title: Efficient Triplet-Triplet Annihilation-Based Upconversion for Nanoparticle Phototargeting.
abstract: High-efficiency upconverted light would be a desirable stimulus for triggered drug delivery. Here we present a general strategy to achieve photoreactions based on triplet-triplet annihilation upconversion (TTA-UC) and Förster resonance energy transfer (FRET). We designed PLA-PEG micellar nanoparticles containing in their cores hydrophobic photosensitizer and annihilator molecules which, when stimulated with green light, would undergo TTA-UC. The upconverted energy was then transferred by FRET to a hydrophobic photocleavable group (DEACM), also in the core. The DEACM was bonded to (and thus inactivated) the cell-binding peptide cyclo-(RGDfK), which was bound to the PLA-PEG chain. Cleavage of DEACM by FRET reactivated the PLA-PEG-bound peptide and allowed it to move from the particle core to the surface. TTA-UC followed by FRET allowed photocontrolled binding of cell adhesion with green light LED irradiation at low irradiance for short periods. These are attractive properties in phototriggered systems.
authors.affiliation: Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States.|David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Weiping
authors.initials: W
authors.lastname: Wang
authors.affiliation: Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States.|David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States.|David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Changyou
authors.initials: C
authors.lastname: Zhan
authors.affiliation: Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States.|David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Aoune
authors.initials: A
authors.lastname: Barhoumi
authors.affiliation: Institute of Advanced Materials, School of Materials Science and Engineering, Nanjing University of Posts and Telecommunications , 9 Wenyuan Road, Nanjing 210023, People's Republic of China.
authors.forename: Tianshe
authors.initials: T
authors.lastname: Yang
authors.affiliation: Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States.|David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Ryan G
authors.initials: RG
authors.lastname: Wylie
authors.affiliation: Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States.|David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Armstrong
authors.affiliation: Laboratory for Biomaterials and Drug Delivery, Department of Anesthesiology, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School , 300 Longwood Avenue, Boston, Massachusetts 02115, United States.|David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Kohane
mesh_terms: D031541:Fluorescence Resonance Energy Transfer; D008027:Light; D053758:Nanoparticles; D010456:Peptides, Cyclic / Q000737:chemistry; D066244:Proton Magnetic Resonance Spectroscopy
chemical_list: D010456:Peptides, Cyclic
keywords: Caged ligands; photocleavage; photoresponsive; phototargeted; shielding; upconverting micelles