This thesis work is focused on the design and synthesis of photo-sensitive azo derived compounds, in order to modulate biological systems with light. In the first part three chapters are presented. The first two describe the attempted approaches followed to bestow light sensitivity into glutamate receptor channels (responsible for neuronal transmission and synapses) based on PTLs without exogenous gene expresion techniques. In the third chapter the development of photochromic benzodiazepine ligands is explained to modulate GABAa receptor channels optically, responsible for inhibition of neurotransmission. The second part describes the enantioselective optical control of lipase 2 (from Bacillus Thermocathenolatus) in solid phase. Using engineering techniques we have expressed and introduced some cysteine residues close to the active catalytic site and conjugated with azobenzene and spiropyran dyes. The result is a photosensitive heterogenous biocatalysts, able to modulate its catalytic enantiopreference with different wavelenghts of light.