Efficient Drug Delivery Carrier Surface without Unwanted Adsorption Using Sulfobetaine Zwitterion

Many studies describing the high colloidal stability and antifouling effects of zwitterion nanoparticles are reported; however, to date, disadvantages including complex synthetic methods and lack of methods for hydration layer analysis persist. In this study, zwitterion nanoparticles (SiZwit) are synthesized using (3-aminopropyl)triethoxysilane and 1,3-propane sultone and the hydration layer and colloidal stability of SiZwit are analyzed. Investigation of dipole–dipole interactions between zwitterion nanoparticles and H₂O molecules reveals that a stronger hydration layer is formed on the SiZwit. The antifouling effect of SiZwit increases by more than 80–90% due to the hydration layer. The colloidal stability in deionized water, phosphate-buffered saline, and in cell growth media increases more than fourfold compared to the bare silica nanoparticle (SiOH), and amine-functionalized silica nanoparticle (SiNH₂). No cell cytotoxicity of SiZwit is observed and cellular uptake for normal cells and macrophages is significantly reduced. Moreover, as seen from the drug loading and release profile of SiZwit, a fourfold increase in drug loading and sustained release is observed because of stable electrostatic interactions compared to SiOH and SiNH₂.