Biogenic AuNPs Research Articles

Current state and prospects of the phytosynthesized colloidal gold nanoparticles and their applications in cancer theranostics.

The design, development, and biomedical applications of phytochemical-based green synthesis of biocompatible colloidal gold nanoparticles (AuNPs) are becoming an emerging field due to several advantages (safer, eco-friendly, simple, fast, energy efficient, low-cost, and less toxic) over conventional chemical synthetic procedures. Biosynthesized colloidal gold nanoparticles are remarkably attractive in several biomedical applications including cancer theranostics due to small size, unusual physico-chemical properties, facile surface modification, high biocompatibility, and numerous other advantages. Of late, several researchers have investigated the biosynthesis and prospective applications (diagnostics, imaging, drug delivery, and cancer therapeutics) of AuNPs in health care and medicine. However, not a single review article is available in the literature that demonstrates the anti-cancer potential of biosynthesized colloidal AuNPs with detailed mechanistic study. In the present review article, we for the first time discuss the biointerface of colloidal AuNPs, plants, and cancer mainly (i) comprehensive mechanistic aspects of phytochemical-based synthesis of AuNPs; (ii) proposed anti-cancer mechanisms along with biomedical applications in diagnostics, imaging, and drug delivery; and (iii) key challenges for biogenic AuNPs as future cancer nanomedicine.

Green chemical synthesis of gold nanoparticles by using Penicillium aculeatum and their scolicidal activity against hydatid cyst protoscolices of Echinococcus granulosus.

Hydatid disease is a helminth infection with various clinical complications caused by the larval stage of the dog tapeworm Echinococcus granulosus. The scolicidal agents have been broadly applied for inactivation of the fertile cysts up to now, but these scolicidal agents have several side effects on patients. Therefore, this study aimed to explore the scolicidal activity of green synthesized gold nanoparticles (AuNPs) utilizing mycelia-free culture filtrate of Penicillium aculeatum against hydatid cyst protoscolices of E. granulosus. The size and morphology of AuNPs were affirmed by UV-visible spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and dynamic light scattering (DLS) analysis. The Fourier transform infrared (FT-IR) analysis of AuNPs showed the presence of possible functional groups responsible for the bioreduction and capping. The AuNPs were formed relatively uniform with spherical shape and superior monodispersity with the average diameter of 60nm. Consequently, various concentrations (0.05, 0.1, 0.2, and 0.3mg/mL) of green synthesized AuNPs and different exposure times (10, 30, 60, and 120min) were used against hydatid cyst protoscolices. Statistically, the difference between the scolicidal effects of AuNPs were seen extremely significant for all four concentrations and at various exposure times in comparison to the control group (P<0.0001). The most mean protoscolex elimination ratio was 94% (0.3mg/mL AuNPs and 120-min exposure time). The current investigation indicated that applying biogenic AuNPs may be considered as a potential scolicidal agent for cystic hydatid disease. However, further studies are required to evaluate the efficacy of AuNPs in vivo.

Bio-inspired gold nanoparticles synthesis and their anti-biofilm efficacy

Gold nanoparticles (AuNPs) are ‘smart nanomaterials’ with a variety of applications in the different fields. The conventional methods used for AuNPs have some drawbacks and therefore, search of an alternative ‘green method’ is of high importance. In this study, Acinetobacter baumannii AB01 isolated from an infected apple sample was used as a green route for AuNPs synthesis. Effect of various physicochemical parameters such as pH, temperature, cell density and gold chloride salt concentrations on AuNPs synthesis was studied. These AuNPs were further characterized by UV–Vis spectrophotometer, transmission electron microscopy (TEM), energy dispersive spectroscopy, X-ray diffraction and dynamic light scattering. TEM images study showed presence of an extracellular polymeric substance around cells of A. baumannii AB01. The synthesized biogenic AuNPs were tested for their antibacterial activity by well diffusion method. Anti-biofilm efficacy of AuNPs was tested on the glass slide surfaces against the biofilms of Pseudomonas aeruginosa, Vibrio cholera and Brevibacterium linens and visualised by using a fluorescence microscopy. Biofilm formation was reduced about 60–80 % when compared with control biofilm (without AuNPs). Effect of different AuNPs concentrations on biofilm formation in microtiter plates was studied by 96-well plate assay. The bacterial biofilm inhibition (%) was increased with increasing concentrations of AuNPs.

Catalytic reduction of 4-nitrophenol using gold nanoparticles biosynthesized by cell-free extracts of Aspergillus sp. WL-Au

A facile one-pot eco-friendly process for synthesis of gold nanoparticles (AuNPs) with high catalytic activity was achieved using cell-free extracts of Aspergillus sp. WL-Au as reducing, capping and stabilizing agents. The surface plasmon resonance band of UV–vis spectrum at 532nm confirmed the presence of AuNPs. Transmission electron microscopy images showed that quite uniform spherical AuNPs were synthesized and the average size of nanoparticles increased from 4nm to 29nm with reaction time. X-ray diffraction analysis verified the formation of nano-crystalline gold particles. Fourier transform infrared spectra showed the presence of functional groups on the surface of biosynthesized AuNPs, such as OH, NH, CO, CH, COH and COC groups, which increased the stability of AuNPs. The biogenic AuNPs could serve as a highly efficient catalyst for 4-nitrophenol reduction. The reaction rate constant was linearly correlated with the concentration of AuNPs, which increased from 0.59min−1 to 1.51min−1 with the amount of AuNPs increasing form 1.46×10−6 to 17.47×10−6mmol. Moreover, the as-synthesized AuNPs exhibited a remarkable normalized catalytic activity (4.04×105min−1mol−1), which was much higher than that observed for AuNPs synthesized by other biological and conventional chemical methods.

Green synthesis of gold nanoparticles by a newly isolated strain Trichosporon montevideense for catalytic hydrogenation of nitroaromatics.

To investigate green synthesis of gold nanoparticles (AuNPs) by Trichosporon montevideense, and to study their reduction of nitroaromatics. AuNPs had a characteristic absorption maximum at 535nm. Scanning electron microscopy images revealed that the biosynthesized nanoparticles were attached on the cell surface. X-ray diffraction analysis indicated that the particles formed as face-centered cubic (111)-oriented crystals. The average size of AuNPs decreased from 53 to 12nm with increasing biomass concentration. The catalytic reduction of 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, o-nitrophenylamine and m-nitrophenylamine (0.1mM) by NaBH4 had reaction rate constants of 0.32, 0.44, 0.09, 0.24 and 0.39min(-1) with addition of 1.45×10(-2) mM AuNPs. An eco-friendly approach for synthesis of AuNPs by T. montevideense is reported for the first time. The biogenic AuNPs could serve as efficient catalysts for hydrogenation of various nitroaromatics.

Facile and rapid thermo-regulated biomineralization of gold by pullulan and study of its thermodynamic parameters

A novel method for the production of gold nanoparticles (AuNPs) using pullulan as reducing and stabilizing agent has been developed. Quasi-spherical shaped AuNPs in the range of 50–100nm were produced at three different temperature regimes 80°C, 90°C and 100°C as characterized using UV–vis spectrophotometer, TEM and DLS. Study of reaction kinetics and thermodynamic parameters indicated that the reaction between pullulan and chloroauric acid for AuNPs formation followed first order reaction kinetics and higher temperature was favorable for the synthesis of smaller sized AuNPs. FT-IR data analyses, provided an insight towards the mechanism of gold nanoparticle formation which suggested that, the free CH2OH groups of pullulan molecule were oxidized to carboxylate ions resulted in formation of AuNPs whereas the basic skeletal structure of pullulan remained unaltered. This study may open up new avenues for synthesis of tailor made biogenic AuNPs with possible application in biomedical field.

An evidence on G2/M arrest, DNA damage and caspase mediated apoptotic effect of biosynthesized gold nanoparticles on human cervical carcinoma cells (HeLa)

Current prospect of nanobiotechnology involves in the greener synthesis of nanostructured materials particularly noble metal nanoparticles for various biomedical applications. In this study, biologically (Podophyllum hexandrum L.) synthesized crystalline gold nanoparticles (AuNPs) with the size range between 5 and 35nm were screened for its anticancereous potential against human cervical carcinoma cells (HeLa). Stoichiometric proportion of the reaction mixture and conditions were optimized to attain stable nanoparticles with narrow size range. Different high throughput techniques like transmission electron microscope (TEM), X-ray diffraction (XRD) and UV–vis spectroscopy were adopted for the physio-chemical characterization of AuNPs. Additionally, Fourier transform infrared spectroscopy (FTIR) study revealed that the water soluble fractions present in the plant extract solely influences the reduction of AuNPs. Sublimely, synthesized AuNPs exhibits an effective in vitro anticancer activity against HeLa cells via induction of cell cycle arrest and DNA damage. Furthermore, it was evidenced that AuNPs treated cells are undergone apoptosis through the activation of caspase cascade which subsequently leads to mitochondrial dysfunction. Thereby, this study proves that biogenic colloidal AuNPs can be developed as a promising drug candidature for human cervical cancer therapy.