• Journal of the Korean Chemical Society
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• v.65 no.4
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• pp.296-299
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• 2021

• Nano
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• v.13 no.12
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• pp.1850147.1-1850147.14
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• 2018

In this work, water-soluble and blue-emitting carbon nanodots (CDs) were synthesized from apple peels for the first time via one-step hydrothermal method. The synthetic route is facile, green, economical and viable. The as-prepared CDs were characterized thoroughly by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman, Fourier transform infrared (FT-IR), X-ray photoelectron (XPS), fluorescence and UV-Vis absorption spectroscopy in terms of their morphology, surface functional groups and optical properties. The results show that these CDs possessed ultrasmall size, good dispersivity, and high tolerance to pH, ionic strength and continuous UV irradiation. Significantly, the CDs had fast and reversible response towards temperature, and the accurate linear relationship between fluorescence intensity and temperature was used to design a novel nanothermometer in a broad temperature range from 5 to $65^{\circ}C$ facilely. In addition, the fluorescence intensity of CDs was observed to be quenched immediately by Cr(VI) ions based on the inner filter effect. A low-cost Cr(VI) ions sensor was proposed employing CDs as fluorescent probe, and it displayed a wide linear range from 0.5 to $200{\mu}M$ with a detection limit of $0.73{\mu}M$. The practicability of the developed Cr(VI) sensor for real water sample assay was also validated with satisfactory recoveries.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.173-178
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• 2022

A lateral flow immunoassay (LFIA) method using carbon nanodot@silica as a signaling material was developed for analyzing the concentration of retinol-binding protein 4 (RBP4), one of the lung cancer biomarkers. Instead of antibodies mainly used as bioreceptors in nitrocellulose membranes in LFIA for protein detection, aptamers that are more economical, easy to store for a long time, and have strong affinities toward specific target proteins were used. A 5' terminal of biotin-modified aptamer specific to RBP4 was first reacted with neutravidin followed by spraying the mixture on the membrane in order to immobilize the aptamer in a porous membrane by the strong binding affinity between biotin and neutravidin. Carbon nanodot@silica nanoparticles with blue fluorescent signal covalently conjugated to the RBP4 antibody, and RBP4 were injected in a lateral flow manner on to the surface bound aptamer to form a sandwich complex. Surfactant concentrations, ionic strength, and additional blocking reagents were added to the running buffer solution to optimize the fluorescent signal off from the sandwich complex which was correlated to the concentration of RBP4. A 10 mM Tris (pH 7.4) running buffer containing 150 mM NaCl and 0.05% Tween-20 with 0.6 M ethanolamine as a blocking agent showed the optimum assay condition for carbon nanodot@silica-based LFIA. The results indicate that an aptamer, more economical and easier to store for a long time can be used as an alternative immobilizing probe for antibody in a LFIA device which can be used as a point-of-care diagnosis kit for lung cancer diseases.