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Creators/Authors contains: "Ahn, Kyo Han"

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  1. Abstract

    Aryl alcohol‐type or phenolic fluorophores offer diverse opportunities for developing bioimaging agents and fluorescence probes. Due to the inherently acidic hydroxyl functionality, phenolic fluorophores provide pH‐dependent emission signals. Therefore, except for developing pH probes, the pH‐dependent nature of phenolic fluorophores should be considered in bioimaging applications but has been neglected. Here we show that a simple structural remedy converts conventional phenolic fluorophores into pH‐resistant derivatives, which also offer “medium‐resistant” emission properties. The structural modification involves a single‐step introduction of a hydrogen‐bonding acceptor such as morpholine nearby the phenolic hydroxyl group, which also leads to emission bathochromic shift, increased Stokes shift, enhanced photo‐stability and stronger emission for several dyes. The strategy greatly expands the current fluorophores’ repertoire for reliable bioimaging applications, as demonstrated here with ratiometric imaging of cells and tissues.

     
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  2. Abstract

    Aryl alcohol‐type or phenolic fluorophores offer diverse opportunities for developing bioimaging agents and fluorescence probes. Due to the inherently acidic hydroxyl functionality, phenolic fluorophores provide pH‐dependent emission signals. Therefore, except for developing pH probes, the pH‐dependent nature of phenolic fluorophores should be considered in bioimaging applications but has been neglected. Here we show that a simple structural remedy converts conventional phenolic fluorophores into pH‐resistant derivatives, which also offer “medium‐resistant” emission properties. The structural modification involves a single‐step introduction of a hydrogen‐bonding acceptor such as morpholine nearby the phenolic hydroxyl group, which also leads to emission bathochromic shift, increased Stokes shift, enhanced photo‐stability and stronger emission for several dyes. The strategy greatly expands the current fluorophores’ repertoire for reliable bioimaging applications, as demonstrated here with ratiometric imaging of cells and tissues.

     
    more » « less
  3. Abstract

    A major obstacle in luminescence imaging is the limited penetration of visible light into tissues and interference associated with light scattering and autofluorescence. Near‐infrared (NIR) emitters that can also be excited with NIR radiation via two‐photon processes can mitigate these factors somewhat because they operate at wavelengths of 650–1000 nm where tissues are more transparent, light scattering is less efficient, and endogenous fluorophores are less likely to absorb. This study presents photolytically stable, NIR photoluminescent, porous silicon nanoparticles with a relatively high two‐photon‐absorption cross‐section and a large emission quantum yield. Their ability to be targeted to tumor tissues in vivo using the iRGD targeting peptide is demonstrated, and the distribution of the nanoparticles with high spatial resolution is visualized.

     
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