Highly Efficient Antioxidant F- and Cl-Doped Carbon Quantum Dots for Bioimaging

Abstract

The addition of heteroatoms to pristine carbon quantum dots (CQDs) change their structure and optical properties. In this study, fluorine (F)- and chlorine (Cl)-doped CQDs are prepared by the one-step green hydrothermal route from sodium fluoride, sodium chloride, urea, and citric acid as the starting precursors. Microscopy analysis reveals that the average size of these quantum dots is 5 ± 2 nm, whereas the chemical study shows the existence of C–F and C–Cl bonds. The produced F- and Cl-doped CQDs have fluorescence quantum yields of 0.151 and 0.284, respectively, at an excitation wavelength of 450 nm. Charge transfer resistance of F- and Cl-doped CQDs films is 2 orders of magnitude higher than in the pristine CQD films. Transport band gap of the doped CQDs is 2 eV bigger than that of pristine CQDs. Radical scavenging activity shows very good antioxidant activity of doped CQDs. Antibacterial testing reveals poor antibacterial activity against Staphylococcus aureus and Escherichia coli. The F- and Cl-doped CQDs are successfully used as fluorescent probes for cell imaging as shown by confocal microscopy.

Highly sensitive and selective detection of butachlor based on the resonance light scattering of doped carbon quantum dots

“…XPS was performed to analyze elemental and functional groups of the D-CQDs, and indicated that the D-CQDs contained mainly C, N, O and a small amount of other elements with the composition of 64.85%, 9.42%, 23.63% and 2.1%, respectively. 54,55 The XPS spectrum of D-CQDs in Fig. 3a indicated the presence of five peaks at ∼285, ∼532, and ∼398 eV.…”

Carbon Dots as an Emergent Class of Antimicrobial Agents

“…In a further example reported by Zhang et al [ 48 ], the correlation between the photo-oxidative activity of CDs and the CDs’ phosphorescent quantum yield and N content was established, highlighting the importance of N-doping to increase the CDs’ photosensitization performance. On the other hand, Marković et al [ 85 ] showed that F- and Cl-doped CDs reduce the photodynamic antibacterial effect of the nanoparticles as compared to nondoped ones, as a result of a reduced ROS production. The collective analysis of these data, points to the fundamental importance of N-doping during the CD synthesis as an essential feature to generate CDs with good antibacterial activity.…”

A Highly Sensitive and Selective Probe for the Colorimetric Detection of Mn(II) Based on the Antioxidative Selenium and Nitrogen Co-Doped Carbon Quantum Dots and ABTS•+

“…In addition, CQDs as antioxidants have been attracted attention by scavenging free radicals (Sachdev and Gopinath, 2015;Chunduri et al, 2016;Shen et al, 2017), which have the advantage of good antioxidant activity, excellent water stability and solubility, high quantum yield, stable photoluminescence, easy surface functionalization, excellent biocompatibility, low-cost, and negligible toxicity (Wang et al, 2019;Mahat and Shamsudin, 2020;Surendran et al, 2020). The action principles of CQDs as antioxidants for free radical scavenging could be attributed to the large number of carboxyl and hydroxyl groups present on the surface (Chunduri et al, 2016;Wang et al, 2019), adduct formation at the sp 2 sites of the carbon network (Wang et al, 2019), heteroatom (N, S, Cl) doping (Zou et al, 2019;Markovi et al, 2020). What's more, due to the synergetic effect of multiple heteroatoms doping in the carbon lattice (Wang et al, 2015;Liu et al, 2020;Tripathi et al, 2020), the multielement (like N, Se, B, S, and P) co-doped CQDs have attracted much attention because of their novel properties different from single heteroatom doped CQDs and simple CQDs (Ruiqi et al, 2018;.…”