Characterization and Analytical Separation of Fluorescent Carbon Nanodots

Abstract

Carbon nanodots (C-dots) are recently discovered fluorescent carbon nanoparticles with typical sizes of <10 nm. The C-dots have been reported to have excellent photophysical and chemical characteristics. In recent years, the advances in the development and improvement in C-dots synthesis, characterization, and applications are burgeoning. In this review, we introduce the most commonly used techniques for the characterization of C-dots. The characterization techniques for C-dots are briefly classified, described, and illustrated with applied examples. In addition, the analytical separation methods for C-dots (including electrophoresis, chromatography, density gradient centrifugation, differential centrifugation, solvent extraction, and dialysis) are included and discussed according to their analytical characteristics. The review concludes with an outlook towards the future developments in the characterization and the analytical separation of C-dots. The comprehensive overview of the characterization and the analytical separation techniques will safeguard people to use each technique more wisely.

Carbon Dots: Classification, Properties, Synthesis, Characterization, and Applications in Health Care—An Updated Review (2018–2021)

“…When compared to other microscopies, AFM offers two-dimensional (2D) as well as three-dimensional (3D) information from the images of CDs. The dimensions of CDs can be measured via random computation of the particles' heights on the 2D images, whereas 3D images determine the morphology of the surface of CDs [153][154][155]. The 2D and 3D topographical AFM images of CDs are illustrated in Figure 4A,B, respectively.…”

“…The ratio of the distance between the objective lens, the CD specimen, and the image plane are considered as magnified by the lens. Precise particle size of bright field images as well as dark field images are provided by the TEM, and it gives details about the morphology, composition, and crystallographic information of CDs as it utilizes energetic electrons [104,155,159]. Nowadays, high resolution TEM (HRTEM) is broadly employed for studying the lattice and surface imperfections of CDs.…”

“…Nowadays, high resolution TEM (HRTEM) is broadly employed for studying the lattice and surface imperfections of CDs. HRTEM generates an interference image by using scattered as well as transmitted beams [155]. The examples of TEM and HRTEM images of CDs are depicted in Figure 4E,F, respectively [158].…”

High-performance size exclusion chromatography with online fluorescence and multi-wavelength absorbance detection for isolation of high-purity carbon dots fractions, free of non-fluorescent material

“…Currently, a number of methods were suggested for CDs separation and purification including electrophoretic techniques, ultrafiltration and dialysis, solvent extraction, density gradient centrifugation or differential centrifugation, reverse phase, and anion exchange highperformance liquid chromatography [15][16][17][18][19]. Due to the fact that most as-prepared CD mixtures contain nanoparticles of different sizes, size-exclusion chromatography (SEC) becomes one of the most promising methods for the task.…”

Precursor Concentration Effect on Optical Properties of Carbon Dots from Cassava’s Peels

“…Top-down methods include the method of arc discharge, laser ablation, electrochemical oxidation, chemical oxidation,and ultrasonic synthesis. The method bottom-up uses atoms or molecules that form the desired nanometer-sized particles, such as microwave synthesis, thermal decomposition, hydrothermal treatment, templated routes, and plasma treatment (Baker & Baker, 2010;Goryacheva, Sapelkin, & Sukhorukov, 2017;Hu, Gong, Liu, & Choi, 2017;Liu, Zhao, & Zhang, 2014;R. Wang, Lu, Tang, & Xu, 2017).…”