Self-Assembly, In Vitro Gene Transfection, and Antimicrobial Activity of Biodegradable Cationic Bolaamphiphiles

Bolaamphiphiles or bolaforms have drawn particular interestindrug and gene delivery, and studies of bolaforms have been growingcontinuously. Bolaforms, due to their unique structure, exhibit specificself-assembly behavior in water. The present work aims to developbiodegradable cationic bolaforms with a better gene transfection ability.In this work, a novel cationic bolaform (Bola-1) with head groupsbearing hydroxyl (OH) functionality was designed and synthesized toinvestigate self-assembly and gene transfection efficiency. The self-assemblybehavior of Bola-1 in water was compared with that of the hydrochloridesalt (Bola-2) of its precursor molecule to investigate the effectof the -OH functionality on their solution properties. Severaltechniques, including surface tension, electrical conductivity, fluorescenceprobe, calorimetry, dynamic light scattering, and atomic force microscopy,were employed for the physicochemical characterization of Bola-1 andBola-2. Despite the presence of polar urea groups in the spacer chain,both bolaforms were found to form spherical or elongated micellesabove a relatively low critical aggregation concentration (CAC). Thepresence of the OH group was found to significantly affect the CACvalue. The results of calorimetric measurements suggested a thermodynamicallyfavorable aggregate formation in salt-free water. Despite strongerbinding efficiency with calf thymus DNA, in vitro gene transfection studies performed using adherent cell Hek 293suggested that both Bola-1 and Bola-2 have gene transfection efficiencycomparable to that of turbofectamine standard. Both bolaforms werefound to exhibit significant in vitro cytotoxicityat higher concentrations. Also, the bolaforms showed beneficial antibacterialactivity at higher concentrations.