Modified facile synthesis for quantitatively fluorescent carbon dots

Abstract

A simple yet consequential modification was made to the popular carbonization processing of citric acid - polyethylenimine precursor mixtures to produce carbon dots (CDots). The modification was primarily on pushing the carbonization processing a little harder at a higher temperature, such as the hydrothermal processing condition of around 330 °C for 6 hours. The CDots thus produced are comparable in spectroscopic and other properties to those obtained in other more controlled syntheses including the deliberate chemical functionalization of preprocessed and selected small carbon nanoparticles, demonstrating the consistency in CDots and reaffirming their general definition as carbon nanoparticles with surface passivation by organic or other species. Equally significant is the finding that the modified processing of citric acid - polyethylenimine precursor mixtures could yield CDots of record-setting fluorescence performance, approaching the upper limit of being quantitatively fluorescent. Thus, the reported work serves as a demonstration on not only the need in selecting the right processing conditions and its associated opportunities in one-pot syntheses of CDots, but also the feasibility in pursuing the preparation of quantitatively fluorescent CDots, which represents an important milestone in the development and understanding of these fluorescent carbon nanomaterials.

High‐Performance Red/Near‐IR Carbon Dots as Fluorescence Probes for Tumor Imaging In Vivo

“…As bioimaging probes, CDots are known to be biocompatible without any significant toxicity in vitro and in vivo ,,. Their optical performance is also high, with observed fluorescence quantum yields approaching unity in the spectral region overlapping that of green fluorescent protein (GFP) ,. The combination of high performance and non‐/low‐toxicity has stimulated broad interests in using CDots for cell and in vivo imaging applications ,,.…”

Controllable Synthesis of Carbon Dots with Excitation‐Wavelength‐Dependent or Independent Photoluminescence for the Selective and Sensitive Detection of Co2+ Ions

“…Li et al reported the preparation of CDs with excitation‐dependent and independent emission by controlling reaction temperature . Sun et al reported that the preparation of quantitatively fluorescent CDs is a promising approach for the improvement of optical properties and practical applications ,. However, the synthesis of CDs with both controllable excitation‐dependent or excitation‐independent emission and highly selective and sensitive PL properties continues to be a challenge for the present research field of CDs, preventing the development of these novel nanomaterials as well as investigation into the origin of these intriguing excitation dependent or independent PL properties.…”

“…However, the synthesis of CDs with both controllable excitation‐dependent or excitation‐independent emission and highly selective and sensitive PL properties continues to be a challenge for the present research field of CDs, preventing the development of these novel nanomaterials as well as investigation into the origin of these intriguing excitation dependent or independent PL properties. In the past decades, it has been documented that the chemical functionalization, reaction time, elemental content in CDs are key factors for controlling their optical properties …”

“…In this work, CDs with different PL properties were synthesized by pyrolyzing a range of the mixture of CA + x •NaBH 4 + y •PEI‐EC according to a widely reported method . The material and optical properties of each CDs sample were carefully characterized with the aid of TEM, Raman and fluorescence spectrophotometer.…”

Fluorinated Boron Nitride Quantum Dots: A New 0D Material for Energy Conversion and Detection of Cellular Metabolism

“…a) The variation in optical bandgap with increasing concentration of fluorine in FBN estimated from plotting the Tauc plot using absorbance measurement that is fitted to an exponentially decaying curve. b) A plot comparing the various reported values for quantum yield of different 2D quantum dots with the FBN QDs having the highest value among them . c) The PL spectrum of FBN with the excitation shown in blue and emission in green.…”