Résumé
The Guanosine, G-quartet macrocyclic architecture represents a dynamic constitutional system which undergoes reversible conformational exchanges between linear G-ribbons and the G-quadruplex, the columnar system formed by the vertical stacking of four G-quartets. The G-quadruplex plays a very important role in biology, as it is present in nucleic acid telomeres of potential interest to many therapies, and as it seems to play an important role in numerous other cellular processes. The reversible exchanges between the G-ribbons and the G-quadruplex systems may generate distinct self-adaptive mesophases, with the simultaneous formation of mixed polymorphic domains. They may also mutually adapt their distribution based on their own geometrical and interactional internal stability or in response to external factors such as scaffolding confining matrices or ion effectors. Here we use porous silicon (pSi) columnar nanostructured films as a scaffolding matrix to stabilize the G-quadruplexes under confined conditions. The pSi matrix also serves as an optical transducer to monitor in real time the formation of the G-quadruplexes using reflective interferometric Fourier transform spectroscopy (RIFTS). Under confined conditions, we show that the formation of the G quadruplexes induces a significant red shift of the optical signal in the reflectivity spectrum of the pSi host matrix, which is attributed to changes of the refractive index in the pSi film. Furthermore, the formation and stabilization of the Na+, K+ and Ba2+ G-quadruplexes induced by incorporation of the corresponding cations in the pSi matrix is investigated using RIFTS and the optical response correlates well with the expected stability of the cationic complexes. Direct detection of the stabilization of the G-quadruplexes using color-change pSi Rugate filters is also demonstrated. We anticipate this strategy to be a starting point for more sophisticated constitutional reorganization studies under confined conditions and directed at understanding the fundamental aspects of the self-organization of matter, involving in particular controlled structure generation, adaptation and replication processes. 1. G. B. Rusu, F. Cunin, M. Barboiu, Real-Time Optical Detection of Stabilized Artificial G-Quadruplexes Under Confined Conditions, Angew. Chem. Int. Ed. 2013, DOI: 10.1002/anie. 201306230.