Search

Hyperbranched poly(amido amine) is grown from the surface of carbon nanotubesvia a multi-step Michael addition reaction, hence the amido and amine units are linked onto the surface of carbon nanotubes. These amido and amine units can facilitate the assembly of carbon nanotubes with other functional polymersviahydrogen bonds. The external ultrasound-stimulus is found to induce the assembly of functionalized multi-walled carbon nanotubes with linear poly(amido amine) into a smart carbon nanotube gel viahydrogen bonds. The notable advantages of this method are that the gelation is very fast and controlled by ultrasound strength, the formed carbon nanotube gels are not only responsive to some mechanical stimuli such as vigorous agitating, but also responsive to some chemical stimuli such as water and acids. The carbon nanotubes are homogenously embedded in the gel network, and the sol–gel switching is easily realized via heating and ultrasonicating. It is interesting that sonication can untangle the bundles of MWNT via breaking the van der Waals forces between them to disperse MWNTs at high temperature, but induce the assembly of MWNTs functionalized with poly(amido amine) viahydrogen bonds into a smart carbon nanotube based gel at room temperature.

A facile and versatile method to prepare mesoporous core-shell nanostructures with a reversibly switchable nanoshell is reported. Reversible addition-fragmentation chain transfer (RAFT) functionalities were anchored to the exterior surface of mesoporous silica nanoparticles (MSNs), forming RAFT agent coated MSNs. RAFT polymerization was then conducted to graft a poly(acrylic acid) (PAA) shell onto the exterior surface of MSNs, producing novel smart nanocontainers with a MSN as the container and a pH-responsive PAA nanoshell as a smart nanovalve. The PAA nanovalve can control the access of guest molecules to and from the MSN nanocontainer. This core-shell nanostructure should have potential applications in drug and gene delivery.

Carbon nanotubes (CNTs) have many potential applications in biological and biomedical sciences as nanoscale probes and sensors, which need CNTs to be able to respond to biologically relevant stimuli, such as pH, temperature, glucose, glutathione, various ions, enzymes and proteins, etc. This highlight examines several representative CNTs responsive to pH, temperature, glucose, ions and DNA, covering both noncovalently and covalently functionalized CNTs for advanced biosensors and bioprobes.