Low-energy cathodoluminescence microscopy for the characterization of nanostructures

Abstract

Spatially and spectrally resolved low-energy cathodoluminescence (CL) microscopy was applied to the characterization of nanostructures. CL has the advantage of revealing not only the presence of luminescence centers but also their spatial distribution. The use of electrons as an excitation source allows a direct comparison with other electron-beam techniques. Thus, CL is a powerful method to correlate luminescence with the sample structure and to clarify the origin of the luminescence. However, caution is needed in the quantitative analysis of CL measurements. In this review, the advantages of cathodoluminescence for qualitative analysis and disadvantages for quantitative analysis are presented on the example of nanostructures.     

Nanofabrication with Pulsed Lasers

An overview of pulsed laser-assisted methods for nanofabrication, which are currently developed in our Institute (LP3), is presented. The methods compass a variety of possibilities for material nanostructuring offered by laser–matter interactions and imply either the nanostructuring of the laser-illuminated surface itself, as in cases of direct laser ablation or laser plasma-assisted treatment of semiconductors to form light-absorbing and light-emitting nano-architectures, as well as periodic nanoarrays, or laser-assisted production of nanoclusters and their controlled growth in gaseous or liquid medium to form nanostructured films or colloidal nanoparticles. Nanomaterials synthesized by laser-assisted methods have a variety of unique properties, not reproducible by any other route, and are of importance for photovoltaics, optoelectronics, biological sensing, imaging and therapeutics.     

Enhancing Solar Cell Efficiencies through 1-D Nanostructures

The current global energy problem can be attributed to insufficient fossil fuel supplies and excessive greenhouse gas emissions resulting from increasing fossil fuel consumption. The huge demand for clean energy potentially can be met by solar-to-electricity conversions. The large-scale use of solar energy is not occurring due to the high cost and inadequate efficiencies of existing solar cells. Nanostructured materials have offered new opportunities to design more efficient solar cells, particularly one-dimensional (1-D) nanomaterials for enhancing solar cell efficiencies. These 1-D nanostructures, including nanotubes, nanowires, and nanorods, offer significant opportunities to improve efficiencies of solar cells by facilitating photon absorption, electron transport, and electron collection; however, tremendous challenges must be conquered before the large-scale commercialization of such cells. This review specifically focuses on the use of 1-D nanostructures for enhancing solar cell efficiencies. Other nanostructured solar cells or solar cells based on bulk materials are not covered in this review. Major topics addressed include dye-sensitized solar cells, quantum-dot-sensitized solar cells, and p-n junction solar cells.     

Self‐Assembled Aptamer‐Nanomedicine for Targeted Chemotherapy and Gene Therapy

Chemotherapy is the mainstream treatment of anaplastic large cell lymphoma (ALCL). However, chemotherapy can cause severe adverse effects in patients because it is not ALCL‐specific. In this study, a multifunctional aptamer‐nanomedicine (Apt‐NMed) achieving targeted chemotherapy and gene therapy of ALCL is developed. Apt‐NMed is formulated by self‐assembly of synthetic oligonucleotides containing CD30‐specific aptamer and anaplastic lymphoma kinase (ALK)‐specific siRNA followed by self‐loading of the chemotherapeutic drug doxorubicin (DOX). Apt‐NMed exhibits a well‐defined nanostructure (diameter 59 mm) and stability in human serum. Under aptamer guidance, Apt‐NMed specifically binds and internalizes targeted ALCL cells. Intracellular delivery of Apt‐NMed triggers rapid DOX release for targeted ALCL chemotherapy and intracellular delivery of the ALK‐specific siRNA induced ALK oncogene silencing, resulting in combined therapeutic effects. Animal model studies reveal that upon systemic administration, Apt‐NMed specifically targets and selectively accumulates in ALCL tumor site, but does not react with off‐target tumors in the same xenograft mouse. Importantly, Apt‐NMed not only induces significantly higher inhibition in ALCL tumor growth, but also causes fewer or no side effects in treated mice compared to free DOX. Moreover, Apt‐NMed treatment markedly improves the survival rate of treated mice, opening a new avenue for precision treatment of ALCL.     

Synthesis of palladium dendritic nanostructures on amidoxime modified polyacrylonitrile fibers through a complexing-reducing method

In this paper, three-dimensional fern-leaf-like palladium (Pd) dendritic nanostructures were successfully synthesized on amidoxime modified polyacrylonitrile fibers via a simple and efficient complexing-reducing method. The influence of reaction time, temperature, and concentrations of N₂H₄ and Fe³⁺ on the morphology and structure of Pd nanostructures was investigated. The results indicate that the supply rate of metallic Pd atoms plays a crucial role in the formation of the dendritic nanostructures. The formation mechanism of Pd dendritic nanostructures was proposed.     

Recent Highlights in the Synthesis,Structure, Properties,and Applications of MoS2 Nanotubes

Since the discovery that non-carbon nanotubes can also be synthesized like those of carbon there has been a lot of interest generated in this area, specifically in the case of the transition metal chalcogenide nanotubes. This paper will showcase MoS₂ nanotubes, addressing the advances in terms of the synthesis, properties, and applications that have been observed so far. An update on the current status of the field, including the use of aberration-corrected microscopic techniques in understanding the structure and bonding of these nanotubes, which have been proved to be elusive until recently, will be highlighted. Finally, the catalytic properties of these nanotubes will be addressed in the context of the other possible applications as well.