Preparation of Graphene Quantum Dots by Visible-Fenton Reaction and Ultrasensitive Label-Free Immunosensor for Detecting Lipovitellin of Paralichthys Olivaceus

Abstract

The increasing levels of environmental estrogens are causing negative effects on water, soil, wildlife, and human beings; label-free immunosensors with high specificities and sensitivities are being developed to test estrogeneous chemicals in complex environmental conditions. For the first time, highly fluorescent graphene quantum dots (GQDs) were prepared using a visible-Fenton catalysis reaction with graphene oxide (GO) as a precursor. Different microscopy and spectroscopy techniques were employed to characterize the physical and chemical properties of the GQDs. Based on the fluorescence resonance energy transfer (FRET) between amino-functionalized GQDs conjugated with anti-lipovitellin monoclonal antibodies (Anti-Lv-mAb) and reduced graphene oxide (rGO), an ultrasensitive fluorescent “ON-OFF” label-free immunosensor for the detection of lipovitellin (Lv), a sensitive biomarker derived from Paralichthys olivaceus for environmental estrogen, has been established. The immunosensor has a wide linear test range (0.001–1500 ng/mL), a lower limit of detection (LOD, 0.9 pg/mL), excellent sensitivity (26,407.8 CPS/(ng/mL)), and high selectivity and reproducibility for Lv quantification. The results demonstrated that the visible-Fenton is a simple, mild, green, efficient, and general approach to fabricating GQDs, and the fluorescent “ON-OFF” immunosensor is an easy-to-use, time-saving, ultrasensitive, and accurate detection method for weak estrogenic activity.

An Ultrasensitive Photoluminescent Immunosensing of Lipovitellin by Using N-doped Graphene Quantum Dots

“…Similar to Ref. [34] but with a slight adjust. By dropping aqueous ammonia (25%), the pH of GO aqueous solution was adjusted to 9−10.…”

“…Compared to Ref. [34], the immunosensor upon the N-GQDs has a wider linear test range and time-saving than that immuno-sensor upon on GQDs, showing a broad application prospect in EEs biomarker detection. Scheme 1.…”

“…Le et al designed a FRET-based system by using N-, P-codoped GQDs (NP-GQDs) and AgNPs as donors and acceptors respectively for Cys detection, which provided a new strategy for diagnosis of various diseases [33]. However, few reports are about using FRET strategy to detect Lv [34].…”

Advances in Structural Modifications and Properties of Graphene Quantum Dots for Biomedical Applications

“…The redox cycle Fe 3+ /Fe 2+ catalyzes the dissociation of H 2 O 2 into hydroxyl radicals (·OH), and these are some of the most powerful oxidizing species known. The photoreaction is carried out in aqueous media, and after the reaction for some time, the GO sheets are converted into much smaller GQDs with an average diameter of 40 nm and thickness of about 1.2 nm …”

“…The photoreaction is carried out in aqueous media, and after the reaction for some time, the GO sheets are converted into much smaller GQDs with an average diameter of 40 nm and thickness of about 1.2 nm. 88 2.1.3. Electrochemical Oxidation.…”