Dendrimer-based multivalent vancomycin nanoplatform for targeting the drug-resistant bacterial surface

Area of Science:

• Bioconjugation Chemistry
• Nanotechnology
• Microbiology

Background:

• Vancomycin is a key antibiotic for targeting bacteria, but its efficacy is limited against emerging resistant strains due to poor cell wall affinity.
• Developing novel strategies is crucial to overcome vancomycin resistance and enhance bacterial targeting for therapeutic applications.

Purpose of the Study:

• To investigate a multivalent strategy using poly(amidoamine) (PAMAM) dendrimers to enhance vancomycin's binding avidity to bacterial cell wall models.
• To assess the efficacy of vancomycin-dendrimer conjugates in targeting both vancomycin-susceptible and -resistant bacterial strains.
• To explore the potential of this nanoplatform for developing new methods for bacterial sequestration.

Main Methods:

• Synthesis of fifth-generation (G5) PAMAM dendrimers functionalized with vancomycin at varying valencies.
• Surface Plasmon Resonance (SPR) analysis to quantify binding avidity to synthetic cell wall models ((D)-Ala-(D)-Ala and (D)-Ala-(D)-Lac).
• In vitro assessment of bacterial cell binding using confocal fluorescent microscopy and development of dendrimer-coated magnetic nanoparticles for bacterial sequestration.

Main Results:

• Vancomycin-dendrimer conjugates demonstrated a significant enhancement in binding avidity (4-5 orders of magnitude) compared to free vancomycin, particularly against vancomycin-resistant cell wall models.
• The conjugates effectively bound to vancomycin-susceptible Staphylococcus aureus cells in vitro.
• Dendrimer-coated iron oxide nanoparticles rapidly sequestered bacterial cells, showcasing the nanoplatform's practical application.

Conclusions:

• Multivalent vancomycin conjugation to PAMAM dendrimers effectively overcomes affinity limitations against vancomycin-resistant bacterial cell walls.
• This nanoplatform offers a promising approach for enhanced targeting and sequestration of Gram-positive bacteria, including resistant strains.
• The study elucidates the biophysical basis for tight, multivalent binding, paving the way for new nanomedicine strategies against bacterial infections.