Peptide Terminated Polymer Brush Nanomaterials for Label‐Free Separation of Cancer Cells Based on Relative Adhesion

ABSTRACT

Separation of cell types from complex tissue‐derived populations is a priority goal in biomedical research with direct implications for medical diagnostics and bioprocessing. Dense poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) brush films synthesized by surface‐initiated atom transfer radical polymerization yield a linear growth rate of 0.83 nm min ^{− 1} and thicknesses up to 120 nm. Quartz crystal microbalance with dissipation monitoring confirms suppression of non‐specific protein adsorption from fetal bovine serum. Terminal azide functionalization followed by strain‐promoted copper‐free click chemistry enables immobilization of linear Arg‐Gly‐Asp (linRGD) and cyclic (cRGD) peptides at independently tunable densities, a design space of brush thickness, peptide density, and RGD conformation not previously achieved in microfluidics. Integration into polydimethylsiloxane microfluidic channels with a progressive force ramp (0–25 dynes cm ^{− 2} ) achieves selective displacement of A375 melanoma from A2780 ovarian cancer cells with 88 ± 15% recovery and >93% viability. Differential focal adhesion maturation underlies separation: A375 cells express 29.7% lower α5β1 integrin density and form nascent adhesions retracting at 120 min (actin falls 37%), whereas A2780 cells develop mature focal adhesions with 92% and 125% increases in talin and actin. This platform transduces integrin profiles and cytoskeletal competence into measurable adhesion phenotypes, enabling precise, gentle label‐free cell separation.