Abstract
BackgroundSynthesis of nanoparticles (NPs) and their incorporation in materials are amongst the most studied topics in chemistry, physics and material science. Gold NPs have applications in medicine due to their antibacterial and anticancer activities, in biomedical imaging and diagnostic test. Despite chemical synthesis of NPs are well characterized and controlled, they rely on the utilization of harsh chemical conditions and organic solvent and generate toxic residues. Therefore, greener and more sustainable alternative methods for NPs synthesis have been developed recently. These methods use microorganisms, mainly yeast or yeast cell extract. NPs synthesis with culture supernatants are most of the time the preferred method since it facilitates the purification scheme for the recovery of the NPs. Extraction of NPs, formed within the cells or cell-wall, is laborious, time-consuming and are not cost effective. The bioactivities of NPs, namely antimicrobial and anticancer, are known to be related to NPs shape, size and size distribution.ResultsHerein, we reported on the green synthesis of gold nanoparticles (AuNPs) mediated by pyomelanin purified from the yeast Yarrowia lipolytica. A three levels four factorial Box–Behnken Design (BBD) was used to evaluate the influence of temperature, pH, gold salt and pyomelanin concentration on the nanoparticle size distribution. Based on the BBD, a quadratic model was established and was applied to predict the experimental parameters that yield to AuNPs with specific size. The synthesized nanoparticles with median size value of 104 nm were of nanocrystalline structure, mostly polygonal or spherical. They exhibited a high colloidal stability with zeta potential of − 28.96 mV and a moderate polydispersity index of 0.267. The absence of cytotoxicity of the AuNPs was investigated on two mammalian cell lines, namely mouse fibroblasts (NIH3T3) and human osteosarcoma cells (U2OS). Cell viability was only reduced at AuNPs concentration higher than 160 µg/mL. Moreover, they did not affect on the cell morphology.ConclusionOur results indicate that different process parameters affect significantly nanoparticles size however with the mathematical model it is possible to define the size of AuNPs. Moreover, this melanin-based gold nanoparticles showed neither cytotoxicity effect nor altered cell morphology.
Highlights
Synthesis of nanoparticles (NPs) and their incorporation in materials are amongst the most studied topics in chemistry, physics and material science
Box–Behnken design (BBD) is a well-known optimization approach used to generate a mathematical model that considers the interactions between parameters on the final output
The NPs size distribution (PSD, polydisperse size distribution) for each experiment was analyzed by dynamic light scattering (DLS) and the median value of the size distribution (D50) was used as output response
Summary
Synthesis of nanoparticles (NPs) and their incorporation in materials are amongst the most studied topics in chemistry, physics and material science. Gold nanoparticles (AuNPs) exhibit peculiar physico-chemical proprieties They are chemically inert and highly stable once synthesized [8]. Depending on the type and concentration of the ligand bound on the surface these particles; their immunogenic response, reactivity, stability and sensitivity could be modulated [12]. All these benefits, combined with their low cytotoxicity, enable their utilization in different biomedical applications including computing tomography [13, 14], photoacoustic imaging [15], drugs and genes delivery systems [16,17,18], photothermal therapy [19], radiosensitization [20] and biochemical sensing [21]
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