Multiplexed Fluorescent Microarrays on MIL‐101(Cr) Thin Films as Luminescent Probes for pH and Disease‐Associated Molecules

Recently, metal-organic frameworks (MOFs) have shown high potential in the field of sensing. However, fluorescent-based detection with MOFs in solution needs complex pre-treatments and has stability issues, complicating measurements and handling for sensing applications. Here, an easy-to-handle and low-cost strategy is introduced to convert MOF-based sensing from solution to surface using scanning probe lithography. The MOF is immobilized on the surface by receding meniscus coating, and then fluorescent dyes are patterned on the MOF thin films through microchannel cantilever spotting to generate dye@MOF fluorescent microarrays, which are stable in analyte solutions. The dye@MOF fluorescent microarrays exhibit good pH sensitivity in the pH 5-9 range, and dopamine can be distinguished from three other metabolites in the solution by these microarrays when signals from different dyes are analyzed in combination with principal component analysis. This concept provides a new approach for stable microarray-based detection of small molecule analytes from a fluid environment.