Highly sensitive surface-enhanced Raman scattering-based immunosensor incorporating half antibody-fragment for quantitative detection of Alzheimer's disease biomarker in blood.

Blood-based detection of Alzheimer's disease (AD) biomarker has become a prominent method for diagnosis of AD which can replace the complex and invasive cerebrospinal fluid (CSF)-based diagnostic method. However, the application of blood AD biomarker in actual AD diagnosis is hampered by the extremely low concentration of biomarkers in blood, as well as the existence of interfering proteins. Therefore, it is essential to develop a sensitive and specific detection platform to achieve blood-based diagnosis of AD. Here, a surface-enhanced Raman scattering (SERS)-based sensor is developed for the quantitative determination of tau protein in the plasma of AD patients. To acquire femtomolar-level detection limit, this platform involves the use of half antibody fragment immobilized onto head-flocked gold nanopillar SERS substrates and SERS-nanotags. The small size of the half antibody fragment maximizes the effect of plasmon coupling, by reducing the distance between SERS substrates and SERS-nanotags. Also, the use of half antibody fragment improves the antigen recognition ability by immobilizing the antibody with high density and efficient orientation of the antibody. The sensor using these characteristics showed a low detection limit of 3.21 fM and a wide detection range (10 fM - 1 µM). The platform was also able to accurately quantify the tau protein in the clinical plasma sample and correctly distinguish the AD patient from the healthy control. The ultrasensitive and specific SERS immunoassay platform facilitates accurate and early detection of AD biomarkers and can serve as a valuable tool for simple point-of-care testing in clinical diagnosis.

Improved performance of dye-sensitized solar cells using dual-function TiO(2) nanowire photoelectrode.

A unique, hierarchically structured, aggregated TiO(2) nanowire (A-TiO(2)-nw) is prepared by solvothermal synthesis and used as a dual-functioning photoelectrode in dye-sensitized solar cells (DSSCs). The A-TiO(2)-nw shows improved light scattering compared to conventional TiO(2) nanoparticles (TiO(2)-np) and dramatically enhanced dye adsorption compared to conventional scattering particles (CSP). The A-TiO(2)-nw is used as a scattering layer for bilayer photoelectrodes (TiO(2)-np/A-TiO(2)-nw) in DSSCs to compare the cell performance to that of devices using state-of-the-art photoelectrode architectures (TiO(2)-np/CSP). The DSSCs fabricated using bilayers of TiO(2)-np/A-TiO(2)-nw show improved power conversion efficiency (9.1%) and current density (14.88 mA cm(-2)) compared to those using single-layer TiO(2)-np (7.6% and 11.84 mA cm(-2)) or TiO(2)-np/CSP bilayer structures (8.7% and 13.81 mA cm(-2)). The unique contribution of the A-TiO(2)-nw layers to the device performance is confirmed by studying the incident photon-to-current efficiency. The enhanced external quantum efficiencies at approximately 520 nm and 650 nm clearly reveal the dual functionality of A-TiO(2)-nw. These unique properties of A-TiO(2)-nw may be applied in other devices utilizing light-scattering n-type semiconductor.

Polarized white light from LEDs using remote-phosphor layer sandwiched between reflective polarizer and light-recycling dichroic filter.

This study introduces an efficient polarized, white phosphor-converted, light-emitting diode (pc-LED) using a remote phosphor film sandwiched between a reflective polarizer film (RPF) and a short-wavelength pass dichroic filter (SPDF). The on-axis brightness of polarized white light emission of a RPF/SPDF-sandwiched phosphor film over a blue LED, showed greater recovery than that of a conventional unpolarized remote phosphor film over blue LED, due to the recycling effect of yellow light from an SPDF. The relative luminous efficacy of an RPF/SPDF-sandwiched phosphor film was made 1.40 times better by adding an SPDF on the backside of an RPF-capped phosphor film. A polarization ratio of 0.84 was demonstrated for a white LED with an RPF/SPDF-sandwiched phosphor film, in good agreement with the measured results from the RPF-only sample.

Improved color coordinates of green monochromatic pc-LED capped with a band-pass filter.

This study introduces a "greener" green monochromatic phosphor-converted light-emitting diode (pc-LED) using a band-pass filter (BPF) combined with a long-pass dichroic filter (LPDF) and a short-pass dichroic filter (SPDF) to improve the color quality of our previously developed LPDF-capped green pc-LED. This can also address the drawbacks of III-V semiconductor-type green LEDs, which show a low luminous efficacy and a poor current dependence of the efficacy and color coordinates compared to blue semiconductor-type LEDs. The optical properties of green monochromatic pc-LEDs using a BPF are compared with those of LPDF-capped green pc-LEDs, which have a broad band spectrum, and III-V semiconductor-type green LEDs by changing the transmittance wavelength range of the BPF and the peak wavelength of the green phosphors. BPF-capped green monochromatic pc-LEDs provide a high luminous efficacy (134 lm/W at 60 mA), and "greener" 1931 Commission Internationale d'Eclairage (CIE; CIEx, CIEy) color coordinates (0.24, 0.66) owing to the narrowed emission spectrum. We also propose a two-dimensional (2D) polystyrene (PS) microbead (2-µm diameter) monolayer as a scattering layer to overcome the poor angular dependence of the color coordinates of the transmitted light through a nano-multilayered dichroic filter such as an LPDF or BPF. The 2D PS scattering layer improves the angular dependence of the green color emitted from a BPF-capped green pc-LED with only 3% loss of luminous efficacy.

Excellent color rendering indexes of multi-package white LEDs.

This study introduces multi-package white light-emitting diodes (LEDs) system with the ability to realize high luminous efficacy and an excellent color rendering index (CRI, R a) using the R B,M A B,M G B,M C B (R B,M A B,M G B,M denoted as a long-pass dichroic filter (LPDF)-capped, monochromatic red, amber and green phosphor converted-LED (pc-LED) pumped by a blue LED chip, and C B denoted as a cyan and blue mixed pc-LED pumped by a blue LED) system. The luminous efficacy and color rendering index (CRI) of multi-package white LED systems are compared while changing the concentration of the cyan phosphor used in the paste of a cyan-blue LED package and the driving current of individual LEDs in multi-package white LEDs at correlated color temperatures (CCTs) ranging from 6,500 K (cold white) to 2,700 K (warm white) using a set of eight CCTs as specified by the American National Standards Institute (ANSI) standard number C78.377-2008. A R B,M A B,M G B,M C B white LED system provides high luminous efficacy (≥ 96 lm/W) and a color rendering index (≥ 91) encompassing the complete CCT range. We also compare the optical properties of the R B,M A B,M G B,M C B system with those of the R B,M A B,M G B,M B and RAGB (red, amber, green, and blue semiconductor-type narrow-spectrum-band LEDs) systems. It can be expected that the cyan color added to a blue LED in multi-package white LEDs based on LPDF-capped, phosphor-converted monochromatic LEDs will meet the needs of the high-quality, highly efficient, full-color white LED lighting market in the near future.