Bimetallic interface on an optical microfiber nucleic acid sensor: Early detection in body fluids

Abstract

Nucleic acid detection, which is not limited by the “window period”, is an efficacious approach for detecting human immunodeficiency virus (HIV) infection at an early time. Here, method with a short turn-around time, portability, connectivity and cost-effectiveness is developed to suppress HIV disease in the early stage, especially in remote areas. Specifically, an optical microfiber sensor enhanced by a bimetallic interface is developed for the HIV-related DNA detection in body fluids. A bimetallic interface is constructed on the optical microfiber surface to ensure that target nucleic acid hybridization occurs between two gold nanostructures where the evanescent field is strongest. The selective enhancement of the evanescent field at the binding site prevents nonspecific amplification of the whole fiber surface, which may lead to false-positive results. With the enhancement in the bimetallic interface, the sensor can detect HIV-related DNA at concentrations from 1 aM to 0.1 pM, with a limit of detection (LOD) of 0.3 aM. The portability, flexibility and selectivity of the sensor enable its application in detecting in several body fluids, such as whole serum and artificial saliva, with LODs of 1.15 aM and 1.64 aM, respectively. This work provides a powerful tool for diagnosing HIV in early stages. Ultrasensitive nucleic acid detection in artificial saliva also provides a possibility for noninvasive detection.