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

Abstract

Presented results indicate that in the selected medium, gamma irradiation at low doses induces the lowering in the GQDs height due to the lower number of graphene layers in their structure. Unexpectedly, irradiation in the same medium at 200 kGy induce a significant increase in GQDs height and caused observable agglomeration.

Facile Synthesis of L-Cysteine Functionalized Graphene Quantum Dots as a Bioimaging and Photosensitive Agent

“…These results are in agreement with AFM measurements. As we previously reported for p-GQDs, the average hydrodynamic diameter was 13.85 nm [ 32 ].…”

“…In the case of gamma-irradiated GQDs, this band showed a small shift to 203 nm for gamma-irradiated samples. This can be assigned to the changes in the aromatic structure and modification of GQDs [ 32 ]. For GQD-cys-200 and GQD-cys-50, the peak can be observed in a wavelength of about 324 nm.…”

“…Blue photoluminescence of GQDs is associated with hydroxyl functional groups, while green is related to carboxyl and amide functional groups [ 52 , 53 ]. Gamma irradiation causes changes in the structure of GQDs which affecting the PL properties by tuning them [ 31 , 32 ]. One more difference between the emission spectra of p-GQDs and gamma-irradiated dots is that the highest intensity of the emission was detected for p-GQDs at the excitation wavelength of 320 nm, while in the case of gamma-irradiated dots, the highest intensity of the main emission band was detected at the excitation wavelength of 360 nm.…”

“…The highest PL QY was detected after gamma irradiation at a dose of 25 kGy, while for doses of 50 and 200 kGy, QYs were only 5.15 and 3.12%, respectively. Our previous study showed that PL QY for p-GQDs was only 1.45% at the excitation wavelength of 340 nm [ 32 ]. These results suggest that gamma irradiation improved PL QY of GQDs and that the largest improvement was achieved at a dose of 25 kGy.…”

“…The effects of irradiation strongly depend on material type, irradiation dose, and medium [ 30 ]. The mediums used for irradiation of GQDs were deionized water, a mixture of deionized water and isopropyl alcohol (IPA), ethanol, and ethylenediamine (EDA) [ 31 , 32 , 33 ]. By changing the medium, it is possible to achieve a reductive or oxidative environment during irradiation.…”