Responsive hydrogels applied in the biomedical area show great potential as synthetic extracellular matrix mimics and as host medium for cell growth. The hydrogels often lack the characteristic mechanical properties that are typically seen for natural gels. Here, we demonstrate the unique responsive and mechanical properties of hydrogels based on oligo(ethylene glycol) functionalized polyisocyanopeptides. These stiff helical polymers form gels upon warming at concentrations as low as 0.006 %-wt polymer, with materials properties almost identical to those of their intermediate filaments, a class of cytoskeletal proteins. Using a combination of macroscopic rheology and molecular force microscopy the hierarchical relationship between the macroscopic behaviour of theses peptide mimics has been correlated with the molecular parameters.

Stable helical polymers with a preferred handedness are compounds that offer intriguing characteristics. This review describes the progress in the synthesis of helical polyisocyanides and the investigations to determine their structural properties, such as helical pitch and handedness, by spectroscopic measurements and high resolution AFM. This review is not intended to be comprehensive; its purpose is to highlight recent studies that allow a better understanding of the main aspects of helical polyisocyanides.

Click ‘n’ chips: Azide and alkyne‐bearing sialic acids (purple diamond; see picture) were subjected to high‐throughput click chemistry to generate a library of sialic acid analogues. Microarray printing of the library and screening with the siglec family of sialic‐acid‐binding proteins, led to the identification of high‐affinity ligands for siglec‐9 and siglec‐10.

The siglec family of sialic acid-binding proteins are endocytic immune cell receptors that are recognized as potential targets for cell directed therapies. CD33 and CD22 are prototypical members and are validated candidates for targeting acute myeloid leukaemia and non-Hodgkin’s lymphomas due to their restricted expression on myeloid cells and B-cells, respectively. While nanoparticles decorated with high affinity siglec ligands represent an attractive platform for delivery of therapeutic agents to these cells, a lack of ligands with suitable affinity and/or selectivity has hampered progress. Herein we describe selective ligands for both of these siglecs, which when displayed on liposomal nanoparticles, can efficiently target the cells expressing them in peripheral human blood. Key to their identification was the development of a facile method for chemo-enzymatic synthesis of disubstituted sialic acid analogues, combined with iterative rounds of synthesis and rapid functional analysis using glycan microarrays.

Exciton migration! Spectroscopic analyses and extensive molecular dynamics studies revealed a well-defined 4(1) helix in which the perylene molecules (see figure) form four "helter-skelter-like" overlapping pathways along which excitons and electrons can rapidly migrate.We report on a combined experimental and computational investigation on the synthesis and thorough characterization of the structure of perylene-functionalized polyisocyanides. Spectroscopic analyses and extensive molecular dynamics studies revealed a well defined 4(1) helix in which the perylene molecules form four "helter skelter-like" overlapping pathways along which excitons and electrons can rapidly migrate. The well-defined polymer scaffold stabilized by hydrogen bonding, to which the chromophores are attached, accounts for the precise architectural definition, and molecular stiffness observed for these molecules. Molecular-dynamics studies showed that the chirality present in these polymers is expressed in the formation of stable right-handed helices. The formation of chiral supramolecular structures is further supported by the measured and calculated bisignated Cotton effect. The structural definition of the chromophores aligned in one direction along the backbone is highlighted by the extremely efficient exciton migration rates and charge densities measured with Transient Absorption Spectroscopy.