Sensitive aptasensing of Lysozyme using a polymeric and metalLic nanostructured platform

Lysozyme is an enzyme present in multiple organisms where it plays various vital roles. One of the most important relies on its antibacterial activity, being also called the body’s own antibiotic. Despite its proven utility, lysozyme can potentially trigger allergic reactions in sensitive individuals, even in trace amounts, thus the need of continue monitoring of lysozyme in products rich in lysozyme like wine or egg white is of high importance [1].

In this work, an electrochemical aptasensor was designed for the flow analysis of lysozyme. Firstly, polylysine, polydopamine and poly(lysine-co-dopamine) were electrodeposited at screen printed carbon electrodes (SPCE) in order to obtain a more structured platform with higher electroactive area. The best architecture was further chosen for sensor development. Next, gold nanostructures (nanoleaves) were electrodeposited from a mixture of HAuCl₄ and PEG 6000 solution for enhanced electrocatalytic effect and to serve as immobilization platform for the thiolated aptamer [2]. All platforms were electrochemically and morphologically characterized.

For lysozyme detection, the best platform in terms of electronic conductivity was selected for the 1^st aptamer immobilization within the thiol group from its 3’-end, followed by a blocking step of the remaining free sites of the gold nanoleaves with 6-mercaptohexanol. Next, after the lysozyme solution was dropped casted on the electrode surface and the aptamer-target reaction was performed, a 2^nd aptamer, labelled with biotin, bounds also the lysozyme to obtain a sandwich assay. Further, streptavidin-alkaline phosphatase (ALP) reacted with the biotin bounds to the 2^nd aptamer. For lysozyme quantification, ALP oxidised the substrate, 1-naphtil phosphate and the resulting signal was registered using differential pulse voltammetry.

References

[1] A. Vasilescu, Q, Wang, M. Li, R. Boukherroub, S. Szunerits, Chemosensors, 2016, 4(2), 10

[2] M. Negahdary, H. Heli, Talanta, 2019, 198, 510-517.

Acknowledgements

Ghorghe Melinte thanks: UMF “Iuliu Hațieganu” Cluj-Napoca, for internal grant no. 2462/37/17.01.2020