Bioconjugation of aptamer to fluorescent trimethyl chitosan nanoparticles for bacterial detection

Trimethyl chitosan nanoparticles (TMC NPs), the positively charged chitosan derivative, have been used to deliver medicines to overcome the tissue barrier. Here, fluorescein-labeled TMC NPs were produced by a microemulsion method following the bioconjugation of the single-strand DNA aptamer which can specifically bind to E. coli (DH5 alpha). TMC NPs show uniform spherical particles with an average diameter of 323 +/- 10 nm. The large positive zeta potential, 37.1 +/- 2.2 mV, indicates the net positive charged surface of TMC NPs which is a suitable carrier for crossing tissue barriers. The linear relationship of the maximum fluorescence intensity of aptamer modified TMC NPs and the concentration of E. coli (DH5 alpha) is obtained. We hope that the fluorescent TMC NPs integrating with a suitable aptamer could be used to understand the pathway of bacteria crossing the host barrier to fight against invasive infections. (C) 2020 Elsevier B.V. All rights reserved.