Dark bridge at the interface of hybrid nanosystem: Lanthanide-triplet NIR photosensitization

“Dark” organic triplet states typically require visible light to activate via singlet-triplet intersystem crossing. In this issue of Chem, Deng and co-workers report a new near-infrared photosensitization strategy using lanthanide-doped nanoparticles directly the dark photosensitizers, significantly reducing power requirement irradiance. The current photosensitizers used in photodynamic therapy (PDT) generate singlet oxygen or other reactive species (ROS) states. This process requires ultraviolet excitation through higher-lying excited crossing given that cannot be (Figure 1A). consequence is short penetration depth biological tissue. To enable (NIR) sensitization allows deep tissue penetration, upconversion materials have been convert NIR into further sensitize 1B),1Wang Z. Thang D.C. Han Q. Zhao X. Xie Wang Lin J. Xing B. Near-infrared photocontrolled therapeutic release nanocomposites.J. Control. Release. 2020; 324: 104-123Crossref PubMed Scopus (17) Google Scholar, 2Chen G. Qiu H. Prasad P.N. Chen Upconversion nanoparticles: design, nanochemistry, applications theranostics.Chem. Rev. 2014; 114: 5161-5214Crossref (1777) 3Liu Y. Meng Bu W. Upconversion-based cancer therapy.Coord. Chem. 2019; 379: 82-98Crossref (184) 4Zhou Leaño Jr., J.L. Liu Jin D. Wong K.L. R.S. Bünzli J.G. Impact Lanthanide Nanomaterials on Photonic Devices Smart Applications.Small. 2018; 14: e1801882Crossref (85) Scholar but energy loss at each step transfer results low efficiency, which often high Now, lanthanide-triplet sensitization.5Zheng Zhong T. Zhou Li Ilyas A. et al.Near-infrared direct from lanthanide nanoparticles.Chem. 2021; 7https://doi.org/10.1016/j.chempr.2021.03.008Abstract Full Text PDF (14) They found can “dark” photosensitizers; bypass both singlets organics That is, coupling between lanthanides surface becomes bridge transfers by ions lower-lying photosensitizers. circumvents conventional without need for populating higher multiphoton accumulation does not fluorescence resonance (FRET) together enhance conversion efficiency. As result, authors demonstrated an efficient vivo deep-tumor PDT with 100-fold better performance than upconversion-based ultralow work innovative practical ROS generation under typical hybrid nanosystem—consisting neodymium (Nd3+; 50 mol %)-doped NaGdF4 nanoparticle Chlorin e6 (Ce6) photosensitizer as donor acceptor, respectively—because 4I9/2 ? 4F5/2 transition, Nd3+ ion first absorbs 808 nm (about 1.53 ev), 4f-4f transition Nd (4F3/2 4I11/2; about 1.16 eV) matches well lowest state Ce6 (T1 S0; 1.14eV), transferred (3?g? 1?g; 0.98 1C). are states, making photophysics studies interface within nanosystem highly challenging. Some recent advances include use ions, especially Gd3+, accelerate rate (this enhances triplet-state quantum yield heavy-atom effect thereby attaching dyes antennas)6Garfield D.J. Borys N.J. Hamed S.M. Torquato N.A. Tajon C.A. Tian Shevitski Barnard E.S. Suh Y.D. Aloni S. al.Enrichment molecular antenna triplets amplifies upconverting emission.Nat. Photonics. 12: 402-407Crossref (140) very turning nanoparticles.7Han R. Gu Ni L. Huynh U. Zhang Yi Tamura Pershin al.Lanthanide-doped inorganic turn excitons bright.Nature. 587: 594-599Crossref (60) Apart exciting potential application work, systematic investigations led discovery Dexter certainly noteworthy. verify formation system, obtained transient absorption spectra continuous-wave 808-nm-diode laser excitation; NaGdF4:Nd-Ce6 exhibited narrow bleaching band 660 broad 420 600 characteristic ground-state photo-induced Ce6, respectively. Monitoring 4F3/2 relaxation presence absence time-resolved luminescence lifetime measurements clearly showed non-radiative nanocrystals adjacent molecules. prove existence interrupted adding violanthrone-79 (V79) quencher quench emission oxygen. Remarkably, controlled synthesis series ultra-thin optically inert shell NaGdF4, 0.7 (the equivalent only two crystalline unit cells) ~2.5 nm, dramatic drop 0.7-nm-thin layer could strongly inhibit factor ~70%, showing mainly conjugated polycyclic carbons trivalent lanthanide, provides evidence Dexter-type exchange coupling. Moreover, first-principle calculations revealed origin short-distance discovered broadly applied range combinations donors study examined porphyrin phthalocyanine derivatives (PpIX, TCPP, ZnPcS), replacing Yb3+. Interestingly, ZnPcS was observed when Yb3+, TCPP PpIX, Yb3+ (2F5/2; 1.26 = 1.14 1.13 lower 1.43 PpIX 1.56 levels. Several quantitative reported should also appreciated. For example, ~30 absorbed per nanoparticle. efficiency calculated around 60% singlet-oxygen hybrids 20 mW/cm2 irradiation measured ~0.49), molecules ~0.82. required orders magnitude NaYF4:Yb,[email protected]4 upconversion-nanoparticle-sensitized nanohybrid. Future take account cross-section hinder utilization light, stability issues systems. It would useful measure materials’ explore interesting photophysical behind as-discovered energy-transfer process. summary, exciting, compelling inspiring.8Wen Schuck P.J. Schmidt T.W. challenges nanosystems.Nat. 13: 828-838Crossref (88) Scholar,9Bao Wen Yuan K.-L. J.-C.G. Learning complexes: development dye-lanthanide their biomedical applications.Coord. 429: 213642Crossref (26) will expand toolbox material systems photonics applications. acknowledge National Natural Science Foundation China ( NSFC ) 61729501 ), Major International (Regional) Joint Research Project 51720105015 Technology Innovation Commission Shenzhen KQTD20170810110913065 Australia-China Fund Centre Point-of-Care Testing ACSRF658277 SQ2017YFGH001190 ). nanoparticlesZheng al.ChemApril 9, 2021In BriefA achieve high-performance NIR-light-driven developed, based nanoparticle-organic nanoconjugates, method permits cytotoxic 100-times-lower methods, holding great promising emerging such therapy. Full-Text Open Archive