International Materials Reviews

Three-dimensional (3D) cell cultures have recently garnered great attention because they promote levels of cells differentiation and tissue organisation not possible in conventional two-dimensional (2D) culture systems. Cancer development is a complex process regulated by interactions between epithelial cells, activated stromal cells, and soluble and insoluble components of the extracellular matrix (ECM). As a consequence, in the field of cancer biology a 3D tumour model that accurately recreates the in vivo tumour phenotype would be a valuable tool for studying tumour biology and would allow better pre-clinical evaluation of anticancer drug candidates. Here, we review the 3D tumour models currently available and the more advanced techniques from the tissue-engineering field used to create a more clinically accurate ex vivo tumour model. Moreover, we highlight the drastic differences in drug responses between 3D and 2D models and give a glance to the emerging multi-organ microdevices that can mimic in vivo tissue–tissue interactions.

Knowledge about the vibrational characteristics of nanostructures is of fundamental interest, since it is a signature of their morphology and it can be utilised to predict their material properties. Radial breathing-mode (RBM) is a special vibrational mode, displayed by the nanostructures, and can be observed experimentally. Over the past two decades, the study of the RBM of the nanostructures has attracted much attention because of its importance in such applications as structural and material property characterisations. This paper reviews recent theoretical and experimental studies on the RBM frequencies of nanostructures with various morphologies. There is a one-to-one correspondence between the geometrical characteristics of the nanostructures and their RBM frequencies. An overview of the current literature discussing the RBM frequency of carbon nanostructures and their geometrical characterisation is presented first. Authors then discuss the theoretical and experimental studies on the breathing-modes of spherical nanoparticles. Different approaches, which have been utilised to obtain the RBM frequency of circular nanowires, are then reviewed. Finally, conclusions and recommendations for further research in this field are provided. To the best of our knowledge, a specialised review addressing the RBM of the nanostructures has not been available so far. This work is likely to fill this gap.

Lithium-ion batteries (LIBs) with high performance have played indispensable roles in today's portable electronics enabling the highly mobile society with uninterrupted connection; however, their development has lagged far behind the rapid advancement of other technologies including electronic devices and electrical vehicles. The search for better energy storage devices is the investigation of materials with high specific capacity, high-rate capability, and long lasting performance. For LIBs, it is the search for cathode and anode materials with large lithium-ion storage capacity, appropriate charge–discharge voltage, good mass and charge transfer property, and long cyclic stability, in addition to abundance and low processing cost. The common anode material used in current commercial LIBs is graphite, whose theoretical capacity is only 372 mA h g^− 1, much lower than those of silicon, germanium, and tin-based compounds (TBCs). Tin-based compounds have drawn much attention in the field of LIBs because of their advantages in terms of low cost for synthesis and rich source compared with silicon and germanium. However, TBCs as anodes for LIBs suffer from two serious drawbacks: the pulverisation of TBCs arising from the huge volume expansion and contraction change during lithiation/delithiation, and the relatively low Coulombic efficiency owing to the irreversible formation of solid electrolyte interphase (SEI) films, Li₂O or Li₂S. This review paper summarises and analyses a variety of strategies and synthesis methods used to design and create novel nano- and microstructures of TBCs with desired chemical compositions to circumvent above two issues. The discussion focuses mainly on the relationships between various nano- and microstructures and lithium-ion storage properties of TBCs and tries to offer some opinions about the possible future directions of the practical application and research on TBCs as anodes for LIBs.