In this study a low cost and low complexity optical detection method of proteins is presented by employing a detection scheme based on electrostatic interactions, and implemented by sensitization of a polymer optical fiber (POF) surface by thin overlayer of properly designed sensitive copolymer materials with predesigned charges. This method enables the fast detection of proteins having opposite charge to the overlayer, and also the effective discrimination of differently charged proteins like lysozyme (LYS) and bovine serum albumin (BSA). More specifically, as sensitive materials here was used the block and the random copolymers of the same monomers, namely the block copolymer poly(styrene-b-2vinylpyridine) (PS-b-P2VP) and the corresponding random polymer poly(styrene-r-2-vinylpyridine) (PS-r-P2VP), of similar composition and roughly similar molecular weight. Moreover, this work focused on the comparison of the aforementioned sensitive materials regarding the way in which they can adapt on sensing optical platforms and constitute functional sensing bio-materials.