Therapeutic efficacy of glioblastoma multiforme (GBM) is often severely limited by poor penetration of therapeutics through blood-brain barrier (BBB) into brain tissues and lack of tumor targeting. In this regard, a functionalized upconversion nanoparticle (UCNP)-based delivery system which can target brain tumor and convert deep tissue-penetrating near-infrared (NIR) light into visible light for precise phototherapies on brain tumor was developed in this work.Methods: The UCNP-based phototherapy delivery system was acquired by assembly of oleic acid-coated UCNPs with angiopep-2/cholesterol-conjugated poly(ethylene glycol) and the hydrophobic photosensitizers. The hybrid nanoparticles (ANG-IMNPs) were characterized by DLS, TEM, UV/vis and fluorescence spectrophotometer. Cellular uptake was examined by laser scanning confocal microscopy and flow cytometry. The PDT/PTT effect of ANG-IMNPs was evaluated using MTT assay. Tumor accumulation of NPs was determined by a non-invasive in vivo imaging system (IVIS). The in vivo anti-glioma effect of ANG-IMNPs was evaluated by immunohistochemical (IHC) examination of tumor tissues and Kaplan-Meier survival analysis.Results: In vitro data demonstrated enhanced uptake of ANG-IMNPs by murine astrocytoma cells (ALTS1C1) and pronounced cytotoxicity by combined NIR-triggered PDT and PTT. In consistence with the increased penetration of ANG-IMNPs through endothelial monolayer in vitro, the NPs have also shown significantly enhanced accumulation at brain tumor by IVIS. The IHC tissue examination confirmed prominent apoptotic and necrotic effects on tumor cells in mice receiving targeted dual photo-based therapies, which also led to enhanced median survival (24 days) as compared to the NP treatment without angiopep-2 (14 days).Conclusion: In vitro and in vivo data strongly indicate that the ANG-IMNPs were capable of selectively delivering dual photosensitizers to brain astrocytoma tumors for effective PDT/PTT in conjugation with a substantially improved median survival. The therapeutic efficacy of ANG-IMNPs demonstrated in this study suggests their potential in overcoming BBB and establishing an effective treatment against GBM.

Polyethyleneimine (PEI)-capped NaYF 4 nanoparticles (NPs) codoped with Yb 3+ , Er 3+ , and Mn 2+ ions (MnUNPs) were synthesized via a solvothermal method. The MnUNPs showed tissue-penetrable over-1000 nm (OTN-) near-infrared (NIR) and strong red upconversion (UC) emission under NIR excitation. Furthermore, the photosensitizers chlorin e6 (Ce6) and biocompatible poly(ethylene glycol) (PEG) were immobilized on the surface of the MnUNPs (PEG/Ce6-MnUNPs). The prepared PEG/Ce6-MnUNPs generated singlet oxygen ( 1 O 2 ) and displayed effective anticancer activity under NIR excitation. Keywords: Photodynamic therapy | Second biological window | UpconversionPhotodynamic therapy (PDT) is a technique that destroys cancer tissues via photosensitizers and light irradiation.1,2 The photosensitizers absorb the light and produce reactive oxygen species (ROS) that destroy cancer cells. Most current photosensitizers require visible (vis) light for excitation, and their use in cancer treatment suffers from the lack of penetration depth of vis light owing to the scattering it undergoes because of its short wavelength.Because of this drawback of PDT, rare-earth-doped ceramic nanophosphors (RED-CNPs) have attracted much attention as in vivo imaging probes 35 and PDT transducers. 69 The RED-CNPs produce simultaneous tissue-penetrable over-1000 nm near-infrared (OTN-NIR) and vis upconversion (UC) emission under NIR excitation. , Er 3+ NP) showed green and red UC emission under 980-nm NIR excitation and was used as a transducer for PDT. In those studies, the photosensitizer, chlorin e6 (Ce6) ( Figure S1 in Supporting Information (SI)) was immobilized on the surface of the , Mn 2+ NPs (MnUNPs) for the transducer of PDT using a standard solvothermal synthesis method. Ce6 was covalently immobilized on the surface of the polyamine-tethered NPs via amide linkage. Furthermore, for a highly stable PDT probe, the biocompatible polymer poly(ethylene glycol)-blockpoly(acrylic acid) (PEG-b-PAAc) was strongly immobilized on the positive-charged polyamine surface of the NPs via electrostatic interactions (Figure 1).The MnUNPs were synthesized using the solvothermal synthesis method with different nominal Mn 2+ concentrations (4054 mol %)1518 and a fixed concentration of water (4 wt %), as in previous literature. As a control, Mn 2+ -undoped NaYF 4 :Yb 3+ , Er 3+ NPs (UNPs) were also synthesized using the same protocol. X-ray diffraction (XRD) spectroscopy identified the crystal phase of the synthesized MnUNP samples to be pure cubic α-phase NaYF 4 , because all the peaks were indexed to JCPDS data (06- Figure 1. Illustration of NIR-induced PDT and OTN-NIR fluorescence imaging based on PEG/Ce6-MnUNPs.