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Tethered Bichromophoric Fluorophore Quencher Voltage Sensitive Dyes
摘要： Voltage sensitive dyes (VSDs) are used for in vitro drug screening and for imaging of patterns of electrical activity in tissue. Wide application of this technology depends on the availability of sensors with high sensitivity (percent change of fluorescence per 100mV), high fluorescence quantum yield, and fast response kinetics. A promising approach uses a 2-component system consisting of anionic membrane permeable quenchers with fluorophores labeling one side of the membrane; this produces voltage-dependent fluorescence quenching. However, the quencher must be kept at low concentrations to minimize pharmacological effects, thus limiting sensitivity. By developing tethered bichromophoric fluorophore quencher (TBFQ) dyes, where the fluorophore and quencher are covalently connected by a long hydrophobic chain, the sensitivity is maximized and is independent of VSD concentration. A series of 13 TBFQ dyes based on the AminoNaphthylEthenylPyridinium (ANEP) fluorophore and the dipicrylamine anion (DPA) quencher have been synthesized and tested in an artificial lipid bilayer apparatus. The best of these, TBFQ1, shows a 2.5 fold change in fluorescence per 100mV change in membrane potential, and the response kinetics is in 10-20 ms range. This sensitivity is an order of magnitude better than commonly used VSDs. However the fluorescence quantum yield is only 1.6%, which may make this first generation of TBFQ VSDs impractical for in vivo electrical imaging. Nevertheless, the design principles established here can serve as foundation for improved TBFQ VSDs. We believe this approach promises to greatly enhance our ability to monitor electrical activity in cells and tissues.
关键词： voltage sensitive dye,DPA,FRET,fluorescent,quencher,potentiometric
更新于2025-09-09 09:28:46
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A Compact Ka-Band Integrated Doherty Amplifier With Reconfigurable Input Network
摘要： In this paper, we present the design of an ultracompact monolithic millimeter-wave integrated circuit Doherty power amplifier (DPA) using a novel reconfigurable input network at Ka-band. The proposed input network is formed by a compact broadside coupler and two additional field-effect transistors. By reconfiguring the relative phase offset between the main and auxiliary amplifiers, the DPA can be postoptimized to achieve high efficiency and maximal power gain flatness. More importantly, the DPA can be tuned for the highest performance at different frequencies. To verify the concept, a DPA is fabricated in a 0.15-μm enhancement mode Gallium Arsenide (GaAs) process and exhibits a measured output power of 26.5 dBm and gain of 11.8 dB at 28 GHz. The peak power-added efficiency (PAE) is 42%, and the PAE at 6-dB output power backoff (PBO) is 31%, respectively. With reconfigurable capability, the DPA can maintain high performance over a 3-GHz frequency band from 26.5 to 29.5 GHz. To the best of the authors’ knowledge, the proposed DPA achieves among the highest backoff PAE over a wide bandwidth at Ka-band.
关键词： reconfigurable,Ka-band,gallium arsenide (GaAs),Doherty power amplifier (DPA),millimeter-wave integrated circuit (MMIC),Compact coupler
更新于2025-09-04 15:30:14