Editorial

3 pages, 175 KiB

Open AccessEditorial

Special Issue “Synthesis and Applications of Functionalized Gold Nanosystems”

by Paolo Scrimin

Nanomaterials 2019, 9(7), 1046; https://doi.org/10.3390/nano9071046 - 22 Jul 2019

Cited by 1 | Viewed by 2056

When I launched this Special Issue, I wrote: “Gold-based nanosystems are among the most interesting systems in the nanoworld because of their broad spectrum of applications, ranging from analyte detection to nanomedicine and the mimicry of enzymes, just to mention a few examples [...] Read more.

When I launched this Special Issue, I wrote: “Gold-based nanosystems are among the most interesting systems in the nanoworld because of their broad spectrum of applications, ranging from analyte detection to nanomedicine and the mimicry of enzymes, just to mention a few examples [...] Full article

(This article belongs to the Special Issue Synthesis and Applications of Functionalized Gold Nanosystems)

Research

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14 pages, 1587 KiB

Open AccessArticle

Functionalized Gold Nanoparticles as Contrast Agents for Proton and Dual Proton/Fluorine MRI

by Maria Şologan, Francesco Padelli, Isabella Giachetti, Domenico Aquino, Mariangela Boccalon, Gianpiero Adami, Paolo Pengo and Lucia Pasquato

Nanomaterials 2019, 9(6), 879; https://doi.org/10.3390/nano9060879 - 13 Jun 2019

Cited by 22 | Viewed by 3772

Abstract

Gold nanoparticles carrying fluorinated ligands in their monolayer are, by themselves, contrast agents for ¹⁹F magnetic resonance imaging displaying high sensitivity because of the high density of fluorine nuclei achievable by grafting suitable ligands on the gold core surface. Functionalization of these [...] Read more.

Gold nanoparticles carrying fluorinated ligands in their monolayer are, by themselves, contrast agents for ¹⁹F magnetic resonance imaging displaying high sensitivity because of the high density of fluorine nuclei achievable by grafting suitable ligands on the gold core surface. Functionalization of these nanoparticles with Gd(III) chelates allows adding a further functional activity to these systems, developing materials also acting as contrast agents for proton magnetic resonance imaging. These dual mode contrast agents may allow capitalizing on the benefits of ¹H and ¹⁹F magnetic resonance imaging in a single diagnostic session. In this work, we describe a proof of principle of this approach by studying these nanoparticles in a high field preclinical scanner. The Gd(III) centers within the nanoparticles monolayer shorten considerably the ¹⁹F T1 of the ligands but, nevertheless, these systems display strong and sharp NMR signals which allow recording good quality ¹⁹F MRI phantom images at nanoparticle concentration of 20 mg/mL after proper adjustment of the imaging sequence. The Gd(III) centers also influence the T1 relaxation time of the water protons and high quality ¹H MRI images could be obtained. Gold nanoparticles protected by hydrogenated ligands and decorated with Gd(III) chelates are reported for comparison as ¹H MRI contrast agents. Full article

(This article belongs to the Special Issue Synthesis and Applications of Functionalized Gold Nanosystems)

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19 pages, 3837 KiB

Open AccessArticle

Targeted Gold Nanoparticle–Oligonucleotide Contrast Agents in Combination with a New Local Voxel-Wise MRI Analysis Algorithm for In Vitro Imaging of Triple-Negative Breast Cancer

by Rajat Chauhan, Nagwa El-Baz, Robert S. Keynton, Kurtis T. James, Danial A. Malik, Mingming Zhu, Ayman El-Baz, Chin K. Ng, Paula J. Bates, Mohammad Tariq Malik and Martin G. O’Toole

Nanomaterials 2019, 9(5), 709; https://doi.org/10.3390/nano9050709 - 07 May 2019

Cited by 18 | Viewed by 4019

Abstract

Gold nanoparticles (GNPs) have tremendous potential as cancer-targeted contrast agents for diagnostic imaging. The ability to modify the particle surface with both disease-targeting molecules (such as the cancer-specific aptamer AS1411) and contrast agents (such as the gadolinium chelate Gd(III)-DO3A-SH) enables tailoring the particles [...] Read more.

Gold nanoparticles (GNPs) have tremendous potential as cancer-targeted contrast agents for diagnostic imaging. The ability to modify the particle surface with both disease-targeting molecules (such as the cancer-specific aptamer AS1411) and contrast agents (such as the gadolinium chelate Gd(III)-DO3A-SH) enables tailoring the particles for specific cancer-imaging and diagnosis. While the amount of image contrast generated by nanoparticle contrast agents is often low, it can be augmented with the assistance of computer image analysis algorithms. In this work, the ability of cancer-targeted gold nanoparticle–oligonucleotide conjugates to distinguish between malignant (MDA-MB-231) and healthy cells (MCF-10A) is tested using a T1-weighted image analysis algorithm based on three-dimensional, deformable model-based segmentation to extract the Volume of Interest (VOI). The gold nanoparticle/algorithm tandem was tested using contrast agent GNP-Gd(III)-DO3A-SH-AS1411) and nontargeted c-rich oligonucleotide (CRO) analogs and control (CTR) counterparts (GNP-Gd(III)-DO3A-SH-CRO/CTR) via in vitro studies. Remarkably, the cancer cells were notably distinguished from the nonmalignant cells, especially at nanomolar contrast agent concentrations. The T1-weighted image analysis algorithm provided similar results to the industry standard Varian software interface (VNMRJ) analysis of T1 maps at micromolar contrast agent concentrations, in which the VNMRJ produced a 19.5% better MRI contrast enhancement. However, our algorithm provided more sensitive and consistent results at nanomolar contrast agent concentrations, where our algorithm produced ~500% better MRI contrast enhancement. Full article

(This article belongs to the Special Issue Synthesis and Applications of Functionalized Gold Nanosystems)

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13 pages, 5249 KiB

Open AccessArticle

Glucosamine Phosphate Induces AuNPs Aggregation and Fusion into Easily Functionalizable Nanowires

by Álvaro Martínez, Yanchao Lyu, Fabrizio Mancin and Paolo Scrimin

Nanomaterials 2019, 9(4), 622; https://doi.org/10.3390/nano9040622 - 17 Apr 2019

Cited by 10 | Viewed by 3058

Abstract

The challenge to obtain plasmonic nanosystems absorbing light in the near infrared is always open because of the interest that such systems pose in applications such as nanotherapy or nanodiagnostics. Here we describe the synthesis in an aqueous solution devoid of any surfactant [...] Read more.

The challenge to obtain plasmonic nanosystems absorbing light in the near infrared is always open because of the interest that such systems pose in applications such as nanotherapy or nanodiagnostics. Here we describe the synthesis in an aqueous solution devoid of any surfactant of Au-nanowires of controlled length and reasonably narrow dimensional distribution starting from Au-nanoparticles by taking advantage of the properties of glucosamine phosphate under aerobic conditions and substoichiometric nanoparticle passivation. Oxygen is required to enable the process where glucosamine phosphate is oxidized to glucosaminic acid phosphate and H₂O₂ is produced. The process leading to the nanosystems comprises nanoparticles growth, their aggregation into necklace-like aggregates, and final fusion into nanowires. The fusion requires the consumption of H₂O₂. The nanowires can be passivated with an organic thiol, lyophilized, and resuspended in water without losing their dimensional and optical properties. The position of the broad surface plasmon band of the nanowires can be tuned from 630 to >1350 nm. Full article

(This article belongs to the Special Issue Synthesis and Applications of Functionalized Gold Nanosystems)

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8 pages, 2258 KiB

Open AccessArticle

Regioselective DNA Modification and Directed Self-Assembly of Triangular Gold Nanoplates

by Guoqing Wang, Yao Zhang, Xingguo Liang, Tohru Takarada and Mizuo Maeda

Nanomaterials 2019, 9(4), 581; https://doi.org/10.3390/nano9040581 - 09 Apr 2019

Cited by 9 | Viewed by 4292

Abstract

As a class of emerging nanoparticles, gold nanotriangles (AuNTs) are characterized by unique structural anisotropy and plasmonic properties. The organization of AuNTs into well-defined architecture potentially promises collective properties that are difficult to produce by individual AuNTs. To date, however, the orientation-controlled self-assembly [...] Read more.

As a class of emerging nanoparticles, gold nanotriangles (AuNTs) are characterized by unique structural anisotropy and plasmonic properties. The organization of AuNTs into well-defined architecture potentially promises collective properties that are difficult to produce by individual AuNTs. To date, however, the orientation-controlled self-assembly of AuNTs has been achieved with limited success. Here, we describe an effective and straightforward approach to induce directed self-assembly of AuNTs. By taking advantage of the uneven chemical reactivity of AuNT surfaces, we implement regioselective modification of the edges and the top/bottom surfaces with two different double-stranded DNA (dsDNA) sequences. By means of terminal single base pairing/unpairing, controlled assembly of the dsDNA-modified AuNTs evolves in a face-to-face or edge-to-edge manner based on blunt-end stacking interaction on an intentional region of the AuNTs, along with entropic repulsion by unpaired terminal nucleobases on the other region. This approach could be useful for achieving directed self-assembly of other anisotropic nanoparticles. Full article

(This article belongs to the Special Issue Synthesis and Applications of Functionalized Gold Nanosystems)

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15 pages, 3795 KiB

Open AccessArticle

Facile Synthesis of the Composites of Polyaniline and TiO₂ Nanoparticles Using Self-Assembly Method and Their Application in Gas Sensing

by Lei Gao, Changqing Yin, Yuanyuan Luo and Guotao Duan

Nanomaterials 2019, 9(4), 493; https://doi.org/10.3390/nano9040493 - 30 Mar 2019

Cited by 29 | Viewed by 3694

Abstract

The composites of polyaniline and TiO₂ nanoparticles with different contents were prepared in the aqueous solution of phosphoric acid, in which the phosphoric acid was selected as the protonic acid to improve the conductivity of polyaniline. In the composites, the TiO₂ [...] Read more.

The composites of polyaniline and TiO₂ nanoparticles with different contents were prepared in the aqueous solution of phosphoric acid, in which the phosphoric acid was selected as the protonic acid to improve the conductivity of polyaniline. In the composites, the TiO₂ nanoparticles with the size of about 20 nm were coated by a layer of polyaniline film with a thickness of about 5 nm. Then, the gas sensors were constructed by a liquid–gas interfacial self-assembly method. The gas-sensing properties of the composites-based gas sensors obviously improved after doping with TiO₂ nanoparticles, and the sensor response of the composites increased several times to NH₃ from 10 ppm to 50 ppm than that of pure polyaniline. Especially when the mass ratio of TiO₂ to aniline monomer was 2, it exhibited the best gas response (about 11.2–50 ppm NH₃), repeatability and good selectivity to NH₃ at room temperature. The p–n junction structure consisting of the polyaniline and TiO₂ nanoparticles played an important role in improving gas-sensing properties. This paper will provide a method to improve the gas-sensing properties of polyaniline and optimum doping proportion of TiO₂ nanoparticles. Full article

(This article belongs to the Special Issue Synthesis and Applications of Functionalized Gold Nanosystems)

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13 pages, 3621 KiB

Open AccessArticle

Chiral Effect at Nano-Bio Interface: A Model of Chiral Gold Nanoparticle on Amylin Fibrillation

by Jing Li, Rui Chen, Shasha Zhang, Zhongjie Ma, Zhuoying Luo and Guanbin Gao

Nanomaterials 2019, 9(3), 412; https://doi.org/10.3390/nano9030412 - 11 Mar 2019

Cited by 20 | Viewed by 3574

Abstract

Protein/Peptide amyloidosis is the main cause of several diseases, such as neurodegenerative diseases. It has been widely acknowledged that the unnatural fibrillation of protein/peptides in vivo is significantly affected by the physical and chemical properties of multiscale biological membranes. For example, previous studies [...] Read more.

Protein/Peptide amyloidosis is the main cause of several diseases, such as neurodegenerative diseases. It has been widely acknowledged that the unnatural fibrillation of protein/peptides in vivo is significantly affected by the physical and chemical properties of multiscale biological membranes. For example, previous studies have proved that molecule chirality could greatly influence the misfolding, fibrillation and assembly of β-Amyloid peptides at the flat liquid-solid surface. However, how the nanoscale chirality influences this process remains unclear. Here we used gold nanoparticles (AuNPs, d = 4 ± 1 nm)—modified with N-isobutyl-L(D)-cysteine (L(D)-NIBC) enantiomers—as a model to illustrate the chiral effect on the amylin fibrillation at nano-bio interface. We reported that both two chiral AuNPs could inhibit amylin fibrillation in a dosage-dependent manner but the inhibitory effect of L-NIBC-AuNPs was more effective than that of D-NIBC-AuNPs. In-situ real time circular dichroism (CD) spectra showed that L-NIBC-AuNPs could inhibit the conformation transition process of amylin from random coils to α-helix, while D-NIBC-AuNPs could only delay but not prevent the formation of α-helix; however, they could inhibit the further conformation transition process of amylin from α-helix to β-sheet. These results not only provide interesting insight for reconsidering the mechanism of peptides amyloidosis at the chiral interfaces provided by biological nanostructures in vivo but also would help us design therapeutic inhibitors for anti-amyloidosis targeting diverse neurodegenerative diseases. Full article

(This article belongs to the Special Issue Synthesis and Applications of Functionalized Gold Nanosystems)

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8 pages, 1953 KiB

Open AccessArticle

Effect of Size on Hydrogen Adsorption on the Surface of Deposited Gold Nanoparticles

by Andrey Gatin, Maxim Grishin, Nadezhda Dokhlikova, Sergey Ozerin, Sergey Sarvadii, Vasiliy Kharitonov and Boris Shub

Nanomaterials 2019, 9(3), 344; https://doi.org/10.3390/nano9030344 - 03 Mar 2019

Cited by 8 | Viewed by 2522

Abstract

An experimental study of molecular hydrogen adsorption on single gold nanoparticles of various sizes deposited on the surface of highly oriented pyrolytic graphite (HOPG) was carried out by means of scanning tunneling microscopy and spectroscopy. The effect of size on the HOPG/Au system [...] Read more.

An experimental study of molecular hydrogen adsorption on single gold nanoparticles of various sizes deposited on the surface of highly oriented pyrolytic graphite (HOPG) was carried out by means of scanning tunneling microscopy and spectroscopy. The effect of size on the HOPG/Au system was established. Hydrogen was dissociatively chemisorbed on the surface of gold nanoparticles with an average size of 5–6 nanometers. An increase in the size of nanoparticles to 10 nm or more led to hydrogen chemisorption being inhibited and unable to be detected. Full article

(This article belongs to the Special Issue Synthesis and Applications of Functionalized Gold Nanosystems)

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9 pages, 2249 KiB

Open AccessArticle

Resorcinol Functionalized Gold Nanoparticles for Formaldehyde Colorimetric Detection

by Carlos Martínez-Aquino, Ana M. Costero, Salvador Gil and Pablo Gaviña

Nanomaterials 2019, 9(2), 302; https://doi.org/10.3390/nano9020302 - 22 Feb 2019

Cited by 19 | Viewed by 5717

Abstract

Gold nanoparticles functionalized with resorcinol moieties have been prepared and used for detecting formaldehyde both in solution and gas phases. The detection mechanism is based on the color change of the probe upon the aggregation of the nanoparticles induced by the polymerization of [...] Read more.

Gold nanoparticles functionalized with resorcinol moieties have been prepared and used for detecting formaldehyde both in solution and gas phases. The detection mechanism is based on the color change of the probe upon the aggregation of the nanoparticles induced by the polymerization of the resorcinol moieties in the presence of formaldehyde. A limit of detection of 0.5 ppm in solution has been determined. The probe can be deployed for the detection of formaldehyde emissions from composite wood boards. Full article

(This article belongs to the Special Issue Synthesis and Applications of Functionalized Gold Nanosystems)

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14 pages, 6589 KiB

Open AccessArticle

Mesoporous Silica-gold Films for Straightforward, Highly Reproducible Monitoring of Mercury Traces in Water

by Anna Mutschler, Vivian Stock, Lena Ebert, Emma M. Björk, Kerstin Leopold and Mika Lindén

Nanomaterials 2019, 9(1), 35; https://doi.org/10.3390/nano9010035 - 28 Dec 2018

Cited by 10 | Viewed by 3631

Abstract

Trace-level detection of mercury in waters is connected with several complications including complex multistep analysis routines, applying additional, harmful reagents increasing the risk of contamination, and the need for expensive analysis equipment. Here, we present a straightforward reagent-free approach for mercury trace determination [...] Read more.

Trace-level detection of mercury in waters is connected with several complications including complex multistep analysis routines, applying additional, harmful reagents increasing the risk of contamination, and the need for expensive analysis equipment. Here, we present a straightforward reagent-free approach for mercury trace determination using a novel thin film sampling stick for passive sampling based on gold nanoparticles. The nanoparticles supported on a silicon wafer and further covered with a thin layer of mesoporous silica. The mesoporous silica layer is acting as a protection layer preventing gold desorption upon exposure to water. The gold nanoparticles are created by thermal treatment of a homogenous gold layer on silicon wafer prepared by vacuum evaporation. This gold-covered substrate is subsequently covered by a layer of mesoporous silica through dip-coating. Dissolved mercury ions are extracted from a water sample, e.g., river water, by incorporation into the gold matrix in a diffusion-controlled manner. Thus, the amount of mercury accumulated during sampling depends on the mercury concentration of the water sample, the accumulation time, as well as the size of the substrate. Therefore, the experimental conditions can be chosen to fit any given mercury concentration level without loss of sensitivity. Determination of the mercury amount collected on the stick is performed after thermal desorption of mercury in the gas phase using atomic fluorescence spectrometry. Furthermore, the substrates can be re-used several tens of times without any loss of performance, and the batch-to-batch variations are minimal. Therefore, the nanogold-mesoporous silica sampling substrates allow for highly sensitive, simple, and reagent-free determination of mercury trace concentrations in waters, which should also be applicable for on-site analysis. Successful validation of the method was shown by measurement of mercury concentration in the certified reference material ORMS-5, a river water. Full article

(This article belongs to the Special Issue Synthesis and Applications of Functionalized Gold Nanosystems)

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13 pages, 3532 KiB

Open AccessArticle

Green Preparation of Ag-Au Bimetallic Nanoparticles Supported on Graphene with Alginate for Non-Enzymatic Hydrogen Peroxide Detection

by Li Zhao, Yesheng Wang, Xihui Zhao, Yujia Deng, Qun Li and Yanzhi Xia

Nanomaterials 2018, 8(7), 507; https://doi.org/10.3390/nano8070507 - 08 Jul 2018

Cited by 28 | Viewed by 5229

Abstract

In this work, a facile, environmentally friendly method was demonstrated for the synthesis of Ag-Au bimetallic nanoparticles (Ag-AuNPs) supported on reduced graphene oxide (RGO) with alginate as reductant and stabilizer. The prepared Ag-AuNPs/RGO was characterized by scanning electron microscope (SEM), transmission electron microscopy [...] Read more.

In this work, a facile, environmentally friendly method was demonstrated for the synthesis of Ag-Au bimetallic nanoparticles (Ag-AuNPs) supported on reduced graphene oxide (RGO) with alginate as reductant and stabilizer. The prepared Ag-AuNPs/RGO was characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results indicated that uniform, spherical Ag-AuNPs was evenly dispersed on graphene surface and the average particle size is about 15 nm. Further, a non-enzymatic sensor was subsequently constructed through the modified electrode with the synthesized Ag-AuNPs/RGO. The sensor showed excellent performance toward H₂O₂ with a sensitivity of 112.05 μA·cm⁻²·mM⁻¹, a linear range of 0.1–10 mM, and a low detection limit of 0.57 μM (S/N = 3). Additionally, the sensor displayed high sensitivity, selectivity, and stability for the detection of H₂O₂. The results demonstrated that Ag-AuNPs/RGO has potential applications as sensing material for quantitative determination of H₂O₂. Full article

(This article belongs to the Special Issue Synthesis and Applications of Functionalized Gold Nanosystems)

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Review

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21 pages, 4818 KiB

Open AccessReview

DNA-Assisted Assembly of Gold Nanostructures and Their Induced Optical Properties

by Jiemei Ou, Huijun Tan, Xudong Chen and Zhong Chen

Nanomaterials 2018, 8(12), 994; https://doi.org/10.3390/nano8120994 - 01 Dec 2018

Cited by 17 | Viewed by 4289

Abstract

Gold nanocrystals have attracted considerable attention due to their excellent physical and chemical properties and their extensive applications in plasmonics, spectroscopy, biological detection, and nanoelectronics. Gold nanoparticles are able to be readily modified and arranged with DNA materials and protein molecules, as well [...] Read more.

Gold nanocrystals have attracted considerable attention due to their excellent physical and chemical properties and their extensive applications in plasmonics, spectroscopy, biological detection, and nanoelectronics. Gold nanoparticles are able to be readily modified and arranged with DNA materials and protein molecules, as well as viruses. Particularly DNA materials with the advantages endowed by programmability, stability, specificity, and the capability to adapt to functionalization, have become the most promising candidates that are widely utilized for building plenty of discrete gold nanoarchitectures. This review highlights recent advances on the DNA-based assembly of gold nanostructures and especially emphasizes their resulted superior optical properties and principles, including plasmonic extinction, plasmonic chirality, surface enhanced fluorescence (SEF), and surface-enhanced Raman scattering (SERS). Full article

(This article belongs to the Special Issue Synthesis and Applications of Functionalized Gold Nanosystems)

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