A Facile synthesis of superparamagnetic Fe3O4 nanofibers with superior peroxidase-like catalytic activity for sensitive colorimetric detection of l-cysteine

Superaramagnetic Fe 3 O 4 nanomaterials are good candidates as enzyme mimics due to their excellent catalytic activity, high stability and facile synthesis. However, the morphology of Fe 3 O 4 nanomaterials has much influence on their enzyme-like catalytic activity. In this work, we have developed a simple polymer-assisted thermochemical reduction approach to prepare Fe 3 O 4 nanofibers for peroxidase-like catalytic applications. The as-prepared Fe 3 O 4 nanofibers show a higher catalytic activity than commercial Fe 3 O 4 nanoparticles. The steady-state kinetic assay result shows that the Michaelis–Menten constant value of the as-obtained Fe 3 O 4 nanofibers is similar to that of horseradish peroxidase (HRP), indicating their superior affinity to the 3,3′,5,5′-tetramethylbenzidine (TMB) and H 2 O 2 substrate. Based on the outstanding catalytic activity, a sensing platform for the detection of l- cysteine has been performed and the limit of detection is as low as 0.028 μM. In addition, an excellent selectivity toward l- cysteine over other types of amino acids, glucose and metal ions has been achieved as well. This work offers an original means for the fabrication of superparamagnetic Fe 3 O 4 nanofibers and demonstrates their delightful potential applications in the fields of biosensing, environmental monitoring, and medical diagnostics.