Cane Molasses Graphene Quantum Dots Passivated by PEG Functionalization for Detection of Metal Ions

Abstract

Poly(ethylene glycol) passivated graphene quantum dots (PEG-GQDs) were synthesized based on a green and effective strategy of the hydrothermal treatment of cane molasses. The prepared PEG-GQDs, with an average size of 2.5 nm, exhibit a brighter blue fluorescence and a higher quantum yield (QY) (up to approximately 21.32%) than the QY of GQDs without surface passivation (QY = 10.44%). The PEG-GQDs can be used to detect and quantify paramagnetic transition-metal ions including Fe 3+ , Cu 2+ , Co 2+ , Ni 2+ , Pb 2+ , and Mn 2+ . In the case of ethylenediaminetetraacetic acid (EDTA) solution as a masking agent, Fe 3+ ions can be well selectively determined in a transition-metal ion mixture, following the lowest limit of detection (LOD) of 5.77 μM. The quenching mechanism of Fe 3+ on PEG-GQDs belongs to dynamic quenching. Furthermore, Fe 3+ in human serum can be successfully detected by the PEG-GQDs, indicating that the green prepared PEG-GQDs can be applied as a promising candidate for the selective detection of Fe 3+ in clinics.

Recent advances of biomass carbon dots on syntheses, characterization, luminescence mechanism, and sensing applications

“…[ 29 ] prepared nitrogen‐doped GQDs and fluorine‐doped GQDs from plant leaves as carbon sources with a QY of 41.2% and 38.9%, respectively. Our group [ 30 ] prepared cane molasses GQDs and modified their surface defects with polyethene glycol, the QY was twice as high as that of the unpassivated GQDs. These examples show that the heteroatom doping or surface modification can improve the QY of carbon dots to some extent.…”

“…Besides, the QY of 5 nm CQDs prepared from Chinese ink [ 53 ] could reach as high as 78%. Similarly, uniformly distributed carbon dots could also be produced by using sugarcane bagasse pulp [ 54 ] and cane molasses [ 30 ] as carbon sources. Industrial solid waste accounts for a significant part of municipal waste and the reports about coal, coke, and asphalt are common.…”

“…This was due to the fact that PEG is a long‐chain polymer containing abundant hydroxyl groups, which could achieve encapsulate for the inner GQDs (Figure 8D). [ 30 ] Using neem leaves [ 147 ] as carbon source, the fluorescence intensity of GQDs modified by amino was higher and more stable than that of unmodified GQDs. High fluorescence GQDs were prepared from coffee grounds [ 148 ] by functionalization with polyethyleneimine (PEI).…”

<p>Poly(Ethylene Glycol) Functionalized Graphene Oxide in Tissue Engineering: A Review on Recent Advances</p>

“…Interestingly, they observed that stem cell osteogenesis was augmented by GQDs but decreased when the cells were treated with GO. Some studies have been reported on the use of PEGylated GQDs for bioimaging, 57 detection of metal ions, 58 and cancer therapy, 59 etc. However, there is little reported information on the interaction of PEGylated GQDs with stem cells.…”

Progress on the nanoscale spherical TiO2 photocatalysts: Mechanisms, synthesis and degradation applications

“…In recent years, the use of carbon materials and nanoscale spherical TiO 2 composite to improve their photocatalytic activity has become a research hotspot. [ 184,185 ] Carbon materials not only have high electrical conductivity, [ 186 ] large specific surface area, [ 187 ] and so on, but also have a variety of structures (activated carbon, [ 188–190 ] graphene, [ 191–193 ] carbon quantum dots [ 194–197 ] (CQDs), and so on), so the composite of TiO 2 and carbon materials is beneficial to reduce the photogenerated carriers recombination rate; thus, improving the photocatalytic activity of spherical TiO 2.…”