Stem cells: Small 3/2010Collins, John M.; Ayala, Perla; Desai, Tejal A.; Russell, Brenda
doi: 10.1002/smll.201090005pmid: N/A
The cover picture shows several human mesenchymal stem cells (green with blue nuclei) clustered around a stiff polymeric microstructure (blue) in a three‐dimensional matrix. The microstructures are fabricated using photolithographic techniques and then suspended with stem cells in the matrix. The stem cells migrate and attach to the microstructures, and although the volume percentage of the microstructures within the matrix is quite low (0.07%), stem‐cell morphology, clustering, and gene expression are significantly different compared to without the microstructures. The knowledge of how physical and mechanical cues in three dimensions can influence cellular function is necessary for the development of novel platforms for regenerative therapy. For more information, please read the Communication “Three‐Dimensional Culture with Stiff Microstructures Increases Proliferation and Slows Osteogenic Differentiation of Human Mesenchymal Stem Cells by B. Russell et al., beginning on page 355.
Microparticles: Small 3/2010Bhaskar, Srijanani; Pollock, Kelly Marie; Yoshida, Mutsumi; Lahann, Joerg
doi: 10.1002/smll.201090004pmid: N/A
The cover image depicts a collage of confocal laser scanning micrographs and scanning electron micrographs of biodegradable bicompartmental microparticles of different shapes and sizes made from poly(lactide‐co‐glycolide) produced via electrohydrodynamic co‐jetting. In this process, two polymer solutions labeled with different fluorophores are introduced via two parallel capillaries to generate a composite “bicompartmental” droplet. Application of an electric field results in an electrified jet, wherein solvent evaporation causes the formation of particles, which are confined in bicompartmental architecture. Control over the solution and process parameters creates an array of particle sizes and controls the shapes of the bicompartmental particles. Such particles may find applications in drug delivery, diagnostics, and biosensing. For more information, please read the Full Paper “Towards Designer Microparticles: Simultaneous Control of Anisotropy, Shape, and Size” by J. Lahann et al., beginning on page 404.
Nanocrystal formation: Small 3/2010Lopez, Aitziber Eleta; Moreno‐Flores, Susana; Pum, Dietmar; Sleytr, Uwe B.; Toca‐Herrera, José L.
doi: 10.1002/smll.201090007pmid: N/A
The frontispiece shows four different stages of bacterial nanocrystal formation on 3‐aminopropyltriethoxysilane, measured in situ with an atomic force microscope. The growth of protein patches due to individual protein self‐assembly can be seen at the border of the crystal patch. Bacterial S‐layer proteins are able to self‐assemble on many different surfaces to form nanostructured biomimetic crystals. Substrate hydrophobicity affects protein adsorption rate and crystal domain size but has no influence on the protein layer thickness, the crystal‐lattice parameters, or the final adsorbed mass density. The S‐protein crystal formation occurs in three steps: nucleation, growth (self‐assembly), and domain reorganization. For more information, please read the Full Paper ‘Surface Dependence of Protein Nanocrystal Formation” by J. L. Toca‐Herrera et al., beginning on page 396.
Motion Control at the NanoscaleWang, Joseph; Manesh, Kalayil Manian
doi: 10.1002/smll.200901746pmid: 20013944
Synthetic nanoscale motors represent a major step in the development of practical nanomachines. This Review summarizes recent progress towards controlling the movement of fuel‐driven nanomotors and discusses the challenges and opportunities associated with the achievement of such nanoscale motion control. Regulating the movement of artificial nanomotors often follows nature's elegant and remarkable approach for motion control. Such on‐demand control of the movement of artificial nanomotors is essential for performing various tasks and diverse applications. These applications require precise control of the nanomotor direction as well as temporal and spatial regulation of the motor speed. Different approaches for controlling the motion of catalytic nanomotors have been developed recently, including magnetic guidance, thermally driven acceleration, an electrochemical switch, and chemical stimuli (including control of the fuel concentration). Such ability to control the directionality of artificial nanomotors and to regulate their speed offers considerable promise for designing powerful nanomachines capable of operating independently and meeting a wide variety of future technological needs.
Functional Single‐Virus–Polyelectrolyte Hybrids Make Large‐Scale Applications of Viral Nanoparticles More EfficientWang, Xiaoyu; Deng, Yongqiang; Shi, Hongyan; Mei, Zhu; Zhao, Hui; Xiong, Wei; Liu, Peng; Zhao, Yu; Qin, Chengfeng; Tang, Ruikang
doi: 10.1002/smll.200901795pmid: 20077422
Single enveloped viruses can be prepared on a large scale with high efficiency by a layer‐by‐layer method. The virus/polyelectrolyte core/shell nanoparticles (VCSPs) exhibit unique characteristics, such as direct observation by electron microscopy without staining, easy separation and concentration, rapid perinuclear delivery, and improved biological safety, which resolve the conventional shortcomings of viruses in nanoscale applications.