Green Portable Stochastic Sensor With Poly‐Arginine and Bimetallic Nanoparticles on Reduced Graphene Oxide for Simultaneous AFP and CA 72‐4 Detection in Gastric Cancer

Alpha‐fetoprotein (AFP) and carbohydrate antigen 72‐4 (CA 72‐4) are among the most clinically relevant biomarkers in gastric cancer, providing critical pre‐ and postoperative information to clinicians. To address the limitations of conventional assays, we developed a portable, green stochastic sensor based on a screen‐printed carbon electrode (SPCE) modified with poly‐arginine (poly‐Arg) and Pd–Ni@rGO bimetallic nanoparticles for the simultaneous determination of AFP and CA 72‐4 in diverse biological samples. Pd–Ni@rGO nanoparticles were synthesized via a facile chemical reduction technique. The sensor exhibited wide linear dynamic ranges and ultralow limits of quantification (LOQ), ranging from 3 × 10 −16 to 3 × 10 −7 mg mL −1 (LOQ: 3 × 10 −16 mg mL −1 ) for AFP and 4 × 10 −11 to 4 × 10 −8 U mL −1 (LOQ: 4 × 10 −11 U mL −1 ) for CA 72‐4. Comparative analysis using the Student's t ‐test confirmed no statistically significant difference between the results obtained with the proposed sensor and reference methods at a 99% confidence level. The greenness and applicability of the method were further validated using GAPI, AGREE, and BAGI assessment tools, confirming both low environmental impact and strong practical utility. This work represents a significant advancement in electrochemical sensing, providing an innovative and sustainable strategy for clinically relevant AFP and CA 72‐4 detection.