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Microscopy of the Heart || Optogenetic Tools in the Microscopy of Cardiac Excitation-Contraction Coupling
摘要： Microscopy became a scienti?c investigation method in the seventeenth century with the application of the ?rst build microscopes on biological samples [1, 2]. Soon it became a popular method to stain samples in order to visualise particular (cellular and subcellular) structures [3]. These stains, either based on absorption or ?uorescence, have limitations in respect to their speci?city and are often toxic to cells, which limits investigations to short intervals or even dead samples. In 1987 the idea came up to use a ?uorescent protein that was discovered 25 years before [4], in particular a green ?uorescent protein (GFP) form the medusa Aequorea victoria to label cells and cellular structures [5]. With the sequencing and cloning of GFP, a so-called ‘green revolution’ started, which led to regular usage of ?uorescent proteins as markers or sensors (for details see below) in the majority of cellular research in physiology, microbiology, pharmacology, molecular biology, anatomy, cell biology, biophysics and many other biomedical ?elds. Although the expression of the ?uorescent proteins and their optical investigation can already be regarded as optogenetic tools, this term was only applied when the optical properties of proteins were used to manipulate cells. The best-known example of such a protein is the channelrhodopsin, a light-gated ion channel [6, 7]. When this ion channel is expressed in a membrane and illuminated with light of the appropriate wavelength, the channel will be activated and opened, which results in passive transportation of ions across the membrane and a change of the membrane potential. However, within this chapter we consider both aspects, the observation and the manipulation as optogenetic tools. To use the optogenetic tool, the genes of these proteins need to be transferred into the cells to allow the expression of the protein. For an overview of gene delivery into target cells, see [8].
关键词： channelrhodopsins,cardiac excitation-contraction coupling,F?rster Resonance Energy Transfer,genetically encoded biosensors,Optogenetic tools,microscopy
更新于2025-09-04 15:30:14
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Graphene Oxide as an Optical Biosensing Platform: A Progress Report
摘要： A few years ago, crucial graphene oxide (GO) features such as the carbon/oxygen ratio, number of layers, and lateral size were scarcely investigated and, thus, their impact on the overall optical biosensing performance was almost unknown. Nowadays valuable insights about these features are well documented in the literature, whereas others remain controversial. Moreover, most of the biosensing systems based on GO were amenable to operating as colloidal suspensions. Currently, the literature reports conceptually new approaches obviating the need of GO colloidal suspensions, enabling the integration of GO onto a solid phase and leading to their application in new biosensing devices. Furthermore, most GO-based biosensing devices exploit photoluminescent signals. However, further progress is also achieved in powerful label-free optical techniques exploiting GO in biosensing, particularly using optical fibers, surface plasmon resonance, and surface enhanced Raman scattering. Herein, a critical overview on these topics is offered, highlighting the key role of the physicochemical properties of GO. New challenges and opportunities in this exciting field are also highlighted.
关键词： bioanalytical applications,2D materials,label-free biosensors,optical devices,physicochemical properties
更新于2025-09-04 15:30:14