As a model analyte, lysozymeis a large, soluble protein that has been implicated as a biomarkerfor a variety of conditions, including breast cancer and Alzheimer’sdisease., Specifically, lysozyme levels are increasedin Alzheimer’s disease, where the protein interacts with amyloid-β,a peptide that drives plaque formation. We demonstrate the ability of a Mb-based electrochemical biosensorto detect lysozyme at physiologically relevant concentrations andshow that it remains stable through continuous use. Here, LYZ is linked to breast cancer.