Publications by authors named "Xiaogang Liu"

331 Publications

Emerging Design Principle of Near-Infrared Upconversion Sensitizer Based on Mitochondria-Targeted Organic Dye for Enhanced Photodynamic Therapy.

Chemistry 2021 Oct 14. Epub 2021 Oct 14.

Dalian University of Technology, State Key Laboratory of Fine Chemicals, 2 Linggong Road, Hi-tech District, E 232 West Campus, 116024, Dalian, CHINA.

Upconversion luminescent (UCL) triggered photodynamic therapy (PDT) affords superior outcome for cancer treatment. However, conventional UCL materials which all work as multiphoton absorption (MPA) process, inevitably need extremely high power density far over the maximum permissible exposure (MPE) to laser. Here, an one-photon absorption molecular upconversion sensitizer Cy5.5-Br based on frequency upconversion luminescent (FUCL) is designed for PDT. The unusual super heavy atom effect (SHAE) in Cy5.5-Br strongly enhance its spin-orbit coupling (0.23 cm-1), triplet quantum yield (11.1%) and triplet state lifetime (18.8 μs) while the potential hot-band absoption of Cy5.5-Br are well maintained. Importantly, Cy5.5-Br can efficiently target to the tumour site and kill cancer cells by destroying mitochondria under a biosafety MPE to 808 nm laser. The photostability and antitumor results are obviously superior to that of Stoke process. This work first provide a design criterion for FUCL dyes to realize effective PDT upon a biosafety optical density, possibly being more clinical benefits than conventional MPA materials.
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http://dx.doi.org/10.1002/chem.202102866DOI Listing
October 2021

An Edaravone-Guided Design of a Rhodamine-Based Turn-on Fluorescent Probe for Detecting Hydroxyl Radicals in Living Systems.

Anal Chem 2021 Oct 13. Epub 2021 Oct 13.

Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry & Materials Science, Northwest University, Xi'an 710127, P. R. China.

The hydroxyl radical (·OH), one of the reactive oxygen species (ROS) in biosystems, is found to be involved in many physiological and pathological processes. However, specifically detecting endogenous ·OH remains an outstanding challenge owing to the high reactivity and short lifetime of this radical. Herein, inspired by the scavenging mechanism of a neuroprotective drug edaravone toward ·OH, we developed a new ·OH-specific fluorescent probe . is a hybrid of rhodamine and edaravone and exploits a ·OH-specific 3-methyl-pyrazolone moiety to control its fluorescence behavior. itself is almost nonfluorescent in physiological conditions, which was attributed to the formation of a twisted intramolecular charge transfer (TICT) state upon photoexcitation and the acylation of its rhodamine nitrogen at the 3' position. However, upon a treatment with ·OH, its edaravone subunit was converted to the corresponding 2-oxo-3-(phenylhydrazono)-butanoic acid (OPB) derivative (to afford ), thus leading to a significant fluorescence increase (ca. 195-fold). shows a high sensitivity and selectivity to ·OH without interference from other ROS. has been utilized for imaging endogenous ·OH production in living cells and zebrafishes under different stimuli. Moreover, allows a high-contrast discrimination of cancer cells from normal ones by monitoring their different ·OH levels upon stimulation with β-Lapachone (β-Lap), an effective ROS-generating anticancer therapeutic agent. The present study provides a promising methodology for the construction of probes through a drug-guided approach.
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http://dx.doi.org/10.1021/acs.analchem.1c03877DOI Listing
October 2021

Twisted intramolecular charge transfer (TICT) and twists beyond TICT: from mechanisms to rational designs of bright and sensitive fluorophores.

Chem Soc Rev 2021 Oct 11. Epub 2021 Oct 11.

Fluorescence Research Group, Singapore University of Technology and Design, 8 Somapah Road, 487372, Singapore.

The twisted intramolecular charge transfer (TICT) mechanism has guided the development of numerous bright and sensitive fluorophores. This review briefly overviews the history of establishing the TICT mechanism, and systematically summarizes the molecular design strategies in modulating the TICT tendency of various organic fluorophores towards different applications, along with key milestone studies and representative examples. Additionally, we also succinctly review the twisted intramolecular charge shuttle (TICS) and twists during photoinduced electron transfer (PET), and compare their similarities and differences with TICT, with emphasis on understanding the structure-property relationships between the twisted geometries and how they can directly affect the fluorescence of the molecules. Such structure-property relationships presented herein will greatly aid the rational development of fluorophores that involve molecular twisting in the excited state.
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http://dx.doi.org/10.1039/d1cs00239bDOI Listing
October 2021

High-Specificity In Vivo Tumor Imaging Using Bioorthogonal NIR-IIb Nanoparticles.

Adv Mater 2021 Oct 7:e2102950. Epub 2021 Oct 7.

Department of Chemistry and The N.1 Institute for Health, National University of Singapore, Singapore, 117543, Singapore.

Lanthanide-based NIR-IIb nanoprobes are ideal for in vivo imaging. However, existing NIR-IIb nanoprobes often suffer from low tumor-targeting specificity, limiting their widespread use. Here the application of bioorthogonal nanoprobes with high tumor-targeting specificity for in vivo NIR-IIb luminescence imaging and magnetic resonance imaging (MRI) is reported. These dual-modality nanoprobes can enhance NIR-IIb emission by 20-fold and MRI signal by twofold, compared with non-bioorthogonal nanoprobes in murine subcutaneous tumors. Moreover, these bioorthogonal probes enable orthotopic brain tumor imaging. Implementation of bio-orthogonal chemistry significantly reduces the nanoprobe dose and hence cytotoxicity, providing a paradigm for real-time in vivo visualization of tumors.
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http://dx.doi.org/10.1002/adma.202102950DOI Listing
October 2021

Associations between m-type phospholipase A2 receptor,human leukocyte antigen gene polymorphisms and idiopathic membranous nephropathy.

Bioengineered 2021 Oct 5. Epub 2021 Oct 5.

Department of Nephrology, the first affiliated hospital of Harbin medical university.

Background And Purpose: Primary membranous nephropathy, also known as idiopathic membranous nephropathy, is an autoimmune disease. As an autoimmune disease, genetic factors are essential in the pathogenesis of IMN. People pay more and more attention to genetics and bioinformatics. With the continuous improvement and development of high-throughput gene sequencing and genotyping technology, it has been confirmed that many genes and their single nucleotide polymorphisms are strongly correlated with IMN disease susceptibility. However, there are few studies on HLA-DQA1 and PLA2R gene polymorphisms and IMN susceptibility in China. The purpose of this study was to investigate whether PLA2R rs2715928 and rs16844715 are related to IMN, the correlation between five SNP loci of PLA2R and HLA-DQA1 and IMN, and the effect of gene-gene interaction among different genotypes of each locus on disease.

Methods: In this study, 86 patients with IMN confirmed by renal biopsy in the first hospital of Harbin Medical University and 90 healthy controls were selected. All subjects were excluded from secondary membranous nephropathy, pregnant or breastfeeding women, severe primary disease of vital organs, severe infection, major surgery, and severe trauma. Seven selected SNP loci were genotyped using the IMLDR multiple SNP typing kit. Chi-square test and logistic regression were used to analyze the correlation between each SNP and IMN. The general clinical data and laboratory indicators of each subject were recorded, and the relationship between different genotypes and clinical manifestations was analyzed.

Results: Among the 7 SNP loci included in the study, except HLA-DQA1 rs2187668, the other 6 loci all met Hardy-Weiberg equilibrium test (P > 0.05). The allele distribution of PLA2R rs2715928 and rs16844715 was significantly different between the IMN group and the healthy control group, and it was closely related to IMN (P < 0.05). There was no statistical difference in the distribution of alleles of rs2715918 between the IMN group and the control group (P* > 0.05), and there was also statistical difference in the distribution of alleles of rs35771982, rs3749117, and rs4664308 between the IMN group and the healthy control group (P < 0.05).The C allele of rs16844715 (OR=2.03, 95%CI: 1.29-3.19, P*=0.0140) and the A allele of rs2715928 (OR=3.18, 95%CI: 1.94-5.24, P*=3.54E-5), G allele of rs35771982 (OR=4.07, 95%CI: 2.34-7.08, P*=4.96E-6), T allele of rs3749117 (OR=4.07, 95%CI: 2.34-7.08, P*=4.96E-6), the A allele of rs4664308 (OR=2.63, 95%CI: 1.54-4.49, P*=0.0028) was the risk gene of IMN.Through the establishment of different genetic models, we found that,in the additive model, the three SNPs of PLA2R rs2715928 (OR=5.40, 95%CI: 1.77-16.50, P*=0.0217) and rs35771982 (OR=15.15, 95%CI: 2.92-78.48, P*=0.0084), rs3749117 (OR=15.15, 95%CI: 2.92-78.48, P*=0.0084) had a strong correlation with IMN. In the stealth model,homozygous gene risk type of the five SNPs,PLA2R rs16844715 (OR=2.52, 95%CI: 1.38-4.61, P*=0.0189) and rs2715928 (OR=4.30, 95%CI: 2.31-8.03, P*=3.14E-5), rs35771982 (OR=4.85, 95%CI: 5.53-9.31, P*=1.42E-5), rs3749117 (OR=4.85, 95%CI: 5.53-9.31, P*=1.42E-5) and rs4664308 (OR=3.16, 95%CI: 1.67-5.97, P*=0.0028) had a strong correlation with IMN. The distribution of GT haplotypes and CC haplotypes of rs35771982 and rs3749117 and CA haplotypes and TG haplotypes of rs16844715 and rs4664308 were significantly different between IMN group and control group (P < 0.05). When GMDR software was used to establish a model to analyze the interaction between various SNP sites, it was found that the combination of GG genotype at rs35771982 and AA genotype at rs2715928 was the highest risk of disease. The risk genotypes of rs16844715, rs2715928 and rs4664308 had no effect on the clinical manifestations of IMN (P > 0.05).

Conclusion: PLA2R rs2715928 and rs16844715 are associated with susceptibility to IMN. The C allele of rs16844715, the A allele of rs2715928, the G allele of rs35771982, the T allele of rs3749117, and the A allele of rs4664308 are the dangerous genes of IMN. The combination of GG genotype at rs35771982 and AA genotype at rs2715928 poses the greatest risk of disease. Haplotype may affect susceptibility to IMN. The risk genotype had no effect on the clinical manifestations of IMN.
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http://dx.doi.org/10.1080/21655979.2021.1987080DOI Listing
October 2021

Force-Induced Near-Infrared Chromism of Mechanophore-Linked Polymers.

J Am Chem Soc 2021 Sep 29. Epub 2021 Sep 29.

Fluorescence Research Group, Singapore University of Technology and Design, 8 Somapah Road, 487372 Singapore.

A near-infrared (NIR) mechanophore was developed and incorporated into a poly(methyl acrylate) chain to showcase the first force-induced NIR chromism in polymeric materials. This mechanophore, based on benzo[1,3]oxazine (OX) fused with a heptamethine cyanine moiety, exhibited NIR mechanochromism in solution, thin-film, and bulk states. The mechanochemical activity was validated using UV-vis-NIR absorption/fluorescence spectroscopies, gel permeation chromatography (GPC), NMR, and DFT simulations. Our work demonstrates that NIR mechanochromic polymers have considerable potential in mechanical force sensing, damage detection, bioimaging, and biomechanics.
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http://dx.doi.org/10.1021/jacs.1c05923DOI Listing
September 2021

Bio-orthogonal Red and Far-Red Fluorogenic Probes for Wash-Free Live-Cell and Super-resolution Microscopy.

ACS Cent Sci 2021 Sep 20;7(9):1561-1571. Epub 2021 Aug 20.

Institute of Pharmacy and Molecular Biotechnology, Heidelberg University, Im Neuenheimer Feld 364, 69120 Heidelberg, Germany.

Small-molecule fluorophores enable the observation of biomolecules in their native context with fluorescence microscopy. Specific labeling via bio-orthogonal tetrazine chemistry combines minimal label size with rapid labeling kinetics. At the same time, fluorogenic tetrazine-dye conjugates exhibit efficient quenching of dyes prior to target binding. However, live-cell compatible long-wavelength fluorophores with strong fluorogenicity have been difficult to realize. Here, we report close proximity tetrazine-dye conjugates with minimal distance between tetrazine and the fluorophore. Two synthetic routes give access to a series of cell-permeable and -impermeable dyes including highly fluorogenic far-red emitting derivatives with electron exchange as the dominant excited-state quenching mechanism. We demonstrate their potential for live-cell imaging in combination with unnatural amino acids, wash-free multicolor and super-resolution STED, and SOFI imaging. These dyes pave the way for advanced fluorescence imaging of biomolecules with minimal label size.
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http://dx.doi.org/10.1021/acscentsci.1c00703DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8461766PMC
September 2021

Restriction of Twisted Intramolecular Charge Transfer Enables the Aggregation-Induced Emission of 1-(,-Dialkylamino)-naphthalene Derivatives.

J Phys Chem A 2021 Sep 21;125(38):8397-8403. Epub 2021 Sep 21.

School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371 Singapore, Singapore.

Understanding the mechanisms of aggregation-induced emission (AIE) is essential for the rational design and deployment of AIEgens toward various applications. Such a deep mechanistic understanding demands a thorough investigation of the excited-state behaviors of AIEgens. However, because of considerable complexity and rapid decay, these behaviors are often not experimentally accessible and the mechanistic comprehension of many AIEgens is lacking. Herein, utilizing detailed quantum chemical calculations, we provide insights toward the AIE mechanism of 1-(,-dialkylamino)-naphthalene (DAN) derivatives. Our theoretical analysis, corroborated by experimental observations, leads to the discovery that modulating the formation of the twisted intramolecular charge transfer (TICT) state (caused by the rotation of the amino groups) and managing the steric hindrance to minimize solid-state intermolecular interactions provides a plausible explanation for the AIE characteristics of DAN derivatives. These results will inspire the deployment of the TICT mechanism as a useful design strategy toward AIEgen development.
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http://dx.doi.org/10.1021/acs.jpca.1c06263DOI Listing
September 2021

Organic Semiconductor Single Crystals for X-ray Imaging.

Adv Mater 2021 Sep 20:e2104749. Epub 2021 Sep 20.

Department of Chemistry & Biochemistry, University of California at Los Angeles, Los Angeles, CA 90095, USA.

Low-dose, high-resolution X-ray imaging is vital for medical diagnostics and material/device analyses. Current X-ray imagers are dominated by expensive inorganic materials via high-temperature solid processes (up to 1700 °C, e.g., CsI:Tl) with heavy metal elements. It is essential to search for new materials as X-ray imagers with low growth temperature, low cost, high sensitivity, along with high chemical and environmental stability. Here, 9,10-diphenylanthracene (9,10-DPA) single crystals are used as a representative model, which are grown via low-temperature solution processes, exhibiting intense X-ray radioluminescence with ultrahigh photon-conversion efficiency, ultrafast response and high sensitivity. The resolution of devices based on organic crystals exceeds 20.00 lp mm . Meanwhile the crystals exhibit high cycle performance under X-ray irradiation and environmental stability. This study demonstrates that organic semiconductors have potential use in low-cost, high-sensitivity and low-dose X-ray imaging systems.
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http://dx.doi.org/10.1002/adma.202104749DOI Listing
September 2021

Stable super-resolution imaging of lipid droplet dynamics through a buffer strategy with a hydrogen-bond sensitive fluorogenic probe.

Angew Chem Int Ed Engl 2021 Sep 14. Epub 2021 Sep 14.

Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Department of Biological Technology, 457 Zhongshan Road, 116023, Dalian, CHINA.

Although super-resolution imaging offers an opportunity to visualize cellular structures and organelles at the nanoscale level, cellular heterogeneity and unpredictability still pose a significant challenge in the dynamic imaging of live cells. It is thus vital to develop better performing and more photostable probes for long-term super-resolution imaging. Herein, we report a probe LD-FG for imaging lipid droplet (LD) dynamics using structured illumination microscopy (SIM). LD-FG allows wash-free imaging of LDs, owing to hydrogen-bond sensitive fluorogenicity. The replenishment of photobleached LD-FG by intact ones outside LDs further ensure the long-time stability of the fluorescence imaging. With this buffering fluorogenic probe, fast and unpredictable dynamic processes of LDs can be visualized. Two LD coalescence modes (as well as heterogeneity in different regions of the cells and even in between different cells) were discovered for the first time. Notably, the dynamic imaging also allowed us to propose a new model of LD maturation during adipocyte differentiation, i.e. , a fast LD coalescence followed by a slow ripening step. The excellent performance of LD-FG makes the buffer strategy an effective method for designing fluorescent probes for cell dynamic imaging.
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http://dx.doi.org/10.1002/anie.202111052DOI Listing
September 2021

Signal Filtering Enabled by Spike Voltage-Dependent Plasticity in Metalloporphyrin-Based Memristors.

Adv Mater 2021 Sep 12:e2104370. Epub 2021 Sep 12.

Center for Molecular Systems & Organic Devices (CMSOD), Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, Nanjing, 210023, China.

Neural systems can selectively filter and memorize spatiotemporal information, thus enabling high-efficient information processing. Emulating such an exquisite biological process in electronic devices is of fundamental importance for developing neuromorphic architectures with efficient in situ edge/parallel computing, and probabilistic inference. Here a novel multifunctional memristor is proposed and demonstrated based on metalloporphyrin/oxide hybrid heterojunction, in which the metalloporphyrin layer allows for dual electronic/ionic transport. Benefiting from the coordination-assisted ionic diffusion, the device exhibits smooth, gradual conductive transitions. It is shown that the memristive characteristics of this hybrid system can be modulated by altering the metal center for desired metal-oxygen bonding energy and oxygen ions migration dynamics. The spike voltage-dependent plasticity stemming from the local/extended movement of oxygen ions under low/high voltage is identified, which permits potentiation and depression under unipolar different positive voltages. As a proof-of-concept demonstration, memristive arrays are further built to emulate the signal filtering function of the biological visual system. This work demonstrates the ionic intelligence feature of metalloporphyrin and paves the way for implementing efficient neural-signal analysis in neuromorphic hardware.
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http://dx.doi.org/10.1002/adma.202104370DOI Listing
September 2021

Molecular-Dimension-Dependent ESIPT Break for Specific Reversible Response to GSH and Its Real-Time Bioimaging.

Anal Chem 2021 09 9;93(37):12801-12807. Epub 2021 Sep 9.

Xinzhou Teachers University, Xinzhou 034000, China.

Glutathione (GSH) plays many important roles in maintaining intracellular redox homeostasis, and determining its real-time levels in the biological system is essential for the diagnosis, treatment, and pathological research of related diseases. Fluorescence imaging has been regarded as a powerful tool for tracking biomarkers in vivo, for which specificity, reversibility, and fast response are the main issues to ensure the real-time effective detection of analytes. The determination of GSH is often interfered with by other active sulfur species. However, in addition to the common features of nucleophilic addition, GSH is unique in its large molecular scale. 2-(2-Hydroxyphenyl) benzothiazole (HBT) was often formed in the ESIPT process. In this study, HBT was installed with α,β-unsaturated ketone conjugated coumarin derivates or nitrobenzene, which were used to adjust the reactivity of α,β-unsaturated ketone. Experimental and theoretical calculations found ESIPT to be favorable in but not or due to the higher electronic energies in the keto form. Thus, for , in the presence of GSH, the hydrogen-bonding interaction between C═N of the HBT unit and carboxyl of GSH would inhibit the process, simultaneously promoting the Michel addition reaction between α,β-unsaturated ketone and GSH. As a consequence, probe could exhibit a rapid reversible ratiometric response to GSH. Small structures of Hcy and Cys are passivated for such reactions. Cell imaging demonstrated the specific response of the probe to GSH, and the probe was successfully used to monitor fluctuations in GSH concentration during cells apoptosis in real-time.
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http://dx.doi.org/10.1021/acs.analchem.1c03376DOI Listing
September 2021

Self-Assembly of Surface-Functionalized Ag Mn O Nanorods with Reduced Graphene Oxide Nanosheets as an Efficient Bifunctional Electrocatalyst for Rechargeable Zinc-Air Batteries.

Chem Asian J 2021 Sep 8. Epub 2021 Sep 8.

Department Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis, #08-03, 138634, Singapore.

Bifunctional electrocatalysts play a key role in the performance of rechargeable metal-air batteries. Herein, we report a hybrid catalyst, Ag Mn O /rGO, self-assembled by Ag Mn O nanorods and reduced graphene oxide (rGO) nanosheets through electrostatic attraction. The hybrid catalyst exhibits a better oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity than commercial Pt/C in alkaline medium. When employed as an air-cathode catalyst in Zn-air cells, the hybrids enabled higher and more stable output voltage and better durability of the cells, benefitting from the improved electrode conductivity, larger surface area, and synergetic coupling as a result of its high structural integrity.
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http://dx.doi.org/10.1002/asia.202100940DOI Listing
September 2021

The screening of drug-induced nephrotoxicity using gold nanocluster-based ratiometric fluorescent probes.

Nanoscale 2021 Aug 4;13(32):13835-13844. Epub 2021 Aug 4.

State Key Laboratory of Natural Medicine, the School of Basic Medical Sciences and Clinical Pharmacy, China Pharmaceutical University, Nanjing, Jiangsu 211198, China.

Herbal medicines are potential candidates for the treatment of various diseases, but their medication safety remains poorly regulated. Current screening methods for the herbal medicine-induced nephrotoxic effects include histological and serological assessments, which often fail to reflect the kidney dysfunction instantly. Here we report a ratiometric fluorescence approach for the rapid and facile screening of drug-induced acute kidney injury using chromophore-modified gold nanoclusters. These gold nanoclusters are highly sensitive to reactive oxygen species (ROS), with a detection limit of 14 nM for ˙OH. After passing through the glomerular filtration barrier, the gold nanocluster-based probes can quantify the fluctuation of the ROS level in the kidneys and evaluate the risk of drug-induced nephrotoxicity. We further employed nephrotoxic triptolide as the model drug and the screening of drug-induced early renal injury was demonstrated using the nanoprobes, which is unattainable by conventional diagnostic approaches. Our fluorescent probes also allow the identification of other nephrotoxic components from herbal medicine such as aristolochine, providing a high-throughput strategy for the screening of herbal supplement-induced nephrotoxicity.
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http://dx.doi.org/10.1039/d1nr01006aDOI Listing
August 2021

Mapping Drug-Induced Neuropathy through In-Situ Motor Protein Tracking and Machine Learning.

J Am Chem Soc 2021 Sep 1;143(36):14907-14915. Epub 2021 Sep 1.

Department of Chemistry, National University of Singapore, Singapore 117543, Singapore.

Chemotherapy can induce toxicity in the central and peripheral nervous systems and result in chronic adverse reactions that impede continuous treatment and reduce patient quality of life. There is a current lack of research to predict, identify, and offset drug-induced neurotoxicity. Rapid and accurate assessment of potential neuropathy is crucial for cost-effective diagnosis and treatment. Here we report dynamic near-infrared upconversion imaging that allows intraneuronal transport to be traced in real time with millisecond resolution, but without photobleaching or blinking. Drug-induced neurotoxicity can be screened prior to phenotyping, on the basis of subtle abnormalities of kinetic characteristics in intraneuronal transport. Moreover, we demonstrate that combining the upconverting nanoplatform with machine learning offers a powerful tool for mapping chemotherapy-induced peripheral neuropathy and assessing drug-induced neurotoxicity.
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http://dx.doi.org/10.1021/jacs.1c07312DOI Listing
September 2021

Confining isolated chromophores for highly efficient blue phosphorescence.

Nat Mater 2021 Aug 23. Epub 2021 Aug 23.

Key Laboratory of Flexible Electronics and Institute of Advanced Materials, Nanjing Tech University, Nanjing, China.

High-efficiency blue phosphorescence emission is essential for organic optoelectronic applications. However, synthesizing heavy-atom-free organic systems having high triplet energy levels and suppressed non-radiative transitions-key requirements for efficient blue phosphorescence-has proved difficult. Here we demonstrate a simple chemical strategy for achieving high-performance blue phosphors, based on confining isolated chromophores in ionic crystals. Formation of high-density ionic bonds between the cations of ionic crystals and the carboxylic acid groups of the chromophores leads to a segregated molecular arrangement with negligible inter-chromophore interactions. We show that tunable phosphorescence from blue to deep blue with a maximum phosphorescence efficiency of 96.5% can be achieved by varying the charged chromophores and their counterions. Moreover, these phosphorescent materials enable rapid, high-throughput data encryption, fingerprint identification and afterglow display. This work will facilitate the design of high-efficiency blue organic phosphors and extend the domain of organic phosphorescence to new applications.
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http://dx.doi.org/10.1038/s41563-021-01073-5DOI Listing
August 2021

Multiphoton Upconversion Materials for Photocatalysis and Environmental Remediation.

Chem Asian J 2021 Sep 17;16(18):2596-2609. Epub 2021 Aug 17.

Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Singapore, 138634, Singapore.

Solar-driven photocatalysis holds great potential for energy conversion, environmental remediation, and sustainable chemistry. However, practical applications of conventional photocatalytic systems have been constrained by their insufficient ability to harvest solar radiation in the infrared spectrum. Lanthanide-doped upconversion materials possess high photostability, tunable absorption, and the ability to convert low-energy infrared radiation into high-energy emission, making them attractive for infrared-driven photocatalysis. This review highlights essential principles for rational design of efficient photocatalysts. Particular emphasis is placed on current state-of-the-arts that offer enhanced upconversion luminescence efficiency. We also summarize recent advances in lanthanide-doped upconversion materials for photocatalysis. We conclude with new challenges and prospects for future developments of infrared-driven photocatalysts.
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http://dx.doi.org/10.1002/asia.202100751DOI Listing
September 2021

F- regulate the preparation of polyhedral BiVO enclosed by High-Index facet and enhance its photocatalytic activity.

J Colloid Interface Sci 2021 Aug 9;606(Pt 1):393-405. Epub 2021 Aug 9.

Institute of Materials for Energy and Environment, and College of Material Science and Engineering, Qingdao University, Qingdao 266071, PR China. Electronic address:

The selective exposure of high-index facets at the surface of nanocrystals is an important and challenging research topic. Herein, polyhedral bismuth vanadate (BiVO) crystals predominantly surrounded by {2 1 3} and {1 2 1} high-index facets were fabricated through the engineering of high-index surfaces by fluorinion (F) mediated hydrothermal process. The as-prepared BiVO-0.2F (the feeding amount of NaF was 0.2 g) catalyst exhibited high apparent quantum efficiency of 17.7% under 420 nm light irradiation and 9.3 fold enhancement of O evolution relative to its low-index counterparts. Moreover, the growth of high-index facets results in significant enhancement of hydroxyl radical (•OH) production, photocatalytic degradation of Rhodamine B (RhB) and photoelectrochemical (PEC) properties by the BiVO polyhedron, relative to its low-index counterparts. The enhanced photoreactivity is the result of the synergistic effect of F on the surface of the BiVO crystals and exposed high-index facets. For one thing, F on the surface of the BiVO facilitate the separation and transport of photo-induced charge carriers. For another, the exposed high-index facets on polyhedral BiVO provided much more reactive sites for photocatalytic reactions. Hopefully, this F mediated method will be a useful guideline for designing and synthesizing novel high-index faceted micro-/nanostructures for overcoming the practical energy and environment problems.
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http://dx.doi.org/10.1016/j.jcis.2021.08.023DOI Listing
August 2021

Heterostructure engineering of ultrathin SnS/TiCT nanosheets for high-performance potassium-ion batteries.

J Colloid Interface Sci 2021 Aug 2;606(Pt 1):167-176. Epub 2021 Aug 2.

College of Chemistry and Chemical Engineering, Henan Province Key Laboratory of Utilization of Non-Metallic Mineral in the South of Henan, Xinyang Normal University, Xinyang 464000, China.

Layered metal sulfides are considered as promising candidates for potassium ion batteries (KIBs) owing to the unique interlayer passages for ion diffusion. However, the insufficient electronic conductivity, inevitable volume expansion, and sulfur loss hinder the promotion of K-ion storage performance. Herein, few-layered TiCT nanosheets were selected as the multi-functional substrate for cooperating few-layered SnS nanosheets, constructing SnS/TiCT hetero-structural nanosheets (HNs) with the thickness as thin as about 5 nm. In this configuration, the formed Ti-S bonds provide robust interaction between SnS and TiCT nanosheets, which hinders the agglomeration of SnS and the restack of TiCT, endowing the hybrid material with robust nanostructure. Thus, the shortcomings of the SnS anode are muchly relieved. In this way, the as-prepared SnS/TiCT HNs electrode delivers reversible capacities of 462.1 mAh g at 0.1 A g and 166.1 mAh g at 2.0 A g, respectively, and a capacity of 85.5 mAh g is remained even after 460 cycles at 2.0 A g. These results are superior to those of the counterpart electrode, confirming aggressive promotion of K-ion storage performance of SnS anode brought by the cooperation of TiCT, and presenting a reliable strategy to improve the electrochemical performance of sulfide anodes.
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http://dx.doi.org/10.1016/j.jcis.2021.07.146DOI Listing
August 2021

Identifying quantitative trait loci for the general combining ability of yield-relevant traits in maize.

Breed Sci 2021 Apr 17;71(2):217-228. Epub 2021 Apr 17.

Institute of Crop Science, National Key Facility of Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, Beijing 100081, China.

Maize is the most important staple crop worldwide. Many of its agronomic traits present with a high level of heterosis. Combining ability was proposed to exploit the rule of heterosis, and general combining ability (GCA) is a crucial measure of parental performance. In this study, a recombinant inbred line population was used to construct testcross populations by crossing with four testers based on North Carolina design II. Six yield-relevant traits were investigated as phenotypic data. GCA effects were estimated for three scenarios based on the heterotic group and the number of tester lines. These estimates were then used to identify quantitative trait loci (QTL) and dissect genetic basis of GCA. A higher heritability of GCA was obtained for each trait. Thus, testing in early generation of breeding may effectively select candidate lines with relatively superior GCA performance. The GCA QTL detected in each scenario was slightly different according to the linkage mapping. Most of the GCA-relevant loci were simultaneously detected in all three datasets. Therefore, the genetic basis of GCA was nearly constant although discrepant inbred lines were appointed as testers. In addition, favorable alleles corresponding to GCA could be pyramided via marker-assisted selection and made available for maize hybrid breeding.
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http://dx.doi.org/10.1270/jsbbs.20008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8329886PMC
April 2021

Emerging strategies in developing multifunctional nanomaterials for cancer nanotheranostics.

Adv Drug Deliv Rev 2021 Aug 8:113907. Epub 2021 Aug 8.

Department of Chemistry, National University of Singapore, Singapore 117543, Singapore; NUS Graduate School (ISEP), National University of Singapore, Singapore 119077, Singapore. Electronic address:

Cancer involves a collection of diseases with a common trait - dysregulation in cell proliferation. At present, traditional therapeutic strategies against cancer have limitations in tackling various tumors in clinical settings. These include chemotherapeutic resistance and the inability to overcome intrinsic physiological barriers to drug delivery. Nanomaterials have presented promising strategies for tumor treatment in recent years. Nanotheranostics combine therapeutic and bioimaging functionalities at the single nanoparticle level and have experienced tremendous growth over the past few years. This review highlights recent developments of advanced nanomaterials and nanotheranostics in three main directions: stimulus-responsive nanomaterials, nanocarriers targeting the tumor microenvironment, and emerging nanomaterials that integrate with phototherapies and immunotherapies. We also discuss the cytotoxicity and outlook of next-generation nanomaterials towards clinical implementation.
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http://dx.doi.org/10.1016/j.addr.2021.113907DOI Listing
August 2021

An Approach to Developing Cyanines with Simultaneous Intersystem Crossing Enhancement and Excited-State Lifetime Elongation for Photodynamic Antitumor Metastasis.

J Am Chem Soc 2021 Aug 29;143(31):12345-12354. Epub 2021 Jul 29.

State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.

Heavy-atom-based photosensitizers usually exhibit shortened triplet-state lifetimes, which is not ideal for hypoxic tumor photodynamic therapy. Although several heavy-atom-free photosensitizers possess long triplet-state lifetimes, the clinical applicability is limited by their short excitation wavelengths, poor photon capture abilities, and intrinsically hydrophobic structures. Herein we developed a novel NIR heavy-atom-free photosensitizer design strategy by introducing sterically bulky and electron-rich moieties at the position of the pentamethine cyanine (Cy5) skeleton, which simultaneously enhanced intersystem crossing (ISC) and prolonged excited-state lifetime. We found that the O generation ability is directly correlated to the electron-donating ability of the substituent in cyanine, and the excited-state lifetime was simultaneously much elongated when the substituents were anthracene derivatives substituted at the -position. Our star compound, ANOMe-Cy5, exhibits intense NIR absorption, the highest O quantum yield (4.48-fold higher than Cy5), the longest triplet-state lifetime (9.80-fold longer than Cy5), and lossless emission intensity (nearly no change compared with Cy5). Such excellent photophysical properties coupled with its inherently cationic and hydrophilic nature enable the photosensitizer to realize photoablation of solid tumor and antitumor lung metastasis. This study highlights the design of a new generation of NIR photosensitizers for imaging-guided photodynamic cancer treatment.
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http://dx.doi.org/10.1021/jacs.1c06275DOI Listing
August 2021

Solution Epitaxy of Halide Perovskite Thin Single Crystals for Stable Transistors.

ACS Appl Mater Interfaces 2021 Aug 27;13(31):37840-37848. Epub 2021 Jul 27.

School of Physics, Australian Centre for Microscopy and Microanalysis, Sydney Nano Institute, The University of Sydney, Sydney, New South Wales 2006, Australia.

Halide perovskites hold promise for energy and optoelectronic applications due to their fascinating photophysical properties and facile processing. Among various forms, epitaxial thin single crystals (TSCs) are highly desirable due to their high crystallinity, reduced defects, and easy epitaxial integration with other materials. However, a cost-effective method for obtaining TSCs with perfect epitaxial features remains elusive. Here, we demonstrate a direct epitaxial growth of high-quality all-inorganic perovskite CsPbBr TSCs on various substrates through a facile solution process under near-ambient conditions. Structural characterizations reveal a high-quality epitaxy between the obtained perovskite TSCs and substrates, thus leading to efficiently reduced defects. The resultant TSCs display a low trap density (∼10 cm) and a long carrier lifetime (∼10.16 ns). Top-gate/top-contact transistors based on these TSCs exhibit high on/off ratios of over 10, an optimal hole mobility of 3.9 cm V s, almost hysteresis-free operation, and high stability at room temperature. Such a facile approach for the high-yield production of perovskite epitaxial TSCs will enable a broad range of high-performance electronic applications.
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http://dx.doi.org/10.1021/acsami.1c08800DOI Listing
August 2021

Spin-Orbit Torque-Induced Domain Nucleation for Neuromorphic Computing.

Adv Mater 2021 Sep 24;33(36):e2103672. Epub 2021 Jul 24.

Department of Materials Science & Engineering, National University of Singapore, Singapore, 117575, Singapore.

Neuromorphic computing has become an increasingly popular approach for artificial intelligence because it can perform cognitive tasks more efficiently than conventional computers. However, it remains challenging to develop dedicated hardware for artificial neural networks. Here, a simple bilayer spintronic device for hardware implementation of neuromorphic computing is demonstrated. In L1 -CuPt/CoPt bilayer, current-inducted field-free magnetization switching by symmetry-dependent spin-orbit torques shows a unique domain nucleation-dominated magnetization reversal, which is not accessible in conventional bilayers. Gradual domain nucleation creates multiple intermediate magnetization states which form the basis of a sigmoidal neuron. Using the L1 -CuPt/CoPt bilayer as a sigmoidal neuron, the training of a deep learning network to recognize written digits, with a high recognition rate (87.5%) comparable to simulation (87.8%) is further demonstrated. This work offers a new scheme of implementing artificial neural networks by magnetic domain nucleation.
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http://dx.doi.org/10.1002/adma.202103672DOI Listing
September 2021

Enantiospecific Detection of D-Amino Acid through Synergistic Upconversion Energy Transfer.

Angew Chem Int Ed Engl 2021 09 29;60(36):19648-19652. Epub 2021 Jul 29.

SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, 518060, China.

D-amino acids (DAAs) are indispensable in regulating diverse metabolic pathways. Selective and sensitive detection of DAAs is crucial for understanding the complexity of metabolic processes and managing associated diseases. However, current DAA detection strategies mainly rely on bulky instrumentation or electrochemical probes, limiting their cellular and animal applications. Here we report an enzyme-coupled nanoprobe that can detect enantiospecific DAAs through synergistic energy transfer. This nanoprobe offers near-infrared upconversion capability, a wide dynamic detection range, and a detection limit of 2.2 μM, providing a versatile platform for in vivo noninvasive detection of DAAs with high enantioselectivity. These results potentially allow real-time monitoring of biomolecular handedness in living animals, as well as developing antipsychotic treatment strategies.
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http://dx.doi.org/10.1002/anie.202105297DOI Listing
September 2021

Fluorescence umpolung enables light-up sensing of N-acetyltransferases and nerve agents.

Nat Commun 2021 06 23;12(1):3869. Epub 2021 Jun 23.

Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering, Shanghai Key Laboratory of Functional Materials Chemistry, Frontiers Science Center for Materiobiology and Dynamic Chemistry, Institute of Fine Chemicals, School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai, China.

Intramolecular charge transfer (ICT) is a fundamental mechanism that enables the development of numerous fluorophores and probes for bioimaging and sensing. However, the electron-withdrawing targets (EWTs)-induced fluorescence quenching is a long-standing and unsolved issue in ICT fluorophores, and significantly limits the widespread applicability. Here we report a simple and generalizable structural-modification for completely overturning the intramolecular rotation driving energy, and thus fully reversing the ICT fluorophores' quenching mode into light-up mode. Specifically, the insertion of an indazole unit into ICT scaffold can fully amplify the intramolecular rotation in donor-indazole-π-acceptor fluorophores (fluorescence OFF), whereas efficiently suppressing the rotation in their EWT-substituted system (fluorescence ON). This molecular strategy is generalizable, yielding a palette of chromophores with fluorescence umpolung that spans visible and near-infrared range. This strategy expands the bio-analytical toolboxes and allows exploiting ICT fluorophores for light-up sensing of EWTs including N-acetyltransferases and nerve agents.
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http://dx.doi.org/10.1038/s41467-021-24187-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8222306PMC
June 2021

Multimodal Tuning of Synaptic Plasticity Using Persistent Luminescent Memitters.

Adv Mater 2021 Jun 19:e2101895. Epub 2021 Jun 19.

Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore.

Mimicking memory processes, including encoding, storing, and retrieving information, is critical for neuromorphic computing and artificial intelligence. Synaptic behavior simulations through electronic, magnetic, or photonic devices based on metal oxides, 2D materials, molecular complex and phase change materials, represent important strategies for performing computational tasks with enhanced power efficiency. Here, a special class of memristive materials based on persistent luminescent memitters (termed as a portmanteau of "memory" and "emitter") with optical characteristics closely resembling those of biological synapses is reported. The memory process and synaptic plasticity can be successfully emulated using such memitters under precisely controlled excitation frequency, wavelength, pulse number, and power density. The experimental and theoretical data suggest that electron-coupled trap nucleation and propagation through clustering in persistent luminescent memitters can explain experience-dependent plasticity. The use of persistent luminescent memitters for multichannel image memorization that allows direct visualization of subtle changes in luminescence intensity and realization of short-term and long-term memory is also demonstrated. These findings may promote the discovery of new functional materials as artificial synapses and enhance the understanding of memory mechanisms.
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http://dx.doi.org/10.1002/adma.202101895DOI Listing
June 2021

Photon upconversion through triplet exciton-mediated energy relay.

Nat Commun 2021 06 17;12(1):3704. Epub 2021 Jun 17.

Department of Chemistry, National University of Singapore, Singapore, Singapore.

Exploration of upconversion luminescence from lanthanide emitters through energy migration has profound implications for fundamental research and technology development. However, energy migration-mediated upconversion requires stringent experimental conditions, such as high power excitation and special migratory ions in the host lattice, imposing selection constraints on lanthanide emitters. Here we demonstrate photon upconversion of diverse lanthanide emitters by harnessing triplet exciton-mediated energy relay. Compared with gadolinium-based systems, this energy relay is less dependent on excitation power and enhances the emission intensity of Tb by 158-fold. Mechanistic investigations reveal that emission enhancement is attributable to strong coupling between lanthanides and surface molecules, which enables fast triplet generation (<100 ps) and subsequent near-unity triplet transfer efficiency from surface ligands to lanthanides. Moreover, the energy relay approach supports long-distance energy transfer and allows upconversion modulation in microstructures. These findings enhance fundamental understanding of energy transfer at molecule-nanoparticle interfaces and open exciting avenues for developing hybrid, high-performance optical materials.
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http://dx.doi.org/10.1038/s41467-021-23967-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8211736PMC
June 2021

Ladder-like energy-relaying exciplex enables 100% internal quantum efficiency of white TADF-based diodes in a single emissive layer.

Nat Commun 2021 Jun 15;12(1):3640. Epub 2021 Jun 15.

Key Laboratory of Flexible Electronics & Institute of Advanced Materials, Nanjing Tech University, Nanjing, China.

Development of white organic light-emitting diodes based on purely thermally activated delayed fluorescence with a single-emissive-layer configuration has been a formidable challenge. Here, we report the rational design of a donor-acceptor energy-relaying exciplex and its utility in fabricating single-emissive-layer, thermally activated delayed fluorescence-based white organic light-emitting diodes that exhibit 100% internal quantum efficiency, 108.2 lm W power efficiency, and 32.7% external quantum efficiency. This strategy enables thin-film fabrication of an 8 cm × 8 cm thermally activated delayed fluorescence white organic light-emitting diodes (10 inch) prototype with 82.7 lm W power efficiency and 25.0% external quantum efficiency. Introduction of a phosphine oxide-based acceptor with a steric group to the exciplex limits donor-acceptor triplet coupling, providing dual levels of high-lying and low-lying triplet energy. Transient spectroscopic characterizations confirm that a ladder-like energy relaying occurs from the high-lying triplet level of the exciplex to a blue emitter, then to the low-lying triplet level of the phosphine oxide acceptor, and ultimately to the yellow emitter. Our results demonstrate the broad applicability of energy relaying in multicomponent systems for exciton harvesting, providing opportunities for the development of third-generation white organic light-emitting diode light sources.
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http://dx.doi.org/10.1038/s41467-021-23941-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8206214PMC
June 2021
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