Core-shell Fe₃O₄ polydopamine nanoparticles serve multipurpose as drug carrier, catalyst support and carbon adsorbent

We present the synthesis and multifunctional utilization of core-shell Fe₃O₄ polydopamine nanoparticles (Fe₃O ₄@PDA NPs) to serve as the enabling platform for a range of applications including responsive drug delivery, recyclable catalyst support, and adsorbent. Magnetite Fe₃O₄ NPs formed in a one-pot process by the hydrothermal approach were coated with a polydopamine shell layer of ∼20 nm in thickness. The as prepared Fe₃O₄@PDA NPs were used for the controlled drug release in a pH-sensitive manner via reversible bonding between catechol and boronic acid groups of PDA and the anticancer drug bortezomib (BTZ), respectively. The facile deposition of Au NPs atop Fe₃O₄@PDA NPs was achieved by utilizing PDA as both the reducing agent and the coupling agent. The nanocatalysts exhibited high catalytic performance for the reduction of o-nitrophenol. Furthermore, the recovery and reuse of the catalyst was demonstrated 10 times without any detectible loss in activity. Finally, the PDA layers were converted into carbon to obtain Fe₃O₄@C and used as an adsorbent for the removal of Rhodamine B from an aqueous solution. The synergistic combination of unique features of PDA and magnetic nanoparticles establishes these core-shell NPs as a versatile platform for multiple applications.