Monodisperse carboxy polystyrene (PS) spheres were synthesized and utilized as an interface to increase the detection sensitivity of some biomolecules. The binding behavior of dacarbazine (DTIC), an anticancer drug, with DNA bases in the absence and presence of the PS spheres was investigated. The results indicated a remarkable effect of PS on the binding behavior of DTIC to DNA bases and significantly enhanced detection sensitivity for the relative biomolecular recognition.