Work

Quantum-Dot-Based Enzyme Biosensor for Rapid Screening of Antibiotic Susceptibility in Urine Samples

Year: 2026

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide The rising threat of antibiotic resistance necessitates sensitive and specific diagnostic tools for antimicrobial susceptibility testing (AST). Gram-negative bacteria are catalase-positive and the major group that causes urinary tract infections (UTI). The present work focused on developing a novel quantum dot (QD) based dual enzyme assay to differentiate antibiotic-resistant and antibiotic-sensitive bacteria within 2 h. The first step involves oxidation of dopamine on the surface of QDs by a horseradish peroxidase (HRP) enzyme in the presence of hydrogen peroxide (H 2 O 2 ), forming quinone, which quenches the fluorescence of QDs. However, in the presence of the catalase enzyme, H 2 O 2 is catabolized, preventing dopamine oxidation and restoring the QD fluorescence. When treated with antibiotics, resistant bacteria produce catalase; in contrast, sensitive bacteria, with little or no catalase production, modulate QD fluorescence. The QD fluorescence was quenched by the HRP–Dopa system, F / F o 0.63–0.03, whereas the presence of catalase led to fluorescence increase with F / F o 3.53–9.8. Upon treating bacteria with various antibiotics, the resistant strains led to fluorescence enhancement with F / F o ∼ 2–3, whereas sensitive strains led to F / F o ∼ 1–1.2 with P -values of P < 0.05. The assay demonstrated a clinically relevant detection threshold of 10 4 –10 5 CFU/mL for bacteriuria, affirming its relevance in early-stage infection detection and enhancing its diagnostic value. The developed biosensor achieved 100% specificity and was validated using urine samples. The biosensor distinguished resistant and sensitive strains within 2 h, offering a promising platform for rapid screening of antimicrobial susceptibility.

Source: ACS Omega

DOI: 10.1021/acsomega.5c07857

Authors: Nidhi S. Shetty, J. R. Shubha, Akshath Uchangi Satyaprasad

Institution: Nitte University

Language: English

Topic: Biosensors and Analytical Detection

Subfield: Biomedical Engineering

Field: Engineering

Domain: Physical Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $1,935