Efficient Triplet–Triplet Annihilation-Based Upconversion for Nanoparticle Phototargeting

• Published in: Nano letters Vol. 15; no. 10; pp. 6332 - 6338
• Main Authors: Wang, Weiping, Liu, Qian, Zhan, Changyou, Barhoumi, Aoune, Yang, Tianshe, Wylie, Ryan G, Armstrong, Patrick A, Kohane, Daniel S
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 14.10.2015
• Subjects: Binding; Chains; Drug delivery systems; Fluorescence Resonance Energy Transfer; Fretting; Irradiance; Light; Nanoparticles; Nanostructure; Peptides; Peptides, Cyclic - chemistry; Proton Magnetic Resonance Spectroscopy; Upconversion; Caged ligands; phototargeted; shielding; photoresponsive; upconverting micelles; photocleavage
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/acs.nanolett.5b01325

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.