bead from the sample dna side 51 to the condensing agent protamine or protein side 52 of the flow cell 50 as shown in fig3 an optical trap generally indicated at 60 is operatively mounted to common channel 53 of flow cell 50 of fig2 the optical trap is shown holding a bead 61 of a dna molecule 54 in the condensation side 52 containing the protamine solution 56 as seen in fig2 by way of example the bead 61 is 1 u03bcm and the wavelength of the infrared optical trap is 488 nm since optical traps are known in the art further description thereof is deemed unnecessary to provide an understanding of the invention the change in length verses time for four different dna molecules indicated at a b c amp d as they condensed in different concentrations of protamine is shown in fig4 the tests were conducted with a flow speed v 50 u03bcm s with a being 3 1 u03bcm b being 1 6 u03bcm c being 1 2 u03bcm and d being 0 93 u03bcm experiments conducted at different protamine concentrations showed that the rate of condensation was limited by the rate of protamine binding to the dna molecule the change in rate see fig5 was linear with a slope of 2 6 u00b1 0 47 u03bcm u03bcm s this corresponds to a rate of protamine binding to dna of 600 u00b1 110 molecules u03bcm s the rate of condensation was measured at two different concentrations of yoyo 1 0 1 and 0 02 u03bcm to determine whether intercalated yoyo 1 molecules affect the condensation rate no statistically significant difference in the rates was observed the condensation rates of fig5 were determined by collecting data for about 200 individual dna molecules.