Metastasis-induced high mortality of cancers urgently demands new approaches to simultaneously inhibit primary tumor metastasis and distant tumor growth. Herein, by rational design of a trident molecule Nap–Phe–Phe–Lys­(SA-CPT)–Lys­(SA-HCQ)–Tyr­(H2PO3)–OH (Nap–CPT–HCQ–Yp) with three functional “spears” (i.e., a phosphotyrosine motif for enzymatic self-assembly, camptothecin (CPT) motif for chemotherapy, and hydroxychloroquine (HCQ) motif for autophagy inhibition) and nanobrush–nanoparticle–nanofiber transition property, we propose a novel strategy of intracellular enzymatic nanofiber formation and synergistic autophagy inhibition-enhanced chemotherapy and immunotherapy for spatial suppression of tumor metastasis. Under sequential alkaline phosphatase catalysis and carboxylesterase hydrolysis, Nap–CPT–HCQ–Yp undergoes nanobrush–nanoparticle–nanofiber transition, accompanied by the releases of CPT and HCQ. The formed intracellular nanofibers effectively inhibit the metastasis and invasion behaviors of cancer cells. Meanwhile, the released CPT and HCQ synergistically induce a prominent therapeutic effect through autophagy inhibition-enhanced chemotherapy. Furthermore, chemotherapy of Nap–CPT–HCQ–Yp enhances immunogenic cell death, resulting in the activation of toxic T-cells. Finally, a combination of checkpoint blockade therapy and Nap–CPT–HCQ–Yp-mediated chemotherapy elicits systemic antitumor immunity, thereby achieving efficient inhibitions of primary tumors as well as distant tumors in a breast tumor model. Our work offers a simple and feasible strategy for the design of “smart” multifunctional prodrugs to spatially suppress tumor metastasis.

Mild‐temperature photothermal therapy (PTT) of tumors has been intensively explored and adopted in preclinical/clinical trials in recent years. Nevertheless, tumor thermoresistance significantly compromises the therapeutic efficacy of mild‐temperature PTT, and therefore, the extra addition of anti‐thermoresistance agent is needed. Herein, by rational design of a peptide‐hydroxychloroquine (HCQ) conjugate Cypate‐Phe‐Phe‐Lys(SA‐HCQ)‐Tyr(H2PO3)‐OH (Cyp‐HCQ‐Yp), a “smart” strategy of enzyme‐triggered simultaneously intracellular photothermal nanoparticle formation and HCQ release is proposed for autophagy‐inhibited mild‐temperature PTT of tumor. In vitro results show that, under sequential catalysis of enzymes alkaline phosphatase and carboxylesterase, Cyp‐HCQ‐Yp is converted to Cypate‐Phe‐Phe‐Lys(SA)‐Tyr‐OH (Cyp‐Y) which self‐assembles into its nanoparticle Cyp‐NP and HCQ is released from Cyp‐HCQ‐Yp. By comparing with two control agents, it is validated that the exceptional therapeutic effect of Cyp‐HCQ‐Yp on tumor in vivo is achieved by its dual‐enzyme‐controlled intracellular nanoparticle formation and autophagy inhibition in tumors.

Emissive excimers, which are formed by planar polycyclic aromatic fluorophores (e.g., coumarin), enable high contrast tumor imaging. However, it is still challenging to "turn on" excimer fluorescence in physiological dilute solutions. The biocompatible CBT-Cys click condensation reaction enables both intra-and intermolecular aggregations of the as-loaded fluorophores on the probe molecules, which may promote the generation of emissive excimers in a synergistic manner. As a proof-of-concept, we herein design a fluorescence probe Cbz-Gly-Pro-Cys(StBu)-Lys(coumarin)-CBT (Cbz-GPC(StBu)K(Cou)-CBT), which can be activated by FAP-α under tumor-inherent reduction conditions, undergo a CBT-Cys click reaction, and selfassemble into coumarin nanoparticle Cou-CBT-NP to "turn on" the excimer fluorescence. In vitro and in vivo studies validate that this "smart" probe realizes efficient excimer fluorescence imaging of FAP-α-overexpressed tumor cells with high contrast and enhanced accumulation, respectively. We anticipate that this probe can be applied for diagnosis of FAP-α-related diseases in the clinic in near future.

Derived from the D‐luciferin regeneration pathway in firefly body, the click condensation reaction between 2‐cyanobenzothiazole (CBT) and D‐cysteine (Cys) (CBT‐Cys click reaction) possesses unique advantages, including superior biocompatibility, high second order reaction rate, and metal‐free mild conditions, emerging as a powerful bioorthogonal tool for a variety of chemical biological applications. Moreover, owing to its programmable controllability (e.g., pH, reduction, or enzyme), CBT‐Cys click reaction is exploited to fabricate stimuli‐activatable imaging probes with self‐assembling behaviors in physiological context. At stimuli‐rich pathological lesions of interest, these probes undergo CBT‐Cys click reaction to form cyclic dimers/oligomers or linear polymers, and further self‐assemble into nanostructures. The in situ formed nanostructures promote the selective accumulation and retention of imaging agent cargos at pathological lesions, thus enabling precise and enhanced in vivo imaging of diseases (especially tumors). To address the significance and recent breakthroughs of smart CBT‐Cys probes for enhanced optical imaging of tumors/other diseases, we herein propose this mini‐review, in which advances (particularly in recent 5 years) and potential challenges (or chances) in this field are emphasized.

Staphylococcus aureus (S. aureus) remains a leading cause of bacterial infections. However, eradication of S. aureus infections with common antibiotics is increasingly difficult due to outbreaks of drug resistance. Therefore, new antibiotic classes and antibacterial strategies are urgently in demand. Herein, it is shown that an adamantane‐peptide conjugate, upon dephosphorylation by alkaline phosphatase (ALP) constitutively expressed on S. aureus, generates fibrous assemblies in situ to combat S. aureus infection. By attaching adamantane to a phosphorylated tetrapeptide Nap‐Phe‐Phe‐Lys‐Tyr(H2PO3)‐OH, the rationally designed adamantane‐peptide conjugate Nap‐Phe‐Phe‐Lys(Ada)‐Tyr(H2PO3)‐OH (Nap‐FYp‐Ada) is obtained. Upon bacterial ALP activation, Nap‐FYp‐Ada is dephosphorylated and self‐assembles into nanofibers on the surface of S. aureus. As revealed by cell assays, the assemblies of adamantane‐peptide conjugates interact with cell lipid membrane and thereby disrupt membrane integrity to kill S. aureus. Animal experiments further demonstrate the excellent potential of Nap‐FYp‐Ada in the treatment of S. aureus infection in vivo. This work provides an alternative approach to design antimicrobial agents.