Luminescent phosphate sensor based on upconverting graphene quantum dots

Abstract

In this paper, we have presented a novel graphene quantum dots based upconversion fluorescent sensor for detection of phosphate. The upconversion fluorescence of graphene quantum dots with emission wavelength at 407 nm was quenched by rare earth ion, Eu 3+ in proper concentration. The quenching constant is calculated from Stern-Volmer equation. Importantly, quenched fluorescence of graphene quantum dots-Eu 3+ could be recovered with the addition of phosphate based on a competition mechanism, which provides a turn-on sensing strategy for phosphate assay. The recovered fluorescence is proportional to the concentration of phosphate. The linear range for the detection of phosphate was 1 to 12 μM with a detection limit of 100 nM. The proposed sensing system has been successfully used for the assay of phosphate in real river water samples, indicating the practical potential.

Smart-phone, paper-based fluorescent sensor for ultra-low inorganic phosphate detection in environmental samples

“…While this approach had only minor interference, it was not sensitive enough to provide the necessary low-ppb measurements. Alternative fluorescence techniques include the utilization of the fluorescence-quenching effect of Europium when bound to fluorescent graphene quantum dots 30 . The presence of (Pi) solution detaches this complex, restoring fluorescence proportion to the (Pi) concentration.…”

Phosphorescent Differential Sensing of Physiological Phosphates with Lanthanide Ions-Modified Mn-Doped ZnCdS Quantum Dots

“…As hard acids, trivalent lanthanide ions (Ln 3+ ) possess high affinity for oxygen-donor atoms, especially phosphates (Scheme B), which can also be evidenced from the elegant functionalization of lanthanide-based upconversion nanoparticles with DNA . Considering that many Ln 3+ -containing complexes are luminescence-active and their luminescence is largely dependent on the energy antennas, Ln 3+ complexes were frequently explored for the development of sensors for physiological phosphates and phosphate-containing biomolecules. − Besides, Ln 3+ can also cause perturbation to the luminescence of some optically active nanomaterials, thereby acting as cartridges in the “indicator-displacement assay” for the construction of luminescent sensors toward physiological phosphates. − However, the biological functions of phosphates connect with each other (Scheme C); analysis of single phosphate-containing biomolecule therefore cannot reveal the exact biological significance of phosphates.…”