3,3′,5,5′-tetramethylbenzidine-based quadruple-channel visual colorimetric sensor array for highly sensitive discrimination of serum antioxidants

A quadruple-channel visual colorimetric sensor array has been developed to discriminate serum antioxidants. The redox reaction between 3,3′,5,5′-tetramethylbenzidine (TMB) and sodium hypochlorite (NaClO) can successively generate colorful products with strong absorption at different wavelengths. The presence of five antioxidants containing glutathione, cysteine, lipoic acid, melatonin, and uric acid disrupts the redox reaction between TMB and NaClO, giving birth to distinct colorimetric response patterns. By taking advantage of principal component analysis, the five antioxidants are identified with an accuracy of 100%. The sensor array is capable of visually discriminating different concentrations of the same antioxidant and binary mixtures of two antioxidants as well as working well in real fetal bovine serum. The distinguishable lowest concentration of antioxidants using this sensor array is 1 μM, which is about one or three orders of magnitude lower than that of the recently reported colorimetric sensor array.