Synthesis, Characterization, and Use of Asymmetric Pyrenyl-Gemini Surfactants as Emissive Components in DNA−Lipoplex Systems

Abstract

Gemini surfactants are potential candidates as synthetic vectors for the delivery of genes into cells to induce protein expression. With the ultimate objective of obtaining a better understanding of the mechanism of DNA transfection, two new asymmetric gemini surfactants (py-3-12 and py-6-12) have been synthesized as fluorescence probes. The physicochemical properties and morphologies of the self-assembled aggregates formed in aqueous solution have been studied using surface tension, specific conductance, dynamic light scattering (DLS), isothermal titration calorimetry (ITC), and fluorescence techniques. The interaction between pyrene-based gemini surfactants and DNA was investigated by using UV-vis and fluorescence spectroscopy. Binding constants for the DNA (salmon sperm)-gemini lipoplexes were measured. Fluorescence studies show that excimer emission occurs upon complexation with DNA.

A Novel Pyrene‐Based Fluorescing Amphiphile with Unusual Bulk and Interfacial Properties

“…Similar investigations have been undertaken recently for pyrene-labelled lipids, [16] pyrene-labelled Gemini surfactants [17] or other pyrene-labelled compounds of biophysical interest. [18] As in our case, many open questions remain, in particular concerning the organisation of the molecules in the bulk or at interfaces for the entire accessible concentration range, which will have to be addressed in the future.…”

A novel surfactant-like fluorophore and its probing ability to the aggregation of amphiphilic compounds

“…As it is well known, pyrene is a popular and excellent polarity probe [15,23,24]. The so called and widely used "pyrene scale" is the using of intensity ratio of peak 3 and peak 1 (I 384 /I 373 ) of its emission spectrum, which is largely dependent upon the polarity of its micro-environment.…”

Calorimetric Investigations of Non-Viral DNA Transfection Systems

“…This work has recently been extended to the study of a non-symmetric gemini surfactant in which one of the alkyl tails is a dodecyl group (i.e. m = 12) and the other has been replaced with a (pyren-6-yl)-hexyl group which has the same approximate length as a dodecyl group, but is significantly more hydrophobic in character (Wang et al, 2007b). The interaction between these pyrene-based gemini surfactants (Scheme 2B) and DNA using ITC (Donkuru et al, 2010), along with the 12-3-12 and 12-6-12 surfactants (for comparison), and marked differences in the interactions with DNA were observed ( Figure 5).…”

“…The 2010 results for the interaction of the 12-3-12 and 12-6-12 with DNA showed a more complex interaction than that originally proposed in 2007, likely as a result of the difference in calorimeters used in the different studies. The major difference observed in the binding interaction(s) with DNA for the pyrenyl gemini surfactants lies in the ability of the pyrenyl group to intercalated between DNA base pairs; this intercalation was previously hypothesized based upon the results of fluorescence titration studies (Wang et al 2007b). The double-peak feature observed in the enthalpogram for the titration of the 12-3-12 surfactant with DNA ( Figure 5) is common to all of the symmetric gemini surfactants investigated (so far) by our group.…”