A novel TICT-based near-infrared fluorescent probe for light-up sensing and imaging of human serum albumin in real samples

Human serum albumin(HSA) has emerged as a pivotal biomarker and prognostic indicator for various human diseases. Real-time sensing and visual tracking of HSA in plasma or other biological systems will immensely facilitate the basic researchers and clinicians to better understand HSA-associated biological processes. Herein, a novel near-infrared(NIR) fluorescent probe(7-HTCF) was rationally constructed for light-up sensing and in-situ imaging of HSA in real samples, based on the principle of twisted intramolecular charge transfer(TICT). Under physiological conditions, 7-HTCF could be efficiently trapped by HSA to form a stable complex via binding on a non-drug binding site, while the complex emitted strong fluoresce signals around 670 nm. Further investigations demonstrated that 7-HTCF displayed a great combination of excellent selectivity and good chemical stability, as well as rapid fluorescent response and ultra-high sensitivity for HSA detection. Particularly, the newly developed light-up probe has been successfully utilized for quantitative detection of HSA in diluted plasma samples, while its readouts are hardly affected by the addition of therapeutic agents and herbal medicines. 7-HTCF is also successfully used for in-situ imaging of the reabsorbed HSA in living renal cells, while this dye exhibits good cell permeability and high resolution for in-situ imaging in living cells. Collectively, a novel TICT-based near-infrared fluorescent probe was devised for highly selective and ultra-sensitive sensing of HSA in plasma samples or imaging HSA in living cells, which offered a practical tool for clinical tests and for exploring HSA-associated biological processes.

Average BER of coherent optical QPSK systems with phase errors over M turbulence channels

The average bit-error-rate(BER) performance is studied for a coherent free-space optical communication system employing differentially encoded quadrature phase-shift keying(QPSK) with the Mth-power phase estimation method. A closed-form expression, considering the combined effects of the Málaga(M) turbulence fading, pointing errors, and phase estimation errors, is derived in terms of Meijer’s G function. Numerical and Monte Carlo simulation results are presented to verify the derived expression.

All-fiber device for single-photon detection

Fiber components form the standard not only in modern telecommunication but also for future quantum information technology. For high-performance single-photon detection, superconducting nanowire single-photon detectors (SPDs) are typically fabricated on a silicon chip and fiber-coupled for easy handling and usage. The fiber- to-chip interface hinders the SPD from being an all-fiber device for full utilization of its excellent performance. Here, we report a scheme of SPD that is directly fabricated on the fiber tip. A bury-and-planar fabrication technique is developed to improve the roughness of the substrate for all-fiber detectors’ performance for single-photon detection with amorphous molybdenum silicide (MoSi) nanowires. The low material selectivity and universal planar process enable fabrication and packaging on a large scale. Such a detector responds to a broad wavelength range from 405 nm to 1550 nm at a dark count rate of 100 cps. The relaxation time of the response pulse is ~ 15 ns, which is comparable to that of on-chip SPDs. Therefore, this device is free from fiber-to-chip coupling and easy packaging for all-fiber quantum information systems.