Spatial Distribution of Functional Groups in Cellulose Ethers by DNP-Enhanced Solid-State NMR Spectroscopy

Optimizing chemistry at the surface of prodrug-loaded cellulose nanofibrils with MAS-DNP

“…Following our recent work, we used Magic Angle Spinning Dynamic Nuclear Polarization (MAS-DNP) to record sensitivity-enhanced solid-state NMR spectra of the functionalized CNF samples. MAS-DNP has recently become a key NMR approach to study with unprecedented sensitivity and thus atomistic details various types of systems from functional material to complex biomolecular systems [37][38][39][40][41] , including cellulosic materials 21,[42][43][44][45][46][47][48] . This approach complements standard ssNMR experiments which are routinely used to characterize nanocellulose but have also been shown to be limited in terms of sensitivity, especially to detect low weight percent chemical modifications on the surface of CNMs 20 .…”

Fluorine-Labeled N-Boc-l-proline as a Marker for Solid-State NMR Characterization of Biofunctionalizations on Paper Substrates

“…A possible way to overcome this issue is the use of solid-state NMR combined with dynamic nuclear polarization (DNP). − This approach employs the 3 orders of magnitude higher polarization of unpaired electrons and transfers it into nuclear spin polarization. DNP-enhanced solid-state NMR has been applied for the investigation of many functional materials including cellulose-based ones in the past. − Furthermore, spin labels such as 19 F may be introduced to a material to further boost the sensitivity, as shown for a number of biological samples as well as for encapsulated molecules in polymers. − In this context, it has been shown by some of the authors that nanomolar amounts of molecules can be detected by DNP enhanced solid-state NMR at an economic measurement time …”

1H Detected Relayed Dynamic Nuclear Polarization

“… 29 The method, denoted Relayed DNP (R-DNP), has since been successfully applied to determine the de novo structure of lipid nanoparticles (such as those used to deliver mRNA-based vaccines), 30 changes in the topology of lignins in biomass subjected to extraction, 31 the core–shell structure of organic crystalline drug nanoparticles (CNPs), 32 the presence of an insoluble amorphous form of a drug at the surface of crystalline particles of the salt form, 33 and the spatial distribution of functional groups in cellulose ethers. 34 …”

“…Capitalizing on early work by Van Der Wel et al and Rossini et al, in 2017 Pinon et al combined 1 H spin diffusion with hyperpolarization from DNP and quantitative numerical models to measure domain sizes in crystalline powders, mesoporous silica materials, and mixed composition cellulose-based films . The method, denoted Relayed DNP (R-DNP), has since been successfully applied to determine the de novo structure of lipid nanoparticles (such as those used to deliver mRNA-based vaccines), changes in the topology of lignins in biomass subjected to extraction, the core–shell structure of organic crystalline drug nanoparticles (CNPs), the presence of an insoluble amorphous form of a drug at the surface of crystalline particles of the salt form, and the spatial distribution of functional groups in cellulose ethers …”

“…29 The method, denoted Relayed DNP (R-DNP), has since been successfully applied to determine the de novo structure of lipid nanoparticles (such as those used to deliver mRNA-based vaccines), 30 changes in the topology of lignins in biomass subjected to extraction, 31 the core−shell structure of organic crystalline drug nanoparticles (CNPs), 32 the presence of an insoluble amorphous form of a drug at the surface of crystalline particles of the salt form, 33 and the spatial distribution of functional groups in cellulose ethers. 34 Although R-DNP is a powerful method to measure domain sizes, it suffers from low sensitivity. Indeed, while DNP enhanced spectra offer substantial gains in sensitivity, and generally accelerate experiments, the R-DNP approach relies on recording the dynamics of the DNP enhancement as a function of the polarization time, which requires recording signal build-up experiments with and without μwave irradiation.…”