The exciting applications of molecular motion are still limited and are in urgent pursuit, although some fascinating concepts such as molecular motors and molecular machines have been proposed for years. Utilizing molecular motion in a nanoplatform for practical application has been scarcely explored due to some unconquered challenges such as how to achieve effective molecular motion in the aggregate state within nanoparticles. Here, we introduce a class of near infrared-absorbing organic molecules with intramolecular motion-induced photothermy inside nanoparticles, which enables most absorbed light energy to dissipate as heat. Such a property makes the nanoparticles a superior photoacoustic imaging agent compared to widely used methylene blue and semiconducting polymer nanoparticles and allow them for high-contrast photoacoustic imaging of tumours in live mice. This study not only provides a strategy for developing advanced photothermal/photoacoustic imaging nanoagents, but also enables molecular motion in a nanoplatform to find a way for practical application.

The integration of luminescence and chirality in easy-scalable metal-organic frameworks gives rise to the development of advanced luminescent sensors. To date, the synthesis of chiral metal-organic frameworks is poorly predictable and their chirality primarily originates from components that constitute the frameworks. By contrast, the introduction of chirality into the pores of metal-organic frameworks has not been explored to the best of our knowledge. Here, we demonstrate that chirality can be introduced into an anionic Zn-based metal-organic framework via simple cation exchange, yielding dual luminescent centers comprised of the ligand and Tb³⁺ ions, accompanied by a chiral center in the pores. This bifunctional material shows enantioselectivity luminescent sensing for a mixture of stereoisomers, demonstrated for Cinchonine and Cinchonidine epimers and amino alcohol enantiomers, from which the quantitative determination of the stereoisomeric excess has been obtained. This study paves a pathway for the design of multifunctional metal-organic framework systems as a useful method for rapid sensing of chiral molecules.

Spider silks show unique combinations of strength, toughness, extensibility, and energy absorption. To date, it has been difficult to obtain spider silk-like mechanical properties using non-protein approaches. Here, we report on an artificial spider silk produced by the water-evaporation-induced self-assembly of hydrogel fibre made from polyacrylic acid and silica nanoparticles. The artificial spider silk consists of hierarchical core-sheath structured hydrogel fibres, which are reinforced by ion doping and twist insertion. The fibre exhibits a tensile strength of 895 MPa and a stretchability of 44.3%, achieving mechanical properties comparable to spider silk. The material also presents a high toughness of 370 MJ m⁻³ and a damping capacity of 95%. The hydrogel fibre shows only ~1/9 of the impact force of cotton yarn with negligible rebound when used for impact reduction applications. This work opens an avenue towards the fabrication of artificial spider silk with applications in kinetic energy buffering and shock-absorbing.