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Figure 1. Image of 200 nm polystyrol particles in confocal (A) and stimulated emission depletion microscopy (B) mode. Reproduced with permission from Jan Schroeder, Leica-Microsystems, Mannheim, Germany.
(Figure omitted. See article PDF.)
Figure 2. 3D reconstruction of nanoparticle uptake. (A) 3D data set of A549 cells incubated with 50 nm gold particles and (B) 3D reconstruction of one cell from a 3View data set with OpenCar. Reconstruction includes cell membrane, nucleus, lipid drops and gold nanoparticles (smallest objects). Parts (A) and (B) reproduced with permission from Sandy Monteith, Gatan, Inc., Abingdon, UK, and Kurt Saetzler, University of Ulster, UK, respectively.
(Figure omitted. See article PDF.)
Figure 3. Transmission electron microscopy image of A549 lung epithelial cells incubated with 50 nm gold nanoparticles overlaid with an unbiased counting frame.
(Figure omitted. See article PDF.)
In science, quantification is one of the main driving forces underlying the understanding and description of nature. Quantification has been an essential and highly successful strategy prefacing the discovery of general principles and laws. As a consequence, the concept of 'exact science' has been coined to describe research areas where strict quantifiable results are desired [1]. A key requirement for sound quantification is reproducibility of measurements, which in biology and medicine sometimes proves difficult, mainly due to the complexity of living systems and the often unavoidable experimental variability [2]. Since engineered nanoparticles and nanotechnology emerged approximately 20 years ago, research and industry have focused on nonbiological structures and their manipulation, very much as predicted by Richard Feynman in one of his lectures on this subject [3]. Industrial applications and commercialization had already stimulated interest in nanotechnology at this early stage [4] and helped it to grow quickly. The discovery and design of nanostructures and nanodevices have promised huge technological potential, not only simply due to miniaturization but also to novel material characteristics at the nanoscale [5]. As a parallel development, concomitant biotechnology evolved as an exciting field with opportunities for biology and medicine [6], and synergistic developments between bio- and nano-technology provided new stimuli to both fields [7]. In biology, the initial research has focused on basic interaction mechanisms between engineered nanomaterials and living systems [8]. This soon led to the development of nanoparticles as nanomedical devices [9-11]. However, investigation and...