We intend to study the aggregation behaviour of the all-conjugated block catiocopolyelectrolyte PF2/6-P3MAHT in the presence of the biomacroanion guanosine triphosphate (GTP) in D2O.Preliminary SANS studies indicated that on addition of a charge excess of GTP, the PF2/6-P3MAHT confomation tends towards 2D sheet-like aggregates. Our main objective for this experiment is to determine the solution structure of PF2/6-P3MAHT as a function of the GTP mole fraction (above and below the charge neutrality point) using SANS. We will also study the effect of anion size and charge by performing a series of complementary experiments using the mono- and di-phosphate analogues GMP and GDP. Changes in the polymer conformation in the presence of these anions induces a dramatic change in the photophysical properties, which willbe exploited to develop an bioanion sensing platform.