Gold nanoparticles (AuNPs) are considered useful vehicles for medical therapy and diagnosis. Despite the progress made in this field, there is need to find direct, reliable, and versatile synthetic procedures for their preparation as well as new multifunctional coating agents. In this sense, we have explored the use of imidazolium amphiphiles to prepare new AuNPs designed for anion recognition and transport. Thus, in this work we describe (a) the synthesis, by a phase transfer method, of new gold nanoparticles using gemini-type surfactants as ligands based on imidazolium salts, those ligands acting as transfer agents into organic media and also as nanoparticle stabilizers, (b) the examination of their stability in solution, (c) the chemical and physical characterization of the nanoparticles, using a variety of techniques, including UV-visible spectroscopy (UV-vis), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), (d) toxicity data concerning both the imidazolium ligands and the imidazolium coated nanoparticles, (e) the assessment of their molecular recognition ability toward molecules of biological interest, such as anions and carboxylate containing model drugs, such as ibuprofen, (f) the study of their toxicity and those of their coating ligands, as well as their ability for cell internalization, and (g) the study of their ability for delivering anionic pharmaceuticals. The structurally governed triple role of those new gemini-type surfactants is responsible for the preparation, remarkable stability, and delivery properties of these functional AuNPs.

A cationic bis‐imidazolium‐based amphiphile was used to form thermoreversible nanostructured supramolecular hydrogels incorporating neutral and cationic drugs for the topical treatment of rosacea. The concentration of the gelator and the type and concentration of the drug incorporated were found to be factors that strongly influenced the gelling temperature, gel‐formation period, and overall stability and morphology. The incorporation of brimonidine tartrate resulted in the formation of the most homogeneous material of the three drugs explored, whereas the incorporation of betamethasone resulted in a gel with a completely different morphology comprising linked particles. NMR spectroscopy studies proved that these gels kept the drug not only at the interstitial space but also within the fibers. Due to the design of the gelator, drug release was up to 10 times faster and retention of the drug within the skin was up to 20 times more effective than that observed for commercial products. Experiments in vivo demonstrated the rapid efficacy of these gels in reducing erythema, especially in the case of the gel with brimonidine. The lack of coulombic attraction between the gelator–host and the guest–drug seemed particularly important in highly effective release, and the intermolecular interactions operating between them were found to lie at the root of the excellent properties of the materials for topical delivery and treatment of rosacea.

A novel physical gel was obtained using a gemini imidazolium-based amphiphilic molecule dissolved in ethanol-water mixtures. The structure of the gel is comprised of intertwining nanofibres with widths of approximately 80 nm. The ethanol/water ratio has an important influence on the gelation process: the gelator is sparingly soluble in water and soluble in ethanol. The gelator is capable of incorporating anionic drugs in its fibrillar network easily; sodium ibuprofenate, indomethacin and the sodium salt of methotrexate were used as model drugs that were incorporated into the quickly forming gels. The characterization of these composite xerogels was made by different microscopy techniques as well as X-ray powder diffraction. The ability of the amphiphile to form a gel is largely maintained in the presence of the different model drugs and the overall morphology of the gels (that present a fibre like structure in all cases with intertwined ribbons) is very similar. Furthermore the in vitro release of the drugs from the gel and the in vivo anti-inflammatory efficacy was studied. The overall results show better release profiles and anti-inflammatory efficacy for indomethacin, and prove the promise of this molecular gel in controlled drug release, in the present case dermatological application.