Modification of microfluidic paper-based devices with dye nanomaterials obtained by encapsulation of compounds in Y and ZSM5 zeolites

Zeolite nanostructures were used as hosts for dyes normally used in some bioassays (pH and protein), and applied on microfluidic paper-based analytical devices (μPADs). The obtained dye nanomaterials were characterized by several techniques (structural (FTIR and XRD), surface (SEM/EDX), textural (N₂ adsorption) analyses and dye loading determination by TGA analysis), to confirm the stability of both host and guest. After their deposition on the paper's surface, the color change was studied by analyzing the RGB values, taking into account the lifetime and the results stability of the μPADs. These results confirmed that both the lifetime and the color change of the modified devices were stable over one week. It was also demonstrated that the choice of the paper for the μPAD as well as the zeolite nanostructures properties influences the colorimetric response. This strategy by encapsulating dyes into zeolites solve current challenges in colorimetric sensors in where long-term stability of the colorimetric results is an issue. The results obtained were promising for the studied assays, and the strategy could also be extended to other bioassays.