Despite the continued effort globally made to control the growing case of Tuberculosis (TB), it continues to be regarded as the second deadliest disease after the HIV. There are various methods developed to diagnose TB, most of which having the criteria of sensitive, selective, cheap and portable to be used in robust applications. Even with the advancement in medication, the important keys including early stage diagnosis is yet to be considered. In diagnosing TB, the only technique remained as the gold standard method is the culturing method, which is the Acid Fast Bacilli (AFB) staining. On the other hand, molecular technique utilising Polymerase Chain Reaction (PCR) assay is preferred as a non-culturing method. Additionally, as molecular techniques become advanced, real-time PCR or quantitative PCR (qPCR) using multiple probes in one shot has raised interest among researchers, because it can skip the process of gel electrophoresis. Recently, researchers have been working on electrochemical DNA sensors which are sensitive, selective, rapid, cheap and can meet with point of care (POC) testing requirements to diagnose TB.

Death from tuberculosis has resulted in an increased need for early detection to prevent a tuberculosis (TB) epidemic, especially in closed and crowded populations. Herein, a sensitive electrochemical DNA biosensor based on functionalized iron oxide with mercaptopropionic acid (MPA-Fe3O4) nanoparticle and nanocellulose crystalline functionalized cetyl trimethyl ammonium bromide (NCC/CTAB) has been fabricated for the detection of Mycobacterium tuberculosis (MTB). In this study, a simple drop cast method was applied to deposit solution of MPA-Fe3O4/NCC/CTAB onto the surface of the screen-printed carbon electrode (SPCE). Then, a specific sequence of MTB DNA probe was immobilized onto a modified SPCE surface by using the 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling mechanism. For better signal amplification and electrochemical response, ruthenium bipyridyl Ru(bpy)32+ was assigned as labels of hybridization followed by the characteristic test using differential pulse voltammetry (DPV). The results of this biosensor enable the detection of target DNA until a concentration as low as 7.96 × 10−13 M with a wide detection range from 1.0 × 10−6 to 1.0 × 10−12 M. In addition, the developed biosensor has shown a differentiation between positive and negative MTB samples in real sampel analysis.

A novel DNA biosensing platform was designed by the functionalization of iron oxide (Fe3O4)with the carboxylic group via capping agent, mercaptopropionic acid (MPA) and conjugatedwith nanocellulose crystalline (NCC) surface modified with surfactant cetyltrimethylammoniumbromide (CTAB) to assist in the DNA sensing capability. The product of nanocompositescompound was drop-casted on screen printed carbon electrode (SPCE). Characterization by fieldemission scanning electron microscope (FESEM) and energy dispersive X-Ray (EDX)spectroscopy showing that carboxyl functionalized iron oxide (COOH-Fe3O4) can be hybridizedwith NCC-CTA+ via electrostatic interaction.