Self-assembled films containing crude extract of avocado as a source of tyrosinase for monophenol detection.

This paper reports on the use of the crude extract of avocado (CEA) fruit (Persea americana) as a source of tyrosinase enzyme. CEA was immobilized via layer by layer (LbL) technique onto indium tin oxide (ITO) substrates and applied in the detection of monophenol using a potentiometric biosensor. Poly(propylene imine) dendrimer of generation 3 (PPI-G3) was used as a counter ion in the layer by layer process due to its highly porous structure and functional groups suitable for enzyme linkage. After the immobilization of the crude CEA as multilayered films, standard samples of monophenol were detected in the 0.25-4.00 mM linear range with approximately 28 mV mM(-1) of sensitivity. This sensitivity is 14 times higher than the values found in the literature for a similar system. The results show that it is possible to obtain efficient and low-cost biosensors for monophenol detection using potentiometric transducers and alternative sources of enzymes without purification.