Tyrosinase-encapsulated liposomes: Toward enzyme-induced in situ sensitization of semiconductor for sensitive photoelectrochemical immunoassay

Abstract

Liposomal photoelectrochemical (PEC) bioanalysis holds enormous potential for future sensitive PEC bioanalysis. With tyrosinase (Tyr) and TiO₂ as representative enzyme and electrode, respectively, this communication reports the elegant use of Tyr-loaded liposomes (TLL) toward in situ sensitization of the electrode and thereby the realization of ultrasensitive PEC immunoassay. Specifically, Tyr-encapsulated and detection antibody-functionalized liposomes were first prepared and used as the signal probe. The subsequent sandwich immunobinding could confine the functional liposomes, which were then lysed with surfactant to release the encapsulated Tyr. The free Tyr could then initiate the transformation of tyrosine to dopa, the latter could bind with the undercoordinated Ti sites, forming the stable dopa-Ti charge transfer complex and thus generating enhanced anodic photocurrent under visible light for signaling. Since different semiconductors and enzymes may be adapted into this format, this work is expected to stimulate more interest in the enzyme-induced activation of semiconductors for advanced liposomal PEC bioanalysis.

Keywords: Bioanalysis; Liposome; Photoelectrochemical; TiO(2); Tyrosinase.