Split biosensor based on nano-enzymatic ferrocene-tyramine deposition reaction for detection of SMP30 antibody.

The tumor-associated autoantibody against senescence marker protein-30 (SMP30) serves as a critical serum biomarker for the early detection of hepatocellular carcinoma (HCC), enabling rapid and non-invasive cancer diagnosis and monitoring. However, the accurate detection of the SMP30 antibody remains challenging due to the complex composition of blood and the heterogeneity of circulating antibodies. This study introduces a highly sensitive and straightforward method for SMP30 antibody detection, utilizing a graphene oxide-Hemin (GO-Hemin) composite nano-mimetic enzyme in combination with ferrocenyl-tyramine (Fc-Tyr)-mediated tyramine signal amplification (TSA) within microtiter wells. A solid-phase protein with high affinity selectively captures the SMP30 antibody, while the target is identified via nano-mimetic enzyme labeling of a secondary antibody. The subsequent nano-enzymatic reaction facilitates the deposition of Fc-Tyr, generating a strong electrochemical signal. The biosensor achieves high sensitivity through enhanced electrochemical transduction and minimal spatial resistance at the electrode interface. By integrating immunocapture specificity with electrochemical amplification, this approach enables high-throughput analysis in clinical applications. Experimental results demonstrate that this biosensor can detect smp30 antibodies at concentrations as low as 0.1086 ng/mL, with a detection range spanning 0.1 ng/mL to 1 μg/mL. Analysis of authentic serum samples confirmed that when combined with ELISA, the sensor accurately measured SMP30 antibody levels in serum samples from clinical hepatocellular carcinoma patients. The results demonstrated consistent detection outcomes with recovery rates ranging from 93 % to 104 % and relative standard deviations (RSD) between 1.2 % and 3.7 %. This platform provides a practical and efficient tool for detecting SMP30 antibodies and holds broader application potential in tumor marker monitoring and cancer diagnosis.