Laser-fabricated disposable electrodes for electrochemical cardiac diagnostics
Cardiovascular disease remains the leading cause of mortality worldwide, placing increasing pressure on healthcare systems and highlighting the need for rapid, low-cost diagnostic solutions. Laser-driven microfabrication offers a powerful route to engineer electrochemical biosensing interfaces with tuneable morphology, conductivity, and unique surface functional groups for attaching receptors and biomolecules. Here, we report the fabrication and evaluation of two low-cost electrode platforms: planar laser-ablated gold (LAG) and gold nanostructure-modified laser-induced graphene (LIG) electrodes for biosensing C-reactive protein (CRP), an important cardiac biomarker. LIG was produced via semiconductor laser photothermal carbonization of polyimide, producing a porous sp2-rich conductive network and subsequently Au nanostructures were deposited to obtained LIG-Au electrode. Scanning electron microscopy reveals a hierarchical three-dimensional architecture for LIG-Au, in contrast to the relatively planar metallic surface of LAG. Differences in peak-to-peak separation and redox current magnitude in electrochemical measurements are attributed to variations in surface roughness, effective surface area, and underlying graphene support. Thiolated CRP-specific DNA aptamers were covalently immobilized, and the sensing performance of the LAG and LIG-Au was systematically investigated. Both aptasensors exhibited a detection limit of 50 ng ml−1 with clinically relevant linear detection ranges of 100–5000 ng ml−1 for LAG and 250–5000 ng ml−1 for LIG-Au. This work shows that the laser-printing technologies are powerful low-cost fabrication tools to produce affordable electrodes for diagnosing cardiac biomarkers.