Carbon dot functionalization of Areca catechu leaf sheath fibers: Structural, photoluminescent, mechanical, and antibacterial properties

The development of multifunctional lignocellulosic materials from renewable biomass offers a sustainable route toward optically active and antimicrobial platforms. This study investigates carbon dot (CD)-functionalized Areca catechu leaf sheath fibers and evaluates their structural, optical, mechanical, thermal, and antibacterial characteristics. X-ray diffraction revealed a predominantly amorphous lignocellulosic structure with an estimated crystallinity index of 25.5%, while the prominent reflection near 29.48° was considered a possible contribution from residual inorganic constituents rather than cellulose. Fourier-transform infrared spectroscopy identified characteristic lignocellulosic functional groups and spectral features consistent with possible non-covalent interactions between the fiber surface and CDs. UV–visible analysis showed an absorption maximum at approximately 341 nm, while photoluminescence analysis exhibited a maximum emission at 420 nm with a peak intensity of 9900 a.u. Mechanical testing demonstrated a tensile strength of 35.74 MPa and a strain at break of 0.03 (3%). Thermal analysis indicated stability up to approximately 455 °C. The functionalized fiber preparation exhibited inhibition zones of 27 and 24 mm against Escherichia coli and Streptococcus mutans, respectively. These findings demonstrate the multifunctional characteristics of the CD-functionalized lignocellulosic scaffold. However, the absence of matched non-CD fiber controls and independent CD characterization limits direct attribution of these properties to CD functionalization, warranting further controlled investigations.