Multi-Color Luminescence Transition of Upconversion Nanocrystals via Crystal Phase Control with SiO2 for High Temperature Thermal Labels

Upconversion nanocrystals (UCNs)-embedded microarchitectures with luminescence color transition capability and enhanced luminescence intensity under extreme conditions are suitable for developing a robust labeling system in a high-temperature thermal industrial process. However, most UCNs based labeling systems are limited by the loss of luminescence owing to the destruction of the crystalline phase or by a predetermined luminescence color without color transition capability. Herein, an unusual crystal phase transition of UCNs to a hexagonal apatite phase in the presence of SiO2 nanoparticles is reported with the enhancements of 130-fold green luminescence and 52-fold luminance as compared to that of the SiO2-free counterpart. By rationally combining this strategy with an additive color mixing method using a mask-less flow lithography technique, single to multiple luminescence color transition, scalable labeling systems with hidden letters-, and multi-luminescence colored microparticles are demonstrated for a UCNs luminescence color change-based high temperature labeling system

Scalable Design Principle of Anti-Counterfeiting System Based on Dynamic Structural Color Change and Phase Change of Upconversion Nanocrystals

In this presentation, we introduce novel optical anti-counterfeiting systems based on the structural color and upconversion nanocrystals (UCNs) using maskless lithography. To realize the optical signal changes that respond when exposed to the external environment perturbations (e.g., humidity, temperature), we utilized the three-dimensional refractive index change and crystal phase transition of UCNs. In the case of structural color-based system, various structural colors change and holographic patterns were expressed when introduced LCST and hygroscopic material through the volumetric change of hydrogel microstructures. We also introduce a 130-fold enhancement in the luminescence intensity change of UCNs when exposed to extreme thermal conditions above 900 oC. These approaches provide the design principle of scalable anti-counterfeiting systems that overcomes the limitations of conventional anti-counterfeiting systems

Novel phase transition method of upconversion nanocrystals with enhanced luminesecnce intensity

Lanthanide-doped upconversion nanocrystal (UCN) show anti-Stokes effect that absorbs near-infrared (NIR) light and emit visible luminescence. Nowadays, UCN have been used in bio-imaging, drug delivery and photovoltaics because it offers high photo-stability, low toxicity and absence of autofluorescence. In order to become practical application, controlling luminescence color of UCN is required. However, most of modulating method of UCN luminescence color rely on synthetic process. Herein, we suggest novel method for manipulating optical and chemical properties of UCN. It induces color and crystal phase transition with dramatically enhanced luminescence intensity

Highly Stable Upconverting Nanocrystal???Polydiacetylenes Nanoplates for Orthogonal Dual Signaling-Based Detection of Cyanide

Although the unique optical signaling properties of polydiacetylene (PDA) have been exploited in diverse bio-chemosensors, the practical application of most PDA sensor systems is limited by their instability in harsh environments and fluorescence signal weakness. Herein, a universal design principle for a highly stable PDA sensor system with a practical dual signaling capability is developed to detect cyanide (CN) ions, which are commonly found in drinking water. Effective metal intercalation and enhanced hydrophobic intermolecular interactions between PDA???metal supramolecules are used to construct highly stacked PDA???metal nanoplates that feature unusual optical stability upon exposure to strong acids, bases, organic solvents, and thermal/mechanical stresses, and can selectively detect CN anions, concomitantly undergoing a specific supramolecular structure change. To realize the practical dual signaling capability of the PDA sensor system, upconverting nanocrystals (UCNs) are incorporated into highly stacked PDA???metal nanoplates, and practical dual signaling (orthogonal changes in luminescence and visible color) is demonstrated using a portable detection system. The presented universal design principle is expected to be suitable for the development of other highly stable and selective PDA sensor systems with practical dual signaling capability

Noble 3,4-Seco-triterpenoid Glycosides from the Fruits of Acanthopanax sessiliflorus and Their Anti-Neuroinflammatory Effects

Acanthopanax sessiliflorus (Araliaceae) have been reported to exhibit many pharmacological activities. Our preliminary study suggested that A. sessiliflorus fruits include many bioactive 3,4-seco-triterpenoids. A. sessiliflorus fruits were extracted in aqueous EtOH and fractionated into EtOAc, n-BuOH, and H2O fractions. Repeated column chromatographies for the organic fractions led to the isolation of 3,4-seco-triterpenoid glycosides, including new compounds. Ultra-high-performance liquid chromatography (UPLC) mass spectrometry (MS) systems were used for quantitation and quantification. BV2 and RAW264.7 cells were induced by LPS, and the levels of pro-inflammatory cytokines and mediators and their underlying mechanisms were measured by ELISA and Western blotting. NMR, IR, and HR-MS analyses revealed the chemical structures of the nine noble 3,4-seco-triterpenoid glycosides, acanthosessilioside G–O, and two known ones. The amounts of the compounds were 0.01–2.806 mg/g, respectively. Acanthosessilioside K, L, and M were the most effective in inhibiting NO, PGE2, TNF-α, IL-1β, and IL-6 production and reducing iNOS and COX-2 expression. In addition, it had inhibitory effects on the LPS-induced p38 and ERK MAPK phosphorylation in both BV2 and RAW264.7 cells. Nine noble 3,4-seco-triterpenoid glycosides were isolated from A. sessiliflorus fruits, and acanthosessilioside K, L, and M showed high anti-inflammatory and anti-neuroinflammatory effects

Room-Temperature Ring-Opening of Quinoline, Isoquinoline, and Pyridine with Low-Valent Titanium

The complex (PNP)Ti=CHtBu(CH2 tBu) (PNP = N[2-PiPr2-4-methylphenyl]2 -) dehydrogenates cyclohexane to cyclohexene by forming a transient low-valent titanium-alkyl species, [(PNP)Ti(CH2 tBu)], which reacts with 2 equiv of quinoline (Q) at room temperature to form H3CtBu and a Ti(IV) species where the less hindered C2=N1 bond of Q is ruptured and coupled to another equivalent of Q. The product isolated from this reaction is an imide with a tethered cycloamide group, (PNP)Ti=N[C18H13N] (1). Under photolytic conditions, intramolecular C - H bond activation across the imide moiety in 1 occurs to form 2, and thermolysis reverses this process. The reaction of 2 equiv of isoquinoline (Iq) with intermediate [(PNP)Ti(CH2 tBu)] results in regioselective cleavage of the C1=N2 and C1 - H bonds, which eventually couple to form complex 3, a constitutional isomer of 1. Akin to 1, the transient [(PNP)Ti(CH2 tBu)] complex can ring-open and couple two pyridine molecules, to produce a close analogue of 1, complex (PNP)Ti=N[C10H9N] (4). Multinuclear and multidimensional NMR spectra confirm structures for complexes 1-4, whereas solid-state structural analysis reveals the structures of 2, 3, and 4. DFT calculations suggest an unprecedented mechanism for ring-opening of Q where the reactive intermediate in the low-spin manifold crosses over to the high-spin surface to access a low-energy transition state but returns to the low-spin surface immediately. This double spin-crossover constitutes a rare example of a two-state reactivity, which is key for enabling the reaction at room temperature. The regioselective behavior of Iq ring-opening is found to be due to electronic effects, where the aromatic resonance of the bicycle is maintained during the key C - C coupling event. © 2017 American Chemical Society3

Miniaturized Reverse Electrodialysis-Powered Biosensor Using Electrochemiluminescence on Bipolar Electrode

We suggest an electrochemiluminescence (ECL)-sensing platform driven by ecofriendly, disposable, and miniaturized reverse electrodialysis (RED) patches as an electric power source. The flexible RED patches composed of ion-exchange membranes (IEMs) can produce voltage required for ECL sensing by simply choosing the appropriate number of IEMs and the ratio of salt concentrations. We integrate the RED patch with a bipolar electrode on the microfluidic chip to demonstrate the proof-of-concept, i.e., glucose detection in the range of 0.5–10 mM by observing ECL emissions with naked eyes. The miniaturized RED-powered biosensing system is widely applicable for electrochemical-sensing platforms. This is expected to be a solution for practical availability of battery-free electrochemical sensors for disease diagnosis in developing countries

Facile Microfluidic Fabrication of 3D hydrogel SERS Substrate with High Reusability and Reproducibility via Programmable Maskless Flow Microlithography

In the field of surface???enhanced Raman scattering (SERS), advances in nanotechnology and surface chemistry have contributed to fabricating the metal substrates with highly sophisticated architectures and strong binding affinity to target molecules which enhanced the sensitivity to target molecules. However, the elaborate yet complicated steps for the synthesis, patterning, and surface modification of metal substrates have often resulted in compromising the reliability, reproducibility, and reusability as SERS substrates. Here, a fully programmable and automated digital maskless flow microlithography process that spatiotemporally controls the fluid flow, UV irradiation, and the shape and location of SERS polymer matrix is provided to fabricate a reliable, reproducible, and reusable hydrogel???based 3D SERS substrate. The SERS substrates are located inside the microfluidic device in the form of disk???shaped hydrogels. By rationally designing the functional group chemistry of the hydrogel microposts, Ag nanoparticles are homogeneously synthesized in situ, a target molecule is amplified by 25???fold inside the microposts, and an enhancement factor as high as 2.4 ?? 108 is observed. Furthermore, a highly reusable multitarget sensing capability is demonstrated by a sequential analysis of multiple analytes without the trace of former analytes via the intermittent washing step

Room-Temperature Ring-Opening of Quinoline, Isoquinoline, and Pyridine with Low-Valent Titanium

The complex (PNP)­TiCH^<i>t</i>Bu­(CH₂^<i>t</i>Bu) (PNP = N­[2-P^<i>i</i>Pr₂-4-methyl­phenyl]₂^–) dehydrogenates cyclo­hexane to cyclo­hexene by forming a transient low-valent titanium-alkyl species, [(PNP)­Ti­(CH₂^<i>t</i>Bu)], which reacts with 2 equiv of quinoline (<b>Q</b>) at room temperature to form H₃C^<i>t</i>Bu and a Ti­(IV) species where the less hindered C₂N₁ bond of <b>Q</b> is ruptured and coupled to another equivalent of <b>Q</b>. The product isolated from this reaction is an imide with a tethered cyclo­amide group, (PNP)­TiN­[C₁₈H₁₃N] (<b>1</b>). Under photolytic conditions, intra­molecular CH bond activation across the imide moiety in <b>1</b> occurs to form <b>2</b>, and thermolysis reverses this process. The reaction of 2 equiv of isoquinoline (<b>Iq</b>) with intermediate [(PNP)­Ti­(CH₂^<i>t</i>Bu)] results in regio­selective cleavage of the C₁N₂ and C₁H bonds, which eventually couple to form complex <b>3</b>, a constitutional isomer of <b>1</b>. Akin to <b>1</b>, the transient [(PNP)­Ti­(CH₂^<i>t</i>Bu)] complex can ring-open and couple two pyridine molecules, to produce a close analogue of <b>1</b>, complex (PNP)­TiN­[C₁₀H₉N] (<b>4</b>). Multi­nuclear and multi­dimensional NMR spectra confirm structures for complexes <b>1</b>–<b>4</b>, whereas solid-state structural analysis reveals the structures of <b>2</b>, <b>3</b>, and <b>4</b>. DFT calculations suggest an unprecedented mechanism for ring-opening of <b>Q</b> where the reactive intermediate in the low-spin manifold crosses over to the high-spin surface to access a low-energy transition state but returns to the low-spin surface immediately. This double spin-crossover constitutes a rare example of a two-state reactivity, which is key for enabling the reaction at room temperature. The regio­selective behavior of <b>Iq</b> ring-opening is found to be due to electronic effects, where the aromatic resonance of the bicycle is maintained during the key CC coupling event