Ionic liquid modified mesoporous silica nanocarriers for efficient drug delivery and hydrophobic surface engineering†

Attaining covalent attachment of diverse molecules onto carrier surfaces without compromising their chemical identity and biological functionality remains a challenge. Here, a newly synthesized alkyne-functionalized ionic liquid, 1-hexadecyl-3-propargyl imidazolium bromide (HDPI), was chemically attached on the surface of azide-modified mesoporous silica nanocarriers (mSiO₂, av. size 110 nm) based on the Menshutkin reaction and copper-catalyzed click chemistry. The HDPI-functionalized mSiO₂ nanocarriers were loaded with tetracycline (TC) to develop a dual-action drug delivery system. Time-dependent drug release studies conducted at pH 7.4 and 37 °C over 48 h revealed controlled TC release. The long alkyl chain of the surface-bound ionic liquids (ILs) facilitated bacterial cell wall penetration, enhancing TC transport into both Gram-positive and Gram-negative bacteria. This dual-action mechanism was validated through antibacterial assays demonstrating that the surfactant-like IL disrupts bacterial cytoplasmic membranes, while the antibiotic induces cell death. Given the inherent antibacterial properties of ILs, we further investigated their ability to form stable, hydrophobic, and antimicrobial coatings on glass substrates under different environmental conditions. The results indicate that these IL-based coatings are uniform, durable, and hold significant potential for applications in healthcare and industry.