Electrochemical aptasensor for ultrasensitive detection of lipopolysaccharide using silver nanoparticles decorated titanium dioxide nanotube/functionalized reduced graphene oxide as a new redox nanoprobe.

Abstract

Anovel and relatively simple signal-off electrochemical aptasensor was constructed for highly sensitive detection of lipopolysaccharide (LPS). For the first time, silver nanoparticles (AgNPs) decorated titanium dioxide nanotube (TNT) was conjugated with polydiallyldimethylammonium chloride (PDDA) functionalized reduced graphene oxide (rGO) to form a new nanohybrid of Ag-TNT/P-rGO. This nanohybrid with a large specific surface area exhibited excellent electrochemical activity, which not only served as the sensing platform to immobilize LPS binding aptamer (LBA) but wasalso employed as the redox probe to monitor the change of the electrochemical signal. The electrochemical signal responses were measured by cyclic voltammetry (CV) in the potential range-0.3 to 0.5V at a scan rate of 0.1V/s. The proposed aptasensor exhibited acceptable stability, reproducibility, and specificity for LPS detection with a wide linear range from 17fg/mL to 100ng/mL. Thelimit of detection (LOD) was 5fg/mL. Furthermore, the prepared aptasensor showed acceptable recovery ranging from 96% to 103%, and the RSD varied between 1.4% and 8.5% for determining LPS in real samples.Graphical abstract.