title: Observation of non-Förster-type energy-transfer behavior in quantum dot-phthalocyanine conjugates.
abstract: The effect of linker chain length on the energy transfer from CdSe quantum dots (QDs) to silicon phthalocyanine (Pc) photodynamic therapy agents was investigated by steady-state and femtosecond time-resolved spectroscopy with 500 nm light for the specific excitation of the QD energy donor. The conjugation between the QD and the Pc was achieved with linker chains varying from 4 to 9 bond lengths by incorporating 1-6 methylene groups into the axial ligand of the Pc. With increasing chain length, the energy-transfer efficiency increased, which appears to be opposed to a purely Förster-type resonance energy-transfer behavior that is commonly discussed for the energy transfer in QD conjugates. The obtained results provide strong evidence for a capping-layer-mediated energy transfer in the QD-based donor-acceptor conjugates.
authors.affiliation: Center for Chemical Dynamics and Nanomaterials Research, Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA.
authors.forename: Smita
authors.initials: S
authors.lastname: Dayal
authors.forename: Yongbing
authors.initials: Y
authors.lastname: Lou
authors.forename: Anna Cristina S
authors.initials: AC
authors.lastname: Samia
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Berlin
authors.forename: Malcolm E
authors.initials: ME
authors.lastname: Kenney
authors.forename: Clemens
authors.initials: C
authors.lastname: Burda
mesh_terms: D004735:Energy Transfer; D007211:Indoles / Q000737:chemistry*; D054833:Isoindoles; D045663:Quantum Dots
chemical_list: D007211:Indoles; D054833:Isoindoles; C013647:phthalocyanine