Graphene quantum dots as singlet oxygen producer or radical quencher - The matter of functionalization with urea/thiourea

Gamma irradiation of graphene quantum dots with ethylenediamine: Antioxidant for ion sensing

“…The ability of modified GQDs to scavenge radical we conducted DPPH assay and the results of these measurements are presented in The intensity of the main DPPH band decreases with the concentration of gamma-irradiated GQDs, for all GQDs samples. This trend proves that modified GQDs possess antioxidative activity, similar to p-GQDs [12]. By calculating RSA activity (see Methods section), as shown in Fig.…”

“…Oxygen-containing functional groups are responsible for good solubility in polar solvents such as water or ethanol [7,8] in the concentration of 5 mg mL −1 [9] or even higher, > 15 mg mL −1 [10]. Properties that distinguish GQDs from other carbon nanomaterials such as carbon nanotubes and graphene, are high dispersibility in water and polar organic solvents, photoluminescence [11], good biocompatibility [12]. In comparison with conventional inorganic quantum dots, GQDs are less toxic and more resistive to photobleaching under prolonged light irradiation with respect to luminescent organic dyes [13].…”

Graphene Quantum Dots as Flourishing Nanomaterials for Bio-Imaging, Therapy Development, and Micro-Supercapacitors

“…Amidst some graphene-based nanomaterials such as GO, fullerenes, carbon nanotubes (CNTs), GQDs show a significant potential for therapy development in nanomedicine and biotechnology [ 157 , 158 ]. Their exceptional properties discussed in the earlier section render them the new promising tool for biosensing [ 89 ], biomedical imaging [ 63 ], drug delivery [ 46 ], and photo-thermal and photodynamic therapy [ 42 , 98 ].…”

“…Introducing urea and thiourea, the N, S co-doped GQDs were synthesized as a better singlet oxygen generator compared to sole GQDs and accordingly, GQDs with urea were defined to be a good PDT agent. The modification with nitrogen could enhance the capability of GQDs by means of crystallinity and mediate more photo-excited singlet oxygen generation, resulting N, S- doped GQDs to be anti-oxidative [ 98 ].…”

Coffee Grounds-Derived CNPs for Efficient Cr(VI) Water Remediation

“…In the first case, carbon atoms are cut from graphene oxide, nanotubes or carbon fibers. In the bottom-up method, carbon-based materials [ 32 ], such as hexabenzocoronene [ 33 ] arginine [ 34 ] and urea [ 35 ] are used as the carbon source.…”