Fabrication of Graphitic Carbon Nitride Quantum Dots and Their Application for Simultaneous Fluorescence Imaging and pH‐Responsive Drug Release

Abstract

A simple approach is developed to produce fluorescent graphitic carbon nitride quantum dots (g-CNQDs) by refluxing bulk graphitic carbon nitride (g-C 3 N 4 ) in HNO 3 followed by a direct hydrothermal treatment. Owing to their small size, intrinsic optical properties, low toxicity, and useful non-covalent interactions with the antitumor drug doxorubicin (DOX), g-CNQDs are investigated as fluorescent nanocarriers for DOX without any pre-modification. The inherent fluorescence of g-CNQDs and DOX provides the drug delivery system (g-CNQDs-DOX) with dual-color imaging for revealing the intracellular localization of g-CNQDs and DOX release. The release profiles of DOX from g-CNQDs-DOX reveal a strong dependence on the environmental pH value, which is beneficial for mollifying side effects following chemotherapy. Cellular uptake of g-CNQDs-DOX indicates that not only DOX but also some g-CNQDs penetrate cell nuclei after 16 h of incubation, which leads g-CNQDs-DOX to be more toxic than DOX. The results demonstrate the feasibility of using g-CNQDs as a traceable and pHresponsive drug delivery system due to their unique structural properties.[a] Prof.

Graphitic Carbon Nitride Quantum Dots Embedded in Carbon Nanosheets for Near-Infrared Imaging-Guided Combined Photo-Chemotherapy

“…Recently, nonmetallic carbon-based quantum dots (CQDs) have manifested various medical applications for diagnosis and therapy of diseases, such as cancer diagnosis and therapy. − As a subclass of CQDs, graphene carbon nitride quantum dots (CNQDs) possess excellent fluorescence properties (clear mechanism, wide emission range, and high quantum yield) and exhibit a small size distribution and rapid metabolism. − Furthermore, the CNQDs hold great potential as photodynamic agents in photodynamic therapy (PDT) due to their tri- s -triazine structure and near-infrared (NIR)-induced singlet oxygen generation. − Therefore, the combination of CNQDs with 2D carbon-based nanomaterials offers great opportunities for imaging-guided combined cancer treatment in clinical applications. However, several disadvantages are associated with the synthesis of a CNQDs-based nanocomposite, including multiple reaction precursors, complex synthesis processes, and potential weak interaction between CQDs and 2D nanomaterials, which produce considerable waste and limit their scalability and repeatability. − Thus, it is very meaningful to develop a simple method to obtain nanomaterials containing CNQDs and 2D carbon-based nanomaterials for imaging-guided combined cancer therapy.…”

Light-driven carbon nitride microswimmers with propulsion in biological and ionic media and responsive on-demand drug delivery

“…We further anticipate that drug uptake is assisted by the amine surface groups of both CNx, enabling hydrogen bonding interactions with the drug, and by the negative zeta potential of melon and especially PHI, which intrinsically attracts the positively charged DOX molecules at pH 7 (44,60,61). To test this hypothesis, 200 g of DOX was added to a suspension of 100 g of PHI microswimmers dispersed in 1 ml of DMEM, resulting in 185 g of DOX encapsulated with a DOX loading efficiency of 185% on PHI after 24 hours, which is far higher than previously reported values of 20 to 70% (62)(63)(64). Figure 4B shows the fluorescence image of DOX loaded on the PHI particles.…”

Advanced Inorganic Nitride Nanomaterials for Renewable Energy: A Mini Review of Synthesis Methods

“…Because of these properties, g-CNQDs showed wide range of applications that include photocatalysis, fluorescence probes, drug delivery, bioimaging, and security Ink, etc. (Zhang et al, 2014;Yin et al, 2017;Dong et al, 2018;Patir and Gogoi, 2018) Basically, g-CNQDs could be prepared utilizing two methods: the topto-down way, or the bottom-to-up way. The top-to-down strategy might involve the fragmentation of the bulk g-C 3 N 4 by chemical exfoliation, thermal treatment or ultrasonication into g-CNQDs (Song et al, 2016); and the bottom-to-up strategy is usually based on thermal treatment of nitrogen-rich organic precursors into well dispersed g-CNQDs (Barman and Sadhukhan, 2012;Tang et al, 2014).…”