NIR-II photothermal-thermoelectric effect-enhanced electrochemical sensing for dopamine detection in sweat

The accurate and non-invasive detection of dopamine (DA) in sweat is crucial for the early diagnosis of neurological diseases, but the selective and sensitive detection of DA in complex biological matrices still remains a challenge. This study presents a novel screen-printed electrode based on a ternary nanocomposite of gold nanobipyramid@copper selenide@MXene nanosheets (Au NBP@Cu_2-xSe@MXene) for the highly sensitive and selective detection of DA. For the first time, Au NBPs with localized surface plasmon resonance (LSPR) in the near-infrared second window (NIR-II) are employed to enable a one-step, pretreatment-free detection strategy by leveraging the negligible background absorption of biological matrices. Under NIR-II irradiation, the Au NBP core generates an LSPR-induced photothermal effect, which can be harnessed by the Cu_2-xSe shell to generate a thermoelectric field that significantly accelerates the interfacial electrocatalytic oxidation of DA. Besides, Au NBPs can generate LSPR hot carriers, which are injected into Cu_2-xSe to participate in the redox process. Furthermore, the MXene substrate ensures efficient charge transport and structural stability. As a result, this ternary nanocomposite-based sensor exhibits a wide linear detection range for DA from 0.1 to 1000 μM. It achieves a detection limit of 0.107 μM under standard conditions, which is further reduced to 0.068 μM under NIR-II laser irradiation, demonstrating the effective signal amplification via photothermal-thermoelectric coupling. This work provides a robust and innovative material platform that integrates photothermal, thermoelectric, and electrochemical mechanisms, paving the way for the development of next-generation, high-performance wearable sensors for non-invasive health monitoring.