Dataset Information

Ligand enhanced upconversion of near-infrared photons with nanocrystal light absorbers.

ABSTRACT: We designed and synthesized a tetracene derivative 4-(tetracen-5-yl)benzoic acid (CPT) as a transmitter ligand used in PbS/PbSe nanocrystal (NC) sensitized upconversion of near infrared (NIR) photons. Under optimal conditions, comparing CPT functionalized NCs with unfunctionalized NCs as sensitizers, the upconversion quantum yield (QY) was enhanced 81 times for 2.9 nm PbS NCs from 0.021% to 1.7%, and 11 times for 2.5 nm PbSe NCs from 0.20% to 2.1%. The surface density of CPT controls the solubility of functionalized NCs and the upconversion QY. By increasing the concentration of CPT in the ligand exchange solution, the number of CPT ligand per NC increases. The upconversion QY is maximized at a transmitter density of 1.2 nm^-2 for 2.9 nm PbS, and 0.32 nm^-2 for 2.5 nm PbSe. Additional transmitter ligands inhibit photon upconversion due to triplet-triplet annihilation (TTA) between two neighboring CPT molecules on the NC surface. 2.1% is the highest reported QY for TTA-based photon upconversion in the NIR with the use of earth-abundant materials.

SUBMITTER: Huang Z

PROVIDER: S-EPMC6013917 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:The combination of near-infrared (NIR) and visible wavelengths in light microscopy for biological studies is increasingly common. For example, many fields of biology are developing the use of NIR for optogenetics, in which an NIR laser induces a change in gene expression and/or protein function. One major technical barrier in working with both NIR and visible light on an optical microscope is obtaining their precise coalignment at the imaging plane position. Photon upconverting particles (UCPs) can bridge this gap as they are excited by NIR light but emit in the visible range via an anti-Stokes luminescence mechanism. Here, two different UCPs have been identified, high-efficiency micro540-UCPs and lower efficiency nano545-UCPs, that respond to NIR light and emit visible light with high photostability even at very high NIR power densities (>25?000 Suns). Both of these UCPs can be rapidly and reversibly excited by visible and NIR light and emit light at visible wavelengths detectable with standard emission settings used for Green Fluorescent Protein (GFP), a commonly used genetically encoded fluorophore. However, the high efficiency micro540-UCPs were suboptimal for NIR and visible light coalignment, due to their larger size and spatial broadening from particle-to-particle energy transfer consistent with a long-lived excited state and saturated power dependence. In contrast, the lower efficiency nano-UCPs were superior for precise coalignment of the NIR beam with the visible light path (?2 ?m versus ?8 ?m beam broadening, respectively) consistent with limited particle-to-particle energy transfer, superlinear power dependence for emission, and much smaller particle size. Furthermore, the nano-UCPs were superior to a traditional two-camera method for NIR and visible light path alignment in an in vivo Infrared-Laser-Evoked Gene Operator (IR-LEGO) optogenetics assay in the budding yeast Saccharomyces cerevisiae. In summary, nano-UCPs are powerful new tools for coaligning NIR and visible light paths on a light microscope.

Project description:Photodynamic therapy (PDT) has been widely applied in the clinic for the treatment of various types of cancer due to its precise controllability, minimally invasive approach and high spatiotemporal accuracy as compared with conventional chemotherapy. However, the porphyrin-based photosensitizers (PSs) used in clinics generally suffer from aggregation-caused reductions in the generation of reactive oxygen species (ROS) and limited tissue penetration because of visible light activation, which greatly hampers their applications for the treatment of deep-seated tumors. Methods: We present a facile strategy for constructing a NIR-regulated cancer theranostic nanoplatform by encapsulating upconversion nanoparticles (UCNPs) and a luminogen (2-(2,6-bis((E)-4-(phenyl(40-(1,2,2-triphenylvinyl)-[1,10-biphenyl]-4-yl)amino)styryl)-4H-pyran-4-ylidene)malononitrile, TTD) with aggregation-induced emission (AIEgen) characteristics using an amphiphilic polymer, and further conjugating cyclic arginine-glycine-aspartic acid (cRGD) peptide to yield UCNP@TTD-cRGD NPs. We then evaluated the bioimaging and anti-tumor capability of the UCNP@TTD-cRGD NPs under NIR light illumination in an in vitro three-dimensional (3D) cancer spheroid and in a murine tumor model, respectively. Results: With a close match between the UCNP emission and absorption of the AIEgen, the synthesized NPs could efficiently generate ROS, even under excitation through thick tissues. The NIR-regulated UCNP@TTD-cRGD NPs that were developed could selectively light up the targeted cancer cells and significantly inhibit tumor growth during the NIR-regulated PDT treatment as compared with the cells under white light excitation. Conclusion: In summary, the synthesized UCNP@TTD-cRGD NPs showed great potential in NIR light-regulated photodynamic therapy of deep-seated tumors. Our study will inspire further exploration of novel theranostic nanoplatforms that combine UCNPs and various AIEgen PSs for the advancement of deep-seated tumor treatments with potential clinical translations.

Dataset Information

Ligand enhanced upconversion of near-infrared photons with nanocrystal light absorbers.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets