Designed "DNA carriers" have been proposed as a new method for nanopore based specific protein detection. In this system, target protein molecules bind to a long DNA strand at a defined position creating a second level transient current drop against the background DNA translocation. Here, we demonstrate the ability of this system to quantify protein concentrations in the nanomolar range. After incubation with target protein at different concentrations, the fraction of DNA translocations showing a secondary current spike allows for the quantification of the corresponding protein concentration. For our proof-of-principle experiments we use two standard binding systems, biotin-streptavidin and digoxigenin-antidigoxigenin, that allow for measurements of the concentration down to the low nanomolar range. The results demonstrate the potential for a novel quantitative and specific protein detection scheme using the DNA carrier method. ; Other ; The authors thank Howarth Lab, Oxford for providing the monovalent streptavidin sample, Yizhou Tan for the help with Labview programs, and Dr. Janet Kumita for the help with FP measurement. J. Kong acknowledges funding from Chinese Scholarship Council and Cambridge Trust. N.A.W.B. acknowledges funding from an EPSRC doctoral prize award and an ERC starting grant (Passmembrane 261101); U.F.K. acknowledges support from an ERC starting grant (Passmembrane 261101).