High yield synthesis of graphene quantum dots from biomass waste as a highly selective probe for Fe3+ sensing

Abstract

Graphene quantum dots (GQDs), a novel type of zero-dimensional fluorescent materials, have gained considerable attention owing to their unique optical properties, size and quantum confinement. However, their high cost and low yield remain open challenges for practical applications. In this work, a low cost, green and renewable biomass resource is utilised for the high yield synthesis of GQDs via microwave treatment. The synthesis approach involves oxidative cutting of short range ordered carbon derived from pyrolysis of biomass waste. The GQDs are successfully synthesised with a high yield of over 84%, the highest value reported to date for biomass derived GQDs. As prepared GQDs are highly hydrophilic and exhibit unique excitation independent photoluminescence emission, attributed to their single-emission fluorescence centre. As prepared GQDs are further modified by simple hydrothermal treatment and exhibit pronounced optical properties with a high quantum yield of 0.23. These modified GQDs are used for the highly selective and sensitive sensing of ferric ions (Fe3+). A sensitive sensor is prepared for the selective detection of Fe3+ ions with a detection limit of as low as 2.5 × 10–6 M. The utilisation of renewable resource along with facile microwave treatment paves the way to sustainable, high yield and cost-effective synthesis of GQDs for practical applications.

Different spatial distribution of inflammatory cells in the tumor microenvironment of ABC and GBC subgroups of diffuse large B cell lymphoma

“…In this respect, the introduction of spatial statistics tools can provide a substantial support to this type of investigation by providing metrics (such as the here used uniformity index) to further expand the description of the complex structure of this tissue environment. As recently documented in a methodological study [ 27 ] based on CD68-positive macrophages within human head and neck tumors, combinations of spatial statistics-derived parameters can lead to better predictions of macrophage infiltration than any classical morphometric method. This type of approach, therefore, may provide a more accurate description of the functional status of the tumor, potentially leading to a better view on patient prognosis [ 27 ].…”

“…As recently documented in a methodological study [ 27 ] based on CD68-positive macrophages within human head and neck tumors, combinations of spatial statistics-derived parameters can lead to better predictions of macrophage infiltration than any classical morphometric method. This type of approach, therefore, may provide a more accurate description of the functional status of the tumor, potentially leading to a better view on patient prognosis [ 27 ].…”

Graphene Quantum Dots by Eco-Friendly Green Synthesis for Electrochemical Sensing: Recent Advances and Future Perspectives

“…The obtained GQDs showed high biocompatibility and effectiveness for the detection of intracellular temperature. More recently, Abbas et al [ 66 ] synthesized GQDs from tea waste by the microwave assisted oxidative process followed by a hydrothermal treatment in designing selective fluorescent sensors for the detection of the Fe 3+ metal ion. The tea scraps were previously washed and dried for 12 h and, subsequently ground.…”

Recent advances in graphene quantum dot-based optical and electrochemical (bio)analytical sensors

“…The use of these methods (thermal pyrolysis and hydro/solvothermal) is pretty challenging since they exhibit a change in reactor temperature, thereby providing uncontrolled size and structure 89 . To overcome these issues, microwave assisted bottom-up synthesis gained increased interest in view of its several benefits such as high yield, energy saving, reproducibility, low impurity and short reaction time 95,[104][105][106][107] . From this perspective, Tang et al reported a microwave-assisted synthetic method, wherein glucose solution was irradiated with microwave in the NH3 environment (Figure 2D).…”