Intelligent Quantification of Picomolar Protein Concentration in Serum by Functionalized Nanopores

Nanopores have been well established as a promising platform for real time stochastic detection of single biomolecules and have made sufficient commercial progress in terms of DNA sequencing. Amongst the various strategies for specific protein estimation in physiological analyte, aptamer functionalized nanopores have been reported to quantify proteins down to few picomolars in control solution. In this paper, we explore the quantification of target protein in serum down to picomolar concentration using aptamer functionalized nanopores. For such cases, the current settles to a new value in multiple steps due to the low dissociation constants of the receptors and the final current blockade sensitivity is the primary indicator of target protein concentration. It has been observed that the current sensitivity histograms not only have a statistical variation (due to the fluctuations in the device fabrication) but also overlap significantly between the different concentration ranges in the picomolar regime, which makes quantification challenging. Here, we introduce probabilistic fuzzy model based on Monte Carlo simulation and demonstrate its ability by quantifying thrombin down to 50-pM concentration in undiluted serum. The method has been verified with 25 test solutions and the results reveal the potential of this computational approach toward lowering the detection limit by three orders of magnitude compared with the existing status, thus enabling the functionalized glass nanopore platform makes great progress toward clinical testing.