Liposome encapsulated electron donor strategy for signal-on CYFRA 21-1 photoelectrochemical analysis.

Abstract

Anovel electron donor controlled-release system is proposedbased on liposome encapsulated L-cysteine for the sensitive determination of cytokeratin 19 fragment21-1 (CYFRA 21-1). On the one hand, a defective TiO2 modified with methylene blue was employed as a photoactive platform which exhibited a high photoelectrochemical (PEC) response owing to the introduction of oxygen vacancies and the high photosensitivity of the dye. On the other hand, L-cysteine as the sacrificial electron donor was encapsulated in the vesicles of liposomes, and this composite was used as the signal amplification factor, which is labeled on the secondary antibody of CYFRA 21-1 to further improve the photocurrent sensitivity. The excellent electron transfer path in photoactive materials coupled with the skilful electron donor controlled-release system, contributed to the sensitive PEC analysis of CYFRA 21-1 underoptimumconditions. The PEC immunoassay showed a linear current response in the range 0.0001-100ng/mL with a detection limitof37fg/mL. Enhanced stability and satisfactory reproducibility were also achieved. The proposed concept provides a novel signal-on strategy for the sensitive detection of other cancer markers in the electrochemical sensing field.