Synthesis of Graphene Quantum Dots Decorated With Se, Eu and Ag As Photosensitizer and Study of Their Potential to Use in Photodynamic Therapy.

GQDs decorated with europium (Eu), silver (Ag) and selenium (Se) at molar ratios of 0.1%, 0.3% and 0.5% were produced for the first time at different temperatures of 180 °C, 200 °C and 220 °C. Surface passivation was carried out with polyethylene glycol (PEG) to increase the intensity of photoluminescence (PL) of the produced samples. The prepared quantum dots were characterized by X-Ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), transmission electron microscopy (TEM), PL and ultraviolet-visible spectroscopy. GQDs synthesized at 180 °C and decorated with Se (0.3%) had maximum PL intensity along with long lasted afterglow over 90 min compared with other samples. Excitation wavelength at 360 nm produced maximum emission at 600-900 nm and resulted in high singlet oxygen (1O 2) generation which makes it a good candidate for photodynamic therapy applications.

Preparation and characterization of selenium-decorated graphene quantum dots with high afterglow for application in photodynamic therapy.

Graphene quantum dots (GQDs) was synthesized using a simple, rapid and affordable method and decorated with selenium at different molar ratios for the first time to obtain an efficient sample for use in photodynamic therapy. Surface modification of GQDs was carried out using polyethylene glycol (PEG) for conjugation with protoporphyrin IX (PpIX). Synthesized GQDs (Se: 0.3%) at 180°C had an emission spectrum that fairly coincided with the absorption profile of PpIX. A relative decrease of about 62.48% in the emission intensity of anthracene was recorded under illumination with UVC light in the presence of GQDs (Se: 0.3%) and the reduction for clung GQDs (Se: 0.3%) and PpIX during 90 min was about 70.68%. Singlet oxygen (1 O2 ) generation was examined using a chemical method that showed significant enhancement in decomposition rate constant in clung GQDs-PEG-PpIX compared with GQDs and PpIX alone. Afterglow over 600 s showed that GQDs (Se: 0.3%) could be effective for near skin and even deep tumours.