2025 ICIEST

This research seeks to develop an innovative 3D-printed biosensor for the rapid and accurate detection of Escherichia coli (E. coli) bacteria in water samples. The proposed biosensor will incorporate a flow cell design, which allows continuous monitoring and efficient detection of E. coli in real-time. The sensor will be fabricated using conductive polymer-based materials integrated with specific biological recognition elements to ensure high sensitivity and specificity. The 3D printing technology will be utilized to create a precise and reproducible flow cell structure, optimizing the sensor's functionality and scalability. The research will proceed through several key phases: designing and simulating the flow cell structure, selecting and functionalizing the sensing materials, fabricating the biosensor using 3D printing techniques, and conducting extensive testing with water samples containing various concentrations of E. coli. This research will establish a foundation for future advancements in portable and effective biosensing devices for early detection of bacterial contamination.

The increasing prevalence of pathogenic Escherichia coli (E. coli) in water and food sources poses a significant threat to public health, necessitating the development of rapid and accurate biosensor detection methods such as aptamerbased biosensors due to their high specificity and sensitivity. Aptamers are nucleic acids that can bind with high affinity and specificity to a range of target molecules. In this study, 1,000 shuffled variants of a known aptamer (PDB ID: 2AU4) were generated and evaluated for stability using RNAfold and RNALfoldz based on minimum free energy (MFE). The five most stable sequences were selected and analyzed for their secondary and tertiary structures using RNAComposer. The target protein, Shiga toxin (Stx, PDB ID: 1C48), was modeled with AlphaFold 3 and validated through Ramachandran plot analysis. Molecular docking using the HDOCK server revealed aptamer-protein binding interactions, offering insights into the structural features that influence binding specificity and stability. In conclusion, this research bridges theory for future applications, thereby establishing a theoretical framework to support the future development of aptamer-based biosensors targeting E. coli O157:H7.