the present invention provides a method of detecting a biological agent including contacting a sample with a sensor including a polymer system capable of having an alterable measurable property from the group of luminescence , anisotropy , redox potential and uv / vis absorption , the polymer system including an ionic conjugated polymer and an electronically inert polyelectrolyte having a biological agent recognition element bound thereto , the electronically inert polyelectrolyte adapted for undergoing a conformational structural change upon exposure to a biological agent having affinity for binding to the recognition element bound to the electronically inert polyelectrolyte , and , detecting the detectable change in the alterable measurable property . a chemical moiety being the reaction product of a polyelectrolyte monomer and a biological agent recognition element - substituted polyelectrolyte monomer is also provided .