title: Opportunities and Challenges of Fluorescent Carbon Dots in Translational Optical Imaging.
abstract: The fluorescent carbon dot (C-dot) is a new class of carbon nanomaterials. It has a discrete or quasispherical structure, typically measures less than 10 nm and contains sp(2)/sp(3) carbon, oxygen/nitrogen-based groups and surface-modified functional groups. Compared with semiconductor quantum dots (QDs), C-dots offer much lower toxicity and a better biocompatibility profile. Their other favorable features include easy and inexpensive synthesis and surface modification potential. C-dots can be morphologically classified into graphene-based quantum dots (GQDs) and amorphous carbon nanodots (ACNDs). Numerous methods have been developed to synthesize C-dots, and are mainly divided into 'top-down' and 'bottom-up' routes. In the top-down route, C-dots (mostly GQDs) is derived from the separation of large carbon precursors. The 'bottom-up' method primarily involves the dehydration, polymerization and carbonization of small molecules to form the GQDs and ACNDs through thermal/hydrothermal synthesis, microwave irradiation, and solution chemistry. Potential applications of C-dots have been explored in a number of cellular and in-vivo imaging approaches. However, some difficulties remain, including limited penetration depth and poorly controlled in-vivo pharmacokinetics, which depends on multiple factors such as the morphology, physiochemical properties, surface chemistry and formulation of C-dots. The exact mechanism of in-vivo biodistribution, cellular uptake and long-term toxicological effect of C-dots still need to be elucidated. An integrated multi-disciplinary approach involving chemists, pharmacologists, toxicologists, clinicians, and regulatory bodies at the early stage is essential to enable the clinical application of C-dots.
authors.forename: Junqing
authors.initials: J
authors.lastname: Wang
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.forename: Ken Cham-Fai
authors.initials: KC
authors.lastname: Leung
authors.forename: Romaric
authors.initials: R
authors.lastname: Loffroy
authors.forename: Pu-Xuan
authors.initials: PX
authors.lastname: Lu
authors.affiliation: Department of Imaging and Interventional Radiology, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong SAR, P.R. China. yixiang_wang@cuhk.edu.hk.
authors.forename: Yì Xiang J
authors.initials: YX
authors.lastname: Wang
mesh_terms: D000818:Animals; D002244:Carbon / Q000008:administration & dosage / Q000737:chemistry*; D005290:Ferric Compounds / Q000008:administration & dosage / Q000737:chemistry; D005456:Fluorescent Dyes / Q000008:administration & dosage / Q000737:chemistry*; D006801:Humans; D061848:Optical Imaging / Q000379:methods*; D045663:Quantum Dots / Q000737:chemistry*
chemical_list: D005290:Ferric Compounds; D005456:Fluorescent Dyes; C000499:ferric oxide; D002244:Carbon