An Electrochemical Biosensor for Detecting Calreticulin In Situ to Assess Immunogenic Cell Death in Tumor Cells

Immunotherapies centered on inducing immunogenic cell death (ICD) hold promise for overcoming the limitations of current conventional cancer treatments and enable the maximal eradication of residual tumor cells within patients. In this study, by using the unique performance of a porous etched zeolitic imidazolate framework-8 incorporating a methylene blue (eZIF-8@MB) probe and a reduced graphene oxide-multiwalled carbon nanotube (rGO-MWCNT) nanocomposite, we established an electrochemical biosensor that can specifically detect the changes of calreticulin (CRT) on living cells and analyze different stages of ICD. The ICD cellular model was established and confirmed via various conventional techniques. The morphology and performance of the nanocomposite were thoroughly characterized. Differential pulse voltammetry revealed the rapid, sensitive, and stable responses of CRT with a good linear relationship within the cell concentration range of 10² to 10⁶ cells mL^-1. We successfully constructed the ICD mouse model and applied the biosensor to detect differential CRT stages across cancer tissues. This study facilitates the applications of electrochemical sensing techniques in the precise analysis of the progress of ICD, thereby offering a novel method and tool for evaluating ICD-based cancer therapies and screening related pharmaceutical agents.