In vivo monitoring of the neurotransmitter dopamine can potentially improve the diagnosis of neurological disorders and elucidate their underlying biochemical mechanisms. While electrochemical sensors can detect unlabeled dopamine molecules, their sensing performance is dramatically reduced by electrochemical currents generated by other, interfering molecules (e.g., uric acid) in the biological environment. To overcome this caveat, the surface of the sensor is often modified with electrocatalytic materials, which are encapsulated inside a polymeric film; however, the effect of the encapsulating film on the sensing performance of the electrode has not been systematically studied. This study characterizes the effect of loading carbon nanotubes (CNTs) onto a chitosan film on the electrochemical sensing performance of dopamine in the presence of uric acid. Higher CNT loading increases the diffusion and electron transfer rate coefficients of the sensor and, in the presence of uric acid, provides better sensitivity (3.00 µA L µmol⁻¹ for 1.75% CNT loading, vs 0.01 µA L µmol⁻¹ for 1% loading) but a poorer limit-of-detection (2.00 µmol L⁻¹ vs 1.00, respectively), as reported here for the first time. These findings can help optimize the sensitivity and the limit-of-detection of electrochemical sensors in complex biofluids to enable an in vivo monitoring of dopamine and other redox-active molecules.

体内监测神经递质多巴胺可以潜在地改善神经系统疾病的诊断并阐明其潜在的生化机制。尽管电化学传感器可以检测到未标记的多巴胺分子，但由于生物环境中其他干扰分子（例如尿酸）产生的电化学电流，其传感性能会大大降低。为了克服这一警告，通常用电催化材料对传感器的表面进行修饰，这些材料被封装在聚合物膜内。然而，尚未系统地研究封装膜对电极感测性能的影响。这项研究的特征是在尿酸存在下将碳纳米管（CNTs）负载在壳聚糖膜上对多巴胺的电化学传感性能的影响。^如1.75％的CNT负载为^-1，而0.01 ％的Lµmol ^-1为1％的负载，但检测限较差（分别为2.00 µmol L ^-1 和1.00），如此处首次报道。这些发现可以帮助优化复杂生物流体中电化学传感器的灵敏度和检测限，从而能够对多巴胺和其他氧化还原活性分子进行体内监测。