Development of ESAT-6 Based Immunosensor for the Detection of Mycobacterium tuberculosis.

Rishabh Anand Omar,Pankaj Kumar Arora,Nishith Verma

doi:10.3389/fimmu.2021.653853

Abstract

Early secreted antigenic target of 6 kDa (ESAT-6) has recently been identified as a biomarker for the rapid diagnosis of tuberculosis. We propose a stable and reusable immunosensor for the early diagnosis of tuberculosis based on the detection and quantification of ESAT-6 via cyclic voltammetry (CV). The immunosensor was synthesized by polymerizing aniline dispersed with the reduced graphene oxide (rGO) and Ni nanoparticles, followed by surface modification of the electroconductive polyaniline (PANI) film with anti-ESAT-6 antibody. Physicochemical characterization of the prepared materials was performed by several analytical techniques, including FE-SEM, EDX, XRD, FT-IR, Raman, TGA, TPR, and BET surface area analysis. The antibody-modified Ni-rGO-PANI electrode exhibited an approximately linear response (R2 = 0.988) towards ESAT-6 during CV measurements over the potential range of -1 to +1 V. The lower detection limit for ESAT-6 was approximately 1.0 ng mL-1. The novelty of this study includes the development of the reusable Ni-rGO-PANI-based electrochemical immunosensor for the early diagnosis of tuberculosis. Furthermore, this study successfully demonstrates that electro-conductive PANI may be used as a polymeric substrate for Ni nanoparticles and rGO.

Highlights

Tuberculosis (TB) is an airborne disease that can be transmitted through coughing, sneezing, laughing, and even talking [1]
We describe a cyclic voltammetry (CV)-based immunosensor using a Ni-reduced graphene oxide (rGO)-PANI electrode that targets the Early secreted antigenic target of 6 kDa (ESAT-6) virulence factor of Mycobacterium tuberculosis (Mtb) using the anti-ESAT-6 antibody as the recognition element
The prepared sensor is tested at different ESAT-6 concentrations and its performance is compared to published data, wherever possible

Summary

INTRODUCTION

Tuberculosis (TB) is an airborne disease that can be transmitted through coughing, sneezing, laughing, and even talking [1]. Poly L-lysine [5], antigenspecific antibodies [6,7,8], and DNA aptamers [9,10,11,12] have been successfully tested as the recognition elements Such sensors are accurate and fast, extraction of biomolecules (including DNA) from clinical samples is tedious and complex, requiring a sophisticated molecular laboratory to process samples collected from patients infected with tuberculosis. ESAT-6 is secreted only by the Mycobacterium pathogenic species It is a potential biomarker for Mtb, whose detection can be rapid, specific, and accurate at all stages of the infection. To the authors’ knowledge, this is the first study that describes the Ni-rGO-PANI-based electrochemical immunosensor for the detection of Mtb infection at an early stage. The prepared sensor is tested at different ESAT-6 concentrations and its performance is compared to published data, wherever possible

MATERIAL AND METHODS

AND DISCUSSION

Findings

CONCLUSIONS