RESUMO
Controlling the propagation and emission of light via Bloch surface waves (BSWs) has held promise in the field of on-chip nanophotonics. BSW-based optical devices are being widely investigated to develop on-chip integration systems. However, a coherent light source that is based on the stimulated emission of a BSW mode has yet to be developed. Here, we demonstrate lasers based on a guided BSW mode sustained by a gain-medium guiding structure microfabricated on the top of a BSW platform. A long-range propagation length of the BSW mode and a high-quality lasing emission of the BSW mode are achieved. The BSW lasers possess a lasing threshold of 6.7 µJ/mm2 and a very narrow linewidth reaching a full width at half maximum as small as 0.019 nm. Moreover, the proposed lasing scheme exhibits high sensitivity to environmental changes suggesting the applicability of the proposed BSW lasers in ultra-sensitive devices.
RESUMO
Although chiral semiconductors have shown promising progress in direct circularly polarized light (CPL) detection and emission, they still face potential challenges. A chirality-switching mechanism or approach integrating two enantiomers is needed to discriminate the handedness of a given CPL; additionally, a large material volume is required for sufficient chiroptical interaction. These two requirements pose significant obstacles to the simplification and miniaturization of the devices. Here, room-temperature chiral polaritons fulfilling dual-handedness functions and exhibiting a more-than-two-order enhancement of the chiroptical signal are demonstrated, by embedding a 40 nm-thick perovskite film with a 2D chiroptical effect into a Fabry-Pérot cavity. By mixing chiral perovskites with different crystal structures, a pronounced 2D chiroptical effect is accomplished in the perovskite film, featured by an inverted chiroptical response for counter-propagating CPL. This inversion behavior matches the photonic handedness switch during CPL circulation in the Fabry-Pérot cavity, thus harvesting giant enhancement of the chiroptical response. Furthermore, affected by the unique quarter-wave-plate effects, the polariton emission achieves a chiral dissymmetry of ±4% (for the emission from the front and the back sides). The room-temperature polaritons with the strong dissymmetric chiroptical interaction shall have implications on a fundamental level and future on-chip applications for biomolecule analysis and quantum computing.
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Solution-process perovskite quantum dots (QDs) are promising materials to be utilized in photovoltaics and photonics with their superior optical properties. Advancements in top-down nanofabrication for perovskite are thus important for practical photonic and plasmonic devices. However, different from the chemically synthesized nano/micro-structures that show high quality and low surface roughness, the perovskite QD thin film prepared by spin-coating or the drop-casting process shows a large roughness and inhomogeneity. Low-roughness and low-optical loss perovskite QD thin film is highly desired for photonic and optoelectronic devices. Here, this work presents a pressure-assisted ligand engineering/recrystallization process for high-quality and well-thickness controlled CsPbBr3 QD film and demonstrates a low-threshold and single-mode plasmonic lattice laser. A recrystallization process is proposed to prepare the QD film with a low roughness (RMS = 1.3 nm) and small thickness (100 nm). Due to the low scattering loss and strong interaction between gain media and plasmonic nanoparticles, a low lasing threshold of 16.9 µJ cm-2 is achieved. It is believed that this work is not only important to the plasmonic laser field but also provides a promising and general nanofabrication method of solution-processed QDs for various photonic and plasmonic devices.
RESUMO
Perovskite materials prepared in the form of solution-processed nanocrystals and used in top-down fabrication techniques are very attractive to develop low-cost and high-quality integrated optoelectronic circuits. Particularly, integrated miniaturized coherent light sources that can be connected to light-guiding structures on a chip are highly desired. To control light propagating on a small footprint with low-loss optical modes, long-range surface plasmon polariton (LRSPP) waveguides are employed. Herein, we demonstrate an on-chip fabricated photonic-plasmonic hybrid system consisting of a perovskite lasing structure coupled to an LRSPP waveguide achieving a low lasing threshold and a propagation length over 100 µm. Preventing perovskite material degradation and the formation of surface roughness of the laser cavity during fabrication is made possible by designing a fabrication technique without any etching step.
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Abnormal accumulation of acrolein, an α, ß unsaturated aldehyde has been reported as one pathological cause of the CNS neurodegenerative diseases. In the present study, the neuroprotective effect of selumetinib (a MEK-ERK inhibitor) on acrolein-induced neurotoxicity was investigated in vitro using primary cultured cortical neurons. Incubation of acrolein consistently increased phosphorylated ERK levels. Co-treatment of selumetinib blocked acrolein-induced ERK phosphorylation. Furthermore, selumetinib reduced acrolein-induced increases in heme oxygenase-1 (a redox-regulated chaperone protein) and its transcriptional factor, Nrf-2 as well as FDP-lysine (acrolein-lysine adducts) and α-synuclein aggregation (a pathological biomarker of neurodegeneration). Morphologically, selumetinib attenuated acrolein-induced damage in neurite outgrowth, including neuritic beading and neurite discontinuation. Moreover, selumetinib prevented acrolein-induced programmed cell death via decreasing active caspase 3 (a hallmark of apoptosis) as well as RIP (receptor-interacting protein) 1 and RIP3 (biomarkers for necroptosis). In conclusion, our study showed that selumetinib inhibited acrolein-activated Nrf-2-HO-1 pathway, acrolein-induced protein conjugation and aggregation as well as damage in neurite outgrowth and cell death, suggesting that selumetinib, a MEK-ERK inhibitor, may be a potential neuroprotective agent against acrolein-induced neurotoxicity in the CNS neurodegenerative diseases.
Assuntos
Acroleína/toxicidade , Benzimidazóis/administração & dosagem , Doenças Neurodegenerativas/prevenção & controle , Fármacos Neuroprotetores/administração & dosagem , Animais , Apoptose/efeitos dos fármacos , Células Cultivadas , Córtex Cerebral/citologia , Córtex Cerebral/patologia , Humanos , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Quinases de Proteína Quinase Ativadas por Mitógeno/antagonistas & inibidores , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Necroptose/efeitos dos fármacos , Doenças Neurodegenerativas/induzido quimicamente , Doenças Neurodegenerativas/patologia , Crescimento Neuronal/efeitos dos fármacos , Neurônios/patologia , Cultura Primária de Células , Agregados Proteicos/efeitos dos fármacos , Ratos , Testes de Toxicidade Aguda , alfa-Sinucleína/metabolismoRESUMO
Heat-killed Vibrio alginolyticus (HVa), formalin-inactivated V. alginolyticus (FVa), heat-killed Vibrio harveyi (HVh), formalin-inactivated V. harveyi (FVh), live V. alginolyticus (LVa), and live V. harveyi (LVh) were used in this study. White shrimp Litopenaeus vannamei receiving two mixtures (HVa + FVa) or four mixtures (HVa + FVa + HVh + FVh) served as primary exposure, and shrimp receiving LVa or LVh afterward served as secondary exposure. Shrimp receiving marine saline and then receiving either LVa or LVh served as controls. Phagocytic activity and clearance efficiency were examined in shrimp that received two mixtures after 1-8 weeks and then received LVa. Both the phagocytic activity and clearance efficiency of shrimp receiving two mixtures were significantly higher than in control shrimp after 1-8 weeks. In another experiment, phagocytic activity and clearance efficiency were examined in shrimp that received four mixtures after 1-8 weeks and then received LVa and LVh, respectively. The phagocytic activity of shrimp receiving four mixtures was significantly higher than in control shrimp after 1-8 weeks post exposure to LVa and LVh. The clearance efficiency of shrimp receiving four mixtures was significantly higher than in control shrimp after 1-6 weeks post exposure to LVa, and 1-7 weeks post exposure to LVh. In the other experiment, the survival rate of shrimp that received four mixtures after five weeks were challenged with LVa at 6.4 × 107 colony-forming units (cfu) shrimp-1 and LVh at 4.4 × 106 cfu shrimp-1. Shrimp that received marine saline for five weeks and then challenged with LVa and LVh at a same dose served as challenged controls. The survival rate of shrimp that received four mixtures was significantly higher (90%) than that of control shrimp (67%), and significantly higher (73%) than that of control shrimp (53%) after 3-7 days post challenge with LVa and LVh. It is concluded that the mixtures have feature of adjuvant and antigen, and shrimp receiving mixtures of heat-killed and formalin-inactivated V. alginolyticus and V. harveyi even after 5-8 weeks exhibit memory recall and show increased phagocytosis and resistance to Vibrio infections.
Assuntos
Rememoração Mental/fisiologia , Penaeidae/fisiologia , Fagocitose/imunologia , Vibrio alginolyticus/fisiologia , Vibrio/fisiologia , Animais , Formaldeído , Temperatura Alta , Penaeidae/imunologia , Taxa de Sobrevida , Fatores de TempoRESUMO
Invertebrates rely on an innate immune system to combat invading pathogens. The system is initiated in the presence of cell wall components from microbes like lipopolysaccharide (LPS), ß-1,3-glucan (ßG) and peptidoglycan (PG), altogether known as pathogen-associated molecular patterns (PAMPs), via a recognition of pattern recognition protein (PRP) or receptor (PRR) through complicated reactions. We show herein that shrimp hemocytes incubated with LPS, ßG, and PG caused necrosis and released endogenous molecules (EMs), namely EM-L, EM-ß, and EM-P, and found that shrimp hemocytes incubated with EM-L, EM-ß, and EM-P caused changes in cell viability, degranulation and necrosis of hemocytes, and increased phenoloxidase (PO) activity and respiratory burst (RB) indicating activation of immunity in vitro. We found that shrimp receiving EM-L, EM-ß, and EM-P had increases in hemocyte count and other immune parameters as well as higher phagocytic activity toward a Vibrio pathogen, and found that shrimp receiving EM-L had increases in proliferation cell ratio and mitotic index of hematopoietic tissues (HPTs). We identified proteins of EMs deduced from SDS-PAGE and LC-ESI-MS/MS analyses. EM-L and EM-P contained damage-associated molecular patterns (DAMPs) including HMGBa, HMGBb, histone 2A (H2A), H2B, and H4, and other proteins including proPO, Rab 7 GPTase, and Rab 11 GPTase, which were not observed in controls (EM-C, hemocytes incubated in shrimp salt solution). We concluded that EMs induced by PAMPs contain DAMPs and other immune molecules, and they could elicit innate immunity in shrimp. Further research is needed to identify which individual molecule or combined molecules of EMs cause the results, and determine the mechanism of action in innate immunity.
Assuntos
Biomarcadores/metabolismo , Hemócitos/patologia , Imunidade Inata/imunologia , Moléculas com Motivos Associados a Patógenos/farmacologia , Penaeidae/imunologia , Fagocitose/imunologia , Receptores de Reconhecimento de Padrão/metabolismo , Animais , Apoptose/efeitos dos fármacos , Western Blotting , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Hemócitos/efeitos dos fármacos , Hemócitos/imunologia , Imunidade Inata/efeitos dos fármacos , Lipopolissacarídeos/farmacologia , Índice Mitótico , Fagocitose/efeitos dos fármacos , Explosão Respiratória/efeitos dos fármacos , Explosão Respiratória/imunologia , Espectrometria de Massas por Ionização por Electrospray , Espectrometria de Massas em Tandem , Vibrioses/tratamento farmacológico , Vibrioses/imunologia , Vibrioses/microbiologia , Vibrio alginolyticus/efeitos dos fármacos , Vibrio alginolyticus/imunologiaRESUMO
This study investigated the potential effects of natural products ursolic acid (UA) and oleanolic acid (OA) against HBx-mediated tumorigenic activities in vitro and in vivo. HBx transactivated Sp-1 and Smad 3/4 in Huh7 and FL83B hepatocytes and induced cell migration of Huh7 and HepG2. HBx also induced MMP-3 secretion in Huh7 and acted against TGF-ß-induced apoptosis in Hep3B. UA almost completely blocked the HBx-mediated effects, while OA had a partial inhibitive effect. Utilization of specific MAPK inhibitors and immunoblotting demonstrated that UA selectively activated MAPK signaling in certain tested cells. Preintraperitoneal injection of UA fully prevented the tumor growth of HBV-containing 2.2.15 cells, while OA-treated mice had smaller tumors than the control group. Our results suggested that UA possesses a hepatoprotective ability and illustrated the evident effects against HBx-mediated tumorigenic activities without toxicity in a mouse model.