Synthesis and Characterization of Amorphous Lawsone Polymer Dots for Fluorescent Applications

Area of Science:

• Materials Science
• Nanotechnology
• Photochemistry

Background:

• Carbon dots often suffer from unwanted small molecular fluorescence, complicating their purification and application.
• Lawsone (2-hydroxy-1,4-napththoquinone) is an inexpensive and abundant natural compound with potential for functional material development.

Purpose of the Study:

• To develop a straightforward method for synthesizing highly fluorescent lawsone polymer dots (LPDs).
• To investigate the photophysical properties and potential applications of these LPDs in energy and biomedical fields.

Main Methods:

• A two-step hydrothermal/solvothermal process was employed to synthesize LPDs from lawsone.
• Spectroscopic, electrochemical, and theoretical analyses were conducted to understand the formation mechanism and properties.
• LPDs were incorporated into TiO2 photoanodes for dye-sensitized solar cells (DSSCs) and used for cancer cell imaging.

Main Results:

• The synthesis yielded highly fluorescent LPDs with excitation-independent emission and well-defined electronic transitions.
• A cross-linked enhanced emission (CEE) mechanism was proposed, explaining the 2-order magnitude increase in emission intensity and 37% quantum yield.
• LPDs enhanced photocurrent density in DSSCs, and nitrogen-doped LPDs showed potential for cancer cell imaging.

Conclusions:

• The two-step process offers a facile route to purify and enhance the fluorescence of polymer dots derived from lawsone.
• LPDs demonstrate promise as efficient photosensitizers in solar cells and as fluorescent probes in biological imaging.