Iron porphyrin-based porous organic polymer with high peroxidase-like activity as colorimetric sensor for glutathione and ascorbic acid assay.

A new iron porphyrin-based organic polymer (Fe-POP) was synthesized through the William ether reaction. The as-prepared Fe-POP presented high chemical stability, wide pore distribution, high iron content, and strong affinity with 3,3',5,5'-tetramethylbenzidine (TMB) and hydrogen peroxide (HO), which contributed to its excellent peroxidase-mimicking performance. In the presence of HO, Fe-POP could catalyze the transparent TMB into blue ox-TMB, which could be easily distinguished by the naked eyes. Moreover, glutathione (GSH) and ascorbic acid (AA) could convert blue ox-TMB into colorless TMB due to the inhibitory effect of GSH/AA to the catalytic oxidation of TMB. Based on this phenomenon, a rapid and sensitive colorimetric method for the assay of HO, GSH, and AA was developed using Fe-POP as sensor. The detection limits of HO, GSH, and AA  were 1.37, 0.44, and 0.33 μM, respectively. Finally, the colorimetric method based on Fe-POP was used to evaluate the GSH and AA content in real samples, which provided the guidance for GSH and AA supplements in our daily diet, suggesting the significant potential of Fe-POP in practical applications.