Design and Characterization of Functionalized Polyelectrolyte–Dicephalic Surfactant Complexes as Multipurpose Colloidal Systems

Polyelectrolyte-surfactant complexes (PESCs) have emerged as versatile soft-matter systems, offering unique opportunities for the design of multifunctional delivery platforms. Therefore, this study investigates the design, formation, and characterization of novel PESCs based on antimicrobial-functionalized poly-(acrylic acid) (PAA) derivatives and a newly synthesized cationic dicephalic surfactant, 2-dodecyl-<i>N,N,N,N',N',N'</i>-hexamethyl-propan-1,3-ammonium dibromide (C₁₂-D_CNMe₃Br). Building on our previous work on antimicrobial-decorated PAAs grafted with thymol (PAA-THY-15), menthol (PAA-MEN-15), and carvacrol (PAA-CAR-15), these polyanions were combined with the oppositely charged surfactant to construct multipurpose carrier systems. The designed PESCs were loaded with curcumin (CUR), a model hydrophobic drug with therapeutic properties, to evaluate their potential applicability as drug delivery systems (DDSs). A variety of physicochemical techniques were applied to gain insight into the complexation processes, self-assembly behavior, and functional properties of the resulting PESCs. Surface activity of new complexes was assessed by goniometric measurements, while their colloidal stability over time was studied using the turbidimetric method. Dynamic light scattering (DLS) provided information on particle size, polydispersity, and surface charge. Encapsulation efficiency (EE) and release kinetics were assessed by UV-vis spectrophotometry to evaluate the ability of the complexes to effectively entrap CUR and provide sustained release. The integration of antibacterial PAA derivatives with dicephalic surfactants highlights the versatility of PESCs as tunable, multifunctional carriers that combine antimicrobial protection with controlled drug delivery. These findings demonstrate that the designed complexes are promising candidates for advanced DDSs and pave the way for further development of functional colloidal materials tailored for biomedical applications.