Solid-state NMR Research Articles

Dynamic nuclear polarization solid-state NMR spectroscopy as a tool to rapidly determine degree of modification in dialcohol cellulose

AbstractDialcohol cellulose can be prepared by periodate-mediated oxidation of cellulose followed by reduction with borohydride. The two-step reaction creates a modified cellulose polymer which is ring-opened between the C2 and C3 carbons in the glucose unit. This material has attracted both scientific and commercial interest, due to its potential role in the transition towards a fossil-fuel-free society. In order to become a reliable component in the materials of tomorrow, chemical properties such as degree of modification must be accurately quantified. In this work we describe how solid-state NMR spectroscopy, enhanced by dynamic nuclear polarization (DNP), can be used for this purpose. Our results illustrate that it is possible to obtain high sensitivity enhancements in dialcohol cellulose with the DNP enhanced solid-state NMR technique. Enhancements above a factor of fifty, on a 400 MHz/263 GHz DNP system in the presence of 12 mM AMUPol radical were achieved. This allows us to quantify the degree of modification in dialcohol cellulose samples in time spans as short as 20 min using DNP enhanced multiple-contact cross polarization experiments. We also exemplify how DNP enhanced, 13C-13C dipolar recoupling experiments can be used for the same purpose and for studying chemical shift correlations in dialcohol cellulose. Graphical abstract

Using the Cocrystal Approach as a Promising Drug Delivery System to Enhance the Dissolution and Bioavailability of Formononetin Using an Imidazole Coformer

Background: Natural isoflavones are recognized for their diverse pharmacological activities; however, their low aqueous solubility presents a significant challenge for further development. Here, we aimed to develop a cocrystal of formononetin (FMN) to improve its solubility. Methods: The formononetin-imidazole (FMN-IMD) cocrystal was prepared using liquid-assisted grinding method. The prepared cocrystal was identified through a thermal analysis of physical mixtures with various coformers. FTIR and solid-state NMR confirmed the presence of hydrogen bonds and π-π interactions in the FMN-IMD cocrystal. Results: The solubility of FMN-IMD was two to three times higher than that of crystalline FMN. The FMN-IMD cocrystal showed a 4.93-fold increase in the Cmax value and a 3.58-fold increase in the AUC compared to FMN after oral administration in rats. There were no changes in the PXRD of the FMN-IMD cocrystal after six months of storage at 40 °C. Conclusions: Thus, the FMN-IMD cocrystal is proposed as an effective solid form for oral delivery, offering enhanced solubility and physical stability.

Solid-state nuclear magnetic resonance at low-field as an approach for fertiliser dissolution monitoring

Solid-state nuclear magnetic resonance at low-field as an approach for fertiliser dissolution monitoring

Transforming Nanocrystals into Superhard Boron Carbide Nanostructures.

Boron carbide (B4+δC) possesses a large potential as a structural material owing to its lightness, refractory character, and outstanding mechanical properties. However, its large-scale industrialization is set back by its tendency to amorphize when subjected to an external stress. In the present work, we design a path toward nanostructured boron carbide with greatly enhanced hardness and resistance to amorphization. The reaction pathway consists of triggering an isomorphic transformation of covalent nanocrystals of Na1-xB5-xC1+x (x = 0.18) produced in molten salts. The resulting 10 nm B4.1C nanocrystals exhibit a 4-fold decrease of size compared to previous works. Solid-state 11B and 13C NMR coupled to density functional theory (DFT) reveal that the boron carbide nanocrystals are made of a complex mixture of atomic configurations, which are located at the covalent structural chains between B11C icosahedral building units. These nanocrystals are combined with a spark plasma-sintering-derived method operated at high pressure. This yields full densification while maintaining the particle size. The nanoscaled grains and high density of grain boundaries provide the resulting nanostructured bodies with significantly enhanced hardness and resistance to amorphization, thus delivering a superhard material.

A Syndiotactic Polymer via Spontaneous Exoselective Single-Crystal-To-Single-Crystal Topochemical Diels-Alder Cycloaddition Reaction.

We designed and synthesized an amide-based monomer decorated with furan as the diene unit and maleimide as the dienophile unit at its termini. Single-crystal X-ray diffraction (SCXRD) analysis of its crystal revealed a head-to-tail arrangement of molecules with furan and maleimide groups of neighboring molecules proximally placed in an arrangement suitable for their topochemical Diels-Alder cycloaddition (TDAC) to form a linear polymer. The monomer underwent a spontaneous single-crystal-to-single-crystal (SCSC) polymerization at room temperature, yielding a linear polymer with oxa-bicyclic linkage. SCXRD analysis revealed that the cycloaddition occurred in an exoselective manner, and the absolute stereochemistry of the oxa-bicyclic linkage alternated in successive repeat units, leading to a syndiotactic linear polymer. The polymerization can be accelerated by heating the powder at 120 °C; the topochemical nature of the high-temperature reaction was established by time dependent differential scanning calorimetry (DSC), time-dependent powder X-ray diffraction (PXRD), and UV-visible spectroscopic analysis; the polymer was characterized using solid-state NMR spectroscopy and MALDI-TOF mass spectrometry.

Directional Transport in Hierarchically Aligned ZSM-5 Zeolites with High Catalytic Activity.

Zeolites, the most technically important crystalline microporous materials, are indispensable cornerstones of chemical engineering because of their remarkable catalytic properties and adsorption capabilities. Numerous studies have demonstrated that the hierarchical engineering of zeolites can maximize accessible active sites and improve mass transport, which significantly decreases the internal diffusion limits to achieve the desired performance. However, the construction of hierarchical zeolites with ordered alignments and size-controlled substructures in a convenient way is highly challenging. Herein, we develop a facile procedure using two common structure-directing agents, tetrapropylammonium hydroxide (TPAOH) and tetraethylammonium hydroxide (TEAOH), to synthesize hierarchically aligned ZSM-5 (Hie-ZSM-5) crystals with a-axis alignment substructures of controllable size. The control of the substructure size (α) in the range of 10-60 nm and the corresponding similarity (r = α/β, where β is the size of Hie-ZSM-5) ranging from 0.004 to 0.033 can be tuned by varying the Si/Al ratios (40-120). A systematic investigation of the overall crystallization process, using time-dependent XRD, SEM, TEM, and solid-state magic-angle spinning NMR (13C, 27Al, 29Si) methods, enable us to construct a solid mechanism for the generation of Hie-ZSM-5. Most importantly, directional transport in the unique structures of Hie-ZSM-5 efficiently enhances mass diffusion, as well as catalytic activity and stability. These findings improve our understanding of the zeolite crystallization process and inspire novel methods for the rational design of hierarchical zeolites.

Structure and Dynamics in Solid Electrolyte Composites of the Organic Ionic Plastic Crystal HMGFSI and Lithium Sulphonamide Functional Acrylate Polymer Nanoparticles.

Solid electrolyte composites between organic ionic plastic crystals (OIPCs) and polymers can potentially show enhanced mechanical properties and ion conduction. These properties can be determined by the formation of interfacial regions which affect the structure, thermal properties, and ion transport of the composite material. Here we studied the properties of composites between the OIPC hexamethylguanidinium bis(fluorosulfonyl)imide (HMGFSI) and acrylate polymer nanoparticles functionalised with lithium, using various techniques including solid-state NMR spectroscopy. An enhancement in ionic conductivity of three orders of magnitude as well as increased lithium and OIPC cation and anion dynamics were observed in the composite as prepared with 40 v% of polymer nanoparticles with respect to the pure OIPC at 50 °C. This was attributed to the increased overall structural disorder as a result of the formation of disordered interfacial regions, which were evidenced by solid-state NMR spectroscopy. In addition, the importance of the thermal history of these composites is highlighted, with differences in the conductivity and ion dynamics observed after melting and recrystallizing the OIPC component, leading to less disordered interfacial regions. This study enriches our fundamental understanding of the formation of interfacial regions in OIPC composites and their effect on the bulk properties of the electrolyte.

Strategic approaches to observing 39K NMR signals from potassium–graphite intercalation compounds

Abstract Solid-state nuclear magnetic resonance (NMR) is an invaluable tool for potassium–graphite intercalation compounds (K-GICs), promising anode materials of K-ion batteries, but it has not yet been applied because of several issues. We attempted 39K NMR measurements of K-GICs sealed in glass using an 18.8 T NMR spectrometer with an NMR probe adjusted to the samples. The first observed 39K NMR signal of K-GICs showed the possibility of evaluating intralayer density, which cannot be ascertained from Raman measurements.

Fire and salvage logging increased recalcitrant soil organic matter and reduced soil functionality in Mediterranean pine forests.

Postfire management actions are used to mitigate damage caused by wildfires. Salvage logging, often employed to restore ecosystem functions in burnt stands, plays an essential role in reducing economic losses and the burn severity of future wildfires. However, its ecological implications for soil functionality still need to be understood, especially in the Mediterranean basin, which is prone to erosion and desertification. This study aimed to investigate the effects of fire on (i) soil organic matter (SOM) quality and composition using differential scanning calorimetry-thermogravimetry (DSC-TG) and solid-state nuclear magnetic resonance (13C CPMAS NMR) and (ii) phosphorus (P) forms using solid-state 31P NMR spectroscopy in a wildfire that affected 3200 ha in southeastern Spain in July 2017. One year after the fire, we monitored four Pinus halepensis Mill. stand categories based on soil burn severity (SBS): unburnt, low SBS, high SBS and high SBS areas with salvage logging (n=36, nine plots per SBS level). We collected soil samples and analysed soil pH, SOM content and SOM quality, along with biological activity indicators (carbon biomass, basal respiration, β-glucosidase, phosphatase activities) and P forms. We ran ANOVA statistical tests to identify significant differences in soil properties among SBS levels. We also established general linear regressions of thermo-recalcitrance values and aromaticity with biological soil quality indices to compare both techniques for detecting changes in SOM quality and composition. The results indicated that fire increased soil pH (up to 0.3), particularly in the plots with higher SBS levels. SOM decreased significantly with increasing SBS level (down to < 5 % at the high SBS level), with a shift from labile compounds (carbohydrates) to more recalcitrant ones (aromatics). Organic P forms were depleted, while orthophosphate levels rose, increasing the risk of irreversible fixation. This study also highlights that DSC-TG is a cost-effective technique for assessing SOM quality changes. Understanding these effects is essential for developing policies to conserve and restore fire-affected areas and to promote practices that enhance soil functionality and resilience.

Integrating 19F Distance Restraints for Accurate Protein Structure Determination by Magic Angle Spinning NMR Spectroscopy.

Traditional protein structure determination by magic angle spinning (MAS) solid-state NMR spectroscopy primarily relies on interatomic distances up to 8 Å, extracted from 13C-, 15N-, and 1H-based dipolar-based correlation experiments. Here, we show that 19F fast (60 kHz) MAS NMR spectroscopy can supply additional, longer distances. Using 4F-Trp,U-13C,15N crystalline Oscillatoria agardhii agglutinin (OAA), we demonstrate that judiciously designed 2D and 3D 19F-based dipolar correlation experiments such as (H)CF, (H)CHF, and FF can yield interatomic distances in the 8-16 Å range. Incorporation of fluorine-based restraints into structure calculation improved the precision of Trp side chain conformations as well as regions in the protein around the fluorine containing residues, with notable improvements observed for residues in proximity to the Trp pairs (W10/W17 and W77/W84) in the carbohydrate-binding loops, which lacked sufficient long-range 13C-13C distance restraints. Our work highlights the use of fluorine and 19F fast MAS NMR spectroscopy as a powerful structural biology tool.

The Paradoxical Influence of Hydrothermally Treated Zeolites on the Hydrocarbon Pool Mechanism.

Understanding the mechanistic intricacies of hydrothermally treated zeolite is crucial for valorizing any oxygen-containing renewable feedstocks (e.g., methanol, carbon dioxide, biomass). Additionally, the regeneration of deactivated zeolite catalysts under oxidative conditions, akin to hydrothermal treatment, is essential in industrial processes. While research in this area has predominantly focused on characterizing steaming-induced physicochemical changes in zeolite, their ultimate impact on the organic reaction mechanism governed by the hydrocarbon pool dual-cycle mechanism remains unclear. To bridge this knowledge gap, this study investigates the effect of steamed zeolite on the organic reaction mechanism during the industrially significant methanol-to-hydrocarbons process. We achieved this objective by strategically integrating catalytic and control experiments over the pristine and steamed zeolites and their advanced characterization, including under operando conditions, XRD structural refinement, and using "mobility-dependent" solid-state NMR spectroscopy. This multimodal characterization approach was instrumental in elucidating elusive mechanistic information in the dual-cycle mechanism, shedding light on phenomena such as the unchanged ethylene selectivity despite decreasing aromatics selectivity, while ethylene could solely be derived from arene-based reaction intermediates. This study could improve the process efficiency in zeolite catalysis by connecting steaming-induced changes in the organic reaction mechanisms with inorganic material aspects.

Aspartic Acid Binding on Hydroxyapatite Nanoparticles with Varying Morphologies Investigated by Solid-State NMR Spectroscopy and Molecular Dynamics Simulation.

Hydroxyapatite (HAP) exhibits a highly oriented hierarchical structure in biological hard tissues. The formation and selective crystalline orientation of HAP is a process that involves functional biomineralization proteins abundant in acidic residues. To obtain insights into the process of HAP mineralization and acidic residue binding, synthesized HAP with specific lattice planes including (001), (100), and (011) are structurally characterized following the adsorption of aspartic acid (Asp). The adsorption affinity of Asp on HAP surfaces is evaluated quantitatively and demonstrates a high dependency on the HAP morphological form. Among the synthesized HAP nanoparticles (NPs), Asp exhibits the strongest adsorption affinity to short HAP nanorods, which are composed of (100) and (011) lattice planes, followed by nanosheets with a preferential expression of the (001) facet, to which Asp displays a similar but slightly lower binding affinity. HAP nanowires, with the (100) lattice plane preferentially developed, show significantly lower affinity to Asp and evidence of multilayer adsorption compared to the previous two types of HAP NPs. A combination of solid-state NMR (SSNMR) techniques including 13C and 15N CP-MAS, relaxation measurements and 13C-31P Rotational Echo DOuble Resonance (REDOR) is utilized to characterize the molecular structure and dynamics of Asp-HAP bionano interfaces with 13C- and 15N-enriched Asp. REDOR is used to determine 13C-31P internuclear distances, providing insight into the Asp binding geometry where stronger 13C-31P dipolar couplings correlate with binding affinity determined from Langmuir isotherms. The carboxyl sites are identified as the primary binding groups, facilitated by their interaction with surface calcium sites. The Asp chelation conformations revealed by SSNMR are further refined with molecular dynamics (MD) simulation where specific models strongly agree between the SSNMR and MD models for the various surfaces.

The potential of supramolecular synthon to develop coamorphous systems with tailored physical stability: Mechanistic insights integrating kinetics and thermodynamics

Coamorphous drug delivery systems have received increasing interest owing to their potential to improve the solubility, dissolution and bioavailability of poorly water-soluble drugs. However, the crystallization risk is one of major limitations in their application. It has been widely recognized that the coformer plays a vital role in physical stability of coamorphous formulation. Unfortunately, the screen of optimal coformer still adopts a trial-and-error method, which is time-consuming and expensive. Herein, a supramolecular synthon approach based on the interaction between functional groups, was exploited to design coamorphous systems (CMs) consisting of lurasidone hydrochloride (LH) and three coformers, saccharin (SAC), L-tryptophan (TRP), and L-cysteine hydrochloride (CYS). X-ray powder diffraction suggested the order of physical stability of the coamorphous systems was ranked as LH-CYS CM > LH-TRP CM > LH-SAC CM. The charge-assisted hydrogen bond between LH and coformer was confirmed by infrared spectroscopy and solid-state 13C NMR. Moreover, structural, electronic, and molecular interaction information, especially hydrogen bonding interactions, were quantified by theoretical calculations, including miscibility calculations, molecular dynamics simulations and quantum chemical calculations. It was revealed that LH-CYS CM exhibited the best miscibility, strongest binding energy and strongest H-bond with partially covalent character, demonstrating the significant role of supramolecular synthon in stabilizing coamorphous formulations. Interestingly, LH-TRP CM, not LH-CYS CM, exhibited the lowest molecular mobility among three coamorphous systems, which was inconsistent with their physical stability. But from thermodynamic perspective, the order of configurational entropy and physical stability of coamorphous systems was completely consistent. We shed light on the comprehensive effects of molecular mobility and configurational entropy on physical stability of coamorphous systems. Importantly, the relationship between supramolecular synthon and kinetic/thermodynamic mechanisms was also discussed, and the positive correlation between configurational entropy and intermolecular interactions was proposed in this paper. Our findings demonstrated the great potential of supramolecular synthon in designing coamorphous systems with tailored physical stability, and further provided a deeper insight into the mechanisms of physical stability of coamorphous systems.

Solid-State Lithium Batteries with In Situ Polymerized Acrylate-Based Electrolytes Capable of Electrochemically Stable Operation at 100 °C.

Solid polymer electrolytes (SPEs) typically consist of salts with mobile anions that could cause instabilities and parasitic side reactions in solid-state lithium (Li) batteries. To address this challenge, single-Li-ion conducting (SLIC) SPEs, where anions of Li salts are covalently attached to the polymer backbone, have been utilized to reduce the number of mobile anions. This approach improves the cationic transference number but is accompanied by a loss of ionic conductivity. In this work, we investigate a synergetic approach of using both a polymerizable SLIC salt and a conventional Li salt in a polymer matrix by in situ polymerization of the poly(propylene glycol) acrylate (PPGA) monomer. The synthesized hybrid SPEs show a high ionic conductivity of up to ∼2 × 10-4 S cm-1 and a relatively high Li-ion transference number of ∼0.4. With a significantly reduced fraction of mobile anions in the combined salt SPE, in situ polymerized SPE cells with a LiFePO4 (LFP) cathode achieve a stable performance for over 100 cycles at temperatures as high as 100 °C, which is unattainable with conventional Li salts or electrolytes. Furthermore, solid-state nuclear magnetic resonance spectra provide additional insights into differences in Li nucleus environments and emphasize a reduction in activation energy for hybrid SPEs due to their more open structure. This study opens the path for the fabrication of high-performance solid polymer Li batteries capable of operating at high temperatures using commercial battery fabrication equipment, as in situ polymerized acrylate-based polymers provide drop-in compatibility with conventional battery production, ease of acrylate polymerization, and inexpensive, facile SPE chemistry. We expect that further tuning of the acrylate-based SPE composition may allow further increases in its conductivity without sacrificing its electrochemical stability or mechanical properties.

Lipid Compositions of Liquid-Ordered and Liquid-Disordered Phases in Ternary Membranes of Sphingomyelin, Cholesterol, and Dioleoylphosphatidylcholine Determined by 2H NMR: Stearoyl-Sphingomyelin Compared with Its Palmitoyl Counterpart.

Sphingomyelin (SM) and cholesterol are the major lipids in the signaling platforms of cell membranes, known as lipid rafts. In particular, SM with a stearoyl chain (C18-SM) is abundant in specific tissues such as the brain, the most cholesterol-rich organ, whereas the distribution of palmitoyl (C16)-SM is ubiquitous. Here, we reveal the differences between palmitoyl- and stearoyl-SM in lipid-lipid interactions based on the tie lines obtained from the 2H solid-state NMR spectra of bilayer systems composed of SM/dioleoylphosphatidylcholine/cholesterol 33:33:33 and 40:40:20. Lipid probes carrying position-selective deuterations, 10',10'-d2-SM, 24-d1-cholesterol, and 6″,6″-d2-dioleoyl-phosphatidylcholine, were incorporated into the membranes. 2H NMR peaks from these probes in the membranes directly provide the lipid compositions of the liquid-ordered (Lo) and liquid-disordered (Ld) regions. Without using bulky fluorescent groups, these probes allow us to obtain the end points of the tie lines in a ternary phase diagram based on the lever rule. Consequently, the tie lines of the stearoyl-SM membranes were steeper than those of the palmitoyl-SM membranes, indicating that cholesterol content was higher in the Lo domains of stearoyl-SM, regardless of the total concentration of unsaturated phospholipids. When comparing the content of unsaturated lipids in the Lo domain, the stearoyl-SM membranes had a higher content than palmitoyl-SM membranes. These results revealed that stearoyl-SM is suitable for stabilizing biologically functional microdomains in cholesterol-rich organs, whereas palmitoyl-SM may be better suited for stabilizing domains in tissue membranes with normal cholesterol content. The small but significant differences in the lipid interactions between stearoyl-SM and palmitoyl-SM may be related to the spatiotemporal formation of functional domains in biological environments.

Effects of a Serotonergic Psychedelic on the Lipid Bilayer.

Serotonergic psychedelics, known for their hallucinogenic effects, have attracted interest due to their ability to enhance neuronal plasticity and potential therapeutic benefits. Although psychedelic-enhanced neuroplasticity is believed to require activation of 5-hydroxytryptamine (serotonin) 2A receptors (5-HT2ARs), serotonin itself is less effective in promoting such plasticity. Also, the psychoplastogenic effects of these molecules correlate with their lipophilicity, leading to suggestions that they act by influencing the intracellular receptors. However, their lipophilicity also implies that a significant quantity of lipids is accumulated in the lipid bilayer, potentially altering the physical properties of the membrane. Here, we probe whether the serotonergic psychedelic 2,5-dimethoxy-4-iodoamphetamine (DOI) can affect the properties of artificial lipid bilayers and if that can potentially affect processes such as membrane fusion. Solid-state NMR spectroscopy shows that the DOI strongly induces disorder in the lipid acyl chains. Atomic force microscopy shows that it can shrink the ordered domains in a biphasic lipid bilayer and can reduce the force needed to form nanopores in the membrane. Fluorescence correlation spectroscopy shows that DOI can promote vesicle association, and total internal fluorescence microscopy shows that it enhances vesicle fusion to a supported lipid bilayer. While serotonin has also recently been shown to cause similar effects, DOI is more than two orders of magnitude more potent in evoking these. Our results suggest that the receptor-independent effects of serotonergic psychedelics on lipid membranes may contribute to their biological actions, especially those that require significant membrane remodeling, such as neuronal plasticity.

Selectivity Descriptors of Methanol-to-Aromatics Process over 3-Dimensional Zeolites.

The zeolite-catalyzed methanol-to-aromatics (MTA) process is a promising avenue for industrial decarbonization. This process predominantly utilizes 3-dimensional 10-member ring (10-MR) zeolites like ZSM-5 and ZSM-11, chosen for their confinement effect essential for aromatization. Current research mainly focuses on enhancing selectivity and mitigating catalyst deactivation by modulating zeolites' physicochemical properties. Despite the potential, the MTA technology is at a low Technology Readiness Level, hindered by mechanistic complexities in achieving the desired selectivity towards liquid aromatics. To bridge this knowledge gap, this study proposes a roadmap for MTA catalysis by strategically combining controlled catalytic experiments with advanced characterization methods (including operando conditions and "mobility-dependent" solid-state NMR spectroscopy). It identifies the descriptor-role of Koch-carbonylated intermediates, longer-chain hydrocarbons, and the zeolites' intersectional cavities in yielding preferential liquid aromatics selectivity. Understanding these selectivity descriptors and architectural impacts is vital, potentially advancing other zeolite-catalyzed emerging technologies.

Nature of Reactive Sites in TS-1 from 15N Solid-State NMR and Ti K-Edge X-Ray Absorption Spectroscopic Signatures Upon Pyridine Adsorption.

Ti-containing zeotypes, notably titanosilicalite-1 (TS-1), are prominent examples of heterogeneous catalysts that have found applications in selective oxidation processes with hydrogen peroxide. Despite extensive characterization studies including using various probe molecules to interrogate the nature and the local environment of Ti sites, their detailed structure (as well as reactivity) remains elusive. Here, we demonstrate that using low temperature 15N magic angle spinning (MAS) ssNMR spectroscopy of adsorbed pyridine on TS-1 combined with Ti K-edge XANES on a range of samples (dehydrated, hydrated, contacted with H2O2 and pyridine) provides unique information regarding the Ti sites, highlighting their reactivity and dynamic nature. While dehydrated TS-1 shows only Lewis acid sites, the presence of H2O generates Brønsted acid sites, whose amount correlates with water loading. Moreover, the methodology─based on 15N ssNMR and Ti K-edge XANES─applied to a library of samples with various Ti-loadings and absence of extraframework TiO2 also enables quantification of the amount of Lewis acid sites and to establish a structure-activity descriptor (ratio of pyridine adsorbed on silanols vs titanium). Complementary analysis including computational modeling reveals that the reaction of Ti sites with H2O generates an acidic bridging silanol Ti-(OH)-Si, upon hydrolysis of one Ti-O-Si linkage, where Ti expands its coordination from four to pentacoordinated according to XAS.

Functionalization of cellulose nanocrystals with a potent antimalarial compound: Synthesis, characterization, and biological studies

Cellulosic materials, such as cellulose nanocrystals (CNCs), are biocompatible, biodegradable and have unique and fascinating biomedical applications. Calxinin (CXN), a potent multistage antimalarial compound was functionalised with CNCs to improve biocompatibility and enhance the bioactivity of the resulting CNC-CXN nano-conjugate. Elemental analysis, powder X-ray, SEM, AFM, Infrared, and solid-state NMR spectroscopic techniques confirmed the composition of novel CNC-CXN nano-conjugate. Next, CNC-CXN nano-conjugate did not exhibit apparent cytotoxic effects on the sensitive Vero E6 cell line up to a concentration of 4.66 μg/μl. The CNC-CXN nano-conjugate was also evaluated for its preliminary efficacy on Plasmodium falciparum (3D7) malaria parasite and showed a 50 % inhibitory concentration value of 0.02 μg/μl. Overall, the selectivity index (SI) of the CNC-CXN nano-conjugate significantly improved to 233, indicating its suitability for further validation studies in animal models.

Unveiling the Mechanism of Glycerol Oxidation to Lactic Acid on Pt/Sn-MFI Zeolite: an In situ Solid-state NMR Study

Unveiling the Mechanism of Glycerol Oxidation to Lactic Acid on Pt/Sn-MFI Zeolite: an In situ Solid-state NMR Study