An amino-trisulfonate tetraphenylporphyrin was conjugated to carboxylate cellulose nanocrystals giving rise to a new nanomaterial with interesting binding properties.

This study investigates transgeden (TGD) dendrimers (polyamidoamine (PAMAM)-type dendrimers modified with rigid polyphenylenevinylene (PPV) cores) and compares their heparin-binding ability with commercially available PAMAM dendrimers. Although the peripheral ligands are near-identical between the two dendrimer families, their heparin binding is very different. At low generation (G1), TGD outperforms PAMAM, but at higher generation (G2 and G3), the PAMAMs are better. Heparin binding also depends strongly on the dendrimer/heparin ratio. We explain these effects using multiscale modelling. TGD dendrimers exhibit "shape-persistent multivalency"; the rigidity means that small clusters of surface amines are locally well optimised for target binding, but it prevents the overall nanoscale structure from rearranging to maximise its contacts with a single heparin chain. Conversely, PAMAM dendrimers exhibit "adaptive multivalency"; the flexibility means individual surface ligands are not so well optimised locally to bind heparin chains, but the nanostructure can adapt more easily and maximise its binding contacts. As such, this study exemplifies important new paradigms in multivalent biomolecular recognition.

No abstract

Thanks to their unique properties, such as (i) renewability, (ii) high aspect ratios, (iii) low density, (iv) biodegradability, (v) high strength, and (vi) stiffness, there have been many reports in recent years detailing the isolation and functionalization of cellulose nanowhiskers from cellulose. Moreover, nanocellulose can be produced in large quantities in a cost-effective manner and can be easily functionalized due to its high density of hydroxy groups. In the present work, alkynyl-dendrons of the PAMAM family were covalently attached to azide-functionalized cellulose nanocrystals by click chemistry (Huisgen cycloaddition). The resulting cycloadducts were then used as templates for the preparation of stable and monodispersed gold nanoparticles in aqueous media. The catalytic capabilities of these hybrid materials were studied in the sodium borohydride mediated reduction of 4-nitrophenol to 4-aminophenol, which served as a model reaction