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  1. Abstract

    Despite multiple new‐drug approvals in recent years, prostate cancer remains a global health challenge because of the prostate cancers are resistant to androgen deprivation therapy. Here, we show that a small D‐phosphopeptide undergoes prostatic acid phosphatase (PAP)‐instructed self‐assembly for inhibiting castration‐resistant prostate cancer (CRPC) cells. Specifically, the installation of phosphate at the C‐terminal of a D‐tripeptide results in the D‐phosphopeptide. Dephosphorylating the D‐phosphopeptide by PAP forms uniform nanofibers that inhibit VCaP, a CRPC cell. A non‐hydrolyzable phosphate analogue of the D‐phosphopeptide, which shares similar self‐assembling properties with the D‐phosphopeptide, confirms that PAP‐instructed assembly is critical for the inhibition of VCaP. This work, for the first time, demonstrates PAP‐instructed self‐assembly of peptides for selective inhibiting CRPC cells.

     
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  2. Free, publicly-accessible full text available June 24, 2024
  3. A comparative study was conducted to investigate the 3.9 µm mid-IR emission properties of Ho3+doped NaYF4and CsCdCl3crystals as well as Ho3+doped Ga2Ge5S13glass. Following optical excitation at ∼890 nm, all the studied materials exhibited broad mid-IR emissions centered at ∼3.9 µm at room temperature. The mid-IR emission at 3.9 µm, originating from the5I55I6transition, showed long emission lifetime values of ∼16.5 ms and ∼1.61 ms for Ho3+doped CsCdCl3crystal and Ga2Ge5S13glass, respectively. Conversely, the Ho3+doped NaYF4crystal exhibited a relatively short lifetime of ∼120 µs. Temperature dependent decay time measurements were performed for the5I5excited state for all three samples. The results showed that the emission lifetimes of Ho3+:CsCdCl3and Ho3+:Ga2Ge5S13were nearly temperature independent over the range studied, while significant emission quenching of the5I5level was observed in Ho3+:NaYF4. The temperature dependence of the multi-phonon relaxation rate for 3.9 µm mid-IR emission in Ho3+:NaYF4crystal was determined. The room temperature stimulated emission cross-sections for all three samples were calculated using the Füchtbauer-Landenburg equation. Furthermore, the results of Judd-Ofelt analysis are presented and discussed.

     
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  4. García-Blanco, Sonia M. ; Cheben, Pavel (Ed.)
  5. The mid-IR spectroscopic properties ofEr3+doped low-phononCsCdCl3andCsPbCl3crystals grown by the Bridgman technique have been investigated. Using optical excitations at∼<#comment/>800nmand∼<#comment/>660nm, both crystals exhibited IR emissions at∼<#comment/>1.55,∼<#comment/>2.75,∼<#comment/>3.5, and∼<#comment/>4.5µ<#comment/>mat room temperature. The mid-IR emission at 4.5 µm, originating from the4I9/2→<#comment/>4I11/2transition, showed a long emission lifetime of∼<#comment/>11.6msforEr3+dopedCsCdCl3, whereasEr3+dopedCsPbCl3exhibited a shorter lifetime of∼<#comment/>1.8ms. The measured emission lifetimes of the4I9/2state were nearly independent of the temperature, indicating a negligibly small nonradiative decay rate through multiphonon relaxation, as predicted by the energy-gap law for low-maximum-phonon energy hosts. The room temperature stimulated emission cross sections for the4I9/2→<#comment/>4I11/2transition inEr3+dopedCsCdCl3andCsPbCl3were determined to be∼<#comment/>0.14×<#comment/>10−<#comment/>20cm2and∼<#comment/>0.41×<#comment/>10−<#comment/>20cm2, respectively. The results of Judd–Ofelt analysis are presented and discussed.

     
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  6. We present mid-IR spectroscopic characterization of the low-phonon chalcogenide glass, Ga2Ge5S13 (GGS) doped with Er3+ ions. Under the excitation at ∼800 nm, Er3+:GGS exhibited broad mid-IR emission bands centered at ∼2.7, ∼3.5, and ∼4.5 µm at room temperature. The emission lifetime of the 4I9/2 level of Er3+ ions in GGS glass was found to be millisecond-long at room temperature. The measured fluorescence lifetimes were nearly independent of temperature, indicating negligibly small nonradiative decay rate for the 4I9/2 state, as can be expected for a low-maximum-phonon energy host. The transition line-strengths, radiative lifetimes, fluorescence branching ratios were calculated by using the Judd-Ofelt method. The peak stimulated emission cross-section of the 4I9/2 → 4I11/2 transition of Er3+ ion was determined to be ∼0.10×10−20 cm2 at room temperature. 
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  7. A refractive index of dielectrics was modified by several methods and was known to have direct influence on optical forces in nanophotonic structures. The present contribution shows that isomerization of photoswitching molecules can be used to regulate refractive index of dielectrics in-situ. In particular, spectroscopic study of a polydimethylsiloxane–arylazopyrazole (PDMS–AAP) composite revealed that refractive index of the composite shifts from 2.0 to 1.65 in trans and cis states, respectively, of the embedded AAP. Based on this, a proposition is made for a waveguide structure, in which external UV/Vis source reversibly regulates the conformation of the PDMS–AAP core. Computational study is performed using Maxwell’s equations on buried waveguide structure. The simulation, implemented in PYTHON, sequentially utilizes empirical refractive indices of the composite in the isomeric states in lieu of regulation by a source. The simulation revealed highly confined wave propagations for injected signals of 340 and 450 nm wavelengths. It is observed that the cis state suppresses higher order mode when propagating UV wavelength but allows it for visible light. This modal tuning demonstrated that single mode can be selectively excited with appropriate waveguide dimensions. Further impact of the tuning is seen in the optical force between waveguide pair where the forces shift between attractive and repulsive in relation to the isomeric state of the PDMS–AAP core. These effects which stem from the adjustment of refractive index by photoisomerization suggests that in-situ regulation of index is achievable by successful integration of photoswitching molecules in host materials, and the current PDMS–AAP composites investigated in this study can potentially enhance nanophotonic and opto-mechanical platforms. 
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