A membrane-based plasma separator coupled with ratiometric fluorescent sensor for biochemical analysis in whole blood

Herein, we reported an integrated device that was utilized to directly separate plasma and analyze glucose (Glu), cholesterol (Chol) from whole blood samples. The separating module primarily consists of a porous asymmetric polysulfone membrane. The vertical placement of membrane and the gravity settlement of blood cells can reduce mechanical damage to blood cells and blockage of the membrane, resulting in improved separation efficiency of the membrane. The detection module consists of a smart phone and a ratio fluorescence sensing system based on NH₂−MIL-53(Al) and o-phenylenediamine (OPD). The sensing system presents a dual emission response to H₂O₂ the main oxidation product of Glu and Chol. Due to the fluorescence resonance energy transfer (FRET), the response of the fluorescence intensity ratio (F_{574 nm}/F_{434 nm} or F_{554 nm}/F_{434 nm}) gradually increases with increasing H₂O₂ concentration, accompanied by a color change from weak to strong. The visual detection of Glu and Chol can be realized through the recognition of RGB values by smart phones. The integrated device has been successfully used to analysis Glu and Chol in real blood samples, which provided a universal platform for sensing biocatalytic processes with H₂O₂ production.