Boronic acid-substituted shapeshifting bullvalenes bearing a (13)C label are employed as sensor arrays for polyhydroxylated compounds, such as carbohydrates, flavanols, and sialic acids. The dynamic nature of the bullvalene core allows for covalent binding to a wide variety of analytes, allowing for specific analyte detection by a single NMR measurement. The resulting (13)C NMR patterns permit an inference to the identity of a particular analyte bound. Conversion of the (13)C NMR to an easy-to-read barcode provides a convenient method to catalog polyol analytes. The synthesis and study of a structurally related static sensor, which is not suitable for analyte recognition, underscores the advantages of the shapeshifting nature of the sensor.

The rapidly growing applications of nanomagnets require acid/base stable, oxidation-resistant shells with chemically controlled surface structure. An ideal core should be metallic and highly magnetic. We demonstrate the production of iron-based nanoparticles, ranging from iron oxide to iron and iron carbide, by systematically modifying the degree of reduction during flame spray synthesis under a controlled atmosphere. At a laboratory scale, continuous production yields iron-based particles of 20-50 nm at a production rate of >10 g h -1 . Carbon-encapsulated iron carbide (C/Fe 3 C) combines exceptionally high saturation magnetization (140 emu g -1 ), air stability (up to 200°C), and resistance against acidic dissolution (1 week in 24% HCl). The top graphene-like carbon layer could be covalently functionalized with various linkers, thus allowing us to chemically design the particle surface. Activity was demonstrated by reacting 2-phenyl ethyl amine functionalized nanomagnets with carboxylic acid chlorides as a model reaction. The present nanomagnets consist of biologically well-accepted constituents. They combine the required chemical reliability, improved magnetization if compared to magnetite with the potential for technical scale manufacturing, and therefore open stable nanomagnets to a broad range of fascinating separation problems (extraction/water treatment) and biomedical research.

Three-dimensional (3D) control over the placement of bioactive cues is fundamental to understand cell guidance and develop engineered tissues. Two-photon patterning (2PP) provides such placement at micro-to millimeter scale, but non-specific interactions between proteins and functionalized extracellular matrices (ECMs) restrict its use. Here we report a 2PP system based on non-fouling hydrophilic photocages and Sortase A-based enzymatic coupling offering unprecedented orthogonality and signal-to-noise ratio in both inert hydrogels and complex mammalian matrices. Improved photocaged peptide synthesis, and protein functionalization protocols with broad applicability are introduced. Importantly, the method enables 2PP in a single step and in the presence of fragile biomolecules and cells. As a corollary, we demonstrate the guidance of axons through 3D-patterned nerve growth factor (NGF) within brain-mimetic ECMs. Our approach allows for the interrogation of the role of complex signaling molecules in 3D matrices, thus helping to better understand biological guidance in tissue development and regeneration.

The synthesis of novel PEG-based hydrogel via chemoselective potassium acyl trifluoroborate (KAT) and O-carbamoyl hydroxylamines amide ligation is reported. The gelation kinetics, determined by dynamic rheometry, is pH dependent and allows fine-tuning of the gelation time. For a 4 wt % PEG hydrogel, at low acidic pHs (3 to 6) gelation proceeds rapidly within few minutes, comparable or existing the faster known gelation times. At neutral and physiological pHs (7 and 7.4) the reaction is slower, forming a hydrogel in ca. 80 min. The gels are suitable for the encapsulation of bovine chondrocytes with the high viability (96% after 2 days), demonstrating the biocompatibility of the KAT ligation for the first time.