Integrated Microfluidic Device With MXene Enhanced Laser-Induced Graphene Bioelectrode for Sensitive and Selective Electroanalytical Detection of Dopamine

Microfluidic Electrochemical biosensors present promising means for many critical biosensing applications such as neurotransmitter monitoring, pathogen detection, and molecular diagnostics. However, such biosensors are prone to many challenges like enzyme degradation being the major concern with electrode materials while testing multiple times, hindered detection limit range, low sensitivity due to direct contact of enzyme with the environment, and poor shelf life of the electrodes patterned by conventional techniques. Herein, a microfluidic multi-sensitive biosensor is developed using a layer-by-layer process, incorporating a novel Laccase/MXene/LIG (L-Ti
₃
C
₂
-G) composite designed for selective detection of dopamine and other biochemicals with applicability in human blood serum and synthetic urine. 2D nano-material, MXene, gave an excellent conductivity, more volumetric capacity, flexibility, surface hydrophilicity, and temperature stability, leading to its use in various applications. It was found that laccase immobilized electrode (L-Ti
₃
C
₂
-G) showcased a significant electrocatalytic activity towards biomolecules such as uric acid (0.12 V), L-cysteine (0.62 V), xanthine (0.7 V), ascorbic Acid (0.1 V), and dopamine (0.42 V). For dopamine alone, the proposed biosensor exhibits a LOD of 0.47 nM with a linear concentration range of 1 nM –
$10~\mu \text{M}$
and 6.37 mA nM
⁻¹
cm
⁻²
sensitivity. Moreover, real sample analysis indicated that spiked dopamine can be determined accurately by the electrode with a recovery ratio of more than 97% in synthetic urine and human blood serum samples. The fabricated bioelectrode had high stability and reproducibility with an exceptional selectivity and negligible interference with various biochemicals.