Tailor-Made Porous Materials for the Capturing of Biomolecules and Cells

Porous materials are an extremely technologically attractive and unique class of materials for interaction with low abundance biomarkers due to their highly specific surfaces. When the high porosity of a material is coupled with functionalization for specific interaction with molecules in a penetrating fluid, porous materials can present a powerful tool for many applications in bioanalytics. In this work, two design philosophies were combined and utilized for the development of porous materials: precise pore definition and high surface-to-volume ratio. In the former case, nickel bioaffinity membranes fabricated via a combination of photolithography and electrochemistry with specified pore sizes and locations were developed for CTC isolation. The membranes were primed with a phosphonic acid to add C,H groups for surface attachment of a polystyrene layer via the C,H insertion crosslinking (CHic) reaction with a thermal crosslinker (PS-co-MAz) followed by a layer of PDMAA-co-MABP. EpCAM antibodies were added via streptavidin-biotin bridges for specific interaction with CTCs. Demonstration of the CTC isolation capabilities at very low cell counts (< 10 cells) of MCF-7 cells (as model CTCs) in 7.5 ml and 50 ml of whole blood indicated nearly perfect capture efficiencies. In the second scenario, paper-like fiber mats were fabricated via electrospinning, producing core-sheath fibers with non-swelling cores from PMMA-co-MABP and hydrogel sheaths from PDMAA-co-MABP. The polymers utilized included CHic crosslinker groups (MABP), allowing for improvements to the fiber thermal and solvent stability, and wetting properties. This material was then used in a lateral flow assay for borreliosis with OspC and Bb VlsE1 as the biomarkers, and fluorescence as the readout. Signal-to-background ratios of 4:1 could be achieved. This material was then adapted for a CTC capture by functionalizing with anti-EpCAM, exhibiting high potential as an isolation membrane.