Broadband metamaterial absorber (MA) in the whole visible regime has attracted an enormous amount of attention for its potential applications in thermophotovoltaic cells, thermal emitters, and other optoelectronic devices. Nonetheless, complicated device configuration is still involved in achieving broadband, polarization-independent MA and it results in a cost-ineffective fabrication process. In this paper, a novel MA composed of a periodic array of dielectric cylinder sandwiched by the non-noble metal of nickel (Ni) film is demonstrated. Experimental results show that the proposed MA exhibits strong absorptive behavior independent of polarization in the whole visible regime (400-700 nm). The absorption still remains 80% when the incident angle is 60°. The proposed fabrication method is well compatible with the conventional soft nano-imprinting lithography technique, thus it is economic and scalable for a large-format substrate. These results provide an alternative method for the realization of high-performance visible light absorber and offer new opportunities for potential applications in related fields.

Broadband, wide-angle, and polarization-independent metamaterial absorber for the visible regime.

Large‐Area Ultrabroadband Absorber for Solar Thermophotovoltaics Based on 3D Titanium Nitride Nanopillars

Light Management with Patterned Micro- and Nanostructure Arrays for Photocatalysis, Photovoltaics, and Optoelectronic and Optical Devices

Dielectric Mie resonators have attracted a great deal of attention over the past few years thanks to their remarkable capabilities in manipulating light propagation at the nanoscale. However, the practical implementation of technological products is still elusive. One of the important limits is the absence of a high-performing material and a fabrication method that can be easily integrated into modern microelectronic devices at affordable costs. Here, we provide theoretical and experimental evidence of an alternative semiconductor material, SiGe alloys, for dielectric Mie resonator applications. As a material compatible with the processing requirements of the semiconductor industry, it possesses comparable optical properties to its conventional Si-based counterpart at visible frequencies in spite of its higher optical losses. These dielectric resonant particles can be obtained over very large surfaces on arbitrary silica substrates via spontaneous solid state dewetting of ultrathin (<100 nm) SiGe amorphou...

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All-Dielectric Color Filters Using SiGe-Based Mie Resonator Arrays

The interplay of photonics, nanotechnology, and biochemistry has significantly improved the identification and characterization of multiple types of biomarkers by optical biosensors. Great achievements in fluorescence-based technologies have been realized, for example, by the advancement of multiplexing techniques or the introduction of nanoparticles to biochemical and clinical research. This review presents a concise overview of recent advances in fluorescence sensing techniques for the detection of circulating disease biomarkers. Detection principles of representative approaches, including fluorescence detection using molecular fluorophores, quantum dots, and metallic and silica nanoparticles, are explained and illustrated by pertinent examples from the recent literature. Advanced detection technologies and material development play a major role in modern biosensing and consistently provide significant improvements toward robust, sensitive, and versatile platforms for early detection of circulating diag...

Fluorescence Sensing of Circulating Diagnostic Biomarkers Using Molecular Probes and Nanoparticles

Nanostructure arrays such as nanowire, nanopillar, and nanocone arrays have been proposed to be promising antireflection structures for photovoltaic applications due to their great light trapping ability. In this paper, the optical properties of Si nanopillar and nanocone arrays in visible and infrared region were studied by both theoretical calculations and experiments. The results show that the Mie resonance can be continuously tuned across a wide range of wavelength by varying the diameter of the nanopillars. However, Si nanopillar array with uniform diameter exhibits only discrete resonance mode, thus can't achieve a high broadband absorption. On the other hand, the Mie resonance wavelength in a Si nanocone array can vary continuously as the diameters of the cross sections increase from the apex to the base. Therefore Si nanocone arrays can strongly interact with the incident light in the broadband spectrum and the absorbance by Si nanocone arrays is higher than 95% over the wavelength from 300 to 2000 nm. In addition to the Mie resonance, the broadband optical absorption of Si nanocone arrays is also affected by Wood-Rayleigh anomaly effect and metal impurities introduced in the fabrication process.

/pdf/broadband-optical-absorption-by-tunable-mie-resonances-in-1e6el10c2g.pdf

Broadband optical absorption by tunable Mie resonances in silicon nanocone arrays

Time-Resolved Fluorescence Resonance Energy Transfer (TR-FRET) technology is a widely used immunoassay that enables high-throughput quantitative measurements of proteins of interest One of the well established examples is the TR-FRET assay for mutant huntingtin protein (HTT), which is the major cause of the neurodegenerative Huntington's disease (HD) To measure the mutant HTT protein, the published assays utilize a polyQ antibody, MW1, paired with HTT N-terminal antibodies MW1 has much higher apparent affinity to mutant HTT with expanded polyQ stretch than to wild-type HTT with shorter polyQ, and thus the assays detect mutant HTT preferentially Here we report a reversible temperature dependent change of TR-FRET signals for HTT N-terminal fragments: the signals become higher when the temperature is lowered from room temperature to 4°C Interestingly, the temperature sensitivity of the TR-FRET signals is much higher for the Q25 (wild-type) than for the Q72 (mutant) protein We further revealed that it is likely due to a temperature and polyQ length-dependent structural or spatial change of HTT, which is potentially useful for understanding polyQ structure and toxicity

/pdf/tr-fret-assays-of-huntingtin-protein-fragments-reveal-1w5kvsl0tg.pdf

TR-FRET assays of Huntingtin protein fragments reveal temperature and polyQ length-dependent conformational changes.

The accumulation of disease-causing proteins is a common hallmark of many neurodegenerative disorders. Measuring the degradation of such proteins using high-throughput-compatible assays is highly desired for the identification of genetic and chemical modulators of degradation. For example, Huntington's disease (HD) is an incurable hereditary neurodegenerative disorder caused by the cytotoxicity of mutant huntingtin protein (mHTT). The high-throughput measurement of mHTT degradation is important in HD drug discovery and research. Existing methods for such purposes have limitations due to their dependence on protein tags or pan protein synthesis inhibitors. Here, we report a high-throughput-compatible pulse-chase method (CH-chase) for the measurement of endogenous tag-free huntingtin protein (HTT) degradation based on Click chemistry and Homogeneous Time Resolved Fluorescence (HTRF) technologies. The pulsed-labeled proteins were conjugated with biotin using the click reaction strain-promoted alkyne-azide cycloaddition (SPAAC), and the chase signals were calculated by measuring the reduction percentage of the HTT HTRF signals after pull-down with streptavidin beads. We validated that the signals were within the linear detection range and were HTT-specific. We successfully measured the degradation of endogenous HTT in a high-throughput-compatible format using 96-well plates. The predicted changes of HTT degradation by known modifiers were observed, which confirmed that the assay is suitable for the identification of HTT degradation modifiers. We have established the first high-throughput-compatible assay capable of measuring endogenous, tag-free HTT degradation, providing a valuable tool for HD research and drug discovery. The method could be applied to other proteins and can facilitate research on other neurodegenerative disorders and proteinopathies.

/pdf/a-high-throughput-compatible-assay-to-measure-the-1p86hxjasg.pdf

A high-throughput-compatible assay to measure the degradation of endogenous Huntingtin proteins

High-throughput measurement of huntingtin (Htt) levels is useful for Huntington's disease research. For example, identification of genetic or chemical modifiers that reduce Htt levels by high-throughput screening provides promising strategy for HD drug discovery. In the human cells, high-throughput measurement of Htt levels has been established based on the Time Resolved-Fluorescence Resonance Energy Transfer (TR-FRET) technology, using the 2B7/MW1 antibody pair. Unfortunately, application of this assay in the mouse cells has been problematic due to discrepancies between TR-FRET signals and Western- blots, possibly caused by non-specific antibody binding. Here we report TR-FRET assays that are able to detect endogenous Htt levels of the mouse striatal cell line (STHdh).

TR-FRET Assays for Endogenous Huntingtin Protein Level in Mouse Cells

Time-Resolved Fluorescence Resonance Energy Transfer (TR-FRET) technology is a widely usedimmunoassay that enables high-throughput quantitative measurements of proteins of interest. One of thewell established examples is the TR-FRET assay for mutant huntingtin protein (HTT), which is the majorcause of the neurodegenerative Huntington’s disease (HD). To measure the mutant HTT protein, thepublished assays utilize a polyQ antibody, MW1, paired with HTT N-terminal antibodies. MW1 has muchhigher apparent affinity to mutant HTT with expanded polyQ stretch than to wild-type HTT with shorterpolyQ, and thus the assays detect mutant HTT preferentially. Here we report a reversible temperaturedependentchangeofTR-FRETsignalsforHTTN-terminalfragments:thesignalsbecomehigherwhenthetemperature is lowered from room temperature to 4

Mingxing Lu

Papers

Broadband optical absorption by tunable Mie resonances in silicon nanocone arrays

TR-FRET assays of Huntingtin protein fragments reveal temperature and polyQ length-dependent conformational changes.

A high-throughput-compatible assay to measure the degradation of endogenous Huntingtin proteins

TR-FRET Assays for Endogenous Huntingtin Protein Level in Mouse Cells

TR-FRET Assays of Huntingtin Protein Fragments Reveal Temperature and PolyQ Length-Dependent