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Development of a microwave-based biosensor to detect anti-p53 antibodies as a biomarker for early detection of colorectal cancer

Resumen en inglés

Colorectal cancer (CRC) remains a leading cause of morbidity and mortality worldwide, with early detection playing a critical role in improving patient outcomes. This thesis develops a label-free microwave-based biosensor for detecting anti-p53 antibodies, a biomarker of early CRC. The biosensor employs a transduction mechanism in the microwave region based on stepped impedance resonators integrated into a microstrip line, enabling precise dielectric permittivity measurements and facilitating the detection of biomolecular interactions. The biosensor utilizes a 3,3′-Dithiodipropionic acid di(N-hydroxysuccinimide ester) (DTSP) self-assembled monolayer to covalently immobilize p53 proteins on the sensor surface, ensuring high specificity and sensitivity. Analytical evaluations revealed a linear working range from 0 to 1250 pg/mL and a detection limit of 315.29 pg/mL, making it clinically relevant for early CRC diagnosis. Cross-reactivity studies demonstrated the biosensor's exceptional specificity and selectivity, distinguishing anti-p53 antibodies from potential interferents such as cytokines, antibodies, and small molecules. The biosensor's performance was further validated against the gold-standard ELISA method, achieving a strong correlation with a 0.97 correlation coefficient. Recovery rates of 87.2 to 97.2% and relative standard deviations between 1.5 and 4.3% highlight the biosensor's accuracy and reproducibility. Likewise, stability assessments confirmed consistent performance over two weeks, with minimal variation, underscoring the robustness of the biosensing surface. This master thesis demonstrates that the proposed microwave-based biosensor is a robust, efficient, and cost-effective platform for detecting anti-p53 antibodies. It represents a significant advancement in biosensor technology, offering a practical and accessible solution for early cancer diagnostics and contributing to the broader field of biomedical sensing. The use of cost-effective copper-based materials, combined with the simplicity and scalability of the microwave technology, underscores the biosensor's potential for point-of-care applications. Its compact design, rapid detection capabilities, and compatibility with decentralized diagnostic systems make it a promising tool for improving CRC screening, particularly in resource-limited settings. Future work will focus on expanding the biosensor's applicability to additional biomarkers and refining its integration into clinical workflows