Maela Manzoli

Microwave (MW)‐assisted reductive aminations of aldehydes and ketones were carried out in the presence of commercial and homemade heterogeneous Rh‐based catalysts. Ultrasound (US) was used to improve dispersion and stability of metal nanoparticles, while commercial activated carbon and carbon nanofibers were used as supports. Moreover, various bio‐derived molecules were selected as substrates, and aqueous ammonia was used as a cheap and non‐toxic reagent. MW combined with heterogeneous Rh catalysts gave a 98.2 % yield in benzylamine at 80 °C with 10 bar H 2 for 1 h; and a 43.3 % yield in phenylethylamine at 80 °C and 5 bar H 2 for 2 h. Carbon nanofibers proved to be a better support for the metal active phase than simple activated carbon, since a limited yield in benzylamine (10.6 %) but a high selectivity for the reductive amination of ketones was obtained. Thus, raspberry ketone was converted to raspberry amine in a 63.0 % yield.

Biodegradable nanocarriers represent promising tools for controlled drug delivery. However, one major drawback related to their use is the long-term stability, which is largely influenced by the presence of water in the formulations, so to solve this problem, freeze-drying with cryoprotectants has been proposed. In the present study, the influence of the freeze-drying procedure on the storage stability of poly(lactide-co-glycolide) (PLGA) nanoparticles and liposomes was evaluated. In particular, conventional cryoprotectants were added to PLGA nanoparticle and liposome formulations in various conditions. Additionally, hyaluronic acid (HA), known for its ability to target the CD44 receptor, was assessed as a cryoprotective excipient: it was added to the nanocarriers as either a free molecule or conjugated to a phospholipid to increase the interaction with the polymer or lipid matrix while exposing HA on the nanocarrier surface. The formulations were resuspended and characterized for size, polydispersity index, zeta potential and morphology. It was demonstrated that only the highest percentages of cryoprotectants allowed the resuspension of stable nanocarriers. Moreover, unlike free HA, HA-phospholipid conjugates were able to maintain the particle mean size after the reconstitution of lyophilized nanoparticles and liposomes. This study paves the way for the use of HA-phospholipids to achieve, at the same time, nanocarrier cryoprotection and active targeting.