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

Abstract

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.μM−1 and linear range of 10–90 μM (R2 = 0.99) with detection limit of 0.1013 μM. 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 μM (R2 = 0.94) with detection limit of 0.0801 μM. The prepared PANi/CQDs composite can be promising candidate material for future use as DA biosensor in real sample analysis.