Surfactant-induced morphological evolution of Cu(II) metal organic frameworks: Applicable in picomolar quantification of bilirubin

Highlights: • Cu-organic framework (Cu-MOF) was synthesized via solvothermal technique. • Tunable morphological structures of Cu-MOFs were developed by diverse surfactants. • Surfactants@Cu-MOFs were modified on electrode surfaces for bilirubin oxidation. • Sensor displayed a wide linear range (1 nM–100 µM) and low detection limit (124 pM). • Practical application was demonstrated in human whole blood and urine samples. From a clinical point of view, excessive bilirubin (BR) level in the human body can cause diseases such as jaundice, liver failure, and mental disorders. Therefore, a quantitative detection of BR is an important indicator of liver health. In this study, a non-enzymatic detection of BR biosensor is reported based on a tunable morphological structure of various surfactant-capped Cu-metal organic frameworks (Cu-MOFs). The Cu-MOF was prepared by a solvothermal synthetic route. The structures and properties were tuned by varying different surfactants including polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB) and sodium hydroxymethylglycinate (SHMG). The prepared surfactants@Cu-MOFs were monitored by FE-SEM and they showed well-defined colloidosomes, spherical, dot-spherical and sponge-like morphological structures. Under optimized acquisition parameters, the catalytic performance of the different surfactants@Cu-based MOF was as follows: Cu-MOF < SHMG@Cu-MOF < SDS@Cu-MOF < CTAB@Cu-MOF < PVP@Cu-MOF. A wide linear range (1 nM–100 µM) and a low LOD (124 pM) was obtained for BR quantifications at PVP@Cu-MOF/GCE. The PVP@Cu-MOF was shown to be an excellent interference-free electrocatalyst against BR. Finally, the modified electrode was effectively used for the quantitative determination of BR in the sample of biological human fluids, and the obtained results were validated by spectrophotometer method.