Haem-mediated albumin biosensing: Towards voltammetric detection of PFOA

• Published in: Bioelectrochemistry (Amsterdam, Netherlands) Netherlands), 2023-08, Vol.152, p.108428-108428, Article 108428
• Main Authors: Moro, Giulia, Campos, Rui, Daems, Elise, Moretto, Ligia Maria, De Wael, Karolien
• Format: Article
• Language: English
• Subjects: Albumin; Electrochemical biosensor; Haem; Hemin; Perfluoroalkyl substances; PFOA
• ISSN: 1567-5394; 1878-562X
• DOI: 10.1016/j.bioelechem.2023.108428

•The kinetics of hemin-albumin (hSA) complex formation is influence by PFOA.•The changes in hemin-hSA kinetics allowed discriminating PFOA and PFOS.•Hemin-hSA complexes were studied via UV–Vis spectroscopy and voltammetric techniques.•The electron transfer kinetics of hemin was described using Laviron formalism.•The changes in hemin electrochemical signal were correlated to PFOA levels. The haem group is a promising redox probe for the design of albumin-based voltammetric sensors. Among the endogenous ligands carried by human serum albumin (hSA), haem is characterised by a reversible redox behaviour and its binding kinetics strongly depend on hSA’s conformation, which, in turn, depends on the presence of other ligands. In this work, the potential applicability of haem, especially hemin, as a redox probe was first tested in a proof-of-concept study using perfluorooctanoic acid (PFOA) as model analyte. PFOA is known to bind hSA by occupying Sudlow’s I site (FA7) which is spatially related to the haem-binding site (FA1). The latter undergoes a conformational change, which is expected to affect hemin’s binding kinetics. To verify this hypothesis, hemin:albumin complexes in the presence/absence of PFOA were first screened by UV–Vis spectroscopy. Once the complex formation was verified, haem was further characterised via electrochemical methods to estimate its electron transfer kinetics. The hemin:albumin:PFOA system was studied in solution, with the aim of describing the multiple equilibria at stake and designing an electrochemical assay for PFOA monitoring. This latter could be integrated with protein-based bioremediation approaches for the treatment of per- and polyfluoroalkyl substances polluted waters. Overall, our preliminary results show how hemin can be applied as a redox probe in albumin-based voltammetric sensing strategies.