Silver nanoparticles: influence of stabilizing agent and diameter on antifungal activity against Candida albicans and Candida glabrata biofilms.
OBJECTIVE
The purpose of this work was to evaluate the size-dependent antifungal activity of different silver nanoparticles (SN) colloidal suspensions against Candida albicans and Candida glabrata mature biofilms.


RESULTS
The research presented herein used SN of three different average sizes (5, 10 and 60 nm), which were synthesized by the reduction of silver nitrate through sodium citrate and which were stabilized with ammonia or polyvinylpyrrolidone. Minimal inhibitory concentration (MIC) assays were performed using the microdilution methodology. The antibiofilm activity of SN was determined by total biomass quantification (by crystal violet staining) and colony forming units enumeration. MIC results showed that all SN colloidal suspensions were fungicidal against the tested strains at very low concentrations (0·4-3·3 μg ml(-1) ). With regard to biomass quantification, SN colloidal suspensions were very effective only against C. glabrata biofilms, achieving biomass reductions around 90% at a silver concentration of 108 μg ml(-1) . In general, all SN suspensions promoted significant log(10) reduction of the mean number of cultivable biofilm cells after exposure to silver concentrations at or higher than 108 μg ml(-1) . Moreover, the results showed that the particle size and the type of stabilizing agent used did not interfere in the antifungal activity of SN against Candida biofilms.


CONCLUSIONS
This study suggests that SN have antifungal therapeutic potential, but further studies are still required namely regarding formulation and delivery means.


CONCLUSIONS
SN may contribute to the development of new strategies for the improvement of oral health and quality of life particularly of the complete denture wearers.
Department of Dental Materials and Prosthodontics, Araçatuba Dental School, Universidade Estadual Paulista (UNESP), Araçatuba, São Paulo, Brazil.
D R
DR
Monteiro
S
S
Silva
M
M
Negri
L F
LF
Gorup
E R
ER
de Camargo
R
R
Oliveira
D B
DB
Barbosa
M
M
Henriques
D000935:Antifungal Agents / Q000633:toxicity*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002176:Candida albicans / Q000187:drug effects* / Q000502:physiology; D041221:Candida glabrata / Q000187:drug effects* / Q000502:physiology; D005079:Excipients / Q000633:toxicity; D053768:Metal Nanoparticles / Q000633:toxicity* / Q000648:ultrastructure; D008826:Microbial Sensitivity Tests; D010316:Particle Size; D012834:Silver / Q000633:toxicity*
D000935:Antifungal Agents; D005079:Excipients; D012834:Silver