(302a) Nanofluidic Systems for Concentration and Detection of Biomolecules

Recent developments in fabrication technology allow one to reliably build nanofluidic channels and filters with critical dimension around ~10nm, fully integrated with microfluidic channel systems in an arbitrary manner. These nanochannels act as perm-selective membrane such as Nafion(R), which are widely used in diverse applications. Such nanochannels can be used in lieu of polymeric membrane, much much higher mechanical stability. In addition, experiments done in such nanochannels can provide important insights about complex membrane and interface phenomena. In this talk, several recent examples of nanofluidic engineering will be presented, including the nanofluidic enhancement of biomolecule binding kinetics. One of the bottlenecks of the current bioassay is the diffusive transport limitation (between the target molecule and surface-mount antibody) at low target molecule concentrations. Nanofluidic channels can be used to enhance surface binding reactions, since the target molecules are confined to the surfaces which are coated with specific binding partners. Moreover, diffusion-limited binding can be significantly enhanced if the molecules are steered into the nanochannels via either pressure-driven or electrokinetic flow. By monitoring the nanochannel impedance, which is sensitive to surface binding, low analyte concentrations have been detected electrically in nanofluidic channels within response times of 1-2 hours. This represents a ~54 fold reduction in the response time using convective flow compared to diffusion-limited binding. At high flow velocities the presented method of reaction kinetics enhancement is potentially limited by force-induced dissociations of the receptor-ligand bonds. Optimization of this scheme could be useful for label-free, electrical detection of biomolecule binding reactions within nanochannels on a chip.