Graphene quantum dot-induced photo redox ATRP synthesis of lignin-based copolymers for the fabrication of silver-bearing and camptothecin-loaded micelles.

Photo redox atom transfer radical polymerization (ATRP) represents an excellent technique for forming multifunctional polymers. However, there was little report on photo redox ATRP of graphene quantum dots (GQDs). Herein, we reported that introduced GQDs to ATRP in DMF solvent for the first time, significantly reducing the amount of copper catalyst (<500 ppm) required for the synthesis of alkali lignin-poly(N-isopropylacrylamide)-poly(N, N-dimethylaminoethyl methacrylate)-poly(poly(ethylene glycol) methyl ether methacrylate) (AL-(PNIPAM-PDMAEMA-PPEGMA)2). The copolymer had molecular weight of 46,884 and polydispersity index (PDI) of 1.07. The micelles self-assembled from AL-(PNIPAM-PDMAEMA-PPEGMA)2 in aqueous solution served as an excellent template for the simultaneous in situ preparation of silver nanoparticles (AgNPs) and the encapsulation of the hydrophobic anticancer drug camptothecin (CPT). By adjusting the mole ratio of [DMAEMA]:[AgNO3], a series of AgNPs with controllable sizes (2.5-20.6 nm) could be obtained. AL-(PNIPAM-PDMAEMA-PPEGMA)2@Ag@CPT exhibited temperature and pH-sensitive release properties, releasing 80 % of the drug in an acidic and 37 °C tumor environment within 120 h. Furthermore, 150 μg/mL AL-(PNIPAM-PDMAEMA-PPEGMA)2@Ag@CPT effectively killed 75 % of cells within 48 h. 800 μg/mL AL-(PNIPAM-PDMAEMA-PPEGMA)2@Ag@CPT demonstrated highly efficient antibacterial effects. All these results suggest its potential application value in synergistic antitumor and antibacterial treatment system.