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Recent research tried to analyze the conjugation of some chemotherapeutic drugs to the biologically produced gold nanoparticles (GNPs) in one step, without the use of any additional linkers. GNPs was produced using Fusarium oxysporum and their presence was confirmed using spectrophotometer, transmission electron microscope (TEM), X-ray diffraction (XRD) and fourier transform infrared (FTIR) analyses. In order to carry out the conjugation study, capecitabine, tamoxifen, and paclitaxel were added dropwise to the GNPs solution under stirring condition and spectrophotometer, dynamic light scattering (DLS) and FTIR analyses were performed to prove the successful conjugation. Finally, AGS and MCF7 cell lines were used for methyl thiazol tetrazolium (MTT) assay to determine the toxicity of each drug and its conjugated form. Results showed that the spherical and hexagonal GNPs with maximum absorbance peak around 524 nm and average sizes less than 20 nm were produced. FTIR analysis clarified the presence of proteins on the surfaces of the GNPs. After the conjugation process although the FTIR analysis demonstrated that all the drugs were successfully conjugated to GNPs, MTT assay revealed that unlike the paclitaxel conjugated GNPs, capecitabine and tamoxifen conjugates displayed no toxic effects due to their deactivation and low half-lives. Moreover the average size and polydispersity index (PDI) of the GNPs after conjugation with all the three tested drugs increased. In conclusion different types of drugs could conjugate to the GNPs but it is important to employ high stable forms of the drugs in the conjugation procedure.

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The purpose of this study was the evaluation of two different temperatures on antibacterial activity of the biosynthesized silver nanoparticles. 38 silver nanoparticles-producing bacteria were isolated from soil and identified. Biosynthesis of silver nanoparticles by these bacteria was verified through visible light spectrophotometry. Two strains were relatively active for production of silver nanoparticles. These strains were subjected for molecular identification and recognized as Bacillus sp. and Acinetobacter schindleri. In the present study, the effect of temperatures was evaluated on structure and antimicrobial properties of the silver nanoparrticles by transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis and antimicrobial Agar well diffusion methods. The silver nanoparticles showed antibacterial activity against all the pathogenic bacteria; however, this property was lost after treatment of the silver nanoparticles by high temperatures (100 and 300 °C). TEM images showed that the average sizes of heated silver nanoparticles were >100 nm. However, these were <100 nm for non-heated silver nanoparticles. Although, XRD patterns showed the crystalline structure of heated silver nanoparticles, their antibacterial activities were less. This was possible because of the sizes and accordingly less penetration of the particles into the bacterial cells. In addition, elimination of the capping agents by heat might be considered another reason.

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The mycelium-free supernatant (MFS) of a five-day-old culture medium of Fusarium oxysporum was used to synthesize gold nanoparticles (AuNPs). The experimental design of the study was to answer the question: can this production process of AuNPs be controllable like classical chemical or physical approaches? The process of producing AuNPs from 1 mM tetrachloroauric (III) acid trihydrate in MFS was monitored visually by color change at different pH values and quantified spectroscopically. The produced AuNPs were analyzed by transmission electron microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The presence of capping agents was confirmed by Fourier transform infrared spectroscopy (FTIR). Two AuNP samples with acidic and alkaline pH were selected and adjusted with the pH gradient and analyzed. Finally, the size and zeta potential of all samples were determined. The results confirmed the presence of the proteins as capping agents on the surface of the AuNPs and confirmed the production of AuNPs at all pH values. All AuNP samples exhibited negative zeta potential, and this potential was higher at natural to alkaline pH values. The size distribution analysis showed that the size of AuNPs produced at alkaline pH was smaller than that at acidic pH. Since all samples had negative charge, we suspect that there were other molecules besides proteins that acted as capping agents on the surface of the AuNPs. We conclude that although the biological method of nanoparticle production is safe, green, and inexpensive, the ability to manipulate the nanoparticles to obtain both positive and negative charges is limited, curtailing their application in the medical field.

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