Many toxic analytes including phenols and pesticides have a relatively low solubility in water and therefore, their detection and quantification is usually performed in organic medium. Since most biological sensors are designed to operate in aqueous medium, there is an increased need to develop organic phase biosensors (OPB). In a biosensor design, high concentrations of organic solvent can lead to the inactivation of the biomolecule, probably due to changes in protein structure. One possible way to protect biomolecules from the denaturing effect of organic solvents would be through encapsulation in a hydrophilic polymer network. This presentation will focus on the use and advantages of natural biopolymers for entrapping enzymes for enhancing stability and activity of OPB. The biopolymer membrane could effectively retain the essential hydration layer around the enzyme necessary for maintaining its activity in organic phase. We studied and compared the activity of immobilized enzymes in different types of non-aqueous solvents and we optimized the conditions to produce biosensors with maximum activity and stability for toxicity monitoring.