Multiplexed biomarker detection with porous silicon-based aptasensors in 3D printed microfluidic devices

Sofia Arshavsky-Graham ^1,2 Shanny Ackerman ¹ Omer Sabah ¹ Niklas Maximilian Epping ² Thomas Scheper ² Janina Bahnemann ² Ester Segal ^1,3

¹Department of Biotechnology and Food Engineering, Technion – Israel Institute of Technology, Haifa, Israel
²Institute of Technical Chemistry, Leibniz Universität Hannover, Hanover, Germany
³The Russell Berrie Nanotechnology Institute, Technion – Israel Institute of Technology, Haifa, Israel

Our work presents for the first time the integration of porous silicon (PSi)-based optical aptasensor for protein detection in a 3D-printed microfluidic platform and its application for multiple biomarker detection. PSi is a nanostructured material that has been utilized as an optical transducer in many biosensing platforms, offering significant advantages of high internal surface, tunable nanostructure and simple fabrication. Importantly, it enables real-time and label-free analyte detection, minimizing the need for additional sample pre-treatment steps. Microfluidic integration has the potential to improve the performance of PSi-based optical biosensors, as well as promoting their translation to point-of-care settings. PSi has been integrated with microfluidic devices constructed by soft lithography techniques, which are expensive, labor intensive and do not allow a design change without repeating the whole fabrication process. 3D printing technology offers to simplify the fabrication process into a single step, allowing for rapid customization of microfluidics at low cost.

Herein, an oxidized PSi (PSiO₂) thin film is chemically functionalized with aptamer molecules for specific capture of his-tagged proteins, used as a model system. Microfluidic devices are printed using a commercial MultiJet 3D printer with a transparent acrylic material and bonded to the PSiO₂ aptasensor via an UV-curable adhesive. Successful bonding is characterized by optical microscopy and high-resolution scanning electron microscopy. Target detection is carried out by real time monitoring of the PSiO₂ reflectivity spectrum, using a standard spectrometer. The microfluidic integration results in improved biosensing performance, in terms of sensitivity, by at least one order of magnitude compared to conventional experimental setups. The microfluidic device is further designed for simultaneous detection of several protein targets in a single sample, via an aptasensor microarray.