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Publication Light-Induced Self-Escape of Spherical Nucleic Acid from Endo/Lysosome for Efficient Non-Cationic Gene Delivery(WILEY-V C H VERLAG GMBH, 2020) Shi, Leilei; Wu, Wenbo; Duan, Yukun; Xu, Li; Xu, Yingying; Hou, Lidan; Meng, Xiangjun; Zhu, Xinyuan; Liu, Bin; Prof Bin Liu; MATERIALS SCIENCE AND ENGINEERING; CHEMICAL & BIOMOLECULAR ENGINEERINGDeveloping non-cationic gene carriers and achieving efficient endo/lysosome escape of functional nucleic acids in cytosol are two major challenges faced by the field of gene delivery. Herein, we demonstrate the concept of self-escape spherical nucleic acid (SNA) to achieve light controlled non-cationic gene delivery with sufficient endo/lysosome escape capacity. In this system, Bcl-2 antisense oligonucleotides (OSAs) were conjugated onto the surface of aggregation-induced emission (AIE) photosensitizer (PS) nanoparticles to form core–shell SNA. Once the SNAs were taken up by tumor cells, and upon light irradiation, the accumulative O produced by the AIE PSs ruptured the lysosome structure to promote OSA escape. Prominent in vitro and in vivo results revealed that the AIE-based core–shell SNA could downregulate the anti-apoptosis protein (Bcl-2) and induce tumor cell apoptosis without any transfection reagent. 1 2Publication Chemiluminescence-Guided Cancer Therapy Using a Chemiexcited Photosensitizer(Elsevier Inc., 2017-12-14) MAO DUO; WU WENBO; Ji, Shenglu; Chen, Chao; Hu, Fang; Kong, Deling; Ding, Dan; LIU BIN; Dr Mao Duo; MATERIALS SCIENCE AND ENGINEERING; CHEMICAL & BIOMOLECULAR ENGINEERINGImage-guided therapy is one of the most promising strategies for efficiently curing a tumor. Here, a novel nanomaterial with chemiexcited far-red/near-infrared (FR/NIR) emission and singlet oxygen (1O2) generation is reported for precise diagnosis and treatment of tumors. Bis[2,4,5-trichloro-6-(pentyloxycarbonyl)phenyl] oxalate (CPPO) and a specially designed photosensitizer TBD with aggregation-induced FR/NIR emission were co-encapsulated by pluronic F-127 and soybean oil to form C-TBD nanoparticles (C-TBD NPs). These NPs serve as a specific H2O2 probe to precisely track tumors in vivo through chemiluminescence imaging. In addition, effective 1O2 generation by C-TBD NPs in response to tumor H2O2 was observed, which could efficiently induce tumor cell apoptosis and inhibit tumor growth. Both the chemiluminescence response and the therapeutic function were further enhanced when β-phenylethyl isothiocyanate was used to enhance the H2O2 production at the tumor site. Our results prove that C-TBD NPs provide a new strategy for intelligent, accurate, and non-invasive tumor therapy. Precise image-guided therapy is key to eradicating tumors in clinical practice. Here, we report a new nanomaterial based on a chemiexcited photosensitizer, which can be specifically activated by H2O2 within the tumor environment to produce far-red/near-infrared luminescence and singlet oxygen. Using such a nanoparticle, primary and metastatic breast tumors can be clearly identified through chemiluminescence imaging with a very high signal-to-noise ratio. Accompanied by the use of an anti-tumor drug, FEITC, the signal of the tumor could be further enhanced as a result of elevated H2O2 production at the tumor site. More importantly, specific tumor killing can be achieved through chemiexcited singlet oxygen production, and the effect of therapy is also increased in the presence of FEITC. Considering the multiple advantages of simultaneous tumor theranostics, our nanoparticle design represents a promising strategy for future clinical tumor therapy. Organic nanoparticles exhibiting intense FR/NIR chemiluminescence and strong chemiexcited singlet oxygen generation in the presence of H2O2 have been successfully used for selective tumor imaging and therapy. Both tumor chemiluminescent signals and singlet oxygen production can be further enhanced in the presence of an anti-tumor drug, FEITC, which could increase the amount of H2O2 at the tumor site for effective tumor treatment. Our design represents a new strategy for light-source-free image-guided tumor therapy.Publication Metal-Organic Framework as a Simple and General Inert Nanocarrier for Photosensitizers to Implement Activatable Photodynamic Therapy(Wiley-VCH Verlag, 2018-05-09) Hu, Fang; MAO DUO; KENRY; WANG YUXIANG; Wu, Wenbo; Zhao Dan; Kong, Deling; LIU BIN; Dr Mao Duo; CHEMICAL & BIOMOLECULAR ENGINEERINGThere has been a surging interest in the synthesis of activatable photosensitizers (PSs) as they can be selectively activated with minimum nonspecific phototoxic damages for photodynamic therapy (PDT). Conventional strategies to realize activatable PSs are only applicable to a limited number of molecules. Herein, a simple and general strategy to yield activatable PSs by coupling MIL-100 (Fe) (MIL: Materials Institute Lavoisier) with different kinds of PSs is presented. Specifically, when PSs are encapsulated into MIL-100 (Fe), the photosensitization capability is suppressed due to their isolation from O2. After the reaction between iron(III) in MIL-100 (Fe) and H2O2 occurs, the framework of MIL-100 (Fe) collapses and the encapsulated PSs regain contact with O2, leading to activation of photosensitization. In addition, the decomposition of H2O2 can generate O2 to relieve tumor hypoxia and enhance PDT effect. As O2 is an indispensable factor for PDT, the activation strategy should be generally applicable to different PSs for activatable PDT.Publication Promoted Glycerol Oxidation Reaction in an Interface-Confined Hierarchically Structured Catalyst(WILEY-V C H VERLAG GMBH, 2019-01-01) Chen, Zhongxin; Liu, Cuibo; Zhao, Xiaoxu; Yan, Huan; Li, Jing; Lyu, Pin; Du, Yonghua; Xi, Shibo; Chi, Kai; Chi, Xiao; Xu, Haisen; Li, Xing; Fu, Wei; Leng, Kai; Pennycook, Stephen J; Wang, Shuai; Loh, Kian Ping; Dr Priya Yadav; CHEMISTRY; MATERIALS SCIENCE AND ENGINEERING; CHEMICAL & BIOMOLECULAR ENGINEERING© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Confined catalysis in a 2D system is of particular interest owing to the facet control of the catalysts and the anisotropic kinetics of reactants, which suppress side reactions and improve selectivity. Here, a 2D-confined system consisting of intercalated Pt nanosheets within few-layered graphene is demonstrated. The strong metal–substrate interaction between the Pt nanosheets and the graphene leads to the quasi-2D growth of Pt with a unique (100)/(111)/(100) faceted structure, thus providing excellent catalytic activity and selectivity toward one-carbon (C1) products for the glycerol oxidation reaction. A hierarchically porous graphene architecture, grown on carbon cloth, is used to fabricate the confined catalyst bed in order to enhance the mass-diffusion limitation in interface-confined reactions. Owing to its unique 3D porous structure, this graphene-confined Pt catalyst exhibits an extraordinary mass activity of 2910 mA mgPt−1 together with a formate selectivity of 79% at 60 °C. This paves the way toward rational designs of heterogeneous catalysts for energy-related applications.Publication Confinement of Aggregation-Induced Emission Molecular Rotors in Ultrathin Two-Dimensional Porous Organic Nanosheets for Enhanced Molecular Recognition(AMER CHEMICAL SOC, 2018-03-21) DONG JINQIAO; LI XU; ZHANG KANG; Di Yuan, Yi; WANG YUXIANG; Zhai, Linzhi; LIU GUOLIANG; Yuan, Daqiang; JIANG JIANWEN; Zhao Dan; Assoc Prof Zhao Dan; CHEMICAL & BIOMOLECULAR ENGINEERING© 2018 American Chemical Society. Despite the rapid development of molecular rotors over the past decade, it still remains a huge challenge to understand their confined behavior in ultrathin two-dimensional (2D) nanomaterials for molecular recognition. Here, we report an all-carbon, 2D π-conjugated aromatic polymer, named NUS-25, containing flexible tetraphenylethylene (TPE) units as aggregation-induced emission (AIE) molecular rotors. NUS-25 bulk powder can be easily exfoliated into micrometer-sized lamellar freestanding nanosheets with a thickness of 2-5 nm. The dynamic behavior of the TPE rotors is partially restricted through noncovalent interactions in the ultrathin 2D nanosheets, which is proved by comparative experimental studies including AIE characteristics, size-selective molecular recognition, and theoretical calculations of rotary energy barrier. Because of the partially restricted TPE rotors, NUS-25 nanosheets are highly fluorescent. This property allows NUS-25 nanosheets to be used as a chemical sensor for the specific detection of acenaphthylene among a series of polycyclic aromatic hydrocarbons (PAHs) via fluorescent quenching mechanism. Further investigations show that NUS-25 nanosheets have much higher sensitivity and selectivity than their stacked bulk powder and other similar polymers containing dynamic TPE rotors. The highly efficient molecular recognition can be attributed to the photoinduced electron transfer (PET) from NUS-25 nanosheets to acenaphthylene, which is investigated by time-resolved photoluminescence measurements (TRPL), excitation and emission spectra, and density functional theory (DFT) calculations. Our findings demonstrate that confinement of AIE molecular rotors in 2D nanomaterials can enhance the molecular recognition. We anticipate that the material design strategy demonstrated in this study will inspire the development of other ultrathin 2D nanomaterials equipped with smart molecular machines for various applications.Publication Simultaneous Increase in Brightness and Singlet Oxygen Generation of an Organic Photosensitizer by Nanocrystallization(WILEY-V C H VERLAG GMBH, 2018-12-27) Fateminia, SM Ali; Kacenauskaite, Laura; Zhang, Chong-Jing; Kenry, Suqian Ma; Manghnani, Purnima N; Chen, Junsheng; Xu, Shidang; Hu, Fang; Xu, Bin; Laursen, Bo W; Liu, Bin; Prof Liu Bin; CHEMICAL & BIOMOLECULAR ENGINEERING© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Efficient organic photosensitizers are attractive for cancer cell ablation in photodynamic therapy. Bright fluorescent photosensitizers are highly desirable for simultaneous imaging and therapy. However, due to fundamental competition between emission and singlet oxygen generation, design attempts to increase singlet oxygen generation almost always leads to the loss of fluorescence. Herein, it is shown for the first time that nanocrystallization enables a simultaneous and significant increase in the brightness and singlet oxygen generation of an organic photosensitizer. Spectroscopic studies show simultaneous enhancement in the visible light absorption and fluorescence after nanocrystallization. The enhanced absorption of visible light in nanocrystals is found to translate directly to the enhanced singlet oxygen production, which shows a higher ability to kill HeLa cells as compared to their amorphous counterpart.Publication Precise Two-Photon Photodynamic Therapy using an Efficient Photosensitizer with Aggregation-Induced Emission Characteristics(Wiley-VCH Verlag, 2017-07-26) Gu, Bobo; Wu, Wenbo; Xu, Gaixia; FENG GUANGXUE; Yin, Feng; Chong, Peter Han Joo; Qu, Junle; Yong, Ken-Tye; LIU BIN; Prof Liu Bin; CHEMICAL & BIOMOLECULAR ENGINEERINGTwo-photon photodynamic therapy (PDT) is able to offer precise 3D manipulation of treatment volumes, providing a target level that is unattainable with current therapeutic techniques. The advancement of this technique is greatly hampered by the availability of photosensitizers with large two-photon absorption (TPA) cross section, high reactive-oxygen-species (ROS) generation efficiency, and bright two-photon fluorescence. Here, an effective photosensitizer with aggregation-induced emission (AIE) characteristics is synthesized, characterized, and encapsulated into an amphiphilic block copolymer to form organic dots for two-photon PDT applications. The AIE dots possess large TPA cross section, high ROS generation efficiency, and excellent photostability and biocompatibility, which overcomes the limitations of many conventional two-photon photosensitizers. Outstanding therapeutic performance of the AIE dots in two-photon PDT is demonstrated using in vitro cancer cell ablation and in vivo brain-blood-vessel closure as examples. This shows therapy precision up to 5 µm under two-photon excitation.Publication Probing cell membrane damage using a molecular rotor probe with membrane-to-nucleus translocation(ROYAL SOC CHEMISTRY, 2020-12-01) Wang, Kang-Nan; Qi, Guobin; Chu, Huiying; Chao, Xi-Juan; Liu, Liu-Yi; Li, Guohui; Cao, Qian; Mao, Zong-Wan; Liu, Bin; Dr Jianwu Tian; ECONOMICS; CHEMICAL & BIOMOLECULAR ENGINEERINGDamage to cell membranes, the outermost protection layer, is fatal to cells. However, precisely monitoring and in situ reporting cell membrane damage is not trivial. Herein, we present a molecular rotor probe, TPAE2, which can effectively bind to DNA and 1,2-dioleoyl-sn-glycero-3-phosphocholine in solution. Due to the light-up imaging characteristics of the molecular rotor, TPAE2 offers ultrafast and wash-free staining of plasma membrane with 160-fold fluorescence "turn-on"and excellent photostability. Once the membrane is damaged, TPAE2 can light-up the nucleus as a signal reporter. The cascade imaging of the cell membrane and nucleus using TPAE2 enabled real-Time tracking of the whole process of cell apoptosis. What's more, under irradiation, TPAE2 stained on the cell membrane could penetrate cells rapidly and selectively stain the nucleus, self-reporting the cancer cell ablation process. This is the first example that a single molecule with multiple functions can light up the nucleus as an indication of cell membrane damage. The membrane-To-nucleus translocation strategy opens up a new avenue for the design of membrane damage diagnosis probes for biomedical applications. This journal isPublication Multicolor monitoring of cellular organelles by single wavelength excitation to visualize the mitophagy process(ROYAL SOCIETY OF CHEMISTRY, 2018-03-14) Hu, Fang; Cai, Xiaolei; Manghnani, Purnima Naresh; Kenry; Wu, Wenbo; Liu, Bin; Prof Liu Bin; NUS NANOSCIENCE & NANOTECH INITIATIVE; CHEMICAL & BIOMOLECULAR ENGINEERING© The Royal Society of Chemistry 2018. Multiplexed cellular organelle imaging using single wavelength excitation is highly desirable for unravelling cellular functions but remains challenging. This requires the design of organelle specific fluorophores with distinct emission but similar absorption. Herein, we present two unique aggregation-induced emission (AIE) probes to track mitochondria and lysosomes simultaneously with emission colors that can be distinguished from that of the nucleus stain Hoechst 33342 upon single wavelength excitation. Compared to conventional organelle stains, the two AIE probes have larger Stokes shifts and higher photostability, which endow them with the capability to monitor bioprocesses, such as mitophagy with strong and sustained fluorescent signals. Moreover, both probes can also stain intracellular organelles in zebrafish larvae with good cell-penetrating capabilities, showing their great potential to monitor bioprocesses in vivo.Publication Nanocrystallization: A Unique Approach to Yield Bright Organic Nanocrystals for Biological Applications(Wiley-VCH Verlag, 2017-01-04) Fateminia, SM Ali; Wang, Zhiming; Goh, Chi Ching; Manghnani, Purnima N; Wu, Wenbo; MAO DUO; Ng, Lai Guan; Zhao, Zujin; Tang, Ben Zhong; LIU BIN; Dr Mao Duo; CHEMICAL & BIOMOLECULAR ENGINEERINGA new bottom-up method is developed for the fabrication of uniform organic nanocrystals with high brightness and good water dispersity. The effectiveness of the approach is demonstrated through the developing of an AIEgen with significant color and brightness difference in crystalline and amorphous states, which allows us to clearly visualize the amorphous-crystalline transition in solution. Fine-tuning the solvent to antisolvent ratio controls the morphology of the nanoaggregates formed in the aqueous media, but to a much lesser extent, the size. A stress-induced seed assisted crystallization method was subsequently developed to produce uniform nanocrystals with around 100 nm size. The nanocrystals have been successfully applied for cancer cell imaging and in vivo vascular imaging, which clearly reveal the importance of nanocrystallization in improving the fluorescent signals of organic nanoparticles. The nanocrystallization strategy thus opens new opportunities to bring crystallization-associated optical properties into aqueous media for biomedical applications.