DNA is considered as one of the main targets for anticancer drug design. The planar structure of acridines confers to the molecules the ability to bind DNA by intercalation and therefore to interfere with metabolic processes. A large number of natural alkaloids and synthetic acridine derivatives have been tested as anticancer agents. So far, a few molecules have entered clinical trials and have been approved for chemotherapy. The mechanisms of action are not fully understood. Cytotoxicity may be related to potent enzyme inhibition. Topoisomerase and telomerase activities may be strongly affected by acridines. The affinity of acridines for DNA has also been used to design new active compounds in which a DNA modifying group is tethered to the acridine nucleus. Acridine derivatives display other pharmacological properties such as antibacterial and antimalarial activities. They are also tested for Alzheimers disease.

Nucleic acids are the structural supports of genetic material and therefore the key factors in many vital cellular processes. The double-stranded right-handed helix is a regular conformation adopted by both DNA and RNA in cells, but an increasing number of results point to the biological importance of alternative structures such as bulges, hairpins, branched junctions or quadruplexes. Progress in the chemical synthesis of oligonucleotides and in the knowledge of the factors that favour a particular conformation has opened new fields of research in molecular recognition and drug design.

The π-extended ligand of a ruthenium complex stores two photo-generated electrons, mimicking a key step in photosynthesis.

Cellulose nanofibrils (CNF) are renewable bio-based materials with high specific area, which makes them ideal candidates for multiple emerging applications including for instance on-demand drug release. However, in-depth chemical and structural characterization of the CNF surface chemistry is still an open challenge, especially for low weight percentage of functionalization. This currently prevents the development of efficient, cost-effective and reproducible green synthetic routes and thus the widespread development of targeted and responsive drug-delivery CNF carriers. We show in this work how we use dynamic nuclear polarization (DNP) to overcome the sensitivity limitation of conventional solid-state NMR and gain insight into the surface chemistry of drug-functionalized TEMPO-oxidized cellulose nanofibrils. The DNP enhanced-NMR data can report unambiguously on the presence of trace amounts of TEMPO moieties and depolymerized cellulosic units in the starting material, as well as coupling agents on the CNFs surface (used in the heterogeneous reaction). This enables a precise estimation of the drug loading while differentiating adsorption from covalent bonding (∼1 wt% in our case) as opposed to other analytical techniques such as elemental analysis and conductometric titration that can neither detect the presence of coupling agents, nor differentiate unambiguously between adsorption and grafting. The approach, which does not rely on the use of ¹³C/¹⁵N enriched compounds, will be key to further develop efficient surface chemistry routes and has direct implication for the development of drug delivery applications both in terms of safety and dosage.