Photodynamic therapy (PDT) is an excellent therapeutic modality for various malignant and nonmalignant cancers. This approach utilizes reactive oxygen species generated through the reaction between photosensitizer and oxygen in tissues upon light irradiation to achieve effective treatment. However, limited penetration depth and oxygen-deficient microenvironment hinder the efficiency of PDT. In this work, we design a multifunctional near-infrared (NIR)-triggered theranostic agent based on upconversion-nanoparticles-Polyoxyethylene bis (amine)-trismethylpyridylporphyrin-fullerene nanocomposite (UCNP-PEG-FA/ PC 70 ) for imaging (fluorescence/upconversion luminescence/magnetic resonance imaging)-guided photodynamic therapy. In this multimodal nanocompsite, UCNPs are employed as light transducers to convert NIR light into ultraviolet-visible light to activate PC 70 to generate singlet oxygen ( 1 O 2 ) even under low-oxygen conditions. Meanwhile, the upconversion emission, magnetic resonance imaging and fluorescence signal coming from UCNPs and PC 70 nanocomposite enable UCNP-PEG-FA/PC 70 to act as a multimodal imaging diagnostic agent, which facilitates the imaging-guided PDT. Furthermore, folate-mediated active targeting would enhance the accumulation of multifunctional hybrid in tumor. In vitro as well as in vivo results suggest that this smart nanocomposite is promising as an NIR light-triggered and -targeted theranostic platform for imaging-guided PDT of cancer, which may provide a solution to the bottleneck problems of PDT, namely, limited penetration depth and oxygen-deficient microenvironment.

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A series of carbazole derivatives was synthesized and their electrical and photophysical properties were investigated. It is shown that the triplet energy levels of these hosts are higher than that of the most popular blue phosphorescent material iridium(III) bis [(4,6-difluorophenyl)pyridinato-N,C 2′ ] picolinate (FIrpic) and the most extensively used phosphorescent host material 4,4′-N,N′-dicarbazole-biphenyl (CBP). These new host materials also showed good thermal stability and high glass transition temperatures (T g ) ranging from 78 to 115 °C as the linkage group between the carbazoles was altered. Photophysical measurements indicate that the energy transfer between these new hosts and FIrpic is more efficient than that between CBP and FIrpic. Devices incorporating these novel carbazole derivatives as the host material doped with FIrpic were fabricated with the configurations of ITO/NPB (40 nm)/host:FIrpic (30 nm)/BCP (15 nm)/AlQ (30 nm)/LiF (1 nm)/Al (150 nm). High efficiencies (up to 13.4 cd/A) have been obtained when 1,4-bis (4-(9H-carbazol-9yl)phenyl)cyclohexane (CBPCH) and bis(4-(9H-carbazol-9-yl)phenyl) ether (CBPE) were used as the host, respectively. Efficiencies obtained from these devices are significantly higher than the efficiency obtained with CBP as the host. At a bias voltage of ∼20 V the maximum luminances of 20 342 and 17 766 cd/m 2 were achieved for CBPCH-and CBPE-based devices, respectively, which demonstrates that CBPCH and CBPE can be excellent host materials for blue electrophosphorescent OLEDs.