Design and synthesis of biologically active cationic amphiphiles built on the calix[4]arene scaffold

A promising strategy to design safer and more effective cationic lipids for gene delivery with inherent antibacterial properties is to covalently tether a lipophilic moiety with oligomeric aminoglycosides (AGs), a large family of Gram-negative-active antibiotics. Herein, we reported the development of a new class of multicationic-head AG-based amphiphiles built on the tetramino-tetrahexyloxycalix[4]arene (4A4Hex-calix-calix[4]) scaffold. Three different conjugates, namely 4A4Hex-calix-calix[4]-neomycin, -neamine, and -paromomycin, were synthesized and characterized. Due to the inherent multivalency of AGs and the amphiphilic behaviour, every 4A4Hex-calix-calix[4]-AG exhibited greater DNA binding ability than the gold standard transfectant 25 kDa bPEI and striking DNA packing ability. DNA/4A4Hex-calix-calix[4]-AG complexes at charge ratios (CRs, +/-) used for transfections displayed good colloidal stability, with a hydrodynamic diameters of ≈150 nm and an overall surface charges of ≈+30 mV. DNA/4A4Hex-calix[4]-AGs nanoassemblies, everyone tested at the optimal CR, invariably showed good transfection efficiency in two cell lines, along with low-to-negligible cytotoxicity. Besides, DNA/4A4Hex-calix-calix[4]-AG complexes exhibited appreciable antimicrobial activity against Gram-negative bacteria, even greater than uncomplexed 4A4Hex-calix-calix[4]-AGs. Altogether, these results disclose 4A4Hex-calix[4]-AGs as promising gene delivery tools with unique antibacterial properties.