Development and Application of Nanomaterial-Modified Electrochemical Biosensors for the Detection of Pathogens
Project no. 24143 · Status: Kapanmış (Yayın bekleniyor) · 2022
Summary
<p><em>Stenotrophomonas maltophilia</em> is a Gram-negative aerobic bacterium. Among the most common nosocomial infections it causes are surgical wound infections, bloodstream infections, and lung infections. <em>Shigella sonnei</em> is a Gram-negative facultative bacterium. <em>Shigella</em> infections such as shigellosis pose a significant global public health challenge due to low infectious doses and high incidences. Recently, the increasing incidence and antibiotic resistance of these two bacteria have made rapid, sensitive, and economical analysis methods crucial for their identification and antibiotic susceptibility testing. Current immunological, genetic, and culture-based methods are slow, expensive, less selective, and multistep. Current antibiotic susceptibility tests are also prolonged, expensive, and time-consuming. Electrochemical sensors are miniaturized devices that generate specific and reversible electrical signals in response to chemicals. These sensors form biosensors by incorporating biological materials such as enzymes, antibodies, and nucleic acids. Electrochemical biosensors provide the opportunity for analysis with faster, sensitive, cost-effective, and simplified protocols. Integration of nanomaterials into biosensors enables high sensitivity, selectivity, and repeatability. Single-walled carbon nanotubes are commonly used for this purpose, providing high durability and stability.</p><p>In the study, nanomaterial-modified electrochemical DNA biosensors were developed for the rapid, highly sensitive, selective, and cost-effective detection of <em>S. maltophilia</em> and <em>S. sonnei</em> bacteria for the first time. Initially, single-walled carbon nanotubes were coated on the electrode surface via passive adsorption. Modification of the electrode surface with this nanomaterial provided a more stable surface. Subsequently, probe sequences specific to each bacterium were individually immobilized on the electrode surface via covalent bonding. Following this, hybridization with target sequences from both bacteria was performed. Hybridization took place on the nanomaterial and probe DNA-coated electrode surface. The determination of the target DNA of bacteria was performed using differential pulse voltammetry based on the oxidation current of the guanine base. The detection limits for the target DNA regions of <em>S. maltophilia</em> were found to be 2.21 µM and for <em>S. sonnei</em>, the detection limit was found to be 1.26 µM.</p><p>The selectivity of DNA biosensors for <em>S. maltophilia</em> and <em>S. sonnei</em> was evaluated using sequences completely different from the target sequences and sequences differing by 3 base pairs from the target sequences. The responses of the developed biosensors to these sequences were found to be insignificant. Compared to current methods that are expensive, time-consuming, and labor-intensive for bacterial detection, the developed biosensors enable a faster, cheaper, and more sensitive detection with a shorter procedure.</p>