Highly Reusable Electrochemical Immunosensor for Ultrasensitive Protein Detection

• Published in: Advanced Sensor Research Vol. 3; no. 9
• Main Authors: Singampalli, Kavya L., Neal – Harris, Camille, Yee, Cassian, Lin, Jamie S., Lillehoj, Peter B.
• Format: Journal Article
• Language: English; Catalan
• Published: Wiley-VCH 01.09.2024
• Subjects: CXCL9; diagnostic; electrochemical; gold nanoparticles; immunosensor; magnetic nanoparticles; reusable
• ISSN: 2751-1219; 2751-1219
• DOI: 10.1002/adsr.202400004

The detection and quantification of protein biomarkers in bodily fluids is important for many clinical applications, including disease diagnosis and health monitoring. Current techniques for ultrasensitive protein detection, such as enzyme‐linked immunosorbent assay (ELISA) and electrochemical sensing, involve long incubation times (1.5–3 h) and rely on single‐use sensing electrodes which can be costly and generate excessive waste. This work demonstrates a reusable electrochemical immunosensor employing magnetic nanoparticles (MNPs) and dually labeled gold nanoparticles (AuNPs) for ultrasensitive measurements of protein biomarkers. As proof of concept, this platform is used to detect C‐X‐C motif chemokine ligand 9 (CXCL9), a biomarker associated with kidney transplant rejection, immune nephritis from checkpoint inhibitor therapy, and drug‐associated acute interstitial nephritis, in human urine. The sensor successfully detects CXCL9 at concentrations as low as 27 pg mL−1 within ≈1 h. This immunosensor was also adapted onto a handheld smartphone‐based diagnostic device and used for measurements of CXCL9, which exhibited a lower limit of detection of 65 pg mL−1. Lastly, this work demonstrates that the sensing electrodes can be reused for at least 100 measurements with a negligible loss in analytical performance, reducing the costs and waste associated with electrochemical sensing. This work reports a highly reusable electrochemical immunosensor for ultrasensitive measurements of protein biomarkers. This immunosensor is based on a unique sensing scheme employing antibody‐labeled magnetic nanoparticles and dually labeled gold nanoparticles, enabling rapid immunomagnetic enrichment and enhanced signal amplification. Furthermore, the sensing electrodes can be reused for at least 100 measurements with a negligible loss in analytical performance.