Synergistic in-vitro antiviral effects of combination treatment using anidulafungin and T-1105 against Zika virus infection.

Zika virus (ZIKV) has been the cause of some epidemics since 2007. The correlations of microcephaly and Guillain-Barré syndrome with ZIKV have been noticed. Unfortunately, researchers have yet to develop an effective vaccine or drug approved for ZIKV infection. Anidulafungin is a member of echinocandins that is used to treat candida infections. This study assessed the antiviral capability of anidulafungin against ZIKV. Anidulafungin was shown to significantly decrease viral RNA levels, protein expression levels, viral yields, and the rate of infection. In time of addition assays, anidulafungin exhibited inhibitory activities in the early stages of ZIKV infection. In binding and entry assays, administering anidulafungin did not lead to a corresponding decrease in quantity of viral RNA, but a significant decrease in ZIKV infectivity was observed in virucidal assays. This indicated that anidulafungin interferes directly with virions. T-1105 is a viral polymerase inhibitor, which functions in the late stage of ZIKV infection. When anidulafungin was administered in combination with T-1105, an obvious synergistic effect was observed, resulting in a combination index (CI) value of 0.85 ± 0.13. Finally, we evaluated the effects of echinocandins in terms of half-maximal inhibitory concentration (IC50), calculation of cytotoxicity concentration 50% (CC50), selectivity index (SI), and Patchdock score. Among the tests, anidulafungin bears the lowest IC50 and highest Patchdock score. Although anidulafungin is classified as a pregnancy category C agent; however, combination therapy of anidulafungin with a viral RNA replication inhibitor could expand treatment options for ZIKV infection.

Temperature-dependent characteristics of GeSn/Ge multiple-quantum-well photoconductors on silicon.

Temperature-dependent characteristics of GeSn/Ge multiple-quantum-well (MQW) photoconductors (PCs) on silicon substrate were investigated. The high quality GeSn/Ge MQW epitaxial structure was grown on a silicon substrate using low temperature molecular beam epitaxy techniques with atomically precise thickness control. Surface-illuminated GeSn/Ge MQW PCs were fabricated using complementary metal-oxide-semiconductor-compatible processing and characterized in a wide temperature range of 55-320 K. The photodetection range was extended to λ=2235nm at T=320K due to bandgap shrinkage with Sn alloying. Measured spectral responsivity was enhanced at reduced temperatures. These results provide better understanding of GeSn/Ge MQW structures for efficient short-wave infrared photodetection.

GeSn lateral p-i-n waveguide photodetectors for mid-infrared integrated photonics.

In this Letter, we demonstrate mid-infrared (MIR) lateral p-i-n GeSn waveguide photodetectors (WGPDs) on silicon, to the best of our knowledge for the first time, as a key enabler of MIR electronic-photonic integrated circuits (EPICs). Narrow-bandgap GeSn alloys were employed as the active material to enable efficient photodetection in the MIR region. A lateral p-i-n homojunction diode was designed and fabricated to significantly enhance the optical confinement factor of the guided modes and thus enhance the optical responsivity. Thus, a photodetection range of up to 1950 nm and a good responsivity of 0.292 A/W at 1800 nm were achieved. These results demonstrate the feasibility of planar GeSn WGPDs for monolithic MIR EPICs on silicon.

Metal-Semiconductor-Metal GeSn Photodetectors on Silicon for Short-Wave Infrared Applications.

Metal-semiconductor-metal photodetectors (MSM PDs) are effective for monolithic integration with other optical components of the photonic circuits because of the planar fabrication technique. In this article, we present the design, growth, and characterization of GeSn MSM PDs that are suitable for photonic integrated circuits. The introduction of 4% Sn in the GeSn active region also reduces the direct bandgap and shows a redshift in the optical responsivity spectra, which can extend up to 1800 nm wavelength, which means it can cover the entire telecommunication bands. The spectral responsivity increases with an increase in bias voltage caused by the high electric field, which enhances the carrier generation rate and the carrier collection efficiency. Therefore, the GeSn MSM PDs can be a suitable device for a wide range of short-wave infrared (SWIR) applications.

Resonant-cavity-enhanced responsivity in germanium-on-insulator photodetectors.

The germanium-on-insulator (GOI) has recently emerged as a new platform for complementary metal-oxide-semiconductor (CMOS)-compatible photonic integrated circuits. Here we report on resonant-cavity-enhanced optical responses in Ge photodetectors on a GOI platform where conventional photodetection is difficult. A 0.16% tensile strain is introduced to the high-quality Ge active layer to extend the photodetection range to cover the entire range of telecommunication C- and L-bands (1530-1620 nm). A carefully designed vertical cavity is created utilizing the insulator layer and the deposited SiO2 layer to enhance the optical confinement and thus optical response near the direct-gap absorption edge. Experimental results show a responsivity peak at 1590 nm, confirming the resonant cavity effect. Theoretical analysis shows that the optical responsivity in the C- and L-bands is significantly enhanced. Thus, we have demonstrated a new type of Ge photodetector on a GOI platform for CMOS-compatible photonic integrated circuits for telecommunication applications.