Optical Properties Of Silica Fluorescent Nanoparticles Prepared From Molecular Organogels

PABLO DI CHENNA; VALERIA C. EDELSZTEIN; FRANCISCO GUAIMAS; CARLA C. SPAGNUOLO

Barcelona

Conferencia; V International Conference on Molecular materials; 2012

Universidad de Barcelona

Molecular organogels, so called supramolecular or physical gels, are materials constructed from the self-assembly of low molecular weight building blocks in an organic solvent. These molecules selfassemble into supramolecular structures at the nanoscale level as a consequence of non covalent interactions such as hydrogen bonds, ð-ð stacking, Van der Waals interactions, etc. This three dimensional architecture entrap the solvent molecules within their entangled fibrillar network forming the gel.[1] Materials science has found a promising new area of research in the development of lowmolecular mass organogelators due to their well defined supramolecular structures, and their potential application in electrooptics/photonics, confined reaction media, light harvesting systems, sensors (photosensors, chimiosensors, etc), biomaterials, as structure directing agents, etc.[2] In particular, the nanoscopic superstructures formed by a given gelator molecule define a unique morphology (rods, ribbons, tapes, tubes, helices etc) that can be used as template for the preparation of well defined inorganic (SiO2, TiO2, etc) and/or hybrid nanomaterials which also have a great potential of applications in different fields.[3] In particular, recent studies on fluorescent silica NPs for intracellular analyte monitoring, cellular targeting and cancer cell diagnosis suggests that these NPs possess great potential for real clinical and biomedical applications.[4] In this communication we report a method for the preparation of fluorescent Silica NPs (nanospheres) through the in situ sol-gel polimerization of TEOS based on an organogel previously developed by us.[5] Highly fluorescent gels were prepared from the steroidal low molecular weight organogelator doped with an ultraphotostable perylene fluorophore. This material was used to obtain fluorescent silica nanospheres (Figure 1). In order to improve the control of the fluorescence signal over such a system, an alkoxysilane modified perylene derivative was also used as dopant. The morphology of the nanoparticles was analysed by SEM and optical properties were investigated by means of steady state as well as time-resolved fluorescence techniques.