Nanobioimaging

Optical far-field microscopy such as confocal fluorescence microscopy is a very popular technique for investigating the living cell. Unfortunately, its spatial resolution is limited to around 200 nm, impeding the imaging of small molecular assemblies. Recent decades have seen the development of optical nanoscopy, optical far-field microscopy with a spatial resolution down to molecular scales. STED microscopy was the first of such nanoscopy techniques. Despite the fact, that it in principle only requires the addition of a strong STED laser to a conventional microscope, STED nanoscopy was for a long time considered as a very complex technique, impossible to be applicable as a turn-key technique in everyday biological research. However, recent years has seen important improvements of the STED nanoscopy approach which have significantly simplified the setup. These developments mainly followed from optimization of fluorescent labels, laser technology and optical simplifications. As a result, STED microscopy setups have got more compact and have been realized on commercial instruments, allowing access to lessexperienced users in open imaging facilities. Here, we give a brief overview of the recent improvements in STED microscopy that made these important developments possible.

Many plant systems accumulate silica in solid form, creating intracellular or extracellular silica bodies (phytoliths) that are essential for growth, mechanical strength, rigidity, predator and fungal defence, stiffness and cooling. Silica is an inorganic amorphous oxide formed by polymerization processes within plants. There has been much research to gain new insights into its biochemistry and to mimic biosilicification. We review the background on plant silica bodies, silica uptake mechanisms and applications, and suggest possible ways of producing plant silica bodies with new functions. Silica bodies offer complementary properties to diatoms for nanotechnology, including large-scale availability from crop wastes, lack of organic impurities (in some), microencapsulation and microcrystalline quartz with possibly unique optical properties.