Silk-polyurethane composite based flexible electrochemical biosensing platform for pathogen detection

The upcoming era of flexible and wearable electronics necessitates the development of low-cost, flexible, biocompatible substrates amenable to the fabrication of active devices such as electronic devices, sensors and transducers. While natural biopolymers such as Silk are robust and biocompatible, long-term flexibility is a concern due to the inherent brittle nature of soft Silk thin films. This work elucidates the preparation and characterization of Silk-polyurethane (Silk-PU) composite film that provides long-duration flexibility. More importantly, an electrochemical biosensing platform is developed by creating a three-electrode system using a screen-printing technique. The solvents in the Ink had little impact on the film. As a proof of concept, the detection of E. coli, a highly infectious pathogen, was demonstrated using screen-printed electrodes (SPEs) modified with gold nanoparticles. This method effectively detected E. coli across a wide range of concentrations, with a detection limit of 0.12 CFU/mL. The entire surface functionalization and detection process did not impact the Silk-PU substrate. Even after rigorous bending tests, the results were consistent, demonstrating the robustness and flexibility of the Silk-PU film. The platform demonstrated is scalable and amenable for multi-pathogen detection as it not only can integrate several working electrodes, each catering to detection of a particular pathogen, but also serve as a platform for lab-on-chip devices wherein PDMS-based microfluidics can be seamlessly integrated along with the proposed platform.