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.

Langmuir-Blodgett monolayer stabilization using supramolecular clips.

We introduce the concept of stabilization of Langmuir-Blodgett (LB) films using dicarboxylate supramolecular clips, as demonstrated by Langmuir isotherms, spectroscopic ellipsometry, atomic force microscopy, X-ray photoelectron spectroscopy (XPS), and contact angle measurements.

DNA surface coating of calixarene-based nanoparticles: a sequence-dependent binding mechanism.

An amphiphilic calix[4]arene derivative bearing four guanidino moieties at the upper rim and four dodecyl chains at the lower rim was shown to form stable solid lipid nanoparticles (SLNs) in water. The study of the interactions of these cationic SLNs with DNA revealed a sequence-dependent groove binding mechanism.