Fluorescent Calixarene-Schiff as a Nanovehicle with Biomedical Purposes

Gene therapy is a technique that is currently under expansion and development. Recent advances in genetic medicine have paved the way for a broader range of therapies and laid the groundwork for next-generation technologies. A terminally substituted difluorene-diester Schiff Base calix[4]arene has been studied in this work as possible nanovector to be used in gene therapy. Changes to luminescent behavior of the calixarene macrocycle are reported in the presence of ct-DNA. The calixarene macrocycle interacts with calf thymus DNA (ct-DNA), generating changes in its conformation. Partial double-strand denaturation is induced at low concentrations of the calixarene, resulting in compaction of the ct-DNA. However, interaction between calixarene molecules themselves takes place at high calixarene concentrations, favoring the decompaction of the polynucleotide. Based on cytotoxicity studies, the calixarene macrocycle investigated has the potential to be used as a nanovehicle and improve the therapeutic efficacy of pharmacological agents against tumors.

A self-assembled white-light-emitting system in aqueous medium based on a macrocyclic amphiphile

White light emission was successfully achieved with high quantum yield in a novel FRET platform based on a macrocyclic amphiphile.

Moulding calixarenes for biomacromolecule targeting

After their successful use as a preorganized platform for the preparation of receptors for metal ions and small neutral molecules over the last 15 years, calixarenes are enjoying a renaissance of popularity as scaffolds for ligands that are able to efficiently and selectively target macromolecules such as proteins/enzymes, nucleic acids and lipids. This feature article summarizes the peculiar factors characterizing the calixarene structure and properties, as well as outlines the main rules that can be used to turn such macrocycles into efficient and successful ligands for these classes of biomacromolecules. Factors that affect the multivalent properties of calixarenes, such as the size, conformation and stereochemical presentation of binding groups or their amphiphilicity and hybrid character, are described in detail with the use of a few selected examples from the literature. Perspectives and applications of these ligands in bionanotechnology and nanomedicine, such as protein sensing and inhibition, gene-delivery, targeted drug-delivery and cell imaging, are also discussed.

Host-guest complexation of a pyrogallol[4]arene derivative at the air-water interface

The host-guest properties of acetylated aryl pyrogallol[4]arene (AcPy) were studied as a Langmuir monolayer at the air-water interface. The self-assembled Langmuir monolayer properties and interactions with monovalent and divalent metal cations were investigated using surface pressure- and surface potential-area isotherms, compression-decompression cycles, stability, and infrared reflection-absorption spectroscopy (IRRAS). A favorable interaction is observed for complexation between acetylated aryl pyrogallol[4]arene with divalent calcium and cadmium cations, while no interaction is observed for monovalent sodium and potassium cations. Spectroscopic techniques allow for discrimination between cadmium and calcium complexation.

Investigation of DNA binding abilities of solid lipid nanoparticles based on p-tert-butylthiacalix[4]arene platform

Amphiphilic thiacalix[4]arene functionalized with guanidinium groups forms stable solid lipid nanoparticles (SLNs) with high binding affinity to double-stranded DNA.

Sequence-specific DNA interactions with calixarene-based langmuir monolayers

The interactions of an amphiphilic calixarene, namely p-guanidino-dodecyloxy-calix[4]arene, 1, self-assembled as Langmuir monolayers, with short double stranded DNA, were investigated by surface pressure-area (π-A) isotherms, surface ellipsometry and Brewster angle microscopy (BAM). Three DNA 30mers were used as models, poly(AT), poly(GC) and a random DNA sequence with 50% of G:C base pairs. The interactions of these model DNA duplexes with 1-based Langmuir monolayers were studied by measuring compression isotherms using increasing DNA concentrations (10(-6), 10(-5), 10(-4), and 5 × 10(-4) g L(-1)) in the aqueous subphase. The isotherms of 1 showed an expansion of the monolayer with, interestingly, significant differences depending on the duplex DNA sequence studied. Indeed, the interactions of 1-based monolayers with poly(AT) led to an expansion of the monolayer that was significantly more pronounced that for monolayers on subphases of poly(GC) and the random DNA sequence. The structure and thickness of 1-based Langmuir monolayers were investigated by BAM and surface ellipsometry that showed differences in thickness and structure between a monolayer formed on pure water or on a DNA subphase, with here again relevant dissimilarities depending on the DNA composition.

Conformational changes of DNA in the presence of 12-s-12 gemini surfactants (s=2 and 10). Role of the spacer's length in the interaction surfactant-polynucleotide

A multifaceted study on the interaction of calf-thymus DNA with two different cationic gemini surfactants alkanediyl-α-ω-bis(dodecyldimethyl-amonium)bromide, 12-s-12,2Br(-) (with s=2, G2, and 10, G10) was carried out. The measurements were done at different molar ratios X=[surfactant]/[DNA]. Results show two different conformational changes in DNA: a first compaction of the polynucleotide corresponding to a partial conformational (not total) change of DNA from an extended coil state to a globular state that happens at the lower molar ratio X. A second change corresponds to a breaking of the partial condensation, that is, the transition from the compacted state to a new more extended conformation (for the higher X values) different to the initial extension. According to circular dichroism spectra and dynamic light scattering measurements, this new state of DNA seems to be similar to a ψ-phase. Measurements confirm that interactions involved in the compaction are different to those previously obtained for the analog surfactant CTAB. X values at which the conformational changes happen depend on the length of the spacer in the surfactant along with the charge of the polar heads.