Synthesis of carbon nanoparticles from carboxymethyl cellulose using one-pot hydrothermal carbonization for drug delivery

Abstract

Carbon nanoparticles (CNPs) were synthesized from carboxymethyl cellulose (CMC) using a sustainable hydrothermal carbonization approach, followed by nitrogen doping and high-temperature activation to tailor their structural and surface properties for drug delivery applications. Nitrogen-doped activated carbon nanoparticles (N-ACNP) exhibited a significantly reduced particle size of 51 ± 6 nm and a high specific surface area of 351.0 ± 15.2 m² g⁻¹, compared to their non-activated counterparts. Surface functionalization introduced nitrogen-containing groups and increased aromaticity, enhancing interactions with drug molecules. Clindamycin, a positively charged antibiotic, was successfully encapsulated into the negatively charged carbon nanocarriers, with N-ACNP showing the highest encapsulation efficiency of 88.04 ± 0.18% and a loading capacity of 88.05 ± 0.73% at a drug concentration of 0.001 g mL⁻¹. In vitro release studies demonstrated a sustained and diffusion-controlled release profile over 48 h, with cumulative release reaching approximately 90 \(\pm\) 4%. Release kinetics were best described by first-order and Korsmeyer-Peppas models, indicating a combination of diffusion and matrix-controlled mechanisms. Overall, the enhanced performance of N-ACNP is attributed to the synergistic effects of electrostatic attraction, hydrogen bonding, π–π interactions, and physical confinement within the porous structure. These findings highlight N-ACNP as a promising, sustainable nanocarrier for controlled drug delivery applications with high cell viability over 3 days.