Study of Fluorescence Quenching Ability of Graphene Oxide with a Layer of Rigid and Tunable Silica Spacer

Abstract

The fluorescence quenching property of graphene oxide (GO) has been newly demonstrated and applied for fluorescence imaging and biosensing. In this work, a new nanostructure was designed for effectively studying the quenching ability of GO. The key element in this design is the fabrication of a layer of rigid and thickness adjustable silica spacer for manipulating the distance between the GO and fluorophores. First, a silica core modified with organic dye molecules was prepared, followed by the formation of a silica shell with a tunable thickness. Afterward, the GO was wrapped around silica nanoparticles based on the electrostatic interaction between the negatively charged GO and positively charged silica. The quenching efficiency of GO to different dye molecules was studied at various spacer thicknesses and varying concentrations of GO. Fluorescence lifetime of fluorophores was measured to determine the quenching mechanism. We found that the quenching efficiency of GO was still around 30% when the distance between dyes and GO was increased to more than 30 nm, which indicated the long-distance quenching ability of GO and confirmed the previous theoretical calculation. The quenching mechanisms were proposed schematically based on our experimental results. We expected that the proposed nanostructure could act as a feasible model for studying GO quenching property and shed light on designing GO-based fluorescence sensing systems.

A Smart Nanovector for Cancer Targeted Drug Delivery Based on Graphene Quantum Dots

“…The presence of a stable interaction between the targeting module Pyr-RF and the GQD surface was also proved by evaluating the fluorescence properties of GQD@Pyr-RF and GQD-PEG-BFG@Pyr-RF and comparing their PL spectra with those of GQD and of the unbound Pyr-RF samples at the excitation wavelength of 360 (Figure 4). As reported, some small molecules exhibit fluorescence quenching ability after their π–π stacking with the surface of graphene-based materials [41]. The PL spectra of the GQD-based samples conjugated with the Pyr-RF module reveal a quenching phenomenon of the vitamin fluorescence, which is ascribable to an electron transfer process triggered by π–π stacking interactions between the aromatic rings of RF and the p-cloud of GQD.…”

Recent advances in graphene-based biosensor technology with applications in life sciences

“…Furthermore, graphene-based nanomaterial can act as a quencher in the transducer to generate fluorescent biosensors. Studies have determined that graphene (G), graphene oxide (GO), and reduced graphene oxide (rGO) have a very high efficiency of fluorescent quenching [ 20 – 22 ].…”

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“…The quenching could be due to the energy transfer from the fluorophore to the metal [42] or in the case of graphenes, it could be due to the excitation of an exciton too [43]. Wu et al found that the quenching efficiency of GO was still around 30% when the distance between dyes and GO was increased to more than 30 nm [44].…”