Electrochemical temperature-controlled switch for nonenzymatic biosensor based on Fe3O4-PNIPAM microgels

• Published in: Journal of electroanalytical chemistry (Lausanne, Switzerland) Switzerland), 2019-10, Vol.851, p.113410, Article 113410
• Main Authors: Wang, Yin-zhu, Zhong, Hui, Li, Xiao-rong, Zhang, Xue-qiong, Cheng, Zhi-peng, Zhang, Zai-chao, Zhang, Yu-jie, Chen, Ping, Zhang, Li-li, Ding, Lian-shu, Wang, Ji-kui
• Format: Article
• Language: English
• Subjects: Biosensors; Electrocatalytic; Electrochemical impedance spectroscopy; Electrodes; Fe3O4-PNIPAM; H2O2; Hydrogen peroxide; Iron oxides; Isopropylacrylamide; Microgels; Nanoparticles; Nonenzymatic; Oxidation; Peroxidase; Photon correlation spectroscopy; Stimuli; Switchable
• ISSN: 1572-6657; 1873-2569
• DOI: 10.1016/j.jelechem.2019.113410

The objective of the study is to construct a stimuli responsive membrane on the electrode and regulate the bioelectrocatalysis of hydrogen peroxide by temperature stimulation. Fe3O4-poly(N-isopropylacrylamide) microgels (Fe3O4-PNIPAM microgels) were prepared and developed as temperature-controlled nonenzymatic electrochemical switchable hydrogen peroxide biosensors in this study. The microgels were fabricated through a two-step way and characterizations such as scanning electron microscopy (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC), dynamic light scattering (DLS) were used to prove the microgels. Then, Fe3O4-PNIPAM microgels were assembled to the electrode surface and the switchable electrochemical function relating to temperature stimuli was illustrated by electrochemical impedance spectroscopy (EIS). Cyclic voltammetry (CV) study showed a switchable electrocatalytic activity towards the oxidation process of H2O2 between 26.0 and 37.0 °C due to peroxidase-like behaviour of Fe3O4 nanoparticles (Fe3O4 NPs) and temperature-sensitive properties of PNIPAM. On the basis of concept, we constructed a switchable biosensor for the detection of H2O2. Under optimal conditions, we successfully detected H2O2 as low as 0.005 μM at 26.0 °C and 0.01 μM at 32.0 °C. By using Fe3O4 NPs instead of enzyme to construct the switchable biosensor in the experiment, the operation is simple and the strategy meets the demands of switchable biosensors when used in bioscience and biotechnology, which broadens the applications of electrochemical switching biosensors. The temperature-controlled nonenzymatic electrochemical switchable sensor was proposed for the detection of H2O2 based on Fe3O4-PNIPAM microgels. When the temperature was lower than the lower critical solution temperature (LCST) of PNIPAM, Fe3O4-PNIPAM expanded, causing Fe3O4NPs to be exposed on the electrode surface, which could catalyze the oxidation of H2O2 and yield an “on” state. When the temperature was higher than the LCST of PNIPAM, Fe3O4-PNIPAM shrinked and Fe3O4 nanoparticles were encapsulated inside PNIPAM. Therefore, Fe3O4 NPs were unable to electrocatalyze H2O2 on the electrode surface and resulted in a “closed” state. This nonenzymatic electrochemical sensor was used to simulate the switch behavior of the enzyme in vitro, which provided a new idea for exploring the electron transfer of the enzyme in vivo. [Display omitted] •Fe3O4-poly(N-isopr