Abstract

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), remains a leading cause of infectious disease-related mortality worldwide, with latent tuberculosis infection (LTBI) presenting a major diagnostic challenge. Heat shock protein 16.3 (Hsp16.3), a latency-associated antigen strongly expressed during dormancy, has emerged as a promising biomarker for LTBI detection. However, conventional diagnostic methods are costly, complex, and infrastructure-dependent, underscoring the need for portable and reagent-free biosensing solutions. Here, we report a contactless biosensing platform based on the giant magnetoimpedance (GMI) effect for the detection of Hsp16.3. The system integrates a commercial pico-Tesla resolution amorphous wire sensor with an Arduino-based microcontroller and MCP3223 analog-to-digital converter. Detection relies on binding-induced magnetic field perturbations generated by antibody- functionalized iron-oxide nanoparticles, and antibody-antigen complexes, which modulate the local magnetic fields and induce measurable impedance changes. The biosensor achieved reproducible detection of Hsp16.3 in model assays, with limits of detection of ∼99 µg/mL for antibody titration and ∼44 µg/mL for antigen response. More importantly, the platform was successfully validated with plasma samples from LTBI patients, demonstrating specific responses to antibody-antigen complexes in complex biological matrices. This work represents the first demonstration of a GMI-biosensor validated with LTBI plasma samples, highlighting its potential as a portable, scalable, and reagent-free diagnostic tool for future development toward early TB screening in resource-limited settings.