Development of a Porous Silicon-Based Optical Biosensor for Multiplex Detection of Biomarkers Integrated with a 3D-Printed Microfluidic System
Abstract: ** Lecture will be given in English**
Porous silicon (PSi)-based optical biosensors are attractive platforms for label-free biomarker detection because of their large internal surface area, tunable nanostructure, and compatibility with optical transduction. However, the broader implementation of PSi biosensors in real-world applications is often limited by two major challenges: hindered mass transport within the porous matrix and biofouling caused by nonspecific adsorption in complex biological media. These challenges reduce sensitivity, selectivity, reproducibility, and dynamic range, particularly when detecting low-abundance biomarkers in clinically relevant samples.
This work addresses these limitations using a PSi Fabry–Pérot aptasensor platform for lactoferrin (LF), a biomarker associated with gastrointestinal (GI) inflammation. First, we have rationally optimized the porous nanostructure to improve analyte transport to and withing the sensor. Integration with microfluidic mixing devices enhanced convection and LF delivery to the sensor interface and significantly improved sensitivity, reducing the limit of detection from 50 nM under diffusion-dominated conditions to 3 nM under active mixing. The second part of this research focused on improving the biosensor performance in complex GI fluids. Conventional PEG passivation was insufficient to prevent biofouling, leading to a marked loss of sensitivity. To overcome this limit, zwitterionic E/K-rich peptides were covalently immobilized onto the PSi surface. These coatings provided superior resistance to nonspecific adsorption and restored the aptasensor performance in GI fluid, improving LF limit of detection from 600 nM to 49 nM, comparable to the response achieved in buffer solution.
Finally, robotic microspotting was employed to create a multiplexed sensing platform through spatially resolved immobilization of LF-specific aptamers and aptamers for additional targets. This generated spatially resolved sensing domains and demonstrated the feasibility of multiplexed detection on a single PSi chip. Collectively, these advances establish a scalable PSi-based lab-on-chip platform for sensitive and multiplexed biomarker detection in complex biological samples.
