Fluorescence detecting glycopeptide antibiotics via a dynamic molecular switch

Area of Science:

• Analytical Chemistry
• Biochemistry
• Medicinal Chemistry

Background:

• Glycopeptide antibiotics (GPAs), such as vancomycin (VAN), are crucial for treating Gram-positive bacterial infections.
• Accurate and rapid quantification of GPAs is essential for safe and effective clinical management due to strict dosing requirements.

Purpose of the Study:

• To develop a novel, highly sensitive, and selective fluorescent probe for the direct quantification of GPAs.
• To create a probe that simplifies sample preparation and analysis for clinical applications.

Main Methods:

• Design and synthesis of a fluorescent probe (P1) comprising a fluorescein reporter and a D-alanyl-D-alanine (D-Ala-D-Ala) recognition moiety.
• Utilizing the probe's dynamic molecular switch mechanism, where GPA binding shifts equilibrium from a non-fluorescent to a fluorescent state.
• Testing the probe's performance in detecting GPAs in complex biological matrices, including serum.

Main Results:

• The developed probe P1 functions as a molecular switch, transitioning from a non-fluorescent spirolactam to a fluorescent ring-opened form upon GPA binding.
• Probe P1 demonstrated excellent sensitivity and selectivity for GPA detection.
• P1 achieved direct quantification of vancomycin in real serum samples without prior extraction, simplifying the analytical process.

Conclusions:

• P1 represents the smallest fluorescent probe developed for GPAs, integrating a single fluorophore without quenching or secondary dyes.
• The probe enables direct and simplified quantification of GPAs in complex biological samples.
• Additionally, probes P1 and P6 can differentiate GPAs based on their peptide backbones, a novel capability in GPA detection.