No abstract

Eliminated without a trace: The fastest click reaction, the highly selective inverse‐electron‐demand Diels–Alder reaction, has been modified to enable selective bioorthogonal release. Thus, the click reaction of a tetrazine with a drug‐bound trans‐cyclooctene caused the instantaneous release of the drug and CO2 (see scheme). One possible application is the chemically triggered release, and thereby activation, of a drug from a tumor‐bound antibody–drug conjugate.

A modular one-component supramolecular transient network in water, based on poly(ethylene glycol) and end-capped with four-fold hydrogen bonding units, is reported. Due to its nonlinear structural formation, this system allows active proteins to be added to the hydrogel during formation. Once implanted in vivo it releases the protein by erosion of both the protein and polymer via dissolution.

The use of a bioorthogonal reaction for the selective cleavage of tumor-bound antibody-drug conjugates (ADCs) would represent a powerful new tool for ADC therapy, as it would not rely on the currently used intracellular biological activation mechanisms, thereby expanding the scope to noninternalizing cancer targets. Here we report that the recently developed inverse-electron-demand Diels-Alder pyridazine elimination reaction can provoke rapid and self-immolative release of doxorubicin from an ADC in vitro and in tumor-bearing mice.

The creation of a living heart valve is a much-wanted alternative for current valve prostheses that suffer from limited durability and thromboembolic complications. Current strategies to create such valves, however, require the use of cells for in vitro culture, or decellularized human- or animal-derived donor tissue for in situ engineering. Here, we propose and demonstrate proof-of-concept of in situ heart valve tissue engineering using a synthetic approach, in which a cell-free, slow degrading elastomeric valvular implant is populated by endogenous cells to form new valvular tissue inside the heart. We designed a fibrous valvular scaffold, fabricated from a novel supramolecular elastomer, that enables endogenous cells to enter and produce matrix. Orthotopic implantations as pulmonary valve in sheep demonstrated sustained functionality up to 12 months, while the implant was gradually replaced by a layered collagen and elastic matrix in pace with cell-driven polymer resorption. Our results offer new perspectives for endogenous heart valve replacement starting from a readily-available synthetic graft that is compatible with surgical and transcatheter implantation procedures.

Current antibody-drug conjugates (ADCs) target internalising receptors on cancer cells leading to intracellular drug release. Typically, only a subset of patients with solid tumours has sufficient expression of such a receptor, while there are suitable non-internalising receptors and stroma targets. Here, we demonstrate potent therapy in murine tumour models using a non-internalising ADC that releases its drugs upon a click reaction with a chemical activator, which is administered in a second step. This was enabled by the development of a diabody-based ADC with a high tumour uptake and very low retention in healthy tissues, allowing systemic administration of the activator 2 days later, leading to efficient and selective activation throughout the tumour. In contrast, the analogous ADC comprising the protease-cleavable linker used in the FDA approved ADC Adcetris is not effective in these tumour models. This first-in-class ADC holds promise for a broader applicability of ADCs across patient populations.

A challenging target in the noncovalent synthesis of nanostructured functional materials is the formation of uniform features that exhibit well-defined properties, e.g., precise control over the aggregate shape, size, and stability. In particular, for aqueousbased one-dimensional supramolecular polymers, this is a daunting task. Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing out attractive noncovalent forces within the hydrophobic core of the polymerizing building blocks with electrostatic repulsive interactions on the hydrophilic rim we managed to switch from elongated, rod-like assemblies to small and discrete objects. Intriguingly this rod-tosphere transition is expressed in a loss of cooperativity in the temperature-dependent self-assembly mechanism. The aggregates were characterized using circular dichroism, UV and 1H-NMR spectroscopy, small angle X-ray scattering, and cryotransmission electron microscopy. In analogy to many systems found in biology, mechanistic details of the self-assembly pathways emphasize the importance of cooperativity as a key feature that dictates the physical properties of the produced supramolecular polymers.aqueous self-assembly | controlled architecture | supramolecular polymerization | dynamic materials M olecular self-assembly has emerged as a fascinating area in its own right (1, 2). A toolbox initially developed by supramolecular chemists quickly expanded into an interdisciplinary field aiming at the manipulation of matter at the molecular scale (3, 4). Up until recently self-assembly in dilute aqueous environments has predominantly dealt with linear amphiphiles that form closed structures (5-9), such as spherical micelles, cylindrical or rod-like micelles, and vesicles using, for example, phospholipids (10, 11), synthetic block copolymers (12, 13), or dendrimers (14). Morphological control in objects of defined size or shape, and transitions between different morphologies are increasingly well understood (15)(16)(17)(18). Surprisingly, however, the generality of these concepts has not been translocated into another area of increasing interest, namely, the self-assembly of one-dimensional arrays. In that context the development of discotic monomers has proven to be a valuable route to allow for the synthesis of rod-like supramolecular polymers (19), whose potential applications in functional soft matter include electronics, biomedical engineering, and sensors (20)(21)(22)(23)(24)(25)(26). Considering the enormous interest in such systems, it is surprising that efforts to control the size and shape of nano-and micrometer size one-dimensional objects are rare (27-29); successful strategies rely on the use of templates (30, 31), end cappers (32), or selective solvent techniques (33).In order to control the growth of aqueous one-dimensional supramolecular polymers, we propose to utilize electrostatic repulsive contributions in analogy to surfactant...

The bioorthogonal cleavage of allylic carbamates from trans-cyclooctene (TCO) upon reaction with tetrazine is widely used to release amines. We disclose herein that this reaction can also cleave TCO esters, carbonates, and surprisingly, ethers. Mechanistic studies demonstrated that the elimination is mainly governed by the formation of the rapidly eliminating 1,4-dihydropyridazine tautomer, and less by the nature of the leaving group. In contrast to the widely used p-aminobenzyloxy linker, which affords cleavage of aromatic but not of aliphatic ethers, the aromatic, benzylic, and aliphatic TCO ethers were cleaved as efficiently as the carbamate, carbonate, and esters. Bioorthogonal ether release was demonstrated by the rapid uncaging of TCO-masked tyrosine in serum, followed by oxidation by tyrosinase. Finally, tyrosine uncaging was used to chemically control cell growth in tyrosine-free medium.