Engineering Hetero-Layered Mannodendrimers to Enhance Macrophage Receptor Binding

Cell surface carbohydrate-binding proteins like mannose-binding proteins, mannose receptors (MRs), Dectin-2, and DC-SIGN are key players in immune surveillance and serve as useful targets for gene, drug, and vaccine delivery. Macrophage mannose receptors (MMRs), in particular, are ideal for targeted therapeutic strategies. This study presents a library of heterolayered mannosylated dendrimers with selective affinity for MMRs on HL60-derived macrophage-like cells. Using click chemistry, di- to hexavalent scaffolds were synthesized and convergently linked to dendrons harboring α-d-mannopyranoside moieties. Silencing MRC1/CD206 reduced the uptake of Nile Red-labeled mannosylated liposomes (∼100 nm), confirming its role in internalization. Competitive inhibition assays showed a 12-valent mannodendrimer nanoparticle (∼2.5 nm) on a cyclotriphosphazene core had the highest affinity (IC₅₀ = 28.9 ± 0.2 μM), outperforming larger liposomal constructs. These results highlight the importance of nanoscale geometry and ligand presentation, supporting glycodendrimers as effective platforms for targeted immunotherapy.