Related Experiment Video
Updated: Mar 28, 2026
A Soluble Tetrazolium-Based Reduction Assay to Evaluate the Effect of Antibodies on Candida tropicalis Biofilms
Published on: September 16, 2022
Effect of silver nanoparticles on Candida albicans biofilms: an ultrastructural study
Humberto H Lara1, Dulce G Romero-Urbina1, Christopher Pierce2
1Department of Physics and Astronomy, The University of Texas at San Antonio, One UTSA Circle, San Antonio, TX, 78249, USA. miguel.yacaman@utsa.edu.
Background:
Candida albicans is the most common pathogenic fungus isolated in bloodstream infections in hospitalized patients, and candidiasis represents the fourth most common infection in United States hospitals, mostly due to the increasing numbers of immune- and medically-compromised patients. C. albicans has the ability to form biofilms and morphogenetic conversions between yeast and hyphal morphologies contribute to biofilm development and represent an essential virulence factor. Moreover, these attached communities of cells are surrounded by a protective exopolymeric matrix that effectively shelters Candida against the action of antifungals. Because of dismal outcomes, novel antifungal strategies, and in particular those targeting biofilms are urgently required. As fungi are eukaryotic, research and development of new antifungal agents has been difficult due to the limited number of selective targets, also leading to toxicity.
Results:
By microwave-assisted techniques we obtained pure 1 nm spherical silver nanoparticles ideal for their potential biological applications without adding contaminants. A phenotypic assay of C. albicans demonstrated a potent dose-dependent inhibitory effect of silver nanoparticles on biofilm formation, with an IC50 of 0.089 ppm. Also silver nanoparticles demonstrated efficacy when tested against pre-formed C. albicans biofilms resulting in an IC50 of 0.48 ppm. The cytotoxicity assay resulted in a CC50 of 7.03 ppm. The ultrastructural differences visualized under SEM with silver nanoparticles treatment were changes in the surface appearance of the yeast from smooth to rough thus indicating outer cell wall damage. On the fungal pre-formed biofilm true hyphae was mostly absent, as filamentation was inhibited. TEM measurement of the cell-wall width of C. albicans after treatment resulted in significant enlargement (206 ± 11 nm) demonstrating membrane permeabilization.
Conclusions:
Our results demonstrate that silver nanoparticles are potent inhibitors of C. albicans biofilm formation. SEM observations are consistent with an overall loss of structure of biofilms mostly due to disruption of the outer cell membrane/wall and inhibition of filamentation.TEM indicates the permeabilization of the cell wall and subsequent disruption of the structural layers of the outer fungal cell wall. The anti-biofilm effects are via cell wall disruption.
Insights
Silver nanoparticles effectively inhibit Candida albicans biofilm formation and disrupt fungal cell walls. These findings offer a promising new strategy against challenging fungal infections.
Area of Science:
- Nanotechnology
- Mycology
- Microbiology
Background:
- Candida albicans is a leading cause of hospital-acquired bloodstream infections, particularly in immunocompromised patients.
- Biofilm formation and morphological changes are key virulence factors for C. albicans, protecting it from antifungals.
- Developing new antifungal agents is challenging due to limited selective targets and potential toxicity.
Purpose of the Study:
- To investigate the efficacy of silver nanoparticles (AgNPs) as an antifungal agent against Candida albicans biofilms.
- To evaluate the mechanism of action of AgNPs on C. albicans cell structure and biofilm integrity.
Main Methods:
- Microwave-assisted synthesis of 1 nm spherical silver nanoparticles.
- Phenotypic assays to assess AgNP inhibition of C. albicans biofilm formation.
- Cytotoxicity assays to determine the safety profile of AgNPs.
- Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) to visualize ultrastructural changes.
Main Results:
- Silver nanoparticles demonstrated potent, dose-dependent inhibition of C. albicans biofilm formation (IC50 = 0.089 ppm).
- AgNPs were also effective against pre-formed biofilms (IC50 = 0.48 ppm) with a cytotoxicity concentration (CC50) of 7.03 ppm.
- SEM revealed surface damage and rough appearance of yeast cells, while TEM showed significant cell wall enlargement, indicating membrane permeabilization and disruption.
Conclusions:
- Silver nanoparticles are potent inhibitors of Candida albicans biofilm formation.
- The anti-biofilm mechanism involves disruption of the outer cell membrane/wall and inhibition of filamentation.
- AgNPs show promise as a novel therapeutic strategy against C. albicans infections, particularly those involving biofilms.
