The design of multifunctional microcarriers has attracted significant attention because they combine various functions within a single system. In this study, we developed a set of multilayered hydrogel microcarriers, which were first loaded with chemotherapeutic curcumin (CUR), then, using the layer-by-layer (LbL) technique, coated through a polyelectrolyte shell consisting of chitosan (CHIT) or poly(allylamine hydrochloride) (PAH). As an outer layer with antimicrobial function, newly synthesised alkylene quaternary ammonium salt functionalised polyelectrolytes (A-QAS-PEs) were applied. For this purpose, poly(acrylic acid) (PAA) was decorated with different hydrophobic side chains (n-hexane and n-dodecane side entities) and different degrees of substitution (m) of quaternary ammonium groups (abbreviated as PAA-C(O)O-(CH₂)_n-N⁺(CH₃)₃(m); n = 6, 12; m = 8–14%). The grafting approach of PAA with the alkylene quaternary ammonium salt moiety was performed under mild reaction conditions using Steglich esterification followed by quaternisation. The structure of antimicrobial decorated PAA was confirmed by ¹H NMR and FTIR, and the mean diameter of all multifunctional microparticles was characterised by SEM. The viscoelastic properties of the functional layers were studied using quartz crystal microbalance with a dissipation (QCM-D). The release of CUR from the microcarriers was described using a hybrid model, i.e., a combination of first-order kinetics and the Korsmeyer-Peppas model. The antimicrobial activity of functionalised PAA and multilayered CUR-loaded hydrogel microcarriers with quaternary ammonium function was assessed against Staphylococcus aureus and Serratia marcescens by the agar diffusion assay method. Only a limited inhibition zone of PAA was observed, but in the case of both antimicrobial decorated PAA and the corresponding multilayered nanocarriers, the inhibitory activity increase was achieved against both strains of bacteria.

Contemporary research concerning surfactant science and technology comprises a variety of requirements relating to the design of surfactant structures with widely varying architectures to achieve physicochemical properties and dedicated functionality. Such approaches are necessary to make them applicable to modern technologies, such as nanostructure engineering, surface structurization or fine chemicals, e.g., magnetic surfactants, biocidal agents, capping and stabilizing reagents or reactive agents at interfaces. Even slight modifications of a surfactant’s molecular structure with respect to the conventional single-head–single-tail design allow for various custom-designed products. Among them, multicharge structures are the most intriguing. Their preparation requires specific synthetic routes that enable both main amphiphilic compound synthesis using appropriate step-by-step reaction strategies or coupling approaches as well as further derivatization toward specific features such as magnetic properties. Some of the most challenging aspects of multicharge cationic surfactants relate to their use at different interfaces for stable nanostructures formation, applying capping effects or complexation with polyelectrolytes. Multiheaded cationic surfactants exhibit strong antimicrobial and antiviral activity, allowing them to be implemented in various biomedical fields, especially biofilm prevention and eradication. Therefore, recent advances in synthetic strategies for multiheaded cationic surfactants, their self-aggregation and performance are scrutinized in this up-to-date review, emphasizing their applications in different fields such as building blocks in nanostructure engineering and their use as fine chemicals.

The construction of multipurpose particles with functional coatings of varying structure and composition provides the opportunity to modify their physicochemical and biological characteristics. In accordance with the aforementioned, new polyelectrolytes (PEs) decorated with an antimicrobial function (PEs-DAF) were designed and prepared to apply them as building blocks of a various carrier systems. A series of hydrogel nano- and microparticles were developed and coated with an outer PE shell with antimicrobial functionality. To this end, poly­(acrylic acid) (PAA) was grafted with different degrees of substitution (DS) of antimicrobial essential oils such as thymol (THY), menthol (MEN), and carvacrol (CAR) (abbreviated as PAA-X-DS% (X = THY, MEN, CAR; DS = 5,15)) using Steglich esterification under mild reaction conditions. Their structures were confirmed by ¹H NMR and FTIR spectroscopy. The particles’ morphology and mean diameter were determined by dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The physicochemical properties of the novel functional coatings were characterized using quartz crystal microbalance with a dissipation (QCM-D) analysis and spectroscopic ellipsometry. The antimicrobial properties of the functionalized PAA and the alginate microgel particles decorated with these PEs were evaluated against Staphylococcus aureus and Escherichia coli using the agar disc diffusion assay and minimal inhibitory concentration evaluation. The particles exhibited satisfactory antimicrobial activity, and some examples showed higher bioactivity than the functionalized PAAs. Moreover, the designed systems were loaded with resveratrol (RES), a model chemotherapeutic substance, to assess their potential applicability as drug carriers. The analysis proved the effective RES encapsulation and its release in a controlled manner depending on the coating properties. The results found in our study indicate potential therapeutic applications of the new antimicrobial-decorated carrier systems in the treatment of multidrug-resistant pathogenic infections.

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-N,N,N,N’,N’,N’-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.