Development of dopamine biosensor based on polyaniline/carbon quantum dots composite

Low level of dopamine (DA) in human brain may lead to neurological diseases, therefore, detection of DA is necessary. This study aims to develop 2 types of DA biosensor, i.e., electrochemical and fluorescent biosensors based on conducting polymer and quantum dot composite. The polyaniline/carbon quantum dots (PANi/CQDs) composite was prepared and characterized by UV-Vis absorption spectroscopy, fluorescence spectroscopy, FT-IR spectroscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). For electrochemical biosensor, the electrospun nanofiber film of PANi/CQDs was fabricated on fluorine doped tin oxide (FTO)-coated glass substrate. Cyclic voltammetry and amperometry were performed to study the electrochemical activity of the PANi/CQDs film toward detection of DA in neutral solution. The obtained film showed good sensitivity for DA sensing with sensitivity of 8.025 nA.cm(-2).mu M(-1)and linear range of 10-90 mu M (R-2 = 0.99) with detection limit of 0.1013 mu M. In addition, for fluorescent biosensor, the fluorescent intensity of PANi/CQDs in PBS solution was quenched with increasing DA concentrations. The PANi/CQDs fluorescent biosensor presented the linear range of 0.1-100 mu M (R-2 = 0.94) with detection limit of 0.0801 mu M. The prepared PANi/CQDs composite can be promising candidate material for future use as DA biosensor in real sample analysis.