag NPs.

The adsorption and diffusion of oxygen atom on the O-terminated ZnO surface have been systematically investigated based on first-principles density functional theory. The results show that the surface relaxation of the ZnO surface is significant. In the view of the maximization of the adsorption energy, the preferred site for the adsorption of oxygen atom is the top-O site above the oxygen atom of the first Zn–O bilayer. There is chemical bond formed between the adsorbed oxygen atom and the oxygen atom on the surface, which will result in the redistribution of the charges. The charges transfer from the ZnO surface to the adsorbed oxygen atom, which will heighten the surface potential of ZnO surface and increase the surface work function. Moreover, the diffusion of the oxygen atom on the ZnO surface has also been investigated, and the potential barriers of the diffusion have been identified to reveal the adsorption stability.

Lanthanide-doped luminescent nanoscale materials have great potential applications in biological researches. Herein, we reported a novel and mild method for one-step synthesis of chitosan/NaGdF₄:Eu³⁺ nanocomposites. The luminescent Eu³⁺ ions and magnetic resonance imaging (MRI) contrast agent Gd³⁺ ions were incorporated to these biocompatible nanocomposites. The resultant nanocomposites exhibited strong fluorescence and attractive magnetic features. The nanocomposites also have pure hexagonal phase with uniform size of about 65 nm. FT-IR spectra revealed that these nanocomposites were successfully coated by hydrophilic chitosan, whose amine groups conferred the nanocomposites excellent dispensability in aqueous solution. Besides, the MTT assay and laser confocal microscopy images have confirmed the good biocompatibility of the nanocomposites. These results indicated that the as-prepared nanocomposites could be used as an excellent targeted imaging agent in biological fields.

Nearly monodisperse CaWO₄ and CaWO₄:Eu³⁺ microspheres have been synthesized in large scale by a surfactant-assisted solution route, in which cetyltrimethyl ammonium bromide (CTAB) is used. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and photoluminescence (PL) were used to characterize the resulting samples. The results of XRD indicate that the CaWO₄ and CaWO₄:Eu³⁺ samples have the scheelite structures. The growth process of these nearly monodisperse spheres with an average diameter around 3.2 μm has been examined. The results of FTIR indicate that CTAB plays an important role in the formation of microspheres. The CaWO₄ microspheres exhibit a blue emission band with a maximum at 423 nm. But the CaWO₄:Eu³⁺ microspheres exhibit a red emission band with a maximum at 623 nm.

Superparamagnetic iron oxide nanoparticles (SPIONs) are used in many biological applications, which necessitate intracellular targeting. Here, we investigate intracellular localization and gene expression in HeLa cells after treatment with functionalized SPIONs. Functional groups investigated included positive amino propyl silane (APS), polyethylene glycol and targeting peptides: nuclear targeting peptide (NTP) and/or cancer cell uptake promoting peptide (cRGD). Results revealed that the intracellular localization of SPIONs was strongly dependent on the surface chemistry. Nuclear targeted SPIONs functionalized with only NTP or both NTP and cRGD were mostly localized in perinuclear endosomes with a small fraction entering the nucleus. The biocompatibility of cells after treatment was also dependent on surface chemistry, where SPIONs functionalized with both NTP and cRGD exhibited a more significant reduction of cell proliferation compared to NTP or cRGD individually. Interestingly, gene expression after treatment with SPIONs was similar, regardless of the surface functionalization or intracellular localization. The results of this study showed that cellular uptake and intracellular localization predominantly depended on the surface chemistry, while gene expression exhibited a more generic response to SPION treatment.

We report the one step facile synthesis of graphene nanoribbons (GNRs) by unzipping carbon nanotubes (CNTs) from glucose (C₆H₁₂O₆) precursor, using a simple chemical vapor deposition method. Some nanotubes are partially cut resulting in a GNR–CNT hybrid whereas others are fully cut to form GNRs. The average length of GNRs achieved by this method is typically in the range of 1–10 μm. The formation of GNRs is ascribed to the in situ oxygen-driven unzipping of CNTs. The process is free from aggressive oxidants and utilizes the in situ unzipping. This method offers an alternative approach for making GNRs, compared to previously used techniques to synthesize GNRs.

Functionally graded multiwalled carbon nanotube (MWCNT) reinforced epoxy matrix composites are fabricated using a centrifugal method. Aggregation of the MWCNTs during the epoxy curing process is prevented using a two-step aminosilane modification. Chemical interaction of the silane with the oxidized nanotube surface is confirmed using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Raman spectroscopy of acid-treated MWCNTs corroborates the formation of surface defects owing to the introduction of carboxyl groups. The mechanical and microwave absorption property gradients of the composites correspond with those produced via silane modification indicating potential application to microwave absorbing materials. The MWCNTs are better dispersed in the epoxy resin after the modification, making it possible for them to become efficiently graded in the epoxy matrix. We therefore show that it is possible to fabricate functionally graded nanofiller-reinforced materials using the centrifugal method by modifying the surface of the nanofiller.