A self-oriented beacon liquid crystal assay for kanamycin detection with AuNPs signal enhancement

Abstract

The authors report a self-oriented beacon liquid crystal (LC) biosensor for kanamycin (Kana) detection with gold nanoparticle (AuNPs) signal enhancement. In this study, an assay was proposed for Kana detection using the aptamer as a self-oriented beacon. Without an additional orientation agent, the Kana aptamer was used as a self-oriented beacon both as an orientation agent for the LCs and as a signal recognition probe for biological molecules. Gold nanoparticles are blended with desired concentrations of the target molecules, which can greatly improve the performance of the biosensor. In the presence of Kana, AuNPs–Kana–aptamer conjugates will form on the sensing interface of the biosensor, which can remarkably destroy the orientated arrangement of the LCs, resulting in changes in the corresponding polarized images of the LCs. The limit of Kana detection is as low as 0.1 pmol L⁻¹. It is important to note that the self-oriented beacons are immobilized on the assembled film of the glass slides for the specific recognition of Kana, simultaneously allowing the homeotropic orientation of the LCs. This study also provides a mechanism for the self-orientation beacon and liquid crystal biosensing.