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The purpose of this paper is to study the immobilization of porcine pancreatic lipase (PPL), in an organic matrix by a covalent cross-linking method to sense propylparaben (PP) present in aqueous solution.

PPL immobilization was performed by the covalent cross-linking method, using bovine serum albumin (BSA) in the presence of saturated glutaraldehyde vapor (GA). The preparation of the enzymatic membrane involves the incorporation of porcine pancreatic lipase (PPL), bovine serum albumin (BSA) and glycerol into a phosphate buffer solution (PBS). Characterization of this sensor was performed by impedance spectroscopy (EIS) and scanning electron microscope (SEM). The effect of experimental conditions such as PPL activity, potential, scan rate, PP concentration, pH and presence of interfering elements were studied by cyclic voltammetry.

Under the optimal experimental conditions, a number of significant factors were optimized. The method exhibited good linearity in the range of 10^–14 to 10^–9 mol/L with a good correlation coefficient of 0.957, detection limit (LOD) of 3.66 × 10^–15 mol/L and high sensitivity of 1.086 mA mol⁻¹L. The authors also obtained a very good coverage rate of the surface equal to 91.44%, and hydrolytic activity of lipase is evaluated to 26.64 mmol min⁻¹. The stability and the interference were also evaluated. The equivalent circuit used to explain the electrochemical behavior of modified electrode is a Randle circuit.

The main application of biosensors is the detection of biomolecules that are either indicators of a disease. For example, electrochemical biosensing techniques can be used as clinical tools to detect breast tumors, because these compounds (PP) were found in breast tumors.

The result registered in this paper indicates that the developed sensor is an efficient, fast, simple and inexpensive analytical tool that can be used for the analysis of water containing PP.