Tyrosinase-Responsive Activated Nano-Coated Sensor for Sensitive Detection of Melanoma Biomarkers

Background: Melanoma is a highly metastatic skin cancer with occult early symptoms, making sensitive diagnostic tools essential for early intervention. Tyrosinase (TYR), a key enzyme in melanogenesis, is aberrantly secreted into the bloodstream by melanoma cells and thus serves as a promising biomarker for melanoma. However, the ultralow concentration of TYR in serum (0.066– 0.636 U/L) poses a significant challenge to conventional detection methods, highlighting the need for more sensitive detection strategies. Methods: An electrochemical biosensor was engineered using a screen-printed electrode (SPE) as the base. The SPE was modified with a nanocomposite consisting of tyramine-functionalized carboxylated multi-walled carbon nanotubes (MWCNTs-tyr), gold nanoparticles (Au NPs), and poly(3,4-ethylenedioxythiophene) (PEDOT). To validate the sensor’s performance, differential pulse voltammetry (DPV) was employed, with tests conducted in phosphate-buffered saline (PBS, pH 7.0) and murine serum samples. Results: The MWCNTs-tyr/Au NPs/PEDOT nanocomposite synergistically enhanced the sensor’s conductivity, catalytic activity, and TYR-specific binding capacity. The sensor exhibited a wide linear detection range for TYR (0.05~0.9 U/L, R2 = 0.9914), and a low detection limit of 0.0091 U/L. Additionally, it showed excellent reproducibility (5 consistent measurements at a TYR concentration of 0.1 U/L) and high specificity against common serum interferents. In tumor-bearing mice, TYR serum levels were found to correlate with tumor progression: TYR concentration was 0.084 ± 0.009 U/L when tumor volume was 68 ± 5.25 mm 3 , and increased to 0.653 ± 0.028 U/L when tumor volume reached 1280 ± 89.22 mm 3 . Conclusion: This study presents a proof-of-concept for a MWCNTs-tyr/Au/PEDOT/SPE biosensor. The platform enables rapid and sensitive detection of TYR in small-volume samples and effectively monitors tumor burden in a murine model, demonstrating its potential as a research tool for melanoma biomarker investigation. Keywords: melanoma, tyrosinase, electrochemical biosensor, multi-walled carbon nanotubes, tyramine functionalization, early diagnosis