Amine-Functionalized Graphene Quantum Dots for Fluorescence-Based Immunosensing of Ferritin

Abstract

The current work demonstrates the fabrication and optimization of a fluorescence-based immunosensor for ferritin estimation wherein amine-functionalized graphene quantum dots (afGQDs) and methyl orange are used as a fluorophore–quencher couple. The synthesis of afGQDs is achieved by the hydrothermal method. The synthesized QDs were characterized using analytical techniques such as UV–vis, fluorescence, FTIR, and Raman spectroscopies, XRD diffraction studies, elemental analysis, and morphological studies through transmission electron microscopy. The QDs showed a quantum yield of 51%, which is one of the highest reported for this class of material. Exploiting the high fluorescence of this material, these afGQDs, were conjugated with antiferritin antibodies (Ab) for specific fluorescence-based immunosensing of ferritin. The conjugation was confirmed from contact angle measurements and electrophoresis, which confirmed successful bioconjugation. With methyl orange (MO) as the quencher, the Stern–Volmer plot showed a linear upward trend indicating a static quenching process. After elucidating the quenching mechanism, a nanoprobe-based fluorophore–quencher (Ab@afGQDs-MO) couple was employed for ferritin sensing. Using a dynamic linear range from 10 to 4000 ng·mL–1 with an R 2 value of 0.994, a limit of detection of 0.723 ng·mL–1 is achieved. With optimization of other input parameters, the ferritin is estimated in spiked serum samples as well.

Preparation, Marriage Chemistry and Applications of Graphene Quantum Dots–Nanocellulose Composite: A Brief Review

“…Graphene is widely used in many applications, such as electronics, solar cells and Li-ion batteries [54], whereas GQDs have attracted tremendous interest in photoluminescence [55], cell-imaging [56] and drug delivery [57,58], among many things. GQDs have a great advantage, as their properties can be adjusted by changing their band via doping to produce amine-functionalised GQDs [59], nitrogen-doped GQDs (N-GQDs) [60] and sulphur-nitrogen co-doped GQDs (S, N-GQDs) [61]. Furthermore, the photoluminescence colour of GQDs can also be changed from violet to yellow by setting the reactant concentration and temperature during the hydrothermal method [54].…”

Advancements in 2D Materials Based Biosensors for Oxidative Stress Biomarkers

“…The sensors robustness was evaluated with human serum samples and the method displayed a wide linear range. 206 The following points can be concluded from optical based detection:…”

“…The fluorescence quenching was observed with methyl orange, which was restored with the interactions of the antigen–antibody@amine functionalized graphene quantum dot probe. The sensors robustness was evaluated with human serum samples and the method displayed a wide linear range …”

Host–guest sensing towards sodium cyclamate based on a cationic pillar[6]arene reduced graphene nano-composite

“…[22][23][24][25] However, versus other conventional macrocyclic hosts, pillar [n] arenes have important properties such as strong bonding guest and high selectivity in host-guest recognition, which have special recognition capabilities in the sensing area. [26][27][28][29] In recent years, some studies have reported fluorescent sensors by combining the outstanding fluorescence quenching ability of graphene [30][31][32][33] and excellent supramolecular recognition efficiency of pillar[n]arenes. [34][35][36][37] Therefore, in light of these significant findings, we develop a highly selective and sensitive fluorescent sensing platform for SC detection based on a cationic pillar [6]arene (CP6)-functionalized reduced graphene (RGO) nano-composite (CP6-RGO) as a receptor and probe rhodamine B (RB) and the sensing system is shown in Scheme 1.…”

“…In recent years, some studies have reported fluorescent sensors by combining the outstanding fluorescence quenching ability of graphene 30–33 and excellent supramolecular recognition efficiency of pillar[ n ]arenes. 34–37 Therefore, in light of these significant findings, we develop a highly selective and sensitive fluorescent sensing platform for SC detection based on a cationic pillar[6]arene (CP6)-functionalized reduced graphene (RGO) nano-composite (CP6-RGO) as a receptor and probe rhodamine B (RB) and the sensing system is shown in Scheme 1.…”