Portable electrophoretic lateral flow biosensing for ultra-sensitive human lactate dehydrogenase detection in serum samples

Lateral flow immunoassays are globally recognized for their simplicity, cost-effectiveness, and rapid qualitative and semiquantitative analyses, making them indispensable as point-of-care screening tools. However, their limited sensitivity restricts their application in clinical settings, requiring the detection of ultralow analyte concentrations in complex sample matrices. To address these challenges, we present a portable biosensing platform integrating battery-powered electrokinetic-driven microfluidics to enhance sensitivity while preserving point-of-care functionality. Our lightweight (151 g), 3D-printed electrophoretic device (€82) supports the simultaneous analysis of three samples and operates with an ultra-low power consumption of 225 mAh⁻¹, enabling 44 h of operation on a single charge. By optimizing key parameters such as Joule heating, buffer evaporation, and electroosmotic flow, the device enables iterative incubation and washing steps directly on the nitrocellulose strip, capabilities unattainable with conventional capillarity-driven LFIAs. This advanced biosensing platform achieves a detection limit of 70 pg mL⁻¹ for human lactate dehydrogenase (h-LDH), a key cancer biomarker, using gold nanoparticles as signal transducers. This result means a 367-fold improvement in sensitivity. Offering rapid, cost-effective, and ultra-sensitive biomarker quantification, this approach holds significant promise for transforming precision medicine, particularly in monitoring LDH-related cancer therapies.