Controlling the packing arrangements of dyes is a facile way of tuning their photophysical and/or photochemical properties, thus enabling new sensing mechanisms for photofunctional tools. Here, we present a general and robust strategy toward water-stable J-aggregated dye-templated nanoassemblies by incorporating an amphiphilic diblock copolymer and a stimuli-responsive dye as the only two building components. An iodo-substituted boron dipyrromethene (BODIPY) was adopted as a template to direct the self-assembly of poly(ethylene glycol)-block-polycaprolactone (PEG−PCL), forming a core−shell nanoplate with slip-stacked BODIPYs as core surrounded by hydrophilic PEG shell. The self-assembled nanoplate is stable in cell culture medium and possesses a built-in stimuli-responsiveness that arises from BODIPY bearing meso-carboxylate protecting group, which is efficiently removed upon treatment with peroxynitrite. The resulting negative charges lead to rearrangement of dyes from J-stacking to nonstacking, which activates photoinduced singlet oxygen production from the nanoassemblies. The stimuli-activatable photosensitivity has been exploited for specific photodynamic ablation of activated RAW 264.7 cells with excessive endogenous peroxynitrite. In light of the generality of the sensing mechanism, the concept described herein will significantly expand the palette of design principles to develop diverse photofunctional tools for biological research and clinical needs.

A highly porous and nanostructured CuO-ZnO composite has been synthesized for the sensing electrode of a solid-state electrochemical sensor for the high-temperature detection of carbon monoxide. The sensing electrode is made of ZnO nanotetrapod supported CuO nanoparticles. The ZnO nanotetrapods form a three-dimensional interconnected network, leading to a highly porous electrode. The ZnO nanotetrapods on which the CuO nanoparticles are highly dispersedly supported have a high surface-to-volume ratio while maintaining thermal stability at high temperature. Our approach provides an inexpensive route for large-scale production of porous and nanostructured electrodes, which increases the sensitivity of solid-state electrochemical sensors for on-line gas detection at high temperature.

Utilizing the J-stacking of dyes to drive the assembly of amphiphilic polymers can not only construct supramolecular assemblies with novel architectures but also provide a stabilizing solution for dye J-aggregation to promote its biomedical applications. However, tightly entangled hydrophobic segments can disrupt the orderly arrangement of dye molecules, thereby preventing dye stacking-driven supramolecular assembly of block copolymers. Herein, a "molecular glue" strategy is reported that uses the small dye molecule as a molecular glue to restore the J-stacking of the dye moiety immobilized on the polymer, thereby dominating the supramolecular assembly of the polymer matrix. Very interestingly, the yielded nano-assembly exhibits a novel worm-like structure with alternating straight and bent segments. By passing through nanopores, the bent part is disassembled to afford short nanorod NR-J812 mainly composed of crystalline dye J-aggregates. It shows favorable colloidal and optical stability, suitable size, and high photothermal property, and demonstrates high performance in photoacoustic imaging and photothermal treatment of tumors in vivo. This work provides important insights into not only the self-assembly of amphiphilic polymers with novel supramolecular architectures but also the preparation of J-aggregate materials applicable in vivo, which bring great promise to the biomedical fields.