Reports of the preparation and investigation of fluorescent carbon nanodots have become increasingly popular over the past decade. In addition to their fluorescence, carbon nanodots are facile and inexpensive to synthesize, water-soluble, and relatively non-toxic. Bottom-up methods for carbon nanodot synthesis often involve the thermal or photochemical treatment of organic materials in aqueous solutions (sugars, alcohols, etc.). While others have consistently shown the formation of UV-absorbing, blue-emitting fluorescent products by these methods, few reports have attempted to purify carbon nanodot solutions and identify chemistry key to producing the fluorescent products. We report a method developed to separate, identify, and quantify fluorescent species found in caramelized sugar solutions. Solid-phase extraction was used to isolate and preconcentrate the fluorescent components from non-fluorescent products in an aqueous solution. Subsequently, HPLC coupled with UV and fluorescence detectors has been used to further separate and collect the multiple fluorescent components. Spectroscopic and mass spectrometric analyses are underway to determine the fluorescent characteristics and chemical structure of these compounds. More robust purification methods will elucidate a deeper understanding of carbon nanodots' true chemical, physical, and electronic properties, allowing them to be more effectively used in potential applications.

Extraction and analysis of fluorescent species in sugar-derived carbon nanodot solutions

ACS Spring 2022

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