Coupling Organic Ultralong Lifetime Phosphorescence Materials with Paper-Based Bioanalytical Architectures for...

Minimizing autofluorescence is a crucial step for enhancing fluorescence-based bioanalytical assays. Although inorganic "glow-in-the-dark" persistent luminescence phosphors are commonly used to achieve this, they require rare earth elements and complex synthetic procedures. In this work, we introduce a suite of chemo- and biosensors that leverage the ultralong phosphorescence of pyrene-doped benzophenone, a fully organic host-guest material. By melt-casting the material onto cellulose, we created a modular sensor platform in which the emission is dependent on the variable absorption of the receptor-based sensor architectures. Three distinct sensing mechanisms were demonstrated: optode membranes were cast onto the paper scaffold to link ion-dependent color changes with the output, enabling "glow-in-the-dark" K⁺ and Na⁺ detection. Second, we adapted a multistep enzymatic platform for hydrogen peroxide, glucose, or lactate sensing using the peroxidase-driven oxidation of a colorimetric substrate to modulate the emission. Finally, we show that this approach also works for immunorecognition approaches by developing a paper-based enzyme-linked immunosorbent assay (ELISA) based on the same platform. The simplicity, adaptability, and low-cost fabrication of this platform highlight its potential for integrating organic ultralong phosphorescent materials into bioanalytical sensor devices for autofluorescence-free quantification. Overall, this work provides a practical framework for integrating these materials into receptor-based sensor designs.