Fluorescent organic nanoparticles demonstrating high FRET efficiency for their use as bioimaging probes

J. Morla-Folch, G. Vargas-Nadal, A. Ardizzone, S. Kurhuzenkau, S. Illa-Tuset, M. Kober, C. Sissa, J. Faraudo, K.D. Belfield, A. Painelli, J. Veciana, N. Ventosa
New Jersey Institute of Technology (NJIT),
United States

Keywords: fluorescent probes, nanovesicles, quatsomes, bioimaging


In recent years, FRET-based nanoparticle for biosensing, bioimaging, and theranostic applications have experienced an unprecedented upsurge of interest. Especially, polymeric nanoparticles loaded with organic dyes represent an attractive alternative to bring lipophilic dyes in aqueous media showing photostability, biocompatibility and generally, higher brightness than single fluorophores. However, several problems of current dye-loaded polymer NPs should be addressed before they can be used as bioprobes at the pharmaceutical grade. There is still room to improve the brightness of dye-loaded polymer NPs, mainly by the development of new efficient strategies to avoid Aggregation Caused Quenching (ACQ). Surface chemistry and colloidal stability remain a challenge, and particular attention should be paid to the micelle dissociation once they are exposed to the shear stress of the bloodstream or directly cleared by the reticuloendothelial system (RES) as a whole. To address these limitations, we have developed novel fluorescent organic nanoparticles (FONs) stable during long periods of time and with tremendous FRET efficiencies. Indeed, two cyanine molecules were simultaneously loaded into quatsomes (QS), a new class of nanoscopic unilamellar vesicles made by surfactants and sterols. The obtained FONs allow the dispersion and stability of the FRET pair in aqueous media, ensuring photostability, biocompatibility and attractive spectroscopic properties for their use as bioprobes. The results, together with the capability of QSs to integrate or encapsulate small drugs or large biomolecules and to be easily functionalized with targeting groups, represent a certainly promising platform, especially for theranostic nanomedicine.