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Intracellular Pathogen Detection Based on Dual-Recognition Units Constructed Fluorescence Resonance Energy Transfer
Fei Fu1, Yaqing Zhang2, Linyao Li1
1Key laboratory of Luminescence Analysis and Molecular Sensing (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, People's Republic of China.
Abstract:
The intracellular invasion and survival of a pathogen like Staphylococcus aureus (S. aureus) within host cells enable them to resist antibiotic treatment and colonize long-term in the host, which leads to a series of clinical issues. Rapid and specific detection of intracellular bacteria is important in diagnosis of infection and guiding antibiotic administration. Herein, this work reports a simple one-step fluorescence resonance energy transfer (FRET) platform-based strategy to achieve specific and rapid detection of S. aureus in specimens of phagocytic cells. The aptamer modified quantum dots (Aptamer-QDs) and antibiotic molecule of Teicoplanin functionalized-gold nanoparticles (Teico-AuNPs) dual-recognition units to S. aureus are employed as energy donor and acceptor, respectively. Based on the "off" to "on" signal readout mode, when in the presence of target S. aureus, the donor and acceptor are close to each other and bring high FRET efficiency, which is suitable for analysis of intracellular S. aureus. After it was incubated with the sample for 2 h, the as-prepared FRET sensor showed selectivity to the target S. aureus, and the changed fluorescence signal shows an obvious variation with increasing concentration of S. aureus in pure buffer. When the FRET strategy was further applied to assay intracellular S. aureus, there was an obvious fluorescence signal change obtained both by spectrum analysis and visual fluorescence microscope observation when the average number of S. aureus in one host cell (N) was as low as 1, which can be attributed to the high fluorescence quenching efficiency of about 41.3%. It could be envisioned that this FRET nanoprobe with high fluorescence quenching efficiency may provide a simple approach for the facile, selective, and rapid diagnosis of an intracellular bacterial infection.
Insights
This study presents a novel fluorescence resonance energy transfer (FRET) sensor for rapid and specific detection of intracellular Staphylococcus aureus (S. aureus) bacteria. The sensor utilizes aptamer-conjugated quantum dots and Teicoplanin-functionalized gold nanoparticles for high sensitivity detection.
Area of Science:
- Biomedical Engineering
- Nanotechnology
- Infectious Disease Diagnostics
Background:
- Intracellular Staphylococcus aureus (S. aureus) infections pose significant challenges due to antibiotic resistance and prolonged colonization.
- Accurate and swift detection of intracellular bacteria is crucial for effective diagnosis and antibiotic therapy.
- Current diagnostic methods may lack the speed and specificity required for intracellular bacterial detection.
Purpose of the Study:
- To develop a simple, one-step fluorescence resonance energy transfer (FRET) platform for the rapid and specific detection of intracellular S. aureus.
- To create a dual-recognition nanoprobe utilizing aptamers and an antibiotic for enhanced bacterial targeting.
- To evaluate the sensitivity and selectivity of the FRET sensor for intracellular S. aureus detection.
Main Methods:
- Fabrication of aptamer-modified quantum dots (Aptamer-QDs) as energy donors.
- Functionalization of gold nanoparticles with Teicoplanin (Teico-AuNPs) as energy acceptors.
- Development of a FRET-based sensor with an "off" to "on" signal readout mechanism for S. aureus detection.
- Testing the sensor's performance in pure buffer and within phagocytic host cells.
Main Results:
- The FRET sensor demonstrated high selectivity for S. aureus.
- A concentration-dependent fluorescence signal variation was observed in the presence of S. aureus.
- The sensor achieved sensitive detection of intracellular S. aureus, with a limit as low as one bacterium per host cell.
- High fluorescence quenching efficiency of approximately 41.3% was achieved.
Conclusions:
- The developed FRET nanoprobe offers a facile, selective, and rapid method for diagnosing intracellular bacterial infections.
- This approach holds potential for improving the clinical diagnosis of S. aureus infections.
- The high sensitivity and specificity of the FRET sensor pave the way for advanced diagnostic tools.
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