Quadruple-responsive nanocomposite based on dextran-PMAA-PNIPAM, iron oxide nanoparticles, and gold nanorods.

A quadruple-responsive nanocomposite that responds to temperature, pH, magnetic field, and NIR is obtained by incorporating superparamagnetic iron oxide nanoparticles (SPIONs) and gold nanorods (AuNRs) into a dextran-based smart copolymer network. The dual-sensitive copolymer is prepared by sequential RAFT polymerization of methacrylic acid and N-isopropylacrylamide from trithiocarbonate groups linked to dextran in one pot. These functionalized nanocomposites with superior stability can respond to the four stimuli mentioned above well. As evidenced by UV-vis and TEM measurements, the temperature-induced unusual blue-shift in the longitudinal plasmon band is possibly due to the side-to-side assembly of AuNRs.