title: Photoreponsive Hybrid Nanoparticles with Inherent FRET Activity.
abstract: The photoactivated inherent fluorescence resonance energy transfer (FRET) properties of a hard-and-soft hybrid nanosystem comprising poly(1'-(2-methacryloxyethyl)-3',3'-dimethyl-6-nitrospiro-(2H-1-benzopyran-2,2'-indoline))-co-poly[2-(dimethylamino)ethyl methacrylate] (PSPMA-co-PDMAEMA) random copolymer brushes on silica nanoparticles are described. This unique FRET process is switched on by the simultaneous generation of isomer X and merocyanine (MC), which are bipolar in nature and comprise donor-acceptor dyads, from a single spiropyran (SP) chromophore upon UV irradiation. These X-MC species exhibit sufficient lifetimes to allow the read-out of the FRET process. The phenomenon is gradually switched off because of the thermal relaxation of the bipolar chromophores. This inherent property of the nanoemitters is employed in the development of biosensors of high specificity by monitoring variations in the FRET efficiency and lifetime of the hybrids in the presence of biological substances. More specifically, bovine serum albumin (BSA) augments the formation of MC species and retards the MC photobleaching process, leading to the enhancement of the FRET efficiency and lifetime, respectively. On the other hand, amino acid l-histidine further retards the MC thermal relaxation and prolongs the FRET process. We envisage that this platform opens new perspectives in the development of novel, optical nanosensors for applications in various fields including healthcare products and environmental monitoring.
authors.affiliation: Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), 711 10 Heraklion, Crete, Greece.|Department of Materials Science and Technology, University of Crete , 710 03 Heraklion, Crete, Greece.
authors.forename: Demetra S
authors.initials: DS
authors.lastname: Achilleos
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
authors.forename: T Alan
authors.initials: TA
authors.lastname: Hatton
authors.affiliation: Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), 711 10 Heraklion, Crete, Greece.|Department of Materials Science and Technology, University of Crete , 710 03 Heraklion, Crete, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Vamvakaki