Comparing UV-enhanced and direct reduction strategies for CD8⁺ T-cell electrochemical detection.

A novel electrochemical biosensor was developed for accurate and sensitive detection of CD8+ T cells, as a key biomarker in clinical and immunological analysis. A screen-printed electrode was modified through 20 cycles of electrodeposition using two approaches: a reduced graphene oxide-polypyrrole composite (A20) and graphene oxide reduced under UV irradiation during polymerization (B20). Characterization analysis indicated that A20 exhibited improved structural uniformity and a higher relative abundance of carboxyl groups compared to B20 sample. These features achieved through a simple and cost-effective fabrication process, significantly improved the electrochemical performance of A20, making it as an optimal sensing platform. The A20-based biosensor detected CD8+ T cells with limit of detection 1.19 × 104 cells.mL-1, which the results aligned with flow cytometry by 97%, confirming its precise accuracy. Further experiments using CD20+, CD19+ and CD4+ cells confirmed the biosensor's selectivity. This study introduces a simple, scalable process for creating composites that greatly enhances the sensitivity of biosensors. Because it is affordable and easy to produce, this biosensor is well-suited for clinical and laboratory use, and also creates opportunities for developing sensors that detect other cellular biomarkers.