A sustainable lecithin-based ligand for the bio-functionalization of iron and hybrid metal organic frameworks (MOFs) nanoparticles with the sugar mannose†

The functionalization of nanoparticles with specific ligands, such as antibodies, peptides, and small molecules, plays a critical role in achieving targeted delivery, enhancing biocompatibility, and controlling drug release. However, to date, practically no attention has been paid to the design of green ligands. Herein, an innovative approach to develop a sustainable ligand for nanoparticle functionalization is reported. Its synthesis involved a photochemical thio–ene “click” reaction between the natural compounds phosphatidylcoline, the main component of lecithin, and cysteine, followed by a reductive amination with mannose, a sugar of growing interest for biomedical targeting, in a continuous flow hydrogenation reactor. Comprehensive characterization techniques, including nuclear magnetic resonance (NMR), mass spectrometry (MS), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and elemental analysis, confirmed the structure and properties of the novel ligand. The environmental sustainability of the ligand was evaluated determining some green metrics using the EATOS software. The obtained E-factor was compared with a conventional PEG-based ligand. The newly developed lecithin-derived ligand was successfully used to functionalize diverse NP platforms, including the MOFs MIL-101(Fe), PCN-222, UiO-66, and iron nanoparticles (in the form of akaganeite), demonstrating its potential in nanomedicine applications.