Specif-ically, the folding of aptamers conjugated to the surface of PDAliposomes around target biomolecules results in the formation of of bulky aptamer-target groups which repulse one another. This stericrepulsion at the liposomes surface disrupts the stabilizing hydro-gen bonds between the PDA pendant side chains and translatesinto perturbations at the PDA backbone, which cause the liposometo change from blue to red [15,16,33].