Tetrahexahedral Au nanocrystals/aptamer based ultrasensitive electrochemical biosensor

Abstract

Herein, a very simple, label-free and highly sensitive electrochemical aptasensor for lysozyme detection based on the amplification of tetrahexahedral Au nanocrystals (THH Au NCs) was developed, in which anti-lysozyme aptamers, as the recognition element, were immobilized on a THH Au NCs/glassy carbon electrode (GCE) by means of self assembly, and redox cations [Ru(NH₃)₆]³⁺(RuHex), as the redox probe, bound to the surface via electrostatic interactions with the DNA phosphate backbone. In the presence of lysozyme, the square-wave voltammetry (SWV) response of the surface-bound RuHex changed substantially. The SWV peak current decreased with an increasing concentration of lysozyme. With Au NC modification, the plot of signal suppression against the logarithm of lysozyme concentration increased. A lower detection limit of 0.1 pM was linear over the range from 0.1 pM to 10 nM with a lower detection limit of 0.1 pM. The aptasensor also presented a high specificity for lysozyme, which was not affected by the coexistence of other proteins.