The regeneration of articular cartilage, which scarcely shows innate self-healing ability, is a great challenge in clinical treatment. Stem cell-derived exosomes (SC-Exos), an important type of extracellular nanovesicle, exhibit great potential for cartilage regeneration to replace stem cell-based therapy. Cartilage regeneration often takes a relatively long time and there is currently no effective administration method to durably retain exosomes at cartilage defect sites to effectively exert their reparative effect. Therefore, in this study, we exploited a photoinduced imine crosslinking hydrogel glue, which presents excellent operation ability, biocompatibility and most importantly, cartilage-integration, as an exosome scaffold to prepare an acellular tissue patch (EHG) for cartilage regeneration. It was found that EHG can retain SC-Exos and positively regulate both chondrocytes and hBMSCs in vitro. Furthermore, EHG can integrate with native cartilage matrix and promote cell deposition at cartilage defect sites, finally resulting in the promotion of cartilage defect repair. The EHG tissue patch therefore provides a novel, cell-free scaffold material for wound repair.

An excellent mesoporous silica nanoparticle (MSN) based drug deliver system (DDS) was reported for regulated anticancer drug release upon the irradiation of either one- or two-photon excitation. In this system, the coumarin grafted on MSN acted as both the "phototrigger" for the drug release and fluorescence group for cell luminescence imaging. External light manipulations such as changing irradiation wavelength, intensity, and time can regulate the release of the anticancer drug precisely. Biological studies in vitro suggest that the drug carrier can effectively deliver the anticancer drug into intracellular environs and, hence, promote the drug action to kill the cancer cells upon irradiation. We envision that the good biocompatibility, cellular uptake property, and efficient photoregulated drug release will be of great benefit to future controlled release in vivo biomedical applications.

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Inspired by natural biomolecular machines, synthetic molecular-level machines have been proven to perform well-defined mechanical tasks and measurable work. To mimic the function of channel proteins, we herein report the development of a synthetic molecular shuttle, [2]­rotaxane 3, as a unimolecular vehicle that can be inserted into lipid bilayers to perform passive ion transport through its stochastic shuttling motion. The [2]­rotaxane molecular shuttle is composed of an amphiphilic molecular thread with three binding stations, which is interlocked in a macrocycle wheel component that tethers a K+ carrier. The structural characteristics enable the rotaxane to transport ions across the lipid bilayers, similar to a cable car, transporting K+ with an EC50 value of 1.0 μM (3.0 mol % relative to lipid). We expect that this simple molecular machine will provide new opportunities for developing more effective and selective ion transporters.

A novel photogelling mechanism by the phototriggered-imine-crosslinking (PIC) reaction is demonstrated. Hyaluronic acid grafted with o-nitrobenzene, a photogenerated aldehyde group, can quickly photo-crosslink with amino-bearing polymers or proteins. Once the in situ photogelling on a wound occurs, the PIC gelling process can well integrate a hydrogel with surrounding tissue by covalent bonding, thus making it a powerful tool for tissue engineering and regenerative medicine.

Dynamic assembly is a powerful fabrication method of complex, functionally diverse molecular architectures, but its use in synthetic nanomachines has been hampered by the difficulty of avoiding reversible attachments that result in the premature breaking apart of loosely held moving parts. We show that molecular motion can be controlled in dynamically assembled systems through segregation of the disassembly process and internal translation to time scales that differ by four orders of magnitude. Helical molecular tapes were designed to slowly wind around rod-like guests and then to rapidly slide along them. The winding process requires helix unfolding and refolding, as well as a strict match between helix length and anchor points on the rods. This modular design and dynamic assembly open up promising capabilities in molecular machinery.

A novel OA/ionic liquid two‐phase system combining the merits of thermal decomposition method, the IL‐based strategy, and the two‐phase approach is introduced to synthesize high‐quality lanthanide‐doped NaGdF4 upconversion nanocrystals with different crystal‐phases in OA‐phase and IL‐phase through a one‐step controllable reaction. Oil‐dispersible cubic‐phase NaGdF4:Yb, Er (Ho, Tm) nanocrystals with ultra‐small size (∼5 nm) and monodispersity are obtained in the OA phase of the two‐phase system via an IL‐based reaction. More importantly, water‐soluble hexagonal‐phase NaGdF4:Yb, Er nanocrystals are obtained in the same system simply by adopting an extremely facile method to complete the dual phase‐transition (crystal‐phase transition and OA‐phase to IL‐phase transition) simultaneously. The synthesized lanthanide‐doped NaGdF4 upconversion nanocrystals are effective for dual‐mode UCL imaging and CT imaging in vivo.

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