Nanoscience and nanotechnology

Review

Synthetic nanoparticles for delivery of radioisotopes and radiosensitizers in cancer therapy

Radiotherapy has been, and will continue to be, a critical modality to treat cancer. Since the discovery of radiation-induced cytotoxicity in the late 19th century, both external and internal radiation sources have provided tremendous benefits to extend the life of cancer patients. Despite the dramatic improvement of radiation techniques, however, one challenge persists to limit the anti-tumor efficacy of radiotherapy, which is to maximize the deposited dose in tumor while sparing the rest of the healthy vital organs. Nanomedicine has stepped into the spotlight of cancer diagnosis and therapy during the past decades. Nanoparticles can potentiate radiotherapy by specifically delivering radionuclides or radiosensitizers into tumors, therefore enhancing the efficacy while alleviating the toxicity of radiotherapy. This paper reviews recent advances in synthetic nanoparticles for radiotherapy and radiosensitization, with a focus on the enhancement of in vivo anti-tumor activities. We also provide a brief discussion on radiation-associated toxicities as this is an area that, up to date, has been largely missing in the literature and should be closely examined in future studies involving nanoparticle-mediated radiosensitization.

Jun Zhao, Min Zhou, and Chun Li

Review

Guiding osteogenesis of mesenchymal stem cells using carbon-based nanomaterials

In the field of regenerative medicine, stem cells are highly promising due to their innate ability to generate multiple types of cells that could replace/repair damaged parts of human organs and tissues. It has been reported that both in vitro and in vivo function/survival of stem cells could significantly be improved by utilizing functional materials such as biodegradable polymers, metal composites, nanopatterns and nanohybrid particles. Of various biocompatible materials available for use in stem cell-based therapy and research, carbon-based materials—including fullerenes graphene/graphene oxide and carbon nanotubes—have been found to possess unique physicochemical characteristics that contribute to the effective guidance of stem cell differentiation into specific lineages. In this review, we discuss a number of previous reports that investigated the use of carbon-based materials to control stem cell behavior, with a particular focus on their immense potential to guide the osteogenesis of mesenchymal stem cells (MSCs). We hope that this review will provide information on the full potential of using various carbon-based materials in stem cell-mediated regenerative therapy, particularly for bone regeneration and repair.

Ee-Seul Kang†, Da-Seul Kim†, Intan Rosalina Suhito†, Sung-Sik Choo, Seung-Jae Kim, Inbeom Song and Tae-Hyung Kim

†Contributed equally

Large-area fluidic assembly of single-walled carbon nanotubes through dip-coating and directional evaporation

We present a simple and scalable fluidic-assembly approach, in which bundles of single-walled carbon nanotubes (SWCNTs) are selectively aligned and deposited by directionally controlled dip-coating and solvent evaporation processes. The patterned surface with alternating regions of hydrophobic polydimethyl siloxane (PDMS) (height ~ 100 nm) strips and hydrophilic SiO₂ substrate was withdrawn vertically at a constant speed (~3 mm/min) from a solution bath containing SWCNTs (~0.1 mg/ml), allowing for directional evaporation and subsequent selective deposition of nanotube bundles along the edges of horizontally aligned PDMS strips. In addition, the fluidic assembly was applied to fabricate a field effect transistor (FET) with highly oriented SWCNTs, which demonstrate significantly higher current density as well as high turn-off ratio (T/O ratio ~ 100) as compared to that with randomly distributed carbon nanotube bundles (T/O ratio ~ <10).

Pilnam Kim and Tae June Kang

Self-propagating reactive Al/Ni nanocomposites for bonding applications

Highly reactive integrated material systems have recently gained attention, as they promise a feasible tool for heterogeneous integration of micro electromechanical systems. As integrated energy sources they can be used to join heterogeneous materials without applying too much thermal stress to the whole device. An alternative approach is proposed, comprising a single layer of a reactive nanocomposite made of intermixed metal nanoparticles, instead of multilayer systems. In this study the development of the reactive nanocomposite from choice of materials through processing steps, handling and application methods are described. Eventually the results of the experiments upon the reactivity of the nanocomposites and the feasibility for bonding applications are presented. Analysis of the composites was performed by phase-analysis using x-ray diffraction and reaction propagation analysis by high-speed imaging. Composition of products was found to vary with initial particle sizes. Beside of other phases, the dominant phase was intermetallic NiAl.

Matthias P. Kremer, Ali Roshangias, and Andreas Tortschanoff

Review

Recent Advances of Graphitic Carbon Nitride-Based Structures and Applications in Catalyst, Sensing, Imaging, and LEDs

The graphitic carbon nitride (g-C₃N₄) which is a two-dimensional conjugated polymer has drawn broad interdisciplinary attention as a low-cost, metal-free, and visible-light-responsive photocatalyst in the area of environmental remediation. The g-C₃N₄-based materials have excellent electronic band structures, electron-rich properties, basic surface functionalities, high physicochemical stabilities and are “earth-abundant.” This review summarizes the latest progress related to the design and construction of g-C₃N₄-based materials and their applications including catalysis, sensing, imaging, and white-light-emitting diodes. An outlook on possible further developments in g-C₃N₄-based research for emerging properties and applications is also included.

Aiwu Wang, Chundong Wang, Li Fu, Winnie Wong-Ng, and Yucheng Lan