Cerium metal organic framework mediated molecular threading for point-of-care colorimetric assays

This work prepared a Cerium metal organic framework (Ce-MOF), which exhibits colorimetric and fluorescent response for H₂O₂ simultaneously. The Ce-MOF was integrated in the origami paper SlipChip to directly analyze glucose and uric acid level in serum without sample handling or extra analytical equipment except for a smartphone. Its excellent stability in wide pH and temperature, which ranges from pH 1 to 12 and from 20 to 90 °C respectively, provides wider application prospects than conventional colorimetric strategy in the horseradish peroxidase (HRP) based detection. In colorimetric assays, the "coffee ring effect" is a fatal problem which refers to the instable and inhomogeneous color rendering, and the coating of color rendering zones by dried serum proteins also seriously hinders color reading. Herein, the anchored Ce-MOF not only solves the "coffee ring effect" by modulating the mass transport, but also constructs an ingenious bio-like barrier for selectively blocking proteins in serum. To achieve that, the externally actuated strategy and Ce-MOF mediating molecular threading-dependent transport strategy were employed. Relatively good performance of our device has been demonstrated whatever in color stability and uniformity, serum protein filtration or the direct clinical sample diagnosis.