Gold-loaded nanoporous iron oxide nanocubes: a novel dispersible capture agent for tumor-associated autoantibody analysis in serum

Autoantibodies are produced against tumor associated antigens (TAAs) long before the appearance of anysymptoms and thus can serve as promising, non-invasive biomarkers for early diagnosis of cancer.Current conventional methods for autoantibody detection are highly invasive and mostly providediagnosis in the later stages of cancer. Herein we report a new electrochemical method for earlydetection of p53 autoantibodies against colon cancer using a strategy that combines the strength ofgold-loaded nanoporous iron oxide nanocube (Au@NPFe2O3NC)-based capture and purification whileincorporating the inherent simplicity, inexpensive, and portable nature of the electrochemical and naked-eye colorimetric readouts. After the functionalisation of Au@NPFe2O3NC with p53 antigens, our methodutilises a two-step strategy that involves (i) magnetic capture and isolation of autoantibodies usingp53/Au@NPFe2O3NC as‘dispersible nanocapture agents’in serum samples and (ii) subsequent detectionof autoantibodies through a peroxidase-catalyzed reaction on a commercially available disposablescreen-printed electrode or naked-eye detection in an Eppendorf tube. This method has demonstrated agood sensitivity (LOD = 0.02 U mL−1) and reproducibility (relative standard deviation, %RSD = <5%, forn=3)for detecting p53 autoantibodies in serum and has also been successfully applied to analyse a small cohortof clinical samples obtained from colorectal cancer. We believe that the highly inexpensive, rapid, sensitive,and specific nature of our assay could potentially aid in the development of an early diagnostic tool forcancer and related diseases