Interplay of surface nanotopography and tether flexibility towards analyte capture by tethered receptors

• Nanotopography and tether flexibility- both improve analyte capture on affinity biosensors. • Impact of nanotopography differs for receptors attached to flexible or rigid tethers. • High analyte capture densities observed at tallest nanotopographies for rigid tethers. • High analyte capture densities even at the shortest nanotopographies for flexible tethers. • The findings are generic, and independent of the nature of analyte-receptor interactions. • Nano-QCM is an indispensable tool to investigate nanotopography⬄analyte interactions. Engineering topography and chemistry at the molecular length scale holds significant potential to control analyte binding at the biosensing interface. Here, we investigate the influence of nanotopography on analyte capture, by receptors tethered to the sensor surface via rigid or flexible tethers. Two different scenarios for analyte binding are investigated, viz. gold nanoparticles (as pseudo analyte) to aminated surfaces and neutravidin to biotinylated surfaces. The findings reveal the impact of nanotopography to be different depending on whether the amine or biotin receptors were bound to surface via rigid or flexible tethers. In case of rigid tethers, the nanotopography was found to have an influence beyond what could be attributed to the increase in surface areas. When flexible tethers were used, the increase in analyte capture could be attributed to the increase in surface areas as well as an increase in analyte capture efficiencies due to flexible tethers. The findings highlight the nanotopography and tether flexibility as having unique potential to maximize analyte capture efficiencies on affinity biosensors. The use of nano-QCM sensors exhibiting well-defined, periodic nanotopographies proved indispensable to real-time, label-free quantification of analyte⬄nanostructure interactions at the nano biosensing interface.