Encapsulation of tyrosinase within liposome bioreactors for developing an amperometric phenolic compounds biosensor

Abstract

A novel tyrosinase (Tyr) biosensor based on liposome bioreactor and chitosan (CS) nano-composite has been developed for the detection of phenolic compounds. Liposome-based bioreactors were prepared by encapsulating the enzyme Tyr in l-α-phosphatidylcholine liposome resulting in spherical bioreactor with a mean diameter of 8.5 ± 1.25 μm. The encapsulation efficiency and drug loading content of the Tyr-loaded liposome-based bioreactors were about 46.35 ± 0.85 and 41.15 ± 0.95 %, respectively. Porins were embedded into the lipid membrane, allowing for the free substrate transport, but not that of the enzyme due to size limitations. The glassy carbon electrode (GCE) was alternately immersed in CS and Tyr liposome bioreactor (TLB) to assemble bilayer films [(CS/TLB)/GCE]. The presence of Tyr in the biosensor was confirmed by scanning electron microscopy, cyclic voltammetry, and electrochemical measurements. The results indicated that the biosensor was applied to detect phenol with a broad linear range from 0.25 nM to 25 μM, the detection limit was brought down to 0.091 nM. The apparent Michaelis–Menten constant, Km, for the enzymatic reaction was 34.78 μM. The novel biosensor exhibits good repeatability and stability. Such new biosensor based on encapsulation of Tyr within liposome bioreactors shows great promise for rapid, simple, and cost-effective analysis of phenolic contaminants in environmental samples. The proposed strategy can be extended for the development of other enzyme-based biosensors.