Development of the microfluidic Lab-on-a-Foil platform for pre-analytical separation of human IgG

Serological diagnostics, crucial for disease detection and monitoring, rely on qualitative antibody tests for viral infections (e.g., COVID-19, HIV), bacterial infections, and autoimmune diseases. Immunoenzymatic assays from whole blood often encounter errors due to sample complexity. While pre-separation protocols mitigate these issues, they are costly and time-consuming. Small-scale IgG purification currently involves complex manual processes using microplates coated with bacterial protein, extending analytical time. To address this, cost-effective microfluidic devices using simple technology and materials are being developed, enabling the miniaturization of advanced analytical systems compatible with optical and electrochemical detection. This innovation holds promise for enhancing serological diagnostics by streamlining IgG separation and contributing to the construction of more efficient health monitoring systems.

The presented study investigates the construction of low-cost, flexible and disposable platforms for rapid separation of whole serum antibodies by their reversible capture using protein A/G immobilized on polyester foil substrates. A simple microsystem is fabricated by laser cutting and bonding biomedical films, while the flow is generated by an external pump. The process of capturing and eluting antibodies from the sample is based on a pH-controlled sequence of injections carried out entirely in a single-channel microfluidic system. In addition, a microfluidic mixer module is developed to allow neutralization of the pH of the eluate.

The developed system allows pre-treatment of small-scale samples prior to their further use in bioanalytical assays (e.g., ELISA, lateral flow or homophasic agglutination tests). The developed, simple and versatile IgG separation module can also find application in more advanced, integrated μTAS systems for the analysis of serological profiles or capture of antibody-antigen complexes.