Polymer Gold Research Articles

On Polymeric Gold(I) Complexes with Glutathione in Aqueous Solutions

On Polymeric Gold(I) Complexes with Glutathione in Aqueous Solutions

Evaluation of the Sorption Capacity of a Maleic Acid Copolymer Towards Gold(III) Ions and Production of Catalytically Active Gold Nanoparticles on Its Base

Two spectrophotometric approaches are suggested for the assessment of the concentration of gold(III) cations in an aqueous solution: direct recording of the optical density of gold cations and galvanic substitution of silver atoms in polymer-stabilized silver nanoparticles with gold cations. The sorption capacity of a maleic acid copolymer towards gold cations is estimated. A colloidal composite containing gold nanoparticles is obtained from the polymeric gold salt. The catalytic properties of the resulting polymer-stabilized nanogold are studied in the aerobic oxidation of glucose to gluconic acid.

Smart arginine-equipped polycationic nanoparticles for p/CRISPR delivery into cells

An efficient and safe delivery system for the transfection of CRISPR plasmid (p/CRISPR) into target cells can open new avenues for the treatment of various diseases. Herein, we design a novel nonvehicle by integrating an arginine-disulfide linker with low-molecular-weight PEI (PEI1.8k) for the delivery of p/CRISPR. These PEI1.8k-Arg nanoparticles facilitate the plasmid release and improve both membrane permeability and nuclear localization, thereby exhibiting higher transfection efficiency compared to native PEI1.8k in the delivery of nanocomplexes composed of PEI1.8k-Arg and p/CRISPR into conventional cells (HEK 293T). This nanovehicle is also able to transfect p/CRISPR in a wide variety of cells, including hard-to-transfect primary cells (HUVECs), cancer cells (HeLa), and neuronal cells (PC-12) with nearly 5–10 times higher efficiency compared to the polymeric gold standard transfection agent. Furthermore, the PEI1.8k-Arg nanoparticles can edit the GFP gene in the HEK 293T-GFP reporter cell line by delivering all possible forms of CRISPR/Cas9 system (e.g. plasmid encoding Cas9 and sgRNA targeting GFP, and Cas9/sgRNA ribonucleoproteins (RNPs) as well as Cas9 expression plasmid and in vitro-prepared sgRNA) into HEK 293T-GFP cells. The successful delivery of p/CRISPR into local brain tissue is also another remarkable capability of these nanoparticles. In view of all the exceptional benefits of this safe nanocarrier, it is expected to break new ground in the field of gene editing, particularly for therapeutic purposes.

Flavin-adenine-dinucleotide gold complex nanoparticles: chemical modeling design, physico-chemical assessment and perspectives in nanomedicine.

Flavoproteins play an important role in the regulatory process of cell life, and they are involved in several redox reactions that regulate the metabolism of carbohydrates, amino acids, and lipids. The development of effective drug delivery systems is one of the major challenges in the fight against cancer. This study involves a nanomedicine pathway to encapsulate the cofactor flavin adenine dinucleotide (FAD) using polymeric gold nanoparticles (PEG-AuNPs) through two chemical methods of functionalization (chelation (IN); carbodiimide chemistry (ON)). These hybrid gold nanoparticles and their precursors were characterized by analytical techniques (Raman, UV-Vis, and H1-NMR spectroscopy and transmission electron microscopy (TEM)) which confirmed the grafting of the cofactor agent. The results of the computational studies (Density Functional Theory (DFT)) were in agreement with the experimental observations. We also monitored the interaction of our hybrid nanoparticle systems with small aptamers (APT) in order to validate the hypotheses on the biomolecular mechanisms and also investigate their biological efficiency on pancreatic cancer cells (MIAPaCa-2 cells).

Supramolecular gold(I) compounds with trithiocyanuric acid: Self‐assembly and luminescent properties

Abstract[(N3S3)Au(AuPMe3)2]2 (1) and [(N3S3)Au(AuPEt3)2]2 (2) were prepared by treating AuCl(PMe3) or AuCl(PEt3) with H3N3S3 upon deprotonation by trimethylamine to give respective Au6 supermolecules. Using dppm(AuCl)2 instead of AuCl(PMe3) or AuCl(PEt3) to react with H3N3S3 in a similar reaction condition led to a rare heptanuclear supermolecule of [(N3S3)2Au7(dppm)4]Cl (3). It is noted that besides short intramolecular gold(I)⋯gold(I) distances, both compounds 1 and 2 also show intermolecular gold(I)⋯gold(I) distances of 3.067(1) and 3.241(1) Å, resulting in two‐dimensional and one‐dimensional polymeric gold(I) solid, respectively. In fact, compound 1 shows a similar two‐dimensional polymeric gold(I) solid to that of the reported [(N3S3)Au(AuPPhMe2)2]2 with an intermolecular gold(I)⋯gold(I) distance of 3.130(2) Å. Significantly, these intermolecular gold(I)⋯gold(I) distances are well correlated with their cone angles and emission energies. For example, intermolecular gold(I)⋯gold(I) distances increase in the order of 3.067(1) Å < 3.130(2) Å < 3.241(1) Å for PMe3 (118°), PPhMe2 (122°), and PEt3 (132°), and their emission energies also increase in the order of 542 nm < 530 nm < 504 nm, respectively. This work highlights a very good correlation between intermolecular aurophilic interactions and emission energies for a series of Au6 supermolecules, where the cone angle plays a vital role in the self‐assembly process as well. Finally, the emissions for 1–3 are tentatively assigned to the S → Au charge‐transfer transition, whereas they are most probably modified by gold(I)⋯gold(I) interactions.

Influence of the Number of Metallophilic Interactions and Structures on the Optical Properties of Heterometallic Au/Ag Complexes with Mixed-Donor Macrocyclic Ligands.

The reactivity of the polymeric gold(I)/silver(I) compound [Au2Ag2(C6F5)4(OEt2)2] n toward the 12-membered mixed-donor macrocyclic ligands 1,7-diaza-4,10-dithiacyclododecane (L1), 1-aza-4,7,10-trithiacyclododecane (L2), N-quinolinylmethyl-1-aza-4,7,10-trithiacyclododecane (L3), and N, N'-bis(quinolinylmethyl)-1,7-diaza-4,10-dithiacyclododecane (L4) was studied. The reactions were carried out using different molar ratios depending on the coordination properties of the ligands, which were modified by changing the donor atoms present in the macrocyclic framework (sulfur or nitrogen) or by linking one or two methylquinoline pendant-arms at the secondary nitrogen atom(s). X-ray diffraction analysis of the new complexes obtained show a nuclearity that increases on increasing the number of donor atoms in the ligands. The rich structural diversity observed determines different optical responses when the complexes are irradiated with UV-vis light in the solid state and in THF solution. The study of the optical properties reveals that in complexes for which the luminescence is due to metal-metal interactions, higher emission wavelengths are observed as the number of these metallophilic contacts increases, while the luminescence of ionic complexes has its origin in the macrocyclic ligands. TD-DFT calculations were carried out to verify the origin of these interesting structural-optical property relationships.

Reactivity of Silver(I) Diethyldithiocarbamate and Ion-Polymeric Complexes {[Au(S2CNEt2)2][AgCl2]}n and {[Au(S2CNEt2)2]2[AgCl2]Cl·2H2O}n: Synthesis, Supramolecular Structures, and Thermal Behavior

New ion polymeric gold(III)–silver(I) complexes, {[Au(S2CNEt2)2][AgCl2]}n and {[Au(S2CNEt2)2]2[AgCl2]Cl·2H2O}n have been synthesized and characterized by X-ray diffraction data and IR spectra. The structure of the first complex is represented by [Au{S2CNEt2}2]+ complex cations and polymeric silver chloride anion ([AgCl2]–)n; the second complex consists of isomeric cations, linear [AgCl2]– anions, chloride ions, and water molecules. Gold cations are involved in zigzag (AuAuAu angle 99.06°) and linear polymeric chains via secondary Au···S bond pairs. Thermal decomposition of the complexes with regeneration of gold and silver has been studied by simultaneous thermal analysis (STA).

On Gold(I) Thiomalate Complexes in Aqueous Solution

Certain equilibria involving polymeric gold(I) thiomalate complexes have been studied by spectrophotometry and pH measurements in aqueous solution at 25°С and I = 0.2 M (NaCl). Thiomalate protonation constants Hi–1Tm3– + H+ = HiTmi–3 have been found to be logKH1 = 10.23, logKH2 = 4.51, logKH3 = 3.01. Efficient functions have been used to allow for multiple protonation of polymeric complexes Aun Tm m n-3 m Equilibrium constants for reactions Au4Tm 4 8− + Tm3– = Au4Tm 5 11− (logK45 = 10.1 ± 0.5) and 0.25 Au4Tm48− + Tm3– = AuTm25− (logK12 = 4.9 ± 0.2) have been determined. Standard potential for AuTm25− has been found to be equal to E1/00 =–0.260 ± 0.025 V.

Electrochemical Evaluation of the Number of Au Atoms in Polymeric Gold Thiolates by Single Particle Collisions.

Polymeric gold thiolates, [Au(I)SR] n, are common synthetic intermediate precursors of gold nanoclusters and larger nanoparticles. The size and dispersity of the precursors strongly influence the properties of the synthesis products. Evaluating the size of the precursors is not straightforward because they are irregularly shaped (nonspherical) and hard to isolate from solution. Herein, we propose an effective method for determining the number of Au atoms in polymeric thiolate particles from current transients resulting from single precursor collisions, where individual [Au(I)SR] n species are electrochemically reduced at the collector ultramicroelectrode. The developed approach can lead to a better control over the mean size and dispersity of colloidal metal nanoclusters and nanoparticles.

Effect of the metal nature on hemostatic activity of water-soluble gold and silver nanocomposites

The hemostatic activity of polymeric gold and silver nanocomposites depends on their kinetic stability caused by the interaction of the ligand with nanoparticles. The properties of the nanoparticles are determined by the metal nature.

Electron-transport polymeric gold nanoparticles memory device, artificial synapse for neuromorphic applications

Abstract In this paper, we demonstrate the charge storage in nanoparticles “NPs” organic memory field-effect transistor using an electron-transport polymeric semiconductor layer, poly{[N,N0-bis(2-octyldodecyl)-naphthalene-1,4,5,8-is(dicarboximide)-2,6-diyl]- alt - 5,50-(2,20-bithiophene)} [P(NDI2OD-T2)n], known as its commercial name PolyeraTM N2200. The device exhibited good programmable memory characteristics with respect to the program/erase operations, leading to a reversible threshold voltage (Vth) shifts. Results revealed that OFET based NPs exhibited larger hysteresis and showed a facilitating and a depressing drain current mimicking the behavior of biological synapses, the building block responsible of action potentials transmission between neurons.

Principles of supramolecular polymeric chain formation in heteronuclear gold(III)–iron(III) complexes ([Au(S2CNR2)2][FeCl4]) n (R = C3H7, iso-C3H7): Chemisorption synthesis, structural organization, and thermal behavior

Polymeric gold(III)–iron(III) dithiocarbamate–chloride complexes of the ionic type are synthesized by the chemisorption binding of gold(III) with freshly precipitated iron(III) dipropyl and di-iso-propyl dithiocarbamates from solutions of H[AuCl4] in 2 M HCl. Heteropolynuclear complexes of the compositions ([Au{S2CN(C3H7)2}2][FeCl4])n (I) and ([Au{S2CN(iso-C3H7)2}2][FeCl4])n (II) are preparatively isolated as individual forms of gold(III) binding. The structural organization of the complexes is established by X-ray diffraction analysis (CIF files CCDC no. 1480802 (I) and no. 1480806 (II)). The structures of compounds I and II are characterized at the supramolecular level by the presence of two types of polymeric chains, the methods of formation of which differ substantially. Compound I contains the following structural units: four structurally nonequivalent centrosymmetric complex cations [Au{S2CN(C3H7)2}2]+ (A, B, С, and D) and two complex anions [FeCl4]– related to each other as conformers. Two independent cation-cationic linear polymeric chains (···А···В···)n and (···С···D···)n are formed in the structure of complex I due to pair relatively weak secondary interactions Au···S (nonvalent type) between the adjacent complex cations. The structure of compound II is characterized by zigzag cation-anionic chains (···[Au{S2CN(iso-C3H7)2}2]+···[FeCl4]–···)n in the formation of which the secondary interactions Au···Cl play the determining role. The thermal behavior of complexes I and II is studied by simultaneous thermal analysis. The thermal destruction process includes the thermolysis of the dithiocarbamate moiety of the complexes and [FeCl4]− with the reduction of gold(III) to the metal, the liberation of FeCl3, and the partial transformation of the latter into Fe2O3. In both cases, the final products of the thermal transformations of the studied compounds are elemental gold and Fe2O3.

A novel treatment for metastatic lymph nodes using lymphatic delivery and photothermal therapy

Systemic delivery of an anti-cancer agent often leads to only a small fraction of the administered dose accumulating in target sites. Delivering anti-cancer agents through the lymphatic network can achieve more efficient drug delivery for the treatment of lymph node metastasis. We show for the first time that polymeric gold nanorods (PAuNRs) can be delivered efficiently from an accessory axillary lymph node to a tumor-containing proper axillary lymph node, enabling effective treatment of lymph node metastasis. In a mouse model of metastasis, lymphatic spread of tumor was inhibited by lymphatic-delivered PAuNRs and near-infrared laser irradiation, with the skin temperature controlled by cooling. Unlike intravenous injection, lymphatic injection delivered PAuNRs at a high concentration within a short period. The results show that lymphatic administration has the potential to deliver anti-cancer agents to metastatic lymph nodes for inhibition of tumor growth and could be developed into a new therapeutic method.

Influence of Plasma Polymerized Dielectric Buffer Layer and Gold Film on the Excitation of Long-Range Surface Plasmon Resonance

Recently, long-range surface plasmon resonance (LRSPR) sensor has attracted a great deal of attention as a potentially non-destructive and label-free technique for cellular studies in real time. Thus, much effort has been placed on the fabrication and optimization of multilayered structure required for the excitation of LRSPR. In this work, a detailed study about the influence of both plasma polymerized dielectric buffer layer (DBL) and thin gold film on the excitation of LRSPR was performed. The DBLs of different thicknesses were deposited directly onto SF11 glass slides by radio frequency plasma polymerization (pp) of perfluorooctyl ethylene (PFOE). Thereafter, Au films of different thicknesses were thermally evaporated onto the ppPFOE layers. Atomic force microscopy (AFM) results suggest that the resulting SF11/ppPFOE/Au structure has a smooth surface regardless of Au film’s thickness. LRSPR measurements indicate that the excitation of LRSPR relies not only on the thickness of the ppPFOE buffer layer, but also on the thickness and optical property of thin Au film. Theoretical simulation based on Fresnel’s equation allows for the determination of both the thickness and optical constant of each layer supporting the LRSPR, and also enables us to predict the optimum combination of ppPFOE and Au film in a LRSPR sensor. The performance of various LRSPR sensors to monitor the bulk refractive index variation has also been investigated.

Enhanced stability of ZnTPPS by polymeric gold nanoparticles in acidic aqueous solutions

ABSTRACTNovel kind of core-shell corona complex micelles were prepared, which enhanced both the hydrolytic stability and the photostability of water-soluble zinc tetrakis(4-sulfonatophenyl) porphyrin (ZnTPPS) in acidic aqueous solutions. The core-shell gold nanoparticles (AuNPS) were synthesized by reducing HAuCl4 and di-thioester terminated block copolymer, poly(Nisopropylacrylamide)-block-poly(4-vinylpyridine) (PNIPAM-b-P4VP). The complex micelles with gold core, P4VP/ZnTPPS shell and PNIPAM corona were formed by simple mixing of gold nanoparticles and ZnTPPS. The photochemical properties of the complex micelles were studied by UV–Visiblespectroscopy and fluorescence spectroscopy. The results showed trapping of ZnTPPS in the positively charged micellar shell that effectively prevented demetallation of the ZnTPPS that would occur in acidic aqueous solutions. Furthermore, with appropriate concentration of gold nanoparticles, ZnTPPS in the complex micelle had excellent photostability by suppression of generation of reactive oxygen species (ROS). The enhanced stability of ZnTPPS in acidic aqueous media could be extensively used for photocatalysis and in solar cells.

Shape control synthesis of polymeric hybrid nanoparticles via surface‐initiated atom‐transfer radical polymerization

ABSTRACTPolymeric hybrid nanoparticles were synthesized via surface‐initiated atom‐transfer radical polymerization (SI‐ATRP) method on the surface of gold nanoparticles in cyclohexanone. Tetraoctyl ammonium bromide (TOAB) as a phase transfer agent was used to transfer the gold nanoparticles into cyclohexanone, which will be replaced by disulfide initiator on the surface of gold nanoparticles. Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and UV–vis spectroscopy were utilized to characterize the product to make sure the experiment had been conducted. The results showed that the polymeric gold hybrid nanoparticles with different structures could be controlled by adjusting the ratio of initiator and gold nanoparticles in ATRP. If the ratio is very little, asymmetric polystyrene–gold hybrid nanoparticles were synthesized, and a single gold nanoparticle was attached with a polystyrene sphere. If the ratio becomes larger, core–shell polystyrene–gold nanocomposite particles were obtained resulting in gold nanoparticle encapsulated by a uniform polymer shell. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43584.

Doxorubicin loaded polymeric gold nanoparticles targeted to human folate receptor upon laser photothermal therapy potentiates chemotherapy in breast cancer cell lines

The current research focuses on the application of folate conjugated and doxorubicin loaded polymeric gold nanoparticles (GNPs) for the targeted treatment of folate receptor overexpressing breast cancers, augmented by adjunctive laser photothermal therapy. Herein, GNPs surface modified with folate, drug doxorubicin and polyethylene glycol were engineered and were used as vehicles for folate receptor targeted delivery of doxorubicin into cancer cells. Subsequently, the GNPs were photo-excited using laser light for mediating hyperthermia in the cancer cells. In vitro studies were performed to validate the efficacy of the combined modality of folate conjugated and doxorubicin loaded polymeric GNP mediated chemotherapy followed by photothermal therapy in comparison to treatment with free drug; and the combination modality showed better therapeutic efficacy than that of plain doxorubicin treatment in MDA-MB-231 breast cancer cells that express increased levels of surface folate receptors when compared to MCF-7 breast cancer cells that express low levels of folate receptor. The mechanism of cell death was investigated using fluorescent microscopy. Immunoassays showed the up-regulation of the pro-apoptotic protein p53 and down-regulation of the anti-apoptotic protein Bcl-2. Collectively, these results suggest that the folate tagged doxorubicin loaded GNPs are an attractive platform for targeted delivery of doxorubicin and are agents suitable for photothermal cancer therapy.

Chemisorption of gold(III) from solutions using thallium(I) diisobutyldithiocarbamate: Supramolecular structure and thermal behavior of the polymeric gold(III)-thallium(III) complex ([Au{S2CN(iso-C4H9)2}2][TlCl4]) n

Chemisorption of gold(III) from 2 M HCl using thallium(I) diisobutyldithiocarbamate via an ion exchange/redox process gives a polymeric gold(III)-thallium(III) complex of the formula ([Au{S2CN(iso-C4H9)2}2][TlCl4])n (I). Its supramolecular structure determined by X-ray diffraction (CIF file CCDC no. 1009388) comprises three structurally nonequivalent complex cations [Au{S2CN(iso-C4H9)2{2]+ (A, B, and C) and two nonequivalent [TlCl4]−-anions, both the cations and the anions being conformers. The isomeric cations are united through pairs of relatively weak secondary nonvalent Au⋯S contacts into zigzag polymer chains (⋯A⋯B⋯C⋯B⋯)n, with alternating nonequivalent [TlCl4]− anions on both sides. The thermal behavior of complex I was studied by simultaneous thermal analysis. The TG curve shows two steps of its weight loss. The first step involves thermal decomposition of the dithiocarbamate portion of the complex and [TlCl4]− with reduction of gold(III) to metallic gold and release of TlCl. The second step is due to evaporation of TlCl. The final thermolysis product of complex I is reduced metallic gold.

Polymeric gold(I) diisobutyl dithiophosphate, [Au2{S2P(O-iso-C4H9)2}2]n: Synthesis, supramolecular self-organization (a role of aurophilic interaction), 13C and 31P MAS NMR spectroscopy, and thermal behavior

A new polymeric gold(I) diisobutyl dithiophosphate (Dtph), [Au2{S2P(O-iso-C4H9)2}2]n (I), was preparatively obtained and characterized by 13C and 31P MAS NMR spectroscopy and X-ray diffraction (CIF file CCDC no. 977818). Diagrams of the χ2 statistic were constructed from the complete 31P MAS NMR spectra and used to calculate the 31P chemical shift anisotropy (δaniso = δzz − δiso) and the asymmetry parameter η = (δyy − δxx)/(δzz − δiso). The main structural unit of complex I is the noncentrosymmetric dinuclear molecule [Au2{S2P(O-iso-C4H9)2}2], in which the gold atoms are linked by two bridging ligands Dtph. The central cyclic structural fragment of the dimer [Au2S4P2] is additionally stabilized by the intramolecular aurophilic interaction Au⋯Au. Further supramolecular self-organization of the complex involves intermolecular aurophilic bonds Au⋯Au that serve to unite adjacent dinuclear molecules [Au2{S2P(O-iso-C4H9)2}2] with different spatial orientations into the polymer chains ([Au2{S2P(O-iso-C4H9)2}2])n. The thermal behavior of complex I was examined by synchronous thermal analysis under argon. The character of the thermolysis of the complex to reduced metallic gold as a final product was determined.

Investigation on the Mechanism of the Synthesis of Gold(I) Thiolate Complexes by NMR

In this article, we characterized the polymeric gold(I) thiolates that precipitated from the intermediate solutions during the synthesis process of gold nanoparticles (GNPs) by the Brust–Schiffrin two-phase method and investigated the formation mechanism of the polymeric gold(I) thiolates. The solution 1H NMR confirmed the complete reduction from Au(III) to Au(I) with the addition of the first two equivalents of thiols, while only the third and fourth equivalents of thiols were found to participate in forming gold(I) thiolates. Gold(I) thiolates, [Au(I)SR]n, precipitated from these solutions were further characterized by 1H solid-state NMR spectroscopy under fast magic angle spinning (MAS), Raman spectroscopy, and thermogravimetric analysis. Further quantitative studies revealed that the composition of [Au(I)SR]n could be controlled by changing the order of addition of the third and fourth equivalents of thiols. This work has great significance to better understand the mechanism of gold nanoparticle formation and thus to tailor the properties of the final products.