Carbon nanodots (CNDs): a comprehensive study of the photoluminescence, antioxidation and cellular uptake

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Wendi Zhang (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Jianjun Wei

Abstract: Carbon Nanodots (CNDs) have attracted increasing attention owing to their excellent photoluminescence properties, antioxidation activity, lower toxicity and superior water solubility. These physiochemical properties make CNDs promising candidates for biomedical applications including bioimaging, antioxidative agent and drug delivery, etc. However, the lack of consistency of understanding the fluorescence emission and antioxidation reactions in CNDs impedes their practical development in biomedical applications. Moreover, for CNDs cellular uptake study, there are rare reports on the nucleus penetrability of CNDs. Most uptake mechanisms focus on different types of nanoparticles (e.g. metal NPs or quantum dots). Little is known about the cellular uptake of CNDs especially the concentration influence. This dissertation research attempts to address these issues focusing on three aspects. (1) A new approach combining fluorescence spectroscopy and electrochemistry and energy gap analysis are used to investigate the photoluminescence mechanism of CNDs. (2) Electrochemistry and spectroscopy measurement are performed to investigate the antioxidative activities of CNDs against free radical DPPH• and reactive oxygen species (ROS) generated by xanthine/xanthine oxidase (XO) reaction. (3) nucleus penetrability of CNDs cell uptake is investigated with respect to CNDs’ concentration. We found that the excitation dependent fluorescence of the CNDs may be attributed to multiple energy gap levels arising from a combination of the Sp2 carbon core, surface functionalities (C=O, C–O, and COOH), and surface electronic state transitions. Regarding the antioxidative property, the result ofelectrochemical study for DPPH• scavenging is consistent with UV-Vis absorbance dose dependent manner following a coupled hydrogen atom transfer (HAT) reaction mechanism by the CNDs. For the cellular uptake of CNDs, a three-stage mechanism is proposed to explain the observation of concentration-dependent behavior of the nucleus penetrability. Overall, this comprehensive study of the photoluminescence, antioxidation and cellular uptake of CNDs and the findings should aid future development of practical utilization in bioimaging, antioxidation and drug delivery, such as in-vitro and in-vivo studies.

Additional Information

Language: English
Date: 2019
Carbon nanodots, Cellular uptake, Electrochemistry, Photo-luminescence

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