Synthesis And Characterisation Of Silver Nanoparticles Derived From Pleurotus Sajor Caju And Its Biological Activity On Candida Albicans
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Date
2016-05
Authors
Musa, Siti Fadhilah
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Abstract
Silver nanoparticle (AgNPs) is widely studied due to its antifungal and antimicrobial activities against a wide range of microorganisms. In previous study, C. albicans is one of the pathogenic yeast that has been reported to be inhibited by AgNPs. Green method used to synthesise AgNPs also has been intensively studied due to its environmentally friendly and the used of non-toxic reducing agent. Meanwhile C. albicans was found to be virulent due to its metabolic flexibility to survive in a wide range of growth conditions. It has the ability to grow in the absence or in low glucose concentration. In order for yeast to survive, it must assimilate the non-fermentable carbon sources such as lactate instead of glucose through glyoxylate cycle and the isocitrate lyase (CaICL1) is one of the genes involved in this cycle. Plus, the expression of the gene was reported to be one of the factors contributed to C. albicans virulence. In this study, AgNPs synthesised using Pleurotus sajor caju mushroom or its common name grey oyster mushroom from hot water extraction was used and it has been confirmed to form AgNPs by the color changed from pale yellow to reddish brown after 72 hours of incubation with 1mM AgNO3. The mean particle size of AgNPs obtained was 11.68 nm with the zeta potential value -8.54 mV. The FTIR spectra also showed that the protein and polysaccharide in. P. sajor caju extract was responsible in reducing silver ion to silver nanoparticles. Meanwhile, XRD spectra also showed that the nanoparticle is the face-centred cubic (fcc) structure of silver.
Therefore, the broth microdilution assay was carried out to determine the antifungal activity of AgNPs. As a result, the minimum inhibitory concentration (MIC) of AgNPs was 250 mg/L while the minimum fungicidal concentration (MFC) was 500 mg/L. The impact of AgNPs on CaICL1 at the transcription and protein level also was observed in this study through quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analysis. The result showed that the expression of CaICL1 was downregulated at 2 and 6 hours incubation and then it was upregulated after 6 hours incubation. Meanwhile, CaIcl1 expression in the treated cells decreased after 2 hours and then increased after 4 and 6 hours compared with untreated time which was reduced after 6 hours incubation. Thus, this result suggested that AgNPs was able to inhibit C. albicans growth, but it was not able to repress isocitrate lyase production which is needed for lactate utilization. Hence, the inhibition of C. albicans by AgNPs also occurred at certain period of time might be due to the ability of C. albicans to adapt to osmotic and heavy metal stress caused by the AgNPs.
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Silver nanoparticle (AgNPs) is widely studied due to its antifungal , and antimicrobial activities against a wide range of microorganisms.