Conductive Mesh Electrodes for Electrochemical Biosensors

Introduction: The rate of recruiting a target analyte on a receptor-functionalized electrode is a limiting step in most electrochemical biosensors, and is predominantly diffusion-controlled. Enhancing the interaction dynamics between the target analyte and the electrode-immobilized receptors offer great potential for improving electrochemical assay parameters in terms of assay time and sensitivity. Nanostructured electrodes, such as those modified with nanoparticles, can enhance the functional surface area; however, they have a limited ratio of sample volume to electrode surface area.

Methods: We propose the use of highly conductive mesh electrodes as a solid support for the immobilization of receptors (using antibodies as a model) and apply this in an electrochemical sensor that can be used for the detection of a range of target species. This approach involves coating commercially available mesh supports with low-fouling conductive polymers, which can be further modified with bio-receptors such as antibodies, proteins, or aptamers.

Results and conclusion: These functionalized mesh electrodes are employed for the isolation and detection of target biomarkers. The system is integrated within a 3D-rpinted microfluidic chip to allow real-time isolation and detection of the analytes under continuous flow using impedimetric, voltammetric, or amperometric assays. This integrated system allows for high target recovery within the mesh-like structures, overcoming the mass transport limitations associated with conventional disc or screen-printed electrode-based electrochemical assays. Additionally, this system is applied for dual-mode target isolation, where the mesh electrode enables size-based exclusion of the target analyte, thereby improving assay specificity. This method significantly boosts the ratio of sample volume to surface area (approximately a tenfold increase compared to disc electrodes), facilitating a more effective interaction between target analytes and receptors immobilized on the electrode. This augmentation is bolstered by the flow-through format of the system, as opposed to the traditional sample incubation method used with disc electrodes.