Efficient delivery,Of growth factors is one of the great challenges, of tissue engineering. Polyelectrolyte multi layer films (PEM) made of biopolymers have recently emerged as an interesting carrier for delivering recombinant human bone morphogenetic protein 2 (rhBMP-2 noted here BMP-2) to cells in a matrix bound manner: We recently showed that PEM made Of poly(1,:lysine) and hyaluronan (PLL/HA) Can retain high and tunable quantities of BMP-2 and can deliver it to cells to induce their differentiation in osteoblasts. Here, we investigate quantitatively by Fourier, transform infrared spectroscopy (FTIR) the secondary structure of BMP-2 in solution as Well as trapped,in,a biopolymeric thin filth. We reveal that the major structural L elements of BMP-2 in solution are intramolecular beta-sheets and unordered. structures as well as alpha-helices Furthermore, We studied the secondary structure of rhBMP-1 trapped in :hydrated : films and in dry films since drying is an important step for future applications of these bioactive films onto orthopedic biomaterials. We demonstrate that the structural elements were preserved when BMP-2 was trapped in the biopolymeric-film in hydrated conditions and, to a lesser extent, in dry state. Importantly, its bioactivity was maintained after drying of the film. Our results appear highly promising for future applications of these films as coatings of biomedical materials, to deliver bioactive proteins while preserving their bioactivity upon storage in dry state.