Gold Metal Ions Research Articles

Coordination Complexes of Copper, Silver and Gold with SNO Group Containing Thiosemicarbazones Schiff Base Ligands and their Biological Applications

The thiosemicarbazone Schiff base ligand is very important segment for chemistry, more specifically coordination chemistry. These compounds and their complexes widely used as medicinal agents for different lethal diseases such as cancer and other contagious disease caused by bacteria. The coordinated metal (coinage) complexes exhibited higher activities than free ligand for all the biological investigation of anticancer and antibacterial activities. The TSCs ligands having polydentate S-N-O coordinating sites. The mode of coordination of these ligands is flexible, it can act as tridentate or bidentate ligand. These ligand form mostly square planar complexes with copper, silver and gold metal ions. This research content could guide to identify the synthesized biomaterial. In this review, copper, silver, gold complexes are comprehensively summarized, and their activities and mechanism are documented. This review will provide very cut-edge guide of TSCs and their complexes to use in different field.

(Invited) harnessing the Barrier Oxide Layer of Nanoporous Anodic Alumina for Iontronic Sensing

The hemispherical barrier oxide layer (BOL) closing the tips of hexagonally distributed arrays of cylindrical nanochannels in nanoporous anodic alumina (NAA) membranes is structurally engineered by anodizing aluminum substrates in three distinct acid electrolytes at their corresponding self-ordering anodizing potentials. These nanochannels display a characteristic ionic current rectification (ICR) signal between high and low ionic conduction states, which is determined by the thickness and chemical composition of the BOL, and the pH of the ionic electrolyte solution. Rectification efficiency of ionic current associated with the flow of ions across the anodic BOL increases with its thickness, under optimal pH conditions. The inner surface of nanopores in NAA membranes was chemically modified with thiol-terminated functional molecules. The resultant NAA-based iontronic system provides a model platform to selectively detect gold metal ions (Au3+) by harnessing dynamic ICR signal shifts as the core sensing principle. The sensitivity of the system is proportional to the thickness of the barrier oxide layer, where NAA membranes produced in phosphoric acid at 195 V with a BOL thickness of 232 ± 6 nm achieve the highest sensitivity and low limit of detection in the sub-picomolar range. This study provides exciting opportunities to engineer NAA structures with tailorable ICR signals for specific applications across iontronic sensing and other nanofluidic disciplines. Figure 1

Green Synthesis of Gold Nanoparticles Using Aqueous Extract of Asphodelus Aestivus, Coating with Chitosan Biopolymer and Cytotoxicity Studies

The green synthesis of gold nanoparticles (Au-NPs) was carried out by pouring the aqueous extract of East Anatolian origin Asphodelus aestivus plant onto aqueous gold metal ions and reducing them via single-step one- pot method. The absorption peak of the synthesized nanoparticles gave a maximum at 575 nm. All the X-ray diffraction peaks at 2θ = 38.25 , 44.46 , 64.64 and 77.20 that index to (111), (200), (220), and (311) planes verify the successful synthesis of Au-NPs. Mostly spherical shape particles showed a homogeneous distribution with size range 20±5 nm are measured using TEM. From the FTIR spectrum, the peaks are seems to be related to phenolic compounds, flavonoids, benzophenones, terpenoids and anthocyanins which assume that they could act as the reducing agents. The plant extraction, one-pot, single-step method used is environmentally safe without the role of synthetic materials which is highly potential in mild and green synthesis applications. The Au-NPs were coated with chitosan biopolymer in aquatic solution medium and verified by SEM. Then, cytotoxic investigations of the biosynthesized Au-NPs were carried out by HUVEC cells. Au-NPs were showed toxic effects on cell culture, even if in a small amount. However, chitosan biopolymer coating increased cell viability.Keywords: Gold nanoparticle, Biosynthesis, Asphodelus aestivus, Biopolymer coating, Cytotoxicity

Synthesis of gold nanoparticles (AuNPs) with improved anti-diabetic, antioxidant and anti-microbial activity from Physalis minima

BackgroundGold nanoparticles have come to prominence among noble metals due to their characteristics. Bio-transformed nanoparticles have a low toxicity and are biocompatible and ecologically benign. Physalis minima has been used in traditional medicine for its diuretic, laxative, and anti-inflammatory qualities since ancient times. MethodsGold nanoparticles are formed when water gold metal ions interact with an aqueous plant extract of Physalis minima (Au NPs). ResultsIn a UV–visible spectrophotometer, the resulting Au NPs formed a broad surface peak at 546 nm. According to the FTIR data, the peaks represent flavonoids, phenols and polyphenols meaning that flavonoids, phenols, and polyphenols were utilised as the reducing agent to create gold nanoparticles. According to the XRD pattern, the synthesised gold nanoparticles are crystalline in nature in a cubic system, with average particle sizes of roughly 36 nm. Gold nanoparticles were evaluated and found to have a zeta potential of −20.5mv, suggesting that they were stable and suitable for biological uses. The morphology of gold nanoparticles was confirmed using microscopic imaging. ConclusionThis study looked at the anti-oxidant, anti-diabetic, and antibacterial properties of gold nanoparticles (Au NPs) made from Physalis minima, making it exceedingly promising for biological applications.

Evaluating the Anti-Cancer Effect of Pomegranate Aqueous Extract of Gold Nanoparticles by Using Photodynamic Laser on Laboratory Mice.

Background: This study evaluated the anticancer effects of gold nanoparticles (Au- NPs) generated by reducing hydrated gold metal ions in the presence of aqueous pomegranate peel extract. Aim of study: To test the possibility that Au-NPs generated from the pomegranate aqueous extract could be employed as an anti-cancer therapy. Materials and methods: The study aimed to evaluate Photodynamic therapy (PDT) using a laser at a wavelength of 532 nm with green gold particles as a photosensitizer in in-vivo experiment. Gold nanoparticles (Au-NPs) were produced by reducing hydrated gold metal ions in the presence of aqueous pomegranate peel extract. Using UV-visible spectroscopy, the absorption peak of the gold particles was found near 550- 592 nm. All diffraction peaks for 2θ at = 37.8227º at 43.7014º, 63.8103º and 77.1540º correspond to the (111), (200), (220), and (311) levels, respectively by X-ray diffraction(XRD) analysis, imaging confirmed Au-NP by Transmission electron microscopy (TEM), the nanoparticle size ranged between 19.96 ± 0.784 nm. Forty Mature Swiss females weighing 20–25 g and aged 6–8 weeks were used, the animals were placed in well-ventilated rooms. Results: The best exposure time to eradicate the tumor is with a duration of exposure of 30 minutes using the diode laser, as histological investigations indicated the development of anti-immunity with the same exposure period.

Synthesis of Au50Ag50 Alloy Nanoparticles From Metal Ions and Colloidal Nanoparticles Through Photochemical Reduction Methods Using Femtosecond Laser

Nanoparticles synthesized through photochemical reduction using femtosecond involve reducing agent that reduces metal ions into nanoparticles. We synthesized Au50Ag50 from metal ions and colloidal nanoparticles in four different conditions: (i) gold metal ions and silver metal ion, (ii) colloidal gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs), (iii) gold metal ions and colloidal silver nanoparticles (AgNPs), and (iv) colloidal gold nanoparticles (AuNPs) and silver metal ions. Gold and metal ions were obtained from dilution of gold and silver metal salts. While gold and silver nanoparticles were obtained from gold and metal ions added into a quartz cuvette and irradiated by femtosecond laser in 10 minutes irradiation time. In the synthesis, every condition respectively mixed in 3 ml solution into a 10x10x45 mm quartz cuvette and irradiated by femtosecond laser in 5-, 10- and 15- minutes irradiation time. The result showed that Au50Ag50 alloy nanoparticles were successfully synthesized in four different conditions, and the LSPR (Localized Surface Plasmon Resonance) in 15 minutes irradiation time was observed at 454.51, 458.74, 459.60, and 457.29 nm in the condition (i), (ii), (iii), and (iv), respectively.

Structural Engineering of the Barrier Oxide Layer of Nanoporous Anodic Alumina for Iontronic Sensing.

The hemispherical barrier oxide layer (BOL) closing the bottom tips of hexagonally distributed arrays of cylindrical nanochannels in nanoporous anodic alumina (NAA) membranes is structurally engineered by anodizing aluminum substrates in three distinct acid electrolytes at their corresponding self-ordering anodizing potentials. These nanochannels display a characteristic ionic current rectification (ICR) signal between high and low ionic conduction states, which is determined by the thickness and chemical composition of the BOL and the pH of the ionic electrolyte solution. The rectification efficiency of the ionic current associated with the flow of ions across the anodic BOL increases with its thickness, under optimal pH conditions. The inner surface of the nanopores in NAA membranes was chemically modified with thiol-terminated functional molecules. The resultant NAA-based iontronic system provides a model platform to selectively detect gold metal ions (Au3+) by harnessing dynamic ICR signal shifts as the core sensing principle. The sensitivity of the system is proportional to the thickness of the barrier oxide layer, where NAA membranes produced in phosphoric acid at 195 V with a BOL thickness of 232 ± 6 nm achieve the highest sensitivity and low limit of detection in the sub-picomolar range. This study provides exciting opportunities to engineer NAA structures with tailorable ICR signals for specific applications across iontronic sensing and other nanofluidic disciplines.

Gold nanoparticle decorated graphene for efficient sensing of NO2 gas

We have devised a method to simultaneously reduce graphene oxide and gold metal ions onto the surface of graphene. The nanohybrid was in-turn used for efficient sensing of NO2 gas. The nanohybrid was characterized using X-ray diffractometry, field emission scanning electron microscopy (FESEM), UV–Visible spectroscopy and Raman spectroscopy. Morphological details revealed the successful growth of gold nanoparticles onto graphene sheets. Considerable variations in electrical characteristics of graphene-Au nanohybrid were recorded upon the exposure of NO2 gas. The sensor showed fast response and recovery time and good response of 3.2 % for 50 ​ppm NO2 gas. The method can pave the way to develop miniaturized gas sensors useful for environmental monitoring.

Green Synthesis of Gold Nanoparticles using Aqueous Extract of Clitoria Ternatea Flower

The synthesis of gold nanoparticles (Au-NPs) is being accomplished by the reduction of aqueous gold metal ions, gold(III) chloride trihydrate (HAuCl4.3H2O) reacted with the aqueous flower extract of Clitoria Ternatea (CT). CT flower extract plays an important role in synthesizing Au-NPs. It acts as a reducing (Au3+ to Au) and stabilizing agent that can eliminate the usage of chemicals during the production of Au-NPs. Besides that, it also reduces the production of unwanted by-products which would cause hazardous to the surroundings and environment. In this study, an absorption peak of Au-NPs is observed at the range of 540-550 nm from ultraviolet-visible spectroscopy (UV-vis) analysis. Furthermore, the diffraction peaks at 2θ = 38.44°, 44.41°, 65.03° and 77.58° respectively which correspond to face-centered cubic structure with (111), (200), (220) and (311) plane confirm the successful synthesis of Au-NPs. According to transmission electron microscopy (TEM), the majority of Au-NPs are spherical in shape and having a mean particle size distribution of 18.16 nm with a standard deviation of 4.67 nm.

Therapeutic potential of dithiocarbamate supported gold compounds.

Chrysotherapy or aurotherapy, the use of gold as medicine, is two thousand years old. Hitherto, numerous diverse gold stabilizing ligands for instance vitamins, pyridine, phosphines, naphthylamine and xanthanes have been developed and their ‘chelating effect’ in addition to their anti-proliferative properties have been extensively studied. Recent advances in the field of bioinorganic chemistry have led to the design of biologically relevant metal complexes with appropriate fine-tuned ligands such as metallic conjugates of dithiocarbamates (DTCs). DTC compounds have been recognised to possess diverse applications and have demonstrated interesting biological properties. For instance, the chemoprotective and antitumour properties of gold metal ions and DTC compounds respectively, presents an innovative and effective approach to cancer management. This review presents therefore the therapeutic potential of DTC ligand systems as a support for gold compounds. The importance of dithiocarbamate supported gold compounds as potential therapeutic agents is highlighted with emphasis on the therapeutic potential of gold(iii) and gold(i) dithiocarbamate derivatives.

Enhancement of solar cell efficiency via luminescent downshifting by an optimized coverglass

A novel approach to enhance the solar cell efficiency via employing a luminescent downshifting mechanism is presented in this work. Gold metal ions were diffused into a commercially available sodalime silicate glass using a versatile field-assisted solid-state ion diffusion technique under different experimental conditions. Some of these samples were irradiated with ns-laser to segregate the diffused ions into dimers and trimers to enhance their luminescence characteristics. The consequent structural modifications in the glass matrix were examined using Fourier transform infrared spectroscopy. Optical absorption and luminescence measurements were performed to check the presence of resonant plasmonic absorption of nanoclusters and suitability of the samples as luminescent downshifters, respectively. At UV excitation wavelengths (260 and 340 nm), the doped samples downshifted the solar spectrum compared to their undoped counterparts. Furthermore, ns-laser irradiation of the doped samples significantly enhanced the luminescence intensity in comparison to the unirradiated samples. Real-time performance of these samples was tested by measuring the output power of a Si solar cell covered with the treated coverglass when illuminated with a solar simulator. Finally, the Vicker's micro-indentation was applied to conclude that ionic diffusion increased the glass hardness as well.

Stabilization of Au-Ag Nanoalloys with Polyvinylpyrrolidone (PVP) as Capping Agent

Van der Waals attraction between nanoparticles will create aggregation, therefore, adding a capping agent is needed to stabilize the nanoparticles. We have synthesized Au50Ag50 nanoalloys from a mixture of silver and gold metal ions using a femtosecond laser irradiated for 5, 10, and 15 minutes. The process occurred in a water-only medium and in a water medium added with 0.01 wt% polyvinylpyrrolidone (PVP). Only Au50Ag50 with 5 minutes irradiation times that was characterized by TEM. From TEM result, PVP was proven to generate stabilization of the nanoparticles. It was confirmed that the nanoparticles in Au-Ag nanoalloys with PVP are more disperse than the Au-Ag nanoalloys without PVP. From the result, the particle size of Au-Ag nanoalloys without PVP is 10.72 nm, and 7.94 nm with PVP. This indicates that not only reducing the van der Waals attractive forces and stabilizing the nanoparticles, PVP can also reduce the particle size.

A Facile Approach for Synthesis and Intracellular Delivery of Size Tunable Cationic Peptide Functionalized Gold Nanohybrids in Cancer Cells.

Peptide-based drug delivery systems have become a mainstay in the contemporary medicinal field, resulting in the design and development of better pharmaceutical formulations. However, most of the available reports employ tedious multiple reaction steps for the conjugation of bioactive cationic peptides with drug delivery vehicles. To overcome these limitations, the present work describes a one-step approach for facile and time efficient synthesis of highly cationic cell penetrating peptide functionalized gold nanoparticles and their intracellular delivery. The nanoconstruct was synthesized by the reduction of gold metal ions utilizing cell penetrating peptide (CPP), which facilitated the simultaneous synthesis of metal nanoparticles and the capping of the peptide over the nanoparticle surface. The developed nanoconstruct was thoroughly characterized and tested for intracellular delivery into HeLa cells. Intriguingly, a high payload of cationic peptide over gold particles was achieved, in comparison to conventional conjugation methods. Moreover, this method also provides the ability to control the size and peptide payload of nanoparticles. The nanoconstructs produced showed enhanced cancer cell penetration (μM) and significant cytotoxic effect compared to unlabeled gold nanoparticles. Therefore, this novel approach may also have significant future potential to kill intracellular hidden dreaded pathogens like the human immunodeficiency virus, Mycobacterium tuberculosis, and so forth.

Identification of Gold Sensing Peptide by Integrative Proteomics and a Bacterial Two-Component System.

The proteomics strategy was utilized to analyze and identify the gold adsorption proteins from Tepidimonas fonticaldi AT-A2, due to its outstanding performance in gold-binding and recovery. The results showed that three small proteins, including histidine biosynthesis protein (HisIE), iron donor protein (CyaY) and hypothetical protein_65aa, have a higher ability to adsorb gold ions because of the negatively charged domains or metal binding sites. On the other hand, the Salmonella PmrA/PmrB two-component system first replaces the iron (III)-binding motif using the peptide sequence from hypothetical protein_65aa, and this is then used to reveal the sensing and responsiveness to gold metal ions, which is totally different from the performance of traditional gold binding peptide (GBP) on the crystals on the surface of gold (111). We have successfully demonstrated an integrative proteomics and bacterial two-component system to explore the novel GBP. Finally, the heterologous over-expression of GBP by E. coli and the equilibrium of binding capacity for Au(III) have been conducted.

Green Synthesis of Gold Nanoparticles Using Aqueous Extract ofGarcinia mangostanaFruit Peels

The synthesis of gold nanoparticles (Au-NPs) is performed by the reduction of aqueous gold metal ions in contact with the aqueous peel extract of plant,Garcinia mangostana(G. mangostana). An absorption peak of the gold nanoparticles is observed at the range of 540–550 nm using UV-visible spectroscopy. All the diffraction peaks at 2θ= 38.48°, 44.85°, 66.05°, and 78.00° that index to (111), (200), (220), and (311) planes confirm the successful synthesis of Au-NPs. Mostly spherical shape particles with size range of 32.96 ± 5.25 nm are measured using transmission electron microscopy (TEM). From the FTIR results, the peaks obtained are closely related to phenols, flavonoids, benzophenones, and anthocyanins which suggest that they may act as the reducing agent. This method is environmentally safe without the usage of synthetic materials which is highly potential in biomedical applications.

Cardioprotective potential of biobased gold nanoparticles

In the present investigation, the cardioprotective nature of proanthocyanidin (PAC)-synthesized gold nanoparticles (AuNPs) is addressed in detail. There was a rapid reduction of gold metal ions by PAC and the new-genre AuNPs exhibited remarkable in vitro stability both in biological and chemical solutions. Transmission electron microscopy (TEM) indicated that the newly formed nanoparticles ranged in size from 17 to 29nm (∼24nm). MTT assay carried out with peripheral blood mononuclear cells demonstrated the non-toxic nature of AuNPs. PAC-synthesized AuNPs showed cardioprotective action in isoproterenol-induced myocardial injury at a lowest dosage (9mgkg−1). Cardiac marker enzymes and antioxidant parameters in serum and heart tissue were also measured.

Solvent-Adaptable Poly(vinylpyrrolidone) Binding Induced Anisotropic Shape Control of Gold Nanostructures

Conformational changes in the intrinsic chemical structure of the polymer poly(N-vinyl-2-pyrrolidone) (PVP) in aqueous as well as (in)organic solvents essentially dictates the novel room temperature seedless synthetic procedure for the reduction of hydro-chloroauric acid (HAuCl4.3H2O) leading to the formation of different anisotropic size/shaped gold nanoparticles. The interaction between gold metal ions and PVP at the given specific monomer to metal ratio leads to sequential metal ligand exchange, thereby simultaneously utilizing the mild reducing property as well as distinct structure-directing/capping ability of PVP in different (in)organic solvents, the synchronized features of which have been carefully explored through NMR and FTIR measurements identifying the foolproof signatures of the polymer coordination interaction for the first time in designing the systematic nucleation and growth/stabilization procedures of anisotropic metal gold nanostructures. Furthermore, the complementary XPS data evaluates the quantitative role of coupled oxygen and nitrogen components of the pyrrolidone ring in the PVP–solvent complex in asserting seedless surface mediation as well as the morphology driven localized surface plasmon suitable for wide range of plasmonic as well as photonic applications.

Extraction of noble metal ions from aqueous solution by ionic liquids

Nine ionic liquids containing pyridinium, pyrrolidinium and piperidinium cations with anion bis(trifluoromethylsulfonyl)imide were synthesized to investigate the ability of ionic liquids to extract silver, palladium, or gold metal ions from water at room temperature. Results are reported for distribution coefficients and extraction percentages with these ionic liquids. Ionic liquids containing a disulfide group or a nitrile group exhibit good extraction properties for silver or palladium ions. Gold ions were efficiently and selectively extracted with these functionalized ionic liquids. The influence of the mass ratio of water to ionic liquid on distribution coefficient or extraction percentage for aqueous gold ions was evaluated.

Chemical Functionalization of Diatom Silica Microparticles for Adsorption of Gold (III) Ions

Diatom silica microparticles from natural diatomaceous earth (DE) silica have been functionalized with 3-mercaptopropyltrimethoxysilane (MPTMS) and their application for adsorption of gold (III) ions from aqueous solutions is demonstrated. Fourier transform infrared spectroscopy (FTIR) and X-ray Photoelectron spectroscopy (XPS) analyses of the MPTMS modified diatom microparticles revealed that the silane layer with functional group (-SH) was successfully introduced to the diatom surface. The adsorption study of Au(III) ions using MPTMS-DE indicated that the process depends on initial gold (III) concentration and pH showing maximum adsorption capacity at pH = 3. The Au(III) adsorption kinetics results showed that the adsorption was very fast and followed a pseudo-second-order reaction model. The Langmuir model was used to provide a sound mechanistic basis for the theoretical of the adsorption equilibrium data. Gold recovery from MPTMS-DE structures was also investigated by using acidified thiourea solution and found to be high (> 95%). These results show that chemically modified DE microparticles can be used as a new, cost effective and environmentally benign adsorbent suitable for adsorption of gold metal ions from aqueous solutions.

Metal-Based Inhibition of Poly(ADP-ribose) Polymerase − The Guardian Angel of DNA

The inhibition activity of a series of anticancer metal complexes based on platinum, ruthenium, and gold metal ions was evaluated on the zinc-finger protein PARP-1, either purified or directly on protein extracts from human breast cancer MCF7 cells. Information on the reactivity of the metal complexes with the PARP-1 zinc-finger domain was obtained by high-resolution ESI FT-ICR mass spectrometry. An excellent correlation between PARP-1 inhibition in protein extracts and the ability of the complexes to bind to the zinc-finger motif (in competition with zinc) was established. The results support a model whereby displacement of zinc from the PARP-1 zinc finger by other metal ions leads to decreased PARP-1 activity. In vitro combination studies of cisplatin with NAMI-A and RAPTA-T on different cancer cell lines (MCF7, A2780, and A2780cisR) showed that, in some cases, a synergistic effect is in operation.