High-ionic-strength pre-concentration via ion concentration polarization for blood-based biofluids

Ion concentration polarization (ICP) preconcentration is a pretreatment method that is actively utilized in the analysis of low-abundance biomolecules. In biofluids (e.g. urine, sweat, blood, serum, plasma, saliva, etc.), low-concentrated target analytes presented among large number of background molecules under a high ionic concentration, there still exist several hurdles in the utilization of ICP preconcentration in the such high ionic fluids. This is especially true in the case of blood-based biofluids, such as plasma and serum, wherein on account of the abundance biomolecules as well as high ionic buffer concentration makes the ICP preconcentration process difficult to realize. In this study, we have demonstrated the realization of ICP preconcentration of blood-based biofluids (serum) using a paper-based preconcentrator. We acquired preconcentration factors (PF) for 25.5, 127.5 and 255 mM of human serum were 40, 10, and 5.5 within 20 min. The squared fluorescence intensity is also found to be inversely proportional to ionic concentration, showing that the PF are strongly correlated to the Debye length of the buffer solution. Using the paper-based preconcentrator, we were able to acquire effective preconcentration factor (PFeff) of 5.17, 4.88, 4.58, and 4.23 for the 1X, 0.75X, 0.5X, and 0.1X diluted solutions, demonstrating approximately 5 times increase in PFeff for all prepared human serum samples.