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    Photocatalytically renewable peptide-based electrochemical impedance method for sensing lipopolysaccharide

    Year: 2020

    Journal: Microchim. Acta, Volume 187, MAY 27

    Authors: Yang, Limin; Gao, Yukun; Fang, Kai; Sun, Hui; Sun, Jingtao; Liu, Hanyun; Feng, Weihua; Jiang, Lei

    Keywords: Titanium dioxide (TiO2); 5,10,15,20-Tetrakis(4-aminophenyl)-21H,23H-porphine (TAPP); Gold nanoparticle (AuNP); Electrochemical impedance spectroscopy (EIS); Renewable electrode surface

    A peptide (Li5-025)-modified gold nanoparticle (AuNP)/(titania (TiO2) + 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphine (TAPP))/glassy carbon electrode (GCE) was developed for lipopolysaccharide (LPS) determination. This electrode not only performs well in the electrochemical impedance determination of LPS in serum but can also be easily regenerated under light irradiation. Using Fe(CN)(6)(3-/4-) as a redox probe, LPS recognition can be indicated by the significantly increased electron-transfer resistance (R-et) as a result of the coaction of the increased steric hindrance from the peptide-LPS complex and the electrostatic repulsion between LPS and Fe(CN)(6)(3-/4-). The impedimetric signal was acquired in the frequency range 0.1 Hz similar to 100 kHz with an initial voltage of 174 mV and an amplitude of 10 mV. The resistance changes (Delta R-et) are linearly related to the LPS concentrations in a broad range (0.1 pg mL(-1) similar to 100 ng mL(-1)) with a low detection limit (0.08 pg mL(-1)). Importantly, the electrode shows high selectivity to LPS from Escherichia coli O55:B5 compared to other bacterial sources and considerable anti-interference to 0.1% fetal calf serum, demonstrating its potential application in clinically relevant samples. Another highlight is that the AuNP/(TiO2 + TAPP)/GCE surface can be photocatalytically regenerated under light irradiation (50 mW cm(-2), 300-2500 nm) without any obvious damage to the electrode microstructure. After simple peptide re-immobilization, the regenerated electrode demonstrates LPS response similar to the peptide less one, and the deviation is only 2.89% after 5-cycle reuse.
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