Bottlebrush-Colloid Janus Nanoparticles.

A bottlebrush-colloid Janus nanoparticle (JNP) with a ball-and-stick structure is reported. A single poly(4-vinyl benzyl chloride) (PVBC) polymer chain was grafted onto the amine-capped Fe 3 O 4 @NH 2 nanoparticle. pH-responsive 2-diethylaminoethyl methacrylate (DEAEMA) and water-soluble oligo(ethylene glycol) methacrylate (OEGMA) were sequentially grown from the PVBC backbone by ATRP, forming a core-shell bottlebrush. The synthesized PVBC 208 - g -(PDEAEMA 13 - b -POEGMA 8 )-Fe 3 O 4 @NH 2 JNPs are dispersible in water and can be manipulated by a magnet. The Fe 3 O 4 NPs with exposed -NH 2 groups facilitate accumulation at acidic sites. Hydrophobic dyes can be loaded within the PDEAEMA at pH ≥ 7.5, while they are released at pH values below 6.8. The composite JNPs are promising as a guided pH-responsive delivery vector toward acidic solid tumors.