Metal-catalyzed chemical transformations performed at the cellular level bear great potential for the manipulation of biological processes. The complexity of the cell renders the use of transition metal chemistry difficult in cellular systems. The delivery of the reactive catalyst and the control of its spatial localization remain challenging. Here we report the surface functionalization of the unicellular eukaryote Chlamydomonas reinhardtii with a tailor-made artificial metalloenzyme for on-cell catalysis. The functionalized cells remain viable and are able to uncage a fluorogenic substrate on their surface. This work leverages cell surface engineering to provide live cells with new-to-nature reactivity. In addition, this operationally simple approach is not genetically encoded and thereby transient, which offers advantages with regard to temporal control, cell viability, and safety. Therefore, and as a feature, the movement of the functionalized cells can be directed by light (via phototaxis), allowing for the three-dimensional localization of catalysts by outside stimuli.

N-Mesyloxycarbamates undergo intramolecular C-H amination reactions to afford oxazolidinones in good to excellent yields in the presence of rhodium(ii) carboxylate catalysts. The reaction is performed under green conditions and potassium carbonate is used, forming biodegradable potassium mesylate as a reaction by-product. This method enables the production of electron-rich, electron-deficient, aromatic and heteroaromatic oxazolidinones in good to excellent yields. Conformationally restricted cyclic secondary N-mesyloxycarbamates furnish cis-oxazolidinones in high yields and selectivity; DFT calculations are provided to account for the observed selectivity. trans-Oxazolidinones were prepared from acyclic secondary N-mesyloxycarbamates using Rh(oct). The selectivity was reverted with a cytoxazone N-mesyloxycarbamate precursor using large chiral rhodium(ii) carboxylate complexes, affording the corresponding cis-oxazolidinone. This orthogonal selectivity was used to achieve the formal synthesis of (-)-cytoxazone.

This article presents design strategies to demonstrate approaches to generate functionalized surfaces which have the potential for application in molecular systems; sensing and chemical reactivity applications are exemplified. Some applications are proven, while others are still under active investigation. Adaptation and extension of our strategies will lead to interfacing of different type of surfaces, specific interactions at a molecular level, and possible exchange of signals/cargoes between them. Optimization of the present approaches from each of five research groups within the NCCR will be directed towards expanding the types of functional surfaces and the properties that they exhibit.

Stimulation of the body's immune system toward tumor cells is now well recognized as a promising strategy in cancer therapy. Just behind cell therapy and monoclonal antibodies, small molecule-based strategies are receiving growing attention as alternatives to direct immune response against tumor cells. However, the development of small-molecule approaches to modulate the balance between stimulatory immune factors and suppressive factors in a targeted way remains a challenge. Here, we report the cell surface functionalization of LS174T cancer cells with an abiotic hapten to recruit antibodies to the cell surface. Metabolic glycoengineering followed by covalent reaction with the hapten results in antibody recognition of the target cells. Microscopy and flow cytometry studies provide compelling evidence that metabolic glycoengineering and small molecule stimulators can be combined to direct antibody recognition.