Skin-safe nanophotosensitizers with highly-controlled synthesized polydopamine shell for synergetic chemo-photodynamic therapy.

Although photodynamic therapy (PDT) has been extensively studied as an established modality of cancer treatment, it still suffers from a few clinical limitations, such as skin phototoxicity and tumor hypoxia. To circumvent these hurdles, hollow silica mesoporous nanoparticles (HMSNs) loaded with photosensitizers were employed as the nanoplatform to construct multifunctional nanoparticles (NPs). Specifically, an ultra-uniform polydopamine (PDA) shell was highly controlled grown around HMSNs by photogenerated outwards-diffused 1O2, followed by conjugation of folic acid-poly(ethylene glycol) and chelation of Fe2+ ions. Thanks to the optimal thickness of light-absorbing PDA shell, the multifunctional NPs exhibited not only negligible skin phototoxicity but also efficient 1O2 generation and photothermal (PT)-enhanced •OH generation upon respective photoirradiation. Anti-tumor therapy was then performed on both 4 T1 tumor cells and tumor-bearing mice by the combination of 638 nm PDT and 808 nm PT-enhanced chemodynamic therapy (CDT). As a result, high therapeutic efficacy was achieved compared to single-modality therapy, with a cell inhibitory rate of 86% and tumor growth inhibition of 70.4% respectively. More interestingly, tumor metastasis was effectively inhibited by the synergetic treatment. These results convincingly demonstrate that our multifunctional NPs are very promising skin-safe PDT agents combined with CDT for efficient tumor therapy.

Luminescent ruthenium(II)-containing metallopolymers with different ligands: synthesis and application as oxygen nanosensor for hypoxia imaging.

A series of Ru(II)-containing metallopolymers with different polypyridyl complexes, namely [Ru(N^N)2(L)](PF6)2 (L = bipyridine-branched polymer; N^N = bpy: 2,2'-bipyridine (Ru 1); phen: 1,10-phenanthroline (Ru 2); dpp: 4,7-diphenyl-1,10-phenanthroline (Ru 3)), were synthesized with the motive that adjusting π-conjugation length of ligands might produce competent luminescent oxygen probes. The three hydrophobic metallopolymers were studied with 1H NMR, UV-Vis absorption, and emission spectroscopy, and then were utilized to prepare biocompatible nanoparticles (NPs) via a nanoprecipitation method. Luminescent properties of the NPs were investigated against dissolved oxygen by steady-state and time-resolved spectroscopy respectively. Luminescence quenching of the three NPs all followed a linear behavior in the range of 0-43 ppm (oxygen concentration), but Ru 3-NPs exhibited the highest oxygen sensitivity (82%) and longest emission wavelength (λex = 460 nm; λem = 617 nm). In addition, external interferons from cellular environments (e.g., pH, temperature, and proteins) had been studied on Ru 3-NPs. Finally, dissolved oxygen in monolayer cells under normoxic/hypoxic conditions was clearly differentiated by using Ru 3-NPs as the luminescent sensor, and, more importantly, hypoxia within multicellular tumor spheroids was vividly imaged. These results suggest that such Ru(II)-containing metallopolymers are strong candidates for luminescent nanosensors towards hypoxia. Graphical abstract.

Ultrastable Luminescent Organic-Inorganic Perovskite Quantum Dots via Surface Engineering: Coordination of Methylammonium Bromide and Covalent Silica Encapsulation.

Encapsulation of luminescent perovskite quantum dots (QDs) into a solid matrix has been approved to be an efficient way to improve their stability. In this work, we reported a green encapsulation method to produce ultrastable CH3NH3PbBr3 QDs incorporated into the SiO2 matrix. Specifically, fresh-prepared CH3NH3PbBr3 QDs were covalently embedded into silica by an aqueous sol-gel method assisted with CH3NH3Br, which not only effectively inhibited the water-driven degradation of QDs through surface coordination, but also strongly stabilized the QDs in solid powder via concentration gradient. As far as we know, this silica encapsulation of perovskite QDs in aqueous environments is reported for the first time. Luminescent properties of perovskite QDs during the course of gelation as well as in resulting composite powder were investigated using steady-state and time-resolved spectroscopies, and a 2 wt % QD-doped sample treated with 11.5 mM of CH3NH3Br was demonstrated to be the optimal phosphor. The green-emissive phosphor had a PLQY of 60.3% and a full width at half maxima of ∼25 nm, exhibiting ultrahigh stability tested by cycle heating (120 °C), continuous heating (80 °C, 60 h), and light irradiation (450 nm light, 350 h). The phosphor was readily blended with polymers and applied as a color-converting layer on blue light-emitting diodes.