The portable stochastic sensor as a screening tool for simultaneous determination of HER-1 and CA 125 — a key factor in the rapid recognition of gastric cancer

The significance of HER-1 and CA 125 lies in their ability to guide cancer diagnosis, treatment, and monitoring, improving personalized care and enhancing prognostic accuracy. The utilization of HER-1 and CA 125 as screening biomarkers for the anticipation of early-stage cancer and monitoring cancer progression is expanding due to the invasive and costly nature of present techniques. In this study, a novel stochastic sensor was developed for the simultaneous determination of HER-1 and CA 125 in whole blood, saliva, and gastric tumor tissue samples using a fast, easy, inexpensive, and portable method. The stochastic sensor was prepared by electropolymerization of cysteine on the surface of the Au-TiO₂@rGO/SPCE sensor. The Au-TiO₂@rGO nanocomposite was synthesized using a simple chemical reduction process. The proposed sensor showed wide linear concentration ranges and very low limits of quantification (LOQ). The concentration ranges were from 3.9 × 10⁻¹⁴ to 3.9 × 10⁻⁸ µg mL⁻¹, with a LOQ of 3.9 × 10⁻¹⁴ µg mL⁻¹ for HER-1. For CA 125, the concentration ranges were from 8.3 × 10⁻¹⁴ to 8.3 × 10⁻¹⁰ U mL⁻¹, with a LOQ of 8.3 × 10⁻¹⁴ U mL⁻¹. Both biomarkers exhibit precise discrimination in different biological samples, with recoveries above 96.78% and RSD values below 0.04%. With a confidence level of 99%, the Student t-test revealed that there is no statistically significant difference between the outcomes obtained by using the poly-Cys/Au-TiO₂@rGO/SPCE sensor for screening examinations of biological samples. This was determined because the results were not significantly different from one another.