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Showing papers by "Xiaogang Liu published in 2017"


Journal ArticleDOI
TL;DR: Recent progress in developing methods for preparing lanthanide-activated phosphors, especially those featuring 4f-5d optical transitions, are reviewed, with particular attention given to two widely studied dopants, Ce3+ and Eu2+.
Abstract: The synthesis of lanthanide-activated phosphors is pertinent to many emerging applications, ranging from high-resolution luminescence imaging to next-generation volumetric full-color display. In particular, the optical processes governed by the 4f-5d transitions of divalent and trivalent lanthanides have been the key to enabling precisely tuned color emission. The fundamental importance of lanthanide-activated phosphors for the physical and biomedical sciences has led to rapid development of novel synthetic methodologies and relevant tools that allow for probing the dynamics of energy transfer processes. Here, we review recent progress in developing methods for preparing lanthanide-activated phosphors, especially those featuring 4f-5d optical transitions. Particular attention will be devoted to two widely studied dopants, Ce3+ and Eu2+. The nature of the 4f-5d transition is examined by combining phenomenological theories with quantum mechanical calculations. An emphasis is placed on the correlation of hos...

644 citations


Journal ArticleDOI
TL;DR: S semiconducting polymer nanoparticles <40 nm in diameter are presented that store photon energy via chemical defects and emit long-NIR afterglow luminescence at 780 nm with a half-life of ∼6 min with high-contrast lymph node and tumor imaging in living mice.
Abstract: Afterglow optical agents, which emit light long after cessation of excitation, hold promise for ultrasensitive in vivo imaging because they eliminate tissue autofluorescence. However, afterglow imaging has been limited by its reliance on inorganic nanoparticles with relatively low brightness and short-near-infrared (NIR) emission. Here we present semiconducting polymer nanoparticles (SPNs) <40 nm in diameter that store photon energy via chemical defects and emit long-NIR afterglow luminescence at 780 nm with a half-life of ∼6 min. In vivo, the afterglow intensity of SPNs is more than 100-fold brighter than that of inorganic afterglow agents, and the signal is detectable through the body of a live mouse. High-contrast lymph node and tumor imaging in living mice is demonstrated with a signal-to-background ratio up to 127-times higher than that obtained by NIR fluorescence imaging. Moreover, we developed an afterglow probe, activated only in the presence of biothiols, for early detection of drug-induced hepatotoxicity in living mice.

583 citations


Journal ArticleDOI
TL;DR: An efficient solid-state photoswitch based on a spiropyran-functionalized distyrylanthracene derivative that exhibits exceptional reversible absorption/luminescence modulation ability and is highly applicable as both anticounterfeiting inks and super-resolution imaging agents is constructed.
Abstract: Solid-state organic photoswitches with reversible luminescence modulation property are highly attractive because of their wide prospects in advanced photonic applications, such as optical data storage, anticounterfeiting and bioimaging. Yet, developing such materials has long been a significant challenge. In this work, we construct an efficient solid-state photoswitch based on a spiropyran-functionalized distyrylanthracene derivative (DSA-2SP) that exhibits exceptional reversible absorption/luminescence modulation ability. Efficient photoswitching between DSA-2SP and its photoisomer DSA-2MC are facilitated by large free volumes induced by nonplanar molecular structures of DSA moieties, as well as the intramolecular hydrogen bonds between the DSA and MC moieties. Consequently, the excellent solid-state photochromic property of DSA-2SP is highly applicable as both anticounterfeiting inks and super-resolution imaging agents.

284 citations


Journal ArticleDOI
TL;DR: The authors engineer nanoparticles that produce binary color codes on different timescales by combining the long-lived luminescence of Mn2+ with the relatively short-lived emission of lanthanides.
Abstract: Optical characteristics of luminescent materials, such as emission profile and lifetime, play an important role in their applications in optical data storage, document security, diagnostics, and therapeutics. Lanthanide-doped upconversion nanoparticles are particularly suitable for such applications due to their inherent optical properties, including large anti-Stokes shift, distinguishable spectroscopic fingerprint, and long luminescence lifetime. However, conventional upconversion nanoparticles have a limited capacity for information storage or complexity to prevent counterfeiting. Here, we demonstrate that integration of long-lived Mn2+ upconversion emission and relatively short-lived lanthanide upconversion emission in a particulate platform allows the generation of binary temporal codes for efficient data encoding. Precise control of the particle’s structure allows the excitation feasible both under 980 and 808 nm irradiation. We find that the as-prepared Mn2+-doped nanoparticles are especially useful for multilevel anti-counterfeiting with high-throughput rate of authentication and without the need for complex time-gated decoding instrumentation. Luminescent materials that are capable of binary temporal coding are desirable for multilevel anti-counterfeiting. Here, the authors engineer nanoparticles that produce binary color codes on different timescales by combining the long-lived luminescence of Mn2+ with the relatively short-lived emission of lanthanides.

267 citations


Journal ArticleDOI
TL;DR: A new class of lanthanide-doped upconversion nanoparticles are presented that are without Yb3+ or Nd3+ sensitizers in the host lattice, offering a convenient method for red-emitting upconversions nanoprobes for biological applications.
Abstract: We present a new class of lanthanide-doped upconversion nanoparticles without Yb3+ or Nd3+ sensitizers in the host lattice. We find that in erbium-enriched core-shell NaErF4:Tm (0.5mol%)@NaYF4 nanoparticles a high degree of energy migration between Er3+ ions occurs to suppress the effect of concentration quenching upon surface coating. Unlike the conventional Yb3+-Er3+ system, Er3+ ion can serve as both the sensitizer and activator to enable an effective upconversion process. Importantly, an appropriate doping of Tm3+ has been demonstrated to further enhance upconversion luminescence through energy trapping. This endows the resultant nanoparticles with bright red (about 700-fold enhancement) and near-infrared luminescence that is achievable under multiple excitation wavelengths. Our results provide a fundamental new pathway to mitigate the concentration quenching effect and offer red-emitting upconversion nanoprobes attractive for biological applications.

250 citations


Journal ArticleDOI
TL;DR: A simple, versatile nanoparticulate system for simultaneous deep‐tissue imaging and drug molecule release in vivo is demonstrated.
Abstract: Although multifunctional upconversion imaging probes have recently attracted considerable interest in biomedical research, there are currently few methods for stabilizing these luminescent nanoprobes with oligonucleotides in biological systems. Herein, a method to robustly disperse upconversion nanoprobes in physiological buffers based on rational design and synthesis of nanoconjugates comprising hairpin-DNA-modified gold nanoparticles is presented. This approach imparts the upconversion nanoprobes with excellent biocompatibility and circumvents the problem of particle agglomeration. By combining single-band anti-Stokes near-infrared emission and the photothermal effect mediated by the coupling of gold to upconversion nanoparticles, a simple, versatile nanoparticulate system for simultaneous deep-tissue imaging and drug molecule release in vivo is demonstrated.

186 citations


Journal ArticleDOI
TL;DR: This tutorial review will summarize the concept and mechanisms of MICE for developing single-molecular fluorescent probes, present unique advantages of Mice based sensors, demonstrate their various applications, and discuss technical challenges in this field.
Abstract: The need for detecting and labelling environmentally and biologically important analytes has driven considerable research efforts in developing fluorescent probes. During the sensing process, molecular motions (i.e., molecular rotations or vibrations) of a flexible fluorescent probe can be significantly altered by its embedding micro-environment or analyte, thereby leading to substantial changes in readout signals. Motion-induced change in emission (MICE) can be utilized as an effective sensing mechanism. However, in comparison to the well-understood sensing mechanisms, such as photo-induced electron transfer (PET), intramolecular charge transfer (ICT), aggregation-induced emission (AIE) and disaggregation-induced emission (DIE), MICE has not been systematically discussed to date. In this tutorial review, we will summarize the concept and mechanisms of MICE for developing single-molecular fluorescent probes, present unique advantages of MICE based sensors, demonstrate their various applications, and discuss technical challenges in this field. We expect that this review will promote a deeper understanding of MICE and facilitate the development of novel MICE based probes.

160 citations


Journal ArticleDOI
TL;DR: Taking advantages of the high tissue-penetration capability of near-infrared excitation/emission, these nanoprobes achieve real-time monitoring of hepatot toxicity in living animals, thereby providing a convenient screening strategy for assessing hepatotoxicity of synthetic drugs.
Abstract: Drug toxicity is a long-standing concern of modern medicine. A typical anti-pain/fever drug paracetamol often causes hepatotoxicity due to peroxynitrite ONOO- . Conventional blood tests fail to offer real-time unambiguous visualization of such hepatotoxicity in vivo. Here we report a luminescent approach to evaluate acute hepatotoxicity in vivo by chromophore-conjugated upconversion nanoparticles. Upon injection, these nanoprobes mainly accumulate in the liver and the luminescence of nanoparticles remains suppressed owing to energy transfer to the chromophore. ONOO- can readily bleach the chromophore and thus recover the luminescence, the presence of ONOO- in the liver leads to fast restoring of the near-infrared emission. Taking advantages of the high tissue-penetration capability of near-infrared excitation/emission, these nanoprobes achieve real-time monitoring of hepatotoxicity in living animals, thereby providing a convenient screening strategy for assessing hepatotoxicity of synthetic drugs.

159 citations


Journal ArticleDOI
01 May 2017-Small
TL;DR: A facile and cost-efficient strategy is developed to scalably fabricate binary metal oxides with complex hollow interior structures and tunable compositions for progressive lithium-ion batteries.
Abstract: Metal–organic frameworks (MOFs) featuring versatile topological architectures are considered to be efficient self-sacrificial templates to achieve mesoporous nanostructured materials. A facile and cost-efficient strategy is developed to scalably fabricate binary metal oxides with complex hollow interior structures and tunable compositions. Bimetal–organic frameworks of Ni-Co-BTC solid microspheres with diverse Ni/Co ratios are readily prepared by solvothermal method to induce the Ni x Co3− x O4 multishelled hollow microspheres through a morphology-inherited annealing treatment. The obtained mixed metal oxides are demonstrated to be composed of nanometer-sized subunits in the shells and large void spaces left between adjacent shells. When evaluated as anode materials for lithium-ion batteries, Ni x Co3− x O4-0.1 multishelled hollow microspheres deliver a high reversible capacity of 1109.8 mAh g−1 after 100 cycles at a current density of 100 mA g−1 with an excellent high-rate capability. Appropriate capacities of 832 and 673 mAh g−1 could also be retained after 300 cycles at large currents of 1 and 2 A g−1, respectively. These prominent electrochemical properties raise a concept of synthesizing MOFs-derived mixed metal oxides with multishelled hollow structures for progressive lithium-ion batteries.

116 citations


Journal ArticleDOI
TL;DR: This work is able to significantly enhance the hole and electron mobilities of the perovskite film to record-high values and can be harnessed to construct ambipolar phototransistors with an ultrahigh detectivity and a responsivity on a par with the best devices available to date.
Abstract: Organolead trihalide perovskites have drawn substantial interest for photovoltaic and optoelectronic applications due to their remarkable physical properties and low processing cost. However, perovskite thin films suffer from low carrier mobility as a result of their structural imperfections such as grain boundaries and pinholes, limiting their device performance and application potential. Here we demonstrate a simple and straightforward synthetic strategy based on coupling perovskite films with embedded single-walled carbon nanotubes. We are able to significantly enhance the hole and electron mobilities of the perovskite film to record-high values of 595.3 and 108.7 cm2 V-1 s-1 , respectively. Such a synergistic effect can be harnessed to construct ambipolar phototransistors with an ultrahigh detectivity of 3.7 × 1014 Jones and a responsivity of 1 × 104 A W-1 , on a par with the best devices available to date. The perovskite/carbon nanotube hybrids should provide a platform that is highly desirable for fields as diverse as optoelectronics, solar energy conversion, and molecular sensing.

106 citations


Journal ArticleDOI
TL;DR: It is found that the usage of Pd@Ag@CeO2 bi-metallic core@shell nanostructure as the hard template plays an important role in avoiding the independent nucleation of Pt metal during the galvanic replacement process between K2 PtCl4 and Ag components.
Abstract: Ultrathin (Pt-enriched cage)@CeO2 core@shell nanostructures are successfully fabricated via a facile hard-template method. It is found that the usage of Pd@Ag@CeO2 bi-metallic core@shell nanostructure as the hard template plays an important role in avoiding the independent nucleation of Pt metal during the galvanic replacement process between K2 PtCl4 and Ag components. This unique core@shell samples show extraordinary activity and selectivity for the cinnamaldehyde hydrogenation reaction. It can achieve over 95% conversion with 87% selectivity of hydrocinnamaldehyde in 5 h under 1 atm H2 pressure. It is considered that such high catalytic performance could be attributed to the densely CeO2 -coated core@shell hybrid form as well as the ultrathin nature of the Pt-enriched cage.

Journal ArticleDOI
TL;DR: These fluorophores will serve as a useful platform for developing novel imaging and sensing agents, and the design methodologies will inspire the molecular engineering of abundant high-performance near-infrared fluorideophores.
Abstract: Fluorophores with near-infrared emissions play a crucial role in numerous bioimaging and biosensing applications, owing to their deep penetration depths, low auto-fluorescence, and minimal tissue damages. Herein, the rational development of a new class of near-infrared fluorophores with bright one-photon and two-photon emissions at ≈740 nm, large Stokes shifts (≈80 nm), significant two-photon action absorption cross-section (≈185 GM at 820 nm), excellent water solubility, outstanding photostability, and low toxicity is reported. Their biological applications in mitochondrial labelling, deep tissue imaging, and H2 S detection in live cells and mice are also demonstrated. In addition, a rational design strategy for enlarging the Stokes shifts and enhancing two-photon emissions of these fluorophores is presented. These fluorophores will serve as a useful platform for developing novel imaging and sensing agents, and the design methodologies will inspire the molecular engineering of abundant high-performance near-infrared fluorophores.

Journal ArticleDOI
TL;DR: The ability of glial cells such as OPCs to positively respond to moderate intensity SMF stimulation by exhibiting enhanced differentiation, functionality as well as neurotrophic factor release is emphasized.
Abstract: The cellular-level effects of low/high frequency oscillating magnetic field on excitable cells such as neurons are well established. In contrast, the effects of a homogeneous, static magnetic field (SMF) on Central Nervous System (CNS) glial cells are less investigated. Here, we have developed an in vitro SMF stimulation set-up to investigate the genomic effects of SMF exposure on oligodendrocyte differentiation and neurotrophic factors secretion. Human oligodendrocytes precursor cells (OPCs) were stimulated with moderate intensity SMF (0.3 T) for a period of two weeks (two hours/day). The differential gene expression of cell activity marker (c-fos), early OPC (Olig1, Olig2. Sox10), and mature oligodendrocyte markers (CNP, MBP) were quantified. The enhanced myelination capacity of the SMF stimulated oligodendrocytes was validated in a dorsal root ganglion microfluidics chamber platform. Additionally, the effects of SMF on the gene expression and secretion of neurotrophic factors- BDNF and NT3 was quantified. We also report that SMF stimulation increases the intracellular calcium influx in OPCs as well as the gene expression of L-type channel subunits-CaV1.2 and CaV1.3. Our findings emphasize the ability of glial cells such as OPCs to positively respond to moderate intensity SMF stimulation by exhibiting enhanced differentiation, functionality as well as neurotrophic factor release.

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate that substantial intramolecular charge transfer (ICT) is responsible for the fluorescent properties of 6-aminocoumarins and reanalyzes the sensing mechanism of a 6-amino-couarmin-based fluorescent probe.
Abstract: Coumarins are deployed in numerous bioimaging and biosensing applications Among various coumarin derivatives, 6-aminocoumarins attract increasing attention for their red-shifted emissions, mega Stokes shifts, and significant solvatochromism These spectral characteristics together with weak emission intensities have historically been ascribed to the formation of the twisted intramolecular charge transfer (TICT) state in 6-aminocoumarins In this work, we demonstrate that it is actually substantial intramolecular charge transfer (ICT) that is responsible for these fluorescent properties Based on this new understanding, we reanalyzed the sensing mechanism of a 6-aminocouarmin based fluorescent probe and obtained close agreement with experimental data Our results lead to a deeper understanding of the photophysics of 6-aminocoumarins and will inspire the rational development of novel fluorescent probes

Journal ArticleDOI
TL;DR: The scalable synthesis of upconversion materials with distinct hedgehog-like morphologies by a seed-mediated synthetic procedure is reported, demonstrating that a close match in the crystal lattice between the core and shell components is essential for synthesizing such hierarchical nanostructures.
Abstract: Topological control of nanostructures plays a crucial role in understanding the crystal growth process at the nanometer length scale. Here, the scalable synthesis of upconversion materials with distinct hedgehog-like morphologies by a seed-mediated synthetic procedure is reported. It is demonstrated that a close match in the crystal lattice between the core and shell components is essential for synthesizing such hierarchical nanostructures. These optical nanomaterials also enable the development of a single-particle-based platform for high-sensitivity molecular sensing.

Journal ArticleDOI
TL;DR: The result suggests that human spinal cord reactive astrocytes is potentially neuroprotective at an early onset of reactive astrogliosis, and may be the main CSPG contributory factor in glial scar.
Abstract: Reactive astrogliosis is a critical process in neuropathological conditions and neurotrauma. Although it has been suggested that it confers neuroprotective effects, the exact genomic mechanism has not been explored. The prevailing dogma of the role of astrogliosis in inhibition of axonal regeneration has been challenged by recent findings in rodent model’s spinal cord injury, demonstrating its neuroprotection and axonal regeneration properties. We examined whether their neuroprotective and axonal regeneration potentials can be identify in human spinal cord reactive astrocytes in vitro. Here, reactive astrogliosis was induced with IL1β. Within 24 hours of IL1β induction, astrocytes acquired reactive characteristics. Transcriptome analysis of over 40000 transcripts of genes and analysis with PFSnet subnetwork revealed upregulation of chemokines and axonal permissive factors including FGF2, BDNF, and NGF. In addition, most genes regulating axonal inhibitory molecules, including ROBO1 and ROBO2 were downregulated. There was no increase in the gene expression of “Chondroitin Sulfate Proteoglycans” (CSPGs’) clusters. This suggests that reactive astrocytes may not be the main CSPG contributory factor in glial scar. PFSnet analysis also indicated an upregulation of “Axonal Guidance Signaling” pathway. Our result suggests that human spinal cord reactive astrocytes is potentially neuroprotective at an early onset of reactive astrogliosis.

Journal ArticleDOI
TL;DR: In this paper, the authors report 9 metal organic frameworks constructed with various combinations of the following ligands: trans,trans-9,10-bis(4-pyridylethenyl) anthracene.
Abstract: The development of alternative nonlinear optical metamaterials has attracted much attention recently due to technological demands. Upconversion emission via a simultaneous two-photon absorption process is a nonlinear process that is widely studied in synthetically challenging organic compounds. Hereby, we report 9 metal organic frameworks constructed with various combinations of the following ligands: trans,trans-9,10-bis(4-pyridylethenyl) anthracene, trans,trans-9,10-bis(4-pyridylethynyl) anthracene, 1,4-bis[2-(4′-pyridyl)ethenyl]benzene, 4,4′-stilbene dicarboxylate, 4,4′-biphenyl dicarboxylate, 4,4′-benzene dicarboxylate, and benzene-1,3,5-tricarboxylate. Altering the auxiliary carboxylate ligands not only changes the structure but also varies the two-photon excited fluorescence. The two-photon excited emission is enhanced when longer spacer ligands are used and when they are packed in more expanded structures in hms topology. Unusually, the emission becomes stronger when a pair of pyridyl type ligands ...

Journal ArticleDOI
TL;DR: In this paper, the negative differential resistance (NDR) and hysteresis phenomena in graphene-based OLEDs and their effects on device performance were reported. But, the performance of the OLED was not analyzed.
Abstract: Here, we report the experimental observation of negative differential resistance (NDR) and hysteresis phenomena in graphene-based OLEDs and their effects on device performance. Our results reveal that the NDR and hysteresis mainly originate from the poly(methyl methacrylate) residue resting on graphene. We further demonstrate that current annealing is a facile and effective technique to remove the polymeric residue and eliminate the NDR, leading to the dramatically enhanced luminous efficiency from 30.9 to 41.6 cd A−1, and to 89.2 cd A−1 when equipped with a high index half-ball lens. The demonstrated pretreatment process of graphene establishes a new path for the construction of a wide variety of high performance optoelectronic devices.

Journal ArticleDOI
TL;DR: Two "dual-fluorophore" dyes are reported: DNS-linked tetraphenylethene demonstrates bright aggregation-induced emission, while NBD-linked Tetraphenylthene exhibits aggregation-caused quenching.
Abstract: A fluorophore consisting of two fluorescent moieties could display unusual optical behaviors that are unattainable in a single-fluorophore compound. Herein we reported two "dual-fluorophore" dyes: DNS-linked tetraphenylethene demonstrates bright aggregation-induced emission, while NBD-linked tetraphenylethene exhibits aggregation-caused quenching. Our results have important implications for engineering emission behaviors of molecular aggregates for practical applications.

Journal ArticleDOI
TL;DR: In this article, a solution-derived lead-free piezoelectric thin film with a morphotropic phase boundary (MPB) composition of (1 − x)(K, Na), Sb, Nb)O3-x(Bi, Na, K)ZrO3 (KNSN-BNKZx, 0.01 ≤ x ≤ 0.07).
Abstract: Although high performance piezoelectric properties have been reported in (K, Na)NbO3-based bulk ceramics by constructing morphotropic phase boundary (MPB) with complex compositions, it is still challenging to achieve excellent piezoelectric properties in thin films with the same MPB compositions due to the serious volatile loss of the alkali constituents. Moreover, the stress due to substrate constraint also changes the film's crystal structure and shifts the film's MPB. Here this study demonstrates the highest ever reported effective piezoelectric strain coefficient d33 of 184.0 pm V−1 and voltage coefficient g33 of 39.4 mm V N−1 from macroscale characterization in a solution-derived lead-free piezoelectric thin film with a composition of (1 – x)(K, Na)(Sb, Nb)O3-x(Bi, Na, K)ZrO3 (KNSN-BNKZx, 0.01 ≤ x ≤ 0.07). With the effective suppression of volatile compositional loss by selecting appropriate combinational chemical agents in the precursor solution, phase transitions from orthorhombic, rhombohedral to tetragonal are observed experimentally and further analyzed theoretically with first principle simulation of the KNSN-BNKZx films, and the obtained coexistence of rhombohedral–tetragonal phase at x = 0.05 contributes to the outstanding piezoelectric performance in the tensile stressed films. The results demonstrate a valuable strategy for realizing high-performance piezoelectric properties in thin films with volatile and complex MPB compositions under stress condition.


Journal ArticleDOI
TL;DR: A series of trapezoidal metallacycles were synthesized by the selective combination of a rigid with a flexible arm to obtainCatenane 3 was obtained by self-assembly when the cavity size of the trapezoid rings was optimised.

Journal ArticleDOI
TL;DR: In this article, the authors proposed and demonstrated a new strategy, to achieve ratiometric temperature measurements from 15 °C to 75 °C, based on ground-state conformational isomers of a single type of dye.
Abstract: Fluorescence thermometry based on organic dyes affords high spatial and temporal resolution with a simple system design and low cost, for measuring temperatures in microenvironments. Many fluorescent thermometers consist of two types of fluorophores with distinct temperature responses, and the ratios of their fluorescence intensities afford accurate temperature information. Yet, the reliability of these ratiometric thermometers is vulnerable to photobleaching induced system variations. In this paper, we have proposed and demonstrated a new strategy, to achieve ratiometric temperature measurements from 15 °C to 75 °C, based on ground-state conformational isomers of a single type of dye. These ground-state conformers emit bright fluorescence, in contrast to excited-state conformational changes that generally quench emissions. Moreover, thermal equilibrium of these conformers and their distinct spectra lead to ratiometric temperature readings that are not affected by photobleaching. We expect that our design strategy has significant implications for developing fluorescence thermometry with outstanding reliability.

Journal ArticleDOI
TL;DR: Early local moderate hypothermia can be induced for extended periods of time post SCI in the rodent model and improves functional electrophysiological outcome and motor behavior recovery for a long time, lasting until 8 weeks.

Journal ArticleDOI
TL;DR: The authors showed that static pressure enables the differentiation of rat bone marrow-derived mesenchymal stem cells (MSCs) into neural-like cells within several hours in the absence of disruptive biofactors or chemicals.
Abstract: Growing experimental evidence suggests that physical cues play an important role in regulating the fate of stem cells and stimulating their differentiation behavior. We report here that static pressure enables the differentiation of rat bone marrow-derived mesenchymal stem cells (MSCs) into neural-like cells within several hours in the absence of disruptive bio-factors or chemicals. The realization of such differentiation is supported by the observation of characteristic morphology of neural-like cells with neurites, and an up-regulated expression level of neural-specific markers. Our finding also demonstrates the utility of the static pressure-based approach for in situ and specifically localized creation of neural cell systems, thereby providing profound implications for developing therapeutic application of stem cells.

Journal ArticleDOI
09 Mar 2017-Chem
TL;DR: In this article, Liu et al. devised lanthanide-doped upconversion nanoparticles as luminescent probes for STED nanoscopy with an ultralow-power laser depletion beam.

Book ChapterDOI
01 Jan 2017
TL;DR: This chapter will briefly introduce industrial applications of persistent luminescence in safety signs, luminous fiber, artwork, as well as the rising use as bioprobe in bioimaging and molecular sensing.
Abstract: Persistent luminescence phosphors can be dispersed in various medium and have been widely used in commercial products, including luminous paints, watch dials, fire safety signs and glow-in-the-dark toys. Additionally, the use of persistent luminescence nanomaterials as highly sensitive luminescent probes for real-time bioimaging attracts a growing attention since 2007. In this chapter, we will briefly introduce industrial applications of persistent luminescence in safety signs, luminous fiber, artwork, as well as the rising use as bioprobe in bioimaging and molecular sensing.

Proceedings ArticleDOI
25 Aug 2017
TL;DR: In this paper, a single upconverting particle (NaYF4:Er3+,Yb3+) can be used to determine the optical trap temperature due to the partial absorption of the trapping beam either by the medium (water) or the optically trapped particle itself.
Abstract: Luminescence of a single upconverting particle (NaYF4:Er3+,Yb3+) can be used to determine the optical trap temperature due to the partial absorption of the trapping beam either by the medium (water) or the optically trapped particle itself. This fact is an important drawback can be reduced by shifting the trapping wavelength out of the water absorption band, or by using time-modulated laser trapping beams. Both approaches have been studied and the results have shown that the thermal loading due to the trapping radiation can be minimized.

Proceedings ArticleDOI
25 Aug 2017
TL;DR: In this paper, two new microrheometric techniques are presented, which take advantage of the analysis of the polarized emission of an upconverting particle to determine its orientation inside the optical trap.
Abstract: Rheological parameters (viscosity, creep compliance and elasticity) play an important role in cell function and viability. For this reason different strategies have been developed for their study. In this work, two new microrheometric techniques are presented. Both methods take advantage of the analysis of the polarized emission of an upconverting particle to determine its orientation inside the optical trap. Upconverting particles are optical materials that are able to convert infrared radiation into visible light. Their usefulness has been further boosted by the recent demonstration of their three-dimensional control and tracking by single beam infrared optical traps. In this work it is demonstrated that optical torques are responsible of the stable orientation of the upconverting particle inside the trap. Moreover, numerical calculations and experimental data allowed to use the rotation dynamics of the optically trapped upconverting particle for environmental sensing. In particular, the cytoplasm viscosity could be measured by using the rotation time and thermal fluctuations of an intracellular optically trapped upconverting particle, by means of the two previously mentioned microrheometric techniques.

Book ChapterDOI
01 Jan 2017
TL;DR: In this article, the classification and synthetic methods of inorganic long afterglow phosphors were described in detail, and their optical properties and commercially available ones were introduced to clarify how to obtain inorganic phosphors with promising properties.
Abstract: Inorganic long afterglow phosphors have attracted intense attension due to their high emission intensity and long afterglow time. In this chapter, the classification and synthetic methods of in organic long afterglow phosphor were described in detail. Then, their optical properties and commercially available ones were introduced. The Factors affecting their afterglow properties were also discussed to clarify how to obtain inorganic phosphors with promising properties. The application of inorganic long afterglow phosphors usually need surface modification of them. Hence, the surface modification strategy of the phosphors were also discussed.