Polydiacetylene-supported silica films formed at the air/water interface

► Thin films of silica and polydiacetylene were assembled at the air/water interface. ► Polydiacetylene facilitated formation of the “free-standing” silica film. ► The two components are essential for film stability and homogeneity. ► The unique colorimetric properties of PDA were retained in the mixed films. ► The silica/PDA films were employed for bacterial detection.