One-Step to Prepare Lignin Based Fluorescent Nanoparticles with Excellent Radical Scavenging Activity

Abstract

Fluorescent nanomaterials have attracted much attention, due to their unique luminescent properties and promising applications in biomedical areas. In this study, lignin based fluorescent nanoparticles (LFNP) with high yield (up to 32.4%) were prepared from lignin nanoparticles (LNP) by one-pot hydrothermal method with ethylenediamine (EDA) and citric acid. Morphology and chemical structure of LFNP were investigated by SEM, FT-IR, and zeta potential, and it was found that the structure of LFNP changed with the increase of citric acid addition. LFNP showed the highest fluorescence intensity under UV excitation at wavelengths of 375-385 nm, with emission wavelengths between 454-465 nm, and exhibited strong photoluminescence behavior. Meanwhile, with the increase of citric acid content, the energy gap (ΔE) gradually decreased from 3.87 to 3.14 eV, which corresponds to the gradual enhancement of fluorescence performance. LFNP also exhibited excellent antioxidant activity, with DPPH free radical scavenging rate increased from 80.8% for LNP up to 96.7% for LFNP, confirming the great potential of these materials for application in biomedicine and cosmetic health care.