One-step synthesis of lignin-based fluorescent nanoparticles with excellent radical scavenging activity

Fluorescent nanomaterials have gained significant attention due to their unique luminescent properties and promising applications in biomedical fields. In the recent study, researchers from Jiangnan University, Abu Dhabi University, and Perugia University have developed a simple one-step hydrothermal method to synthesize lignin-based fluorescent nanoparticles (LFNP) with excellent radical scavenging activity.·

"Our simple method utilizes lignin, a renewable resource from pulp and paper industry waste, to create multifunctional nanoparticles," explains Prof. Weijun Yang from Jiangnan University. "By combining lignin with ethylenediamine and citric acid under hydrothermal conditions, we achieved high-yield synthesis of LFNP with tailored properties."

The LFNP exhibit strong photoluminescence with a maximum emission wavelength of 454–465 nm under 375–385 nm excitation. Notably, their DPPH radical scavenging rate reaches 96.7%, significantly higher than the 80.8% observed in unmodified lignin nanoparticles. This enhanced antioxidant activity is attributed to the introduction of nitrogen-containing groups and amide structures during synthesis, which facilitate electron transfer and radical capture.

"LFNP show great potential for applications in biomedicine and cosmetic health care due to their excellent fluorescence and antioxidant properties," Prof. Weijun Yang said. "This work provides a new strategy for preparing multifunctional nanoparticles from renewable resources."

The study also reveals that the fluorescence intensity of LFNP increases with increasing citric acid addition, and their bandgap energy decreases from 3.87 eV to 3.14 eV, reflecting improved photophysical properties. The simple one-step synthesis avoids toxic reagents and high-energy processes, making it environmentally friendly and scalable.