Unlocking the potential of NH2-MIL-101 (Fe) nanoMOF for advanced electrochemical immunosensing in chronic wound diagnostics

Abstract

In this work we take advantage, for the first time, of the porous and functional structure of a nanoscale metal organic framework (nanoMOF), specifically NH2-MIL-101 (Fe) nanoMOF, for its use as advantageous enzyme-carrier nanotag in immunoassays. In particular, the porous structure of the nanoMOF allows accommodating a high loading of enzyme molecules, which, in addition, are protected from degradation inside the pores providing a high stability. This property together with the ability of the nanoMOF to link antibodies through its functional groups make it a very robust and powerful label. Both the enhanced sensitivity, compared with the conventional use of enzyme-labelled antibodies, and the high long-term stability are demonstrated. Such nanotag also offers advantages related to ease of modification and cost effectiveness. The detection of myeloperoxidase (MPO), a key biomarker for chronic wound monitoring, is proposed to demonstrate the applicability of this approach. A sandwich-type immunoassay using magnetic beads (MBs)-based platforms and subsequent amperometric detection allows the determination of MPO in the clinical range (5 – 100 ng mL−1), with a limit of detection of 1.4 ng mL−1, and good reproducibility (RSD(n = 10) = 7.1 %). The developed bio-strategy also exhibits high selectivity against potential interferents and a good stability of the nanotag for at least 2 months. Moreover, the developed method was successfully implemented to determine MPO in simulated chronic wound matrices, demonstrating its feasibility in a real scenario.