Abstract: In one non-limiting aspect, the invention provides a method for detecting the quality of a biological molecule comprising forming a first mixture of ingredients comprising: (i) a first binding agent that specifically binds to a tag, wherein the first binding agent is attached to a solid support; (ii) a decoy comprising a first portion comprising the tag attached to a second portion comprising an anchor; (iii) a sensor attached to a second binding agent that specifically binds to the anchor; and (iv) a sample suspected of containing a high quality biological molecule comprising a tag, wherein the tag of the high quality biological molecule is accessible; allowing interaction of the ingredients such that the sensor provides an output signal.