QCM immunoassay for recombinant cysteine peptidase: A potential protein biomarker for diagnosis of citrus canker

► A potential new biomarker for citrus canker was proposed. ► Anti-CPXaC produced in rabbits was immobilized on quartz crystal. ► A label-free immunosensor for CPXaC detection was developed. ► The piezoelectric immunosensor presented good specificity and selectivity.