Nanoparticle-based diagnosis-therapy integrative systems represent an emerging approach to cancer treatment. However, the diagnostic sensitivity, treatment efficacy, and bioavailability of nanoparticles as well as the heterogeneity and drug resistance of tumors pose tremendous challenges for clinical implementation. We herein report on the fabrication of tumor pH-sensitive magnetic nanogrenades (termed PMNs) composed of self-assembled iron oxide nanoparticles and pH-responsive ligands. These PMNs can readily target tumors via surface-charge switching triggered by the acidic tumor microenvironment, and are further disassembled into a highly active state in acidic subcellular compartments that "turns on" MR contrast, fluorescence and photodynamic therapeutic activity. We successfully visualized small tumors implanted in mice via unique pH-responsive T1MR contrast and fluorescence, demonstrating early stage diagnosis of tumors without using any targeting agents. Furthermore, pH-triggered generation of singlet oxygen enabled pH-dependent photodynamic therapy to selectively kill cancer cells. In particular, we demonstrated the superior therapeutic efficacy of PMNs in highly heterogeneous drug-resistant tumors, showing a great potential for clinical applications.

A photothermally sensitive poly( N -isopropylacrylamide)/graphene oxide (PNIPAM/GO) nanocomposite hydrogel can be synthesized by in situ γ -irradiation-assisted polymerization of an aqueous solution of N -isopropylacrylamide monomer in the presence of graphene oxide (GO). The colors and phase-transition temperatures of the PNIPAM/GO hydrogels change with different GO doping levels. Due to the high optical absorbance of the GO, the nanocomposite hydrogel shows excellent photothermal properties, where its phase transitions can be controlled remotely by near-infrared (NIR) laser irradiation, and it is completely reversible via laser exposure or nonexposure. With a higher GO loading, the NIR-induced temperature of the nanocomposite hydrogel increases more quickly than with a lower doping level and the temperature can be tuned effectively by the irradiation time. The nanocomposite hydrogel with its excellent photothermal properties will have great applications in the biomedical fi eld, especially as microfl uidic devices; this has been demonstrated in our experiments by way of remote microvalves to control fl uidic fl ow. Such an "easy" and "clean" synthetic procedure initiated by γ -irradiation can be extended for the effi cient synthesis of other nanocomposite materials.

Low-density compressible materials enable various applications but are often hindered by structure-derived fatigue failure, weak elasticity with slow recovery speed and large energy dissipation. Here we demonstrate a carbon material with microstructure-derived super-elasticity and high fatigue resistance achieved by designing a hierarchical lamellar architecture composed of thousands of microscale arches that serve as elastic units. The obtained monolithic carbon material can rebound a steel ball in spring-like fashion with fast recovery speed (∼580 mm s−1), and demonstrates complete recovery and small energy dissipation (∼0.2) in each compress-release cycle, even under 90% strain. Particularly, the material can maintain structural integrity after more than 106 cycles at 20% strain and 2.5 × 105 cycles at 50% strain. This structural material, although constructed using an intrinsically brittle carbon constituent, is simultaneously super-elastic, highly compressible and fatigue resistant to a degree even greater than that of previously reported compressible foams mainly made from more robust constituents.