HAuCl4 Research Articles

A novel QCM immunosensor development based on gold nanoparticles functionalized sulfur-doped graphene quantum dot and h-ZnS-CdS NC for Interleukin-6 detection

Interleukin 6 (IL-6) acts as both a proinflammatory and anti-inflammatory cytokine and is generally utilized as an important diagnostic biomarker for sepsis. In addition, the high levels of IL-6 measured in plasma have been associated with pathological inflammation. A novel quartz crystal microbalance (QCM) immunoassay method was presented for high sensitivity and selectivity detection of interleukin-6 (IL-6) based on gold nanoparticles functionalized sulfur-doped graphene quantum dot (AuNPs/S-GQD) and hollow ZnS–CdS nanocage (h-ZnS-CdS NC). Firstly, AuNPs/S-GQD nanocomposite was synthesized in the presence of tetrachloroauric acid and then conjugated onto anti-IL-6 antibodies by amino-gold affinity. The sandwich-type QCM immunoassay probe was prepared by immune-reaction between AuNPs/S-GQD/QCM immobilized with anti-IL-6 capture antibodies and h-ZnS-CdS NC including detection anti-IL-6 antibodies in the presence of target IL-6. The prepared QCM immunoassay probe was characterized by transmission electron microscopy (TEM), scanning electron microscope (SEM), x-ray diffraction (XRD) method, x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The QCM immunosensor showed a linearity range (0.01–2.0 pg mL−1) and a low detection limit (3.33 fg mL−1). Lastly, high stable and selective QCM immunosensor was applied to prepared plasma samples with good recovery.

Rapid and sensitive label-free SERS determination of fucoxanthin in algae using gold nanoparticles

In this paper, we explored a rapid and ultra-sensitive detection method of fucoxanthin in algae by surface-enhanced Raman scattering. Gold nanoparticles (Au NPs) were prepared by the reduction of chloroauric acid with citric acid. An effective Raman indicator molecule, Rhodamine 6G(R6G) dye molecule, was used to characterize Au NPs that were used in SERS analysis to detect fucoxanthin. It was found that the detection limit of fucoxanthin could reach 10−6 mol·L−1. The characteristic peak of fucoxanthin at a wave number of 1520 cm−1was selected as the working curve, and it presents good linearity of fucoxanthin concentration with R2 = 0.932 in the range from 5×10−4∼1×10−7 M. We first proposed the rapid detection of fucoxanthin by surface-enhanced Raman scattering, which took only one minute to detect. In addition, the Raman strength of the pure algae or kelp and the addition of fucoxanthin was compared under the gold nanoparticle substrate, so as to verify the application value of SERS technology in the rapid determination of fucoxanthin.

Removal of Au(III) from Aqueous Au(III) Solution Using Microbial Cells by Biosorption and Biomineralization

The demand for gold has increased in the medical and industrial fields. Therefore, recycling this element has become essential. Although gold recovery using microbes has been investigated, there is a dearth of these studies on identifying the species that have a high gold recovering ability. Herein, gold (III) removal by microbial cells was investigated to obtain basic information on gold (III) removal from aqueous systems by biosorption and biomineralization. High amounts of gold were removed from the solution containing hydrogen tetrachloroaurate (III) by the tested microbial species, which included bacteria, fungi and yeasts. However, relatively less gold was recovered by biosorption using gram-positive bacteria, fungi, and yeasts than that by gram-negative bacteria. Therefore, we first examined gold (III) removal by biosorption and biomineralization by Pseudomonas saccharophila, which was able to remove the largest amounts of gold (III). Incubation time and other factors affecting gold removal were then examined. P. saccharophila removed about half the amount of gold (III) by biosorption and the remaining half by biomineralization.

Rapid and selective detection of aluminum ion using 1,2,3-triazole-4,5-dicarboxylic acid-functionalized gold nanoparticle-based colorimetric sensor.

A highly selective, sensitive, rapid, low-cost, simple and visual colorimetric system for Al3+ ion detection was developed based on gold nanoparticles (AuNPs) modified with 1,2,3-triazole-4,5-dicarboxylic acid (TADA). The modified gold nanoparticles (TADA–AuNPs) were first prepared by sodium citrate (Na3Ct) reduction of chloroauric acid (HAuCl4) and then capped with a TADA ligand. Five TADA–AuNPs sensors were constructed with sodium citrate (Na3Ct)/chloroauric acid (HAuCl4) under different molar ratios. Results showed that the molar ratio of Na3Ct/HAuCl4, TADA–AuNPs concentration, pH range and detection time had obvious influences on the performance of this colorimetric method. The optimal detection conditions for Al3+ ions were as follows: Na3Ct/HAuCl4 molar ratio of 6.4 : 1, 0.1 mM of TADA–AuNPs concentration, 4–10 pH range and 90 s of detection time. Under the optimal conditions and using diphenyl carbazone (DPC) as a Cr3+ masking agent, this colorimetric sensor exhibited outstanding time efficiency, selectivity and sensitivity for Al3+ detection. In particular, the detection limits of this sensor obtained via UV-vis and the naked eye were 15 nM and 1.5 μM, respectively, which were much lower than the current limit (3.7 μM) for drinking water in WHO regulation and better than the previous reports. Moreover, this colorimetric sensing system could be used to for on-site, trace level and real-time rapid detection of Al3+ in real water samples.

Dual-emission ratio fluorescence for selective and sensitive detection of ferric ions and ascorbic acid based on one-pot synthesis of glutathione protected gold nanoclusters.

A fluorometric method was proposed for the determination of Fe3+ and ascorbic acid (AA) based on blue and red dual fluorescence emissions of glutathione (GSH) stabilized-gold nanoclusters (AuNCs). AuNCs were synthesized from GSH and tetrachloroauric acid. The fluorescence peaks of AuNCs were at 425 nm and 585 nm, respectively. In the presence of Fe3+, the fluorescence peak at 425 nm can be enhanced and that at 585 nm can be quenched. There is a good linear relationship between the fluorescence intensity ratio for the 425 and 585 nm peaks (F425/F585) and the concentration of Fe3+ in the range of 0.75–125 μM. However, when AA was added to the AuNCs–Fe3+ system, the value of F425/F585 decreased consistently with the concentration of AA in the range of 0.25–35 μM. The limit of detection for Fe3+ and AA was 227 and 75.8 nM, respectively. The interaction between AuNCs and Fe3+ can induce the ligand–metal charge transfer (LMCT) effect leading to the fluorescence increment at 425 nm, while AA can reduce Fe3+ to Fe2+. The production of Fe2+ can not enhance or quench the fluorescence of AuNCs. By comparison with previous literature, the AuNCs prepared here show two fluorescence peaks without additional fluorescence labels. Furthermore, the method was successfully applied in the determination of Fe3+ and AA in some real samples, such as water, human serum and tablets.

Facile engineering of silk fibroin capped AuPt bimetallic nanozyme responsive to tumor microenvironmental factors for enhanced nanocatalytic therapy.

Background: Reactive oxygen species (ROS), as a category of highly reactive molecules, are attractive for eliminating tumor cells in situ. However, the intrinsic tumor microenvironment (TME) always compromises treatment efficacy. In another aspect, silk fibroin (SF), as a category of natural biomacromolecules, is highly promising for synthesis of metallic nanocrystals via biomineralization.Methods: As a proof-of-concept study, AuPt bimetallic nanozyme derived from bioinspired crystallization of chloroauric acid and chloroplatinic acid was facilely developed in the presence of silk fibroin (SF). Antitumor effects caused by the as-synthesized AuPt@SF (APS) nanozyme were demonstrated in 4T1 tumor cells in vitro and xenograft tumor models in vivo.Results: APS nanozyme can decompose glucose to constantly supply H2O2 and deplete intracellular glutathione (GSH). APS nanozyme can simultaneously convert adsorbed O2 and endogenic H2O2 into superoxide radicals (•O2-) and hydroxyl radical (•OH), respectively, upon highly efficient catalytic reaction. Subsequently, these cytotoxic ROS cause irreversible damage to the cell membrane, nucleic acid and mitochondria of tumors. Upon fluorescence/photoacoustic (FL/PA)-imaging guidance, remarkable tumor damage based on the current nanoplatform was confirmed in vivo.Conclusion: The objective of our investigation is to supply more useful insights on the development of SF-based nanocatalysts, which are specifically responsive to TME for extremely efficient tumor theranostics.

Gold Nanoparticles: Synthesis and Effect on Viability of Human Non-Small Lung Cancer Cells

Gold nanoparticles recently showed great interest for many uses including food, drug and medical applications. The algae Undaria sp. well known as wakame in South Asia are considered to be large edible brown algae. It provides nutritious source of dietary fiber, vitamin Bs and mineral. The present study aimed to investigate the use of Undaria sp. for green synthesis of metallic gold nanoparticles. The synthesized nanoparticles were characterized for physicochemical properties including size measurement and tested in vitro for their effect on viability of human non-small lung cancer H-460 cell line using the MTT assay. From the results, brown algae were able to chemically form nanoparticles with chloroauric acid solution possibly due to the sulphated polysaccharides found in algae. The particle sizes were found to be approximately 10 nm. The gold nanoparticles stabilized by the algae could decrease the cancer cell viability. However, the properties and biological activity of nanoparticles seemed to depend upon reaction time and temperature. Conclusively, gold nanoparticles synthesized and stabilized by the algae could decrease the cancer cell viability, thus indicating the potential of such nanoparticles for further study for anticancer activity.

Application of digital colorimeter for preliminary characterization of gold nanoparticle swarms produced by Termitomyces heimii using a novel Bioinspired Microfluidics assay

In our laboratory work extending over several years we have successfully studied the biogeochemical role of termite mounds and their occupants the termites and the exosymbiont fungus-Termitomyces. Fungi appear to be promising for large scale production of nanoparticles (NPs) as these are simpler to grow both in laboratory and at industrial scale. This paper reports a novel microfluidics based assay system to detect Gold bioreduction capacity of different tissues in tissue based and cell free environment. Using sterile microtest well, different tissues such as umbo, pileus, lamellae, stipe context, stipe epicutis, pseudorrhiza context, pseudorrhiza epicutis of Termitomyces heimii mature fruitbodies were tested with 200μl chloroauric acid (one mM) and after an interval of 5,10, 15, 30, 45, 60, 120 min and 12, 24 and 48 hours. The results in terms production of distinct nanoparticles were directly visualized microscopically and using mobile based digital colorimeter. Membrane filtered sterile water soluble extracts (SWSE) from the same tissues were similarly screened. The results manifested by mono and polydisperse GNPs and microparticles of mixed size groups demonstrated that cell free system can be potentially useful for bioinspired fabrication of GNPs. Further work in this direction is in progress using several termitomyces cultures.

In English

Nowadays nanocomposites based on magnetite doped with noble metal cations or core&shell type nanocomposites including superparamagnetic core and precious metal shells are widely used in new kinds of biocompatible materials creation. The following structures are characterized by unique complexes of physical-chemical properties. The noble metal coatings formed on the magnetite nanoparticles surface supply their corrosive biological media stabilization and effects on electrical, magnetic, catalytic, optical properties of core&shell type nanocomposites as well. This work studies the effect of UV irradiation (253 nm) on the paramagnetic characteristics of biocompatible core&shell type nanocomposites based on magnetite and precious metals (silver, gold). Nanoparticles of magnetite and core&shell type composites Fe3O4&Ag0 and Fe3O4&Au0 were formed under the rotation-corrosion dispergation conditions on the steel 3 (St3) surface contacting with distilled water and aqueous solutions of silver nitrate and tetrachloroauric acid at a free flow of oxygen into the reaction zone. Solutions of precious metals contained from 0.5 to 20 mg/dm3 of Ag(I) and Au(III) aquaforms. The composite nanoparticles were characterized using X-ray diffraction data, scanning electron microscopy and electron paramagnetic resonance spectroscopy. Because of expecting photocatalytic activity of as-prepared nanocomposites, we performed their illumination by ultraviolet irradiation. The effect of UV irradiation (253 nm) on the paramagnetic characteristics of biocompatible core&shell nanocomposites based on magnetite and precious metals (silver, gold) was studied by EPR analysis. The obtained data suggests that after UV irradiation the contribution of Fe2+ spins increases, the band gap for Fe3O4 decreases, the rate of charge redistribution at the oxide-metal interface increases, the number of spins in the composite increases. The study of the occurrence of paramagnetic centers mechanism in the nanocomposites based on magnetite and precious metals may be relevant for determining their bactericidal and photocatalytic activity. Also, such nanocomposites can be used in the creation of technical means for prevention of the spread of infectious diseases in the transport, public places, and hospitals.

Synthesis of Chloroauric Acid from Gold Electrodes in Alkali Halide Salt Solution by AC Electrolysis and the Sequential Formation of Gold Nanoparticles by Turkevich Method

Abstract Gold nanoparticles have been commonly made by a wet process from chloroauric acid or dry process using vacuum evaporation to solid surfaces. Here, we have shown a method to make gold particle from gold electrodes in potassium chloride solution by AC electrolysis and the following Turkevich method. The developed AC electrolysis method provides an environment-friendly process to produce gold particles from gold electrodes without using any strong acids such as aqua regia or hydrochloric acid.

Gallic acid-gold nanoparticles enhance radiation-induced cell death of human glioma U251 cells.

Glioblastoma multiforme (GBM) is among the most common adult brain tumors with invariably fatal character. Following the limited conventional therapies, almost all patients, however, presented with symptoms at the time of recurrence. It is dire to develop novel therapeutic strategies to improve the current treatment of GBM. Gallic acid is a well‐established antioxidant, presenting a promising new selective anti‐cancer drug, while gold nanoparticles (GNPs) can be developed as versatile nontoxic carriers for anti‐cancer drug delivery. Here, we prepared gallic acid‐GNPs (GA‐GNPs) by loading gallic acid onto GNPs, reduction products of tetrachloroauric acid by sodium citrate, through physical and agitation adsorption. GA‐GNPs, rather than GNPs alone, significantly inhibited the survival of U251 GBM cells, as well as enhanced radiation‐induced cell death. Moreover, GA‐GNPs plus radiation arrested the cell cycle of U251 at the S and G2/M phases and triggered apoptotic cell death, which is supported by increased BAX protein levels and decreased expression of BCL‐2. Thus, GA‐GNPs have great potential in the combination with radiation therapy in future studies for GBM treatment.

Induction of Caspase-Mediated Apoptosis in HepG2 Liver Carcinoma Cells Using Mutagen-Antioxidant Conjugated Self-Assembled Novel Carbazole Nanoparticles and In Silico Modeling Studies.

In this study, novel self-assembled carbazole-thiooctanoic acid nanoparticles (CTNs) were synthesized from amino carbazole (a mutagen) and thiooctanoic acid (an antioxidant). The nanoparticles were characterized using hyperspectral techniques. Then, the antiproliferative potential of CTNs was determined in HepG2 liver carcinoma cells. This study employed a solvent–antisolvent interaction method to synthesize a spherical CTN of size less than 50 nm. Moreover, CT was subsequently capped to gold nanoparticles (AuNPs) in the additional comparative studies. The CT derivative was synthesized from carbazole and lipoic acid by the amide bond formation reaction using a coupling agent. Furthermore, it was characterized using infrared (IR), 1H nuclear magnetic resonance, dynamic light scattering (DLS), and transmission electron microscopy techniques. The CT-capped gold nanoparticles (CTAuNPs) were prepared from CT, chloroauric acid, and NaBH4. The CTAuNPs were characterized using ultraviolet–visible, high-resolution TEM, DLS, and Fourier transform IR techniques. The cytotoxicity and apoptosis-inducing ability of both nanoparticles were determined in HepG2 cells. The results demonstrate that CTNs exhibit antiproliferative activity in the cancerous HepG2 cells. Moreover, molecular docking and molecular dynamics studies were conducted to explore the therapeutic potential of CT against human EGFR suppressor protein to gain more insights into the binding mode of the CT, which may show a significant role in anticancer therapy.

Seed-mediated synthesis and PEG coating of gold nanoparticles for controlling morphology and sizes

AbstractA significant area of research is biomedical applications of nanoparticles which involves efforts to control the physicochemical properties through simple and scalable processes. Gold nanoparticles have received considerable attention due to their unique properties that they exhibit based on their morphology. Gold nanospheres (AuNSs) and nanorods (AuNRs) were prepared with a seed-mediated method followed of polyethylene glycol (PEG)-coating. The seeds were prepared with 0.1 M cetyltrimethyl-ammonium bromide (CTAB), 0.005 M chloroauric acid (HAuCl4), and 0.01 M sodium borohydride (NaBH4) solution. Gold nanoparticles with spherical morphology was achieved by growth by aggregation at room temperature, while to achieve the rod morphology 0.1 M silver nitrate (AgNO3) and 0.1 M ascorbic acid solution were added. The gold nanoparticles obtained by the seed-mediated synthesis have spherical or rod shapes, depending on the experimental conditions, and a uniform particle size. Surface functionalization was developed using polyethylene glycol. Morphology, and size distribution of AuNPs were evaluated by Field Emission Scanning Electron Microscopy. The average size of AuNSs, and AuNRs was 7.85nm and 7.96 x 31.47nm respectively. Fourier transform infrared spectrometry was performed to corroborate the presence of PEG in the AuNPs surface. Additionally, suspensions of AuNSs and AuNRs were evaluated by UV-Vis spectroscopy. Gold nanoparticles were stored for several days at room temperature and it was observed that the colloidal stability increased once gold nanoparticles were coated with PEG due to the shield formed in the surface of the NPs and the increase in size which were 9.65±1.90 nm of diameter for AuNSs and for AuNRs were 29.03±5.88 and 8.39±1.02 nm for length and transverse axis, respectively.

Formation and Electrochemical Characterisation of Enzyme-Assisted Formation of Polypyrrole and Polyaniline Nanocomposites with Embedded Glucose Oxidase and Gold Nanoparticles

Enzyme-assisted synthesis of electrochemically active nanocomposite structures based on π-π conjugated polymers polyaniline (PANI) and polypyrrole (Ppy) is reported. The synthesis of both conducting polymers was induced by hydrogen peroxide, which is generated during catalytic action of glucose oxidase (GOx), and this polymerisation was performed in the presence of (i) gold nanoparticles of 6 nm diameter (AuNPs(6nm)) or (ii) tetrachloroauric acid (HAuCl4). Formed nanocomposites were evaluated electrochemically and spectrophotometrically. Field emission scanning electron microscopy results illustrated that nanocomposites are poly-dispersed particles tend to agglomerate during centrifugation. Hydrodynamic diameter evaluated by dynamic light scattering technique for PANI/AuNPs(6nm)&GOx- or PANI/AuNPs(AuCl4 −)&GOx-based nanocomposites after 108 h lasting polymerization was 1.90 or 1.70 times larger than that determined for Ppy/AuNPs(6nm)&GOx or Ppy/AuNPs(AuCl4 −)&GOx, respectively. Oxidation peaks in cyclic voltammograms determined for electrodes modified by PANI/AuNPs(6nm)&GOx-, PANI/AuNPs(AuCl4 −)&GOx- and PANI/GOx-based nanocomposites were observed at +0.332, +0.349, and +0.542 V. For Ppy/AuNPs(6nm)&GOx-, Ppy/AuNPs(AuCl4 −)&GOx- and Ppy/GOx-based nanocomposites oxidation peaks were observed at +0.425, +0.545 and +0.508 V, respectively. Oxidation peaks of PANI nanocomposites without and with AuNPs or AuCl4 - appeared due to the conversion of PANI leucoemeraldine form to emeraldine salt, while for Ppy – are attributed to the transition of cation-polaron into the cation-bipolaron-based state of Ppy.

Silver Antibacterial Synergism Activities with Eight Other Metal(loid)-Based Antimicrobials against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus.

The present study surveys potential antibacterial synergism effects of silver nitrate with eight other metal or metalloid-based antimicrobials (MBAs), including silver nitrate, copper (II) sulfate, gallium (III) nitrate, nickel sulfate, hydrogen tetrachloroaurate (III) trihydrate (gold), aluminum sulfate, sodium selenite, potassium tellurite, and zinc sulfate. Bacteriostatic and bactericidal susceptibility testing explored antibacterial synergism potency of 5760 combinations of MBAs against three bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus) in three different media. Silver nitrate in combination with potassium tellurite, zinc sulfate, and tetrachloroaurate trihydrate had remarkable bactericidal and bacteriostatic synergism effects. Synergism properties of MBAs decreased effective antibacterial concentrations remarkably and bacterial cell count decreased by 8.72 log10 colony-forming units (CFU)/mL in E. coli, 9.8 log10 CFU/mL in S. aureus, and 12.3 log10 CFU/mL in P. aeruginosa, compared to each MBA alone. Furthermore, most of the MBA combinations inhibited the recovery of bacteria; for instance, the combination of silver nitrate–tetrachloroaurate against P. aeruginosa inhibited the recovery of bacteria, while three-fold higher concentration of silver nitrate and two-fold higher concentration of tetrachloroaurate were required for inhibition of recovery when used individually. Overall, higher synergism was typically obtained in simulated wound fluid (SWF) rather than laboratory media. Unexpectedly, the combination of A silver nitrate–potassium tellurite had antagonistic bacteriostatic effects in Luria broth (LB) media for all three strains, while the combination of silver nitrate–potassium tellurite had the highest bacteriostatic and bactericidal synergism in SWF. Here, we identify the most effective antibacterial MBAs formulated against each of the Gram-positive and Gram-negative pathogen indicator strains.

Ultrasmall gold and silver/gold nanoparticles (2\u2009nm) as autofluorescent labels for poly(D,L-lactide-co-glycolide) nanoparticles (140\u2009nm)

Ultrasmall metallic nanoparticles show an efficient autofluorescence after excitation in the UV region, combined with a low degree of fluorescent bleaching. Thus, they can be used as fluorescent labels for polymer nanoparticles which are frequently used for drug delivery. A versatile water-in-oil-in-water emulsion-evaporation method was developed to load poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles with autofluorescent ultrasmall gold and silver/gold nanoparticles (diameter 2 nm). The metallic nanoparticles were prepared by reduction of tetrachloroauric acid with sodium borohydride and colloidally stabilised with 11-mercaptoundecanoic acid. They were characterised by UV–Vis and fluorescence spectroscopy, showing a large Stokes shift of about 370 nm with excitation maxima at 250/270 nm and emission maxima at 620/640 nm for gold and silver/gold nanoparticles, respectively. The labelled PLGA nanoparticles (140 nm) were characterised by dynamic light scattering (DLS), scanning electron microscopy (SEM), and UV–Vis and fluorescence spectroscopy. Their uptake by HeLa cells was followed by confocal laser scanning microscopy. The metallic nanoparticles remained inside the PLGA particle after cellular uptake, demonstrating the efficient encapsulation and the applicability to label the polymer nanoparticle. In terms of fluorescence, the metallic nanoparticles were comparable to fluorescein isothiocyanate (FITC).

Poly (Vinyl Alcohol) Assisted Synthesis and Anti-Solvent Precipitation of Gold Nanoparticles.

Gold nanoparticles (GNPs) are commonly synthesized using the Turkevich method, but there are limitations on the maximum concentration of gold nanoparticles that can be achieved using this method (often < 1 mM (=0.34 mg/mL) gold precursor loading). Here, we report an inverse Turkevich method which significantly increases the concentration of gold nanoparticles (up to 5-fold) in the aqueous phase by introducing poly (vinyl alcohol) (PVA) to the synthesis system for stabilization. The aim of this study is to understand the effect of PVA and other synthesis parameters, such as trisodium citrate and tetrachloroauric acid concentration, with the goal of maximizing concentration while maintaining gold nanoparticle morphology, stability, and narrow size distribution. The size distribution of GNPs is investigated for a range of parameters by dynamic light scattering and electron microscopy, and ultraviolet-visible (UV–vis) spectroscopy is also utilized to explore the localized surface plasmon resonance (LSPR). Further, the interaction between GNPs and PVA is investigated by Fourier-transform infrared spectroscopy. In addition to increasing the gold loading by varying synthesis parameters, we also develop a novel anti-solvent precipitation method for the PVA-coated GNPs, which enables continuous condensation and purification of GNPs by forming a gold/PVA nanocomposite.

Green nanogold activity in experimental breast carcinoma in vivo.

Background: Over the past few years, fabrication of nanoparticles (NPs) has been deployed widely in technologies and many concerns have emerged about the hazardous effect on human health after NPs exposure.Objective: Green synthesis of gold NPs (AuNPs) and assessment of their activity in 7,12-dimethylbenz(a)anthracene (DMBA)-induced breast cancer mouse model.Methods: Chloroauric acid (HAuCl4) was used in formation of AuNPs with the help of Curcuma longa as aqueous reducing extract and stabilizing agent at room temperature. Formed NPs were characterized with UV-Vis spectrometry, Fourier-transform infrared spectroscopy (FTIR), Zetasizer measurement, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Virgin female albino mice with DMBA-induced breast cancer were treated with formed AuNPs for 5 consecutive days and were dissected after 28 days of the beginning of treatment.Results: UV-Vis spectrometry showed absorbance maximum peak at 530 nm for formed AuNPs, FTIR confirmed formation of plant extract layer around formed NPs; zetasizer measurement revealed 278.2 nm as an average size of produced NPs; SEM and TEM approved formation of monodisperse spherical AuNPs. Biochemical analysis of untreated breast cancer group revealed marked changes in liver and kidney functions manifested by raised activity levels of alanine transaminase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN) and creatinine. Whereas, the treated group with AuNPs post-breast cancer induction displayed reduction in the activities (of ALT, AST and creatinine), while the BUN activity level was raised. Histopathological examination showed heavy incidence of tumor foci in the breast and lymph nodes belonged to the untreated breast cancer group confirmed with intense response to Ki-67 antibodies. While the treated group with AuNPs post-breast cancer induction showed degenerated tumor foci in the breast and lymph nodes with weak response to Ki-67 antibodies.Conclusion: AuNPs were successfully synthesized using HAuCl4 and C. longa extract confirmed their ability to control DMBA-induced breast cancer in virgin female Swiss albino mice.

Insight into diffusive and convective processes affecting gold nanoparticles microclustering by multiphoton photoreduction

Multi-photon direct laser writing (MP-DLW) in polymeric matrices doped with a tetrachloroauric acid (HAuCl4) water solution allows creating clusters of gold nanoparticles (GNPs) inside the focus figure of a tightly focused ultrafast laser beam. The key physical phenomena involved in the process are analyzed, with the aim to assess the limits and potential of this promising technology. Multi Photon Absorption (MPA) triggers the photo-reduction of AuCl4– ions and the consequent creation of GNPs in the spotted volume. Thermal electronic decays lead to a local abrupt increase of the temperature, which influences the morphology of the created structures. At the same time, two different effects take place, related to the dehydration of the polymeric matrix, and the concentration gradient of the gold precursor upon localized photoreduction. Given their different timescales, these phenomena allow for controlling the GNPs density and size dispersity when a given energy dose is delivered in multiple exposures, tuning the delay between consecutive laser exposures. A simple yet effective experiment to estimate the temperature distribution at the micron-scale is also proposed.

Electrochemical non-enzymatic sensing of glycoside toxins by boronic acid functionalized nano-composites on screen-printed electrode

Natural glycoside toxins, one of the most ubiquitous toxins in food of plant origin, cause serious health threat on humans and livestock. Evaluation of their health risk is of great significance. We proposed a non-enzymatic sensor based on reduced graphene oxide/gold nanoparticles/boronic acid nano-composites for their rapid and simple detection. The nano-composites were integrally synthesized in liquid dispersion. Gold nanoparticles, which were reduced from chloroauric acid, nucleated and grew on graphene oxide films directly. 4-mercaptophenylboronic acid self-assembled with gold nanoparticles through gold-sulfur bond. With reduction of graphene oxide through cyclic voltammetry, the nano-composites were then one step modified onto the working electrodes as sensing layer. Glycoalkaloids, common glycoside toxins in potatoes, were detected with the functionalized screen-printed electrodes. Electrochemical differential pulse voltammetry was applied for the detection. The sensor exhibited good stability in at least four weeks with a wide detection range from 10 μM to 1000 μM. The limit of detection was as low as 3.4 μM. The developed sensor was successfully applied to the detection of glycoalkaloids in real potato samples. As a proof of concept, the disposable sensor with high sensitivity and selectivity exhibited great application potential for the risk control of natural glycoside toxins in food.