Self-Assembly of Monodisperse Carbon Dots into High-Brightness Nanoaggregates for Cellular Uptake Imaging and Iron(III) Sensing

Abstract

This study describes a bottom-up assembly route for monodisperse carbon dots (CDs) into different sizes of CD aggregates through the control of the concentration of fatty acids. The highly monodisperse CDs were prepared via solvent-thermal treatment of edible soybean oil, which generated glycerol-based polymer as a carbon source and fatty acid as a surface capping in the synthetic process. The as-synthesized CDs exhibited small particle size variation (2.7 ± 0.2 nm) and narrow emission bands (full width at half-maximum <20 nm). The monodisperse CDs can self-assemble into blue-, green-, yellow-, and red-emitting CD aggregates by tuning the concentration of fatty acids. Compared to commercially available organic dyes and semiconductor quantum dots, the CD aggregates provided a 10-7000-fold improvement in brightness. Additionally, their emission wavelength was tunable across the entire visible spectrum by tuning the excitation wavelength. Because of their high brightness, fluorescence imaging of a single carbon dot and CD aggregate was simply achieved using filter-free dark-field fluorescence microscopy (DFM). We also demonstrate the use of filter-free DFM to dynamically image cellular uptake of the monodisperse CDs in MCF-7 cells and Huh-7 liver cancer cells. Without the conjugation of the fluorophore to the CDs, the particle aggregation-induced red-shifted emission enables the development of the CD-based ratiometric sensor for Fe ions and pyrophosphate based on Fe-induced aggregation of the monodisperse CDs.

Non-destructive inspection of food and technical oils by terahertz spectroscopy

“…The above results can be elucidated in terms of oleochemistry. The FAs tend to form so called “inversed micelles” in oil with the hydrophilic end towards the center of sphere 26,27,35,36 . If the water is introduced, it is attracted into the center to form a core of inverse micelle.…”

A Review on Multifunctional Carbon-Dots Synthesized From Biomass Waste: Design/ Fabrication, Characterization and Applications

“…Subsequently, hydronium ion formed from these acids act as a catalyst where these intermediaries undergo dehydration, polymerization, condensation and transform into soluble polymeric product. Then, aromatization reactions and creation of aromatic clusters occur via aldol condensation (Chen and Tseng, 2017) and cycloaddition reactions (De and Karak, 2013). A single burst nucleation formed when the concentration of these aromatic clusters reach a critical supersaturation point, and C-Dots are formed.…”

Near-infrared emissive carbon dots with 33.96% emission in aqueous solution for cellular sensing and light-emitting diodes

“…Hydrophilic groups can increase the water dispersity of the CDs, facilitating cell and biological experiments. The surface carboxyl groups may interact with certain metal ions to cause fluorescence quenching, allowing the detection of specific metal ions [38][39][40][41][42][43]. As the name implies, the reaction solvent used in hydrothermal reactions is water, and the reaction solvent used in the solvothermal treatment is an organic substance, such as ethanol, dichloromethane, or DMF.…”