On-chip nanofilters for biological sample pre-treatment for electrophoretic analysis of small molecules in whole blood

We present a new method for on-chip sample pretreatment based on size and charge exclusion in nanochannels formed by simple electric breakdown of poly(dimethylsiloxane) (PDMS). In contrast to previously published methods, control over pore size was achieved by setting a current limit during the breakdown step, allowing selective transport through the nanopores of different size molecules. Finally, we demonstrate the application of this method for the direct analysis of quinine in whole blood samples at clinically relevant concentrations.