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We report on the irradiation of gold rod–sphere assemblies with ultrashort laser pulses, producing structures that are very difficult to obtain by other methods. The optical response of these assemblies displays several peaks arising from the interaction of the plasmon modes of the individual particles, offering thus great flexibility to control the energy deposited on the individual particles. Judicious selection of the wavelength and fluence of the laser pulses allow fine control over the changes produced: the particles can be melted, welded and/or the organic links cleaved. In this way, it is possible to generate structures “à la carte” with a degree of control unmatched by other synthetic protocols. The method is exemplified with gold nanoparticles, but it can be easily implemented on particles composed of different metals, widening considerably the range of possibilities. The final structures are excellent candidates for surface-enhanced spectroscopies or plasmonic photothermal therapy as they have a very intense electric field located outside the structure, not in the gaps.

The compaction process of calf thymus DNA by cationic liposomes formed by a 1:1 mixture of cationic lipid and zwitterionic lipid is studied using conductometry, cryo-TEM and fluorescence spectroscopy. The results show that when the charge ratio between the cationic liposome and DNA reaches 1, the liposome membranes fuse and cause the lead DNA to collapse onto condensed structures together with the liposomes.

A study was conducted to analyze artificial beta-sheets in competitive solvents. The bruker DRX500 spectrometer was utilized to perform nuclear magnetic resonance experiments. A spin locking field strength of 5 kHz was utilized to collect points in the f2 dimension. Results indicated that artificial beta-sheet is partially folded in methanol and aqueous methanol solutions. Findings also showed that the diurea turn unit can influence the structure of the beta-sheet.

Thermodynamic analyses of the binding of a series of p-nitrophenyl glycosides (PNPGly) of different stereochemistry to alpha-cyclodextrin were performed at three different temperatures utilizing a microcalorimetric procedure. Findings indicated that the thermodynamic values were close in magnitude to those obtained for the binding of monosaccharides to proteins, the complex formation was enthalpy driven, the enthalpy of binding was provided primarily by the PNP moiety, and that the chemical nature and the stereochemistry of the substituents in the carbohydrate had a differential effect on the thermodynamics of binding in aqueous solution.

The theory of mixed micellization is used for studying the micellization of an aqueous mixture of sodium dodecanoate (SDD) and sodium 10-undecenoate (SUD). The phenomenon is interpreted on the basis of the interaction between the vinyl group and water by hydrogen bonding.

The formation of instant mixed prevesicles and vesicles comprising of a cationic double-chain surfactant, didecyldimethylammonium bromide and a cationic single-chain alkyltrimethylammonium bromide with 10 and/or 14 carbon atoms is studied. The presence of two crucial aggregation concentrations in the much diluted concentrations domains where the conductivity plot demonstrates a zigzag pattern is detected and the theoretical predictions confirm the stability of the pure and mixed vesicles.

Conductivity and static fluorescence measurements have been carried out at 25 °C to study the monomeric and micellar phases of aqueous solutions of mixed micelles constituted by a conventional cationic surfactant, dodecyltrimethylammonium bromide (D12TAB), and a tricyclic antidepressant drug, amitriptyline hydrochloride (AMYTP), with aggregation properties. From conductivity data, the total mixed critical micelle concentration and the dissociation degree of the mixed micelle have been obtained, while fluorescence experiments allow for the determination of the total aggregation number, and the micropolarity of micellar inside. Furthermore, the partial contribution of each surfactant to the mixed micellization process, through their critical micelle concentrations and their aggregation numbers have been determined, as well. The solubilization of the drug in the mixed micelles has been also studied through the mass action model, by determining the association constant between the micelles and the drug. From these results, the use of the micelles studied in this work as potential models for vectors of antidepressant drugs of the amitriptyline family has been discussed. The theoretical aspects of the mixed micellization process have been also analyzed. [Copyright &y& Elsevier]

The therapeutic messenger RNA strategies, such as those using small interfering RNAs, take several advantages (versatility, efficiency and selectivity) over plasmid DNA-based strategies. However, the challenge remains to find nanovectors capable of properly loading the genetic material, transporting it through troublesome environments, like a tumoral site, and delivering it into the cytoplasm of target cells. Here, lipid nanoparticles, consisting of a gemini cationic/neutral helper lipid mixture, are proposed as siRNA nanovector. Cells from cervical and brain cancer overexpressing the green fluorescent protein (GFP) were chosen to analyse the biological response as well as the efficiency and safety of the siRNA-loaded nanovector according to the cell phenotype. Flow cytometry and epifluorescence or confocal microscopy were used to follow the gene knockdown in these overexpressed cells. The effect of the nanovector on cellular proliferation was evaluated with cytotoxicity assays while their potential oxidative stress generation was determined by quantifying the generation of reactive oxygen species. To explore the mechanism of cellular uptake, different inhibitors of endocytic pathways were used during incubation with cells. Finally, nanovectors were incubated in 3D-grown cells (spheroids) to see whether they can penetrate the complex tumoral microenvironments, their efficiency to knockdown GFP expression being monitored by confocal microscopy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

The formation of spontaneous mixed prevesicles and vesicles consisting of a cationic double-chain surfactant, didecyldimethylammonium bromide (di-C(10)DMAB), and a cationic single-chain alkyltrimethylammonium bromide with 10 and/or 14 carbon atoms (decyltrimethylammonium bromide, C(10)TAB, and/or tetradecyltrimethylammonium bromide, C(14)TAB) has been investigated by means of a series of (i) highly precise experimental techniques, such as conductometry, transmission electronic microscopies (TEM and cryo-TEM), laser Doppler electrophoresis (LDE), and steady-state fluorescence spectroscopy and (ii) theoretical models, such as the DLVO theory and two of its main further modifications, Inoues's and Sogami's models. Two new potentials, based on the combination of DLVO or Inoue potentials with that of Sogami, have been proposed and checked. This theoretical analysis has been carried out not only for the aggregates studied in this work but also for other di-C(m)DMAB + C(n)TAB (m = 10, 12 and n = 10, 12, 14) systems previously reported by us. In respect to the experimental study, special emphasis has been devoted to the prevesicle domain. We have confirmed the existence of two critical aggregation concentrations in the very diluted concentration domain, where the conductivity plot shows a zigzag pattern: the so-called mixed critical aggregate concentration, CAC* and the mixed critical vesicle concentration, CVC*. Contrarily, only CVC* is detected. The pre-CAC* nanoaggregates, with a variety of sizes and shapes, do not show a clear aggregation pattern, but even at such low concentrations a small number of nanoaggregates with a clear and ordered aggregation pattern has been visualized. In the postvesicle domain, the aggregates (vesicles) are unilamellar and spherical with a medium polidispersity and a net averaged surface density charge of around 14 x 10(-3) (pure vesicles) and 24 x 10(-3) C m(-2) (mixed vesicles). The hydrophobicities of the lipidic bilayer and the surface of the vesicles resemble those of media with dielectric constants of around 30 and 75, respectively. Finally, theoretical predictions confirm the stability of the pure and mixed vesicles studied in this work and in other works previously reported.