Label-Free Visualization of the Antifungal Polyene Drug, Nystatin, in Biological Membranes Using Raman Microscopy

Area of Science:

• Biophysics
• Microbiology
• Pharmacology

Background:

• Polyene macrolides are crucial antifungal drugs for severe fungal infections.
• The precise mechanisms of polyene macrolide interaction with biological membranes are not fully understood.
• Nystatin, a key polyene macrolide, has been used for decades against Candida albicans.

Purpose of the Study:

• To investigate the interaction of nystatin with biological membranes using advanced microscopy.
• To visualize the binding and intracellular localization of nystatin in both mammalian and fungal cells.
• To provide direct, label-free imaging of nystatin's behavior at the cellular level.

Main Methods:

• Label-free stimulated Raman scattering (SRS) microscopy was employed.
• Hyperspectral SRS imaging combined with spectral phasor analysis was used.
• The study focused on nystatin's interaction with mammalian cells and Candida albicans.

Main Results:

• SRS microscopy revealed extracellular nystatin aggregates and plasma membrane binding in mammalian cells.
• In Candida albicans, significant nystatin accumulation in the fungal membrane and drug internalization were observed.
• Spectral phasor analysis successfully distinguished nystatin signals from cellular components.

Conclusions:

• This research offers the first label-free, direct visualization of nystatin binding to biological membranes.
• The study elucidates nystatin's trafficking within fungal cells using SRS microscopy.
• The findings enhance understanding of polyene macrolide-membrane interactions and drug delivery in antifungal therapy.