Graphene Quantum Dot Embedded Hydrogel for Dissolved Iron Sensing

Abstract

A robust and accurate chemical sensor for dissolved iron has been developed, based on highly fluorescent graphene quantum dots (GQDs). This work describes the construction of a GQD embedded hydrogel that displays strong fluorescence emission from the bulk structure. The hydrogel is made from poly(2‐hydroxyethyl methacrylate) (pHEMA) and crosslinked by ethylene glycol dimethacrylate to form a water permeable, flexible and transparent material. Polymerisation in the presence of the GQDs physically entraps the fluorescent nanoparticles within the hydrogel. The fluorescence properties of the GQD‐pHEMA hydrogels have been thoroughly characterised, including by confocal microscopy in the first reported use of this technique for a GQD composite material. Sensing of dissolved Fe(III) by the GQD‐pHEMA hydrogels has been demonstrated, whereby the Fe(III) quenches the GQDs fluorescence emission. The GQD‐pHEMA hydrogels were selective to Fe(III) and showed a linear response for concentrations in the range of 10–200 μM.

Hydrogel-Embedded Quantum Dot–Transcription Factor Sensors for Quantitative Progesterone Detection

“…Previously, QDs have been extensively employed in the context of solution-based sensors; − however, only recently has it been reported that hydrogel-embedded QDs (semiconductor quantum dots, ,− carbon dots, and graphene quantum dots) , elicit effective analytical responses, similar to the results obtained herein. In addition, several studies report the successful integration of solution-based and QD-based sensors into microfluidic lab-on-a-chip systems , or microcapsules, supporting the continued development of these types of sensors for real-world applications.…”

Metal ion sensing with graphene quantum dots: detection of harmful contaminants and biorelevant species

“…21,44,78 Disruption to Fe 3+ homeostasis has been associated with disease states such as anaemia, Parkinson's, Alzheimer's, liver and kidney damage, as well as various types of cancer. 17,21,26,72,77,79,80 Facile methods of detection and differentiation between Fe 3+ and Fe 2+ are required as Fe 2+ is commonly the active ingredient in iron supplements, however is readily oxidised into Fe 3+ within the body, leading to the generation of reactive hydroxyl radicals and subsequent cellular damage. 26,77 Most GQDs which detect Fe 3+ rely on a high affinity for nitrogen and oxygen surface groups in order to quench PL.…”

“…Currently used methods for the detection of metal ions are often expensive, time-consuming, and require the use of specialised equipment to achieve high levels of selectivity and sensitivity. 12,19,26,27 Semiconductor quantum dots (QDs) have previously been employed as sensors, and while they possess many of the same characteristics as GQDs, semiconductor QDs usually present their own environmental and health risks due to the inherent presence of heavy metals within their core structure. 3,28 The development of novel sensors for metal ions that are facile, low cost and can be produced through ‘green’ pathways has been a major focus in recent times.…”

“…There are numerous reports for the detection of Hg + , Fe 3+ and Cu 2+ , as well as more harmful heavy metals, using GQD platforms. 2,4,6 Unfortunately there have been only a handful of GQD sensors for other biologically relevant ions such as the alkali and alkaline earth metals, 11,26 despite their important roles in fundamental biological processes. 10,19,37–40 GQDs offer great potential as imaging probes—particularly for in vivo bioimaging—due to their fluorescence, biocompatibility, high photostability and tuneability, in comparison to currently used biosensing and imaging options.…”

Cross-Coupling of Amide and Amide Derivatives to Umbelliferone Nonaflates: Synthesis of Coumarin Derivatives and Fluorescent Materials

“…With this in mind, copolymerization of 20 with 2-hydroxylethyl methacrylate and ethylene glycol dimethacrylate (cross-linker) was performed to prepare a coumarin poly(2-hydroxylethyl methacrylate) (pHEMA)derived hydrogel 20-pHEMA (see the Supporting Information for synthesis details). Two hydrogels were also prepared as controls, one in the absence of a fluorophore (pHEMA) and one in the presence of propanamide 22, 49 which is not competent in radical polymerization reactions, to give 22-pHEMA. Each method gave hydrogels that were transparent in visible light (Figure 4A).…”