Fluorescent Biosensor Based on Hairpin DNA Stabilized Copper Nanoclusters for Chlamydia trachomatis Detection

Area of Science:

• Biochemistry
• Molecular Biology
• Nanotechnology

Background:

• Chlamydia trachomatis (C. trachomatis) is an intracellular bacterium causing diseases like trachoma.
• Accurate and sensitive detection methods for C. trachomatis are crucial for disease diagnosis and management.

Purpose of the Study:

• To develop a novel fluorescent biosensor for the sensitive and selective detection of C. trachomatis DNA.
• To investigate the mechanism of fluorescence quenching based on DNA hybridization and hairpin DNA-copper nanocluster formation.

Main Methods:

• Design of a specific hairpin DNA probe with recognition sites for C. trachomatis DNA.
• Formation of fluorescent hairpin DNA-copper nanoclusters (CuNCs) using the hairpin DNA as a template.
• Utilizing the fluorescence quenching effect upon hybridization of the probe with C. trachomatis DNA for detection.

Main Results:

• The biosensor exhibited strong fluorescence in the absence of C. trachomatis DNA, with emission peaks at 606 nm.
• The presence of C. trachomatis DNA inhibited hairpin DNA-CuNCs formation, leading to reduced fluorescence.
• A good linear relationship was observed between fluorescence intensity and C. trachomatis concentrations (50–950 nM), with a detection limit of 18.5 nM.
• The biosensor demonstrated good selectivity and was successfully applied to detect C. trachomatis in HeLa cell lysate.

Conclusions:

• A novel, sensitive, and selective fluorescent biosensor for C. trachomatis DNA detection has been developed.
• The biosensor relies on the competitive binding mechanism between C. trachomatis DNA and the hairpin DNA probe.
• This strategy offers a promising new approach for the clinical diagnosis of C. trachomatis infections.