![]() Cylinder-shaped SWNTs with diameters as small as a nanometer (or less) can be grown up to 20 cm in length ( Zhu et al., 2002). Structure and Propertiesĭepending on their number of walls, CNTs are designated single-walled (SWNTs) or multi-walled (MWNTs). ![]() These include: (a) synthesis of CNTs with tailored functionalities and uniform morphology (b) modification of CNTs to make them compatible with biological systems (c) detailed study of their interaction with biological environments (toxicity, interaction with single cells) (d) in vivo testing for specific therapeutic and diagnostic purposes such as imaging (contrast agents, markers), sensing (nanoparticle-based diagnostics) and cancer treatment (hyperthermia, drug delivery). Generally, the successful application of CNTs for biomedical tests faces a variety of challenges prerequisites. This feature and the mechanism of internalization and release of CNTs from the cells are of major interest for biological and in particular intracellular biosensing applications. Importantly, functionalized CNTs can effectively cross biological barriers such as the cell membrane and penetrate individual cells ( Pantarotto et al., 2004b). Moreover, CNTs shells can be opened and filled (endohedral functionalization) without losing their stability ( Sloan et al., 1998). Their advantage compared to other nanomaterials lies in a unique combination of electrical, magnetic, optical, mechanical, and chemical properties, which offer great promises for a wide range of applications, including biosensing ( Le Goff et al., 2011 Biju, 2014).īesides, CNTs can serve as platforms to conjugate other compounds at their surface (exohedral functionalization) ( Arkan et al., 2015 Shobha and Muniraj, 2015). They exhibit a well-ordered arrangement of carbon atoms linked via sp 2 bonds, which makes them the stiffest and strongest fibers known. CNTs are hollow carbon structures, with one or more walls, a nanometer scale diameter and a comparatively more important length. Since his first report on multi-walled carbon nanotubes (MWNTs) ( Iijima, 1991), followed by their single-walled counterparts (SWNTs) ( Iijima and Ichihashi, 1993 Journet et al., 1997), CNTs have emerged as one of the most intensively investigated nanostructured materials ( Balasubramanian and Burghard, 2005), with thousands of papers published every year, offering promises for new applications which have attracted both academic and industrial interest. Here we will focus on carbon nanotubes (CNTs), also called buckytubes and first evidenced in 1991 by the Japanese electron microscopist Sumio Iijima. The impact was so huge that its discoverers, Robert Curl Jr., Harold Kroto and Richard Smalley were awarded the Nobel Prize in Chemistry in 1996. Later, the discovery of buckminsterfullerenes (C 60) ( Kroto et al., 1985) marked the beginning of a new era in carbon science. For example lonsdaleite, also called hexagonal diamond, was first identified in 1967 from the Canyon Diablo meteorite, where it occurred as microscopic crystals associated with diamond. After the Second World War, in the middle of the last century, tremendous progress in the science of carbon led to unexpected and fascinating findings. ![]() Fundamental for the living world, carbon has long been known to exist in three allotropic forms: graphite, diamond, and amorphous carbon. History and Introduction to Carbon Nanotubesīrought to our planet from the red giant stars, carbon is a singular element in the periodic table: it can bind itself or other atoms without a great expense of energy. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we describe their structural and physical properties, functionalization and cellular uptake, biocompatibility, and toxicity issues. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Nanomaterials possess unique features which make them particularly attractive for biosensing applications. Cell Cycle Biosensors and Inhibitors, Faculté de Pharmacie, Institut des Biomolécules Max Mousseron, Centre National de la Recherche Scientifique-UMR 5247, Montpellier, France.
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