Glycan-coated nanoparticles for the enhanced active targeting the doctorate thesis with title Glycan-coated nanoparticles for the enhanced active targeting

Gold nanoparticles (AuNPs) are nanomaterials with excellent physicochemical and optical properties for a broad range of applications. The surface functionalization of the AuNPs enables the formation of glyco-gold nanoparticles (GAuNPs). GAuNPs multivalency properties can trigger the cluster glycoside effect overcoming the low affinity between individual carbohydrate-protein interactions. Therefore, these NPs have been demonstrated to be excellent candidates for lectin targeting among other bio applications. Moreover, AuNPs when in contact with biological media interact with the present proteins forming the protein corona (PC) which has an effect in the final fate and efficacy of the NPs. The study of the PC formation of the NPs is extremely important to assure the activity of the AuNPs. The PC formation can be modulated with the surface coating, size, and shape of the AuNPs. Ligand stabilizers as for example polyethylene glycol (PEG) can prevent the PC formation and the consequent recognition by the immune system and clearance of the body. Additionally, the glycan coating of the AuNPs can also modulate the PC composition and therefore the biodistribution of the GAuNPs can be modified. The second chapter of this thesis consists in a biodistribution study in healthy mice of ultra-small gold nanoparticles (UAuNPs) coated with PEG chains of different length and/or with α-Galactose attached to a short aliphatic ligand. The UAuNPs were synthesized using a bench-top reactor and the NPs were injected to healthy mice. The liver kidneys and spleen were collected at 1,4 and 24 hours. The organs were then digested, and the gold content was analysed by Induced Couple Plasma Optical Emission Spectroscopy (ICP-OES). On the other hand, selected organs were silver stained by autometallography (AMG) and analysed with bright-field microscopy. Moreover, organs were immune stained to detect the UAuNPs by confocal microscopy. The UAuNPs coated solely by PEG5000 presented the highest circulation time in the body, as expected. Additionally, the UAuNPs coated with a mix of PEG500 and α-Gal-C2 had a similar circulation time. These results prove that the length of the PEG chain is important but not the only path to follow to extend the half-life of the UAuNPs. Moreover, the UAuNPs coated with PEG were post-functionalized with α-Mannose and a variation in the biodistribution was observed as the UAuNPs accumulated less in the liver and kidneys. The mannosylated UAuNPs had also a different distribution inside the liver in the as proven by the AMG studies. Microfluidic systems have brought the attention of numerous researchers in the last years for their advantages compares to batch synthetic procedures of AuNPs. These systems offer several advantages as a better control over the reaction parameters, a higher reproducibility between batches as well as a simple scale-up. The drawbacks presented when AuNPs are taken from research to clinical trials can be overcome by microfluidic synthetic procedures. Therefore, in our group we have focused on the development of microfluidic procedures to obtain AuNPs of different size and shape.