Design of a Heterogeneous Catalyst Based on Cellulose Nanocrystals for Cyclopropanation: Synthesis and Solid-State NMR Characterization.

Heterogeneous dirhodium(II) catalysts based on environmentally benign and biocompatible cellulose nanocrystals (CNC-Rh2) as support material were obtained by ligand exchange between carboxyl groups on the CNC surface and Rh2(OOCCF3)4, as was confirmed by solid-state (19)F and (13)C NMR spectroscopy. On average, two CF3COO(-) groups are replaced during ligand exchange, which is consistent with quantitative analysis by a combination of (19)F NMR spectroscopy and thermogravimetry. CNC-Rh2 catalysts performed well in a model cyclopropanation reaction, in spite of the low dirhodium(II) content on the CNC surface (0.

Multi-responsive cellulose nanocrystal-rhodamine conjugates: an advanced structure study by solid-state dynamic nuclear polarization (DNP) NMR.

Multi-stimuli responsive materials based on cellulose nanocrystals (CNCs), especially using non-conventional stimuli including light, still need more explorations, to fulfill the requirements of complicated application environments. The structure determination of functional groups on the CNC surface constitutes a significant challenge, partially due to their low amounts. In this study, rhodamine spiroamide groups are immobilized onto the surface of CNCs leading to a hybrid compound being responsive to pH-values, heat and UV light.

A chemoenzymatic approach to protein immobilization onto crystalline cellulose nanoscaffolds.

The immobilization of bioactive molecules onto nanocellulose leads to constructs that combine the properties of the grafted compounds with the biocompatibility and low cytotoxicity of cellulose carriers and the advantages given by their nanometer dimensions. However, the methods commonly used for protein grafting suffer from lack of selectivity, long reaction times, nonphysiological pH ranges and solvents, and the necessity to develop a tailor-made reaction strategy for each individual case. To overcome these restrictions, a generic two-step procedure was developed that takes advantage of the highly efficient oxime ligation combined with enzyme-mediated protein coupling onto the surface of peptide-modified crystalline nanocellulose.