MWCNTs-Beta-Cyclodextrin-reduced graphene oxide gel based electrochemical sensor for simultaneous detection of...

Accurate determination of dopamine (DA) and uric acid (UA) in biological samples is crucial in diagnosing neurodegenerative disorders and gout, respectively. Here we report a highly sensitive and inexpensive, flexible screen-printed sensor for determining DA and UA in sweat samples. Beta-cyclodextrin-based (βCD) composite gel with reduced graphene oxide (rGO) was synthesized by self-polymerization of βCD at an optimum ratio of "good" and "poor solvent". Multiwall carbon nanotubes (MWCNTs) were incorporated into the composite as a conductive filler. The MWCNTs-βCD-rGO gel provides selective biorecognition of DA and UA at the electrode surface through guest-host interaction. The gels were characterized by XRD, TGA, FTIR, UV-Vis, ¹H NMR, FESEM, XPS and optical microscopy. The flexible printed sensor showed linear DA detection in the range 0.25 to 16 μM with a correlation coefficient (R²) of 0.9890, limit of detection (LoD) of 0.08 μM and sensitivity of 3.63 μA μM^-1 cm^-2. Similarly, UA calibration showed linear detection from 50 to 700 μM with a R² value of 0.9860, LoD of 0.078 μM and sensitivity of 0.118 μA μM^-1 cm^-2. The SPE/MWCNTs-βCD-rGOsensor showed simultaneous determination of DA and UA from exercise induced sweat samples. The proposed sensor demonstrated excellent repeatability and satisfactory recoveries in human sweat.