Interaction Of Gold Nanoparticles Research Articles

Surface-enhanced infrared spectroscopic study of extracellular vesicles using plasmonic gold nanoparticles

Extracellular vesicles (EVs), sub-micrometer lipid-bound particles released by most cells, are considered a novel area in both biology and medicine. Among characterization methods, infrared (IR) spectroscopy, especially attenuated total reflection (ATR), is a rapidly emerging label-free tool for molecular characterization of EVs. The relatively low number of vesicles in biological fluids (~1010 particle/mL), however, and the complex content of the EVs’ milieu (protein aggregates, lipoproteins, buffer molecules) might result in poor signal-to-noise ratio in the IR analysis of EVs. Exploiting the increment of the electromagnetic field at the surface of plasmonic nanomaterials, surface-enhanced infrared spectroscopy (SEIRS) provides an amplification of characteristic IR signals of EV samples. Negatively charged citrate-capped and positively charged cysteamine-capped gold nanoparticles with around 10nm diameter were synthesized and tested with blood-derived EVs. Both types of gold nanoparticles contributed to an enhancement of the EVs’ IR spectroscopic signature. Joint evaluation of UV-Vis and IR spectroscopic results, supported by FF-TEM images, revealed that proper interaction of gold nanoparticles with EVs is crucial, and an aggregation or clustering of gold nanoparticles is necessary to obtain the SEIRS effect. Positively charged gold nanoparticles resulted in higher enhancement, probably due to electrostatic interaction with EVs, commonly negatively charged.

Diverse Role of Buffer Mediums and Protein Concentrations to Mediate the Multimodal Interaction of Phenylalanine-Functionalized Gold Nanoparticle and Lysozyme Protein at Same Nominal pH.

Recently, buffer molecules have been known to affect intermolecular protein-protein interactions at physiological pH. However, the roles of buffer molecules and different monolayer protein concentrations remain elusive in controlling the interaction of gold nanoparticles (Au NPs) with protein molecules. Herein, for the first time taking phenylalanine functionalized gold nanoparticles (Au-Phe NPs) and lysozyme (Lyz) protein as model systems, we report that buffer molecules of different charges (at a particular pH) play diverse roles in protein-Au NPs interaction, particularly in protein induced Au NPs aggregation. Among different buffers, negatively charged buffer (citrate and phosphate) induces aggregation of both Au-Phe NPs and Lyz protein, whereas zwitterionic and positive buffer (HEPES, MOPS, and Tris) only cause the Au NPs aggregation. Taking the diverse role of buffer into account, we propose multimodal models for stability and protein induced aggregation mechanism of NPs at different monolayer (sub-, near-, and excess) concentrations of Lyz in different medium.

Novel theoretical studies based on CIELab and deconvolution methods to characterize AuNPs aggregation processes

The study of the interaction of spherical gold nanoparticles when they undergo aggregation phenomena due to the presence of a ligand in solution is presented, based on both colorimetric parameters (using CIELab space) and traditional deconvolution analysis. The feasibility of using CIELab space for this purpose can be an important method to simplify the required instrumentation (colorimeter versus UV spectrophotometer) as well as being less time consuming compared with the traditional computational analysis. For these reasons, in this work we present the first experimental approach of the proposed methodology for its application in this field of research. The synthetized AuNPs employed in this work have been previously characterized by means of the maxima of their LSPR bands, zeta potential and electron microscopy images. The aggregation of spherical AuNPs (with a diameter of 12 nm) by an inert electrolyte (NaCl) is investigated in a first step with successfully results, allowing to obtain the characteristic CIELab parameters (a*, b* and L*). At a later stage, the color changes induced in the optical properties of the solution due to the interaction of AuNPs (with increasing diameters of 12, 25 and 33 nm) with an amino acid such as lysine at neutral pH, have been also described using the CIELab spatial framework. The obtained a*, b* and L* parameters of the CIELab space allow to characterize satisfactorily the color change from red to blue which describes the aggregation phenomena, relying on deconvolution analysis of the LSPR bands. The results obtained support the validity of the CIELab space as a valid tool for the investigation of the aggregation process of colloidal solutions. It will allow simplifying the whole process using simpler and cheaper instrumentation as well as a decrease in the required analysis time.

Structural and biophysical insights into the interactions of anisotropic gold nanoparticles with human telomeric G-quadruplex DNA: Spectroscopic and calorimetric approach

We are reporting curcumin-induced synthesis of anisotropic citrate capped Gold nanoparticles (ctGNPs). The techniques such as UV–visible spectroscopy, Raman spectroscopy, FT-IR, X-ray diffraction (XRD), and Transmission Electron Microscopy (TEM) were used to characterize the nanoparticles. The synthetic route shows the formation of an anisotropic gold nanostructure consisting of spherical, triangles, hexagonals, and a low-yield rod with an aspect ratio ranging from 4.2 to 8.5. Curcumin-derived ctGNPs shows stability at different physiological conditions and better biocompatibility. Synthesized nanoparticles are found non-toxic towards eukaryotic cells but more effective against the cancer cell lines HeLa and MCF-7. The interaction of these synthesized nanoparticles with human telomeric G-quadruplex (GQ) DNA was studied using different physiochemical methods. The spectroscopic studies show that synthesized nanoparticles have stronger binding affinity towards telomeric GQ as compared to ds DNA through Van der Waals and H-bonding interactions. Thermodynamic interpretation reveals that the formation of the complex between the telomeric GQ and ctGNPs are enthalpy driven and entropy unfavourable process, resulting in motion freezing and, eventually, AuNP aggregation. Thus, our study shows a new approach to understand the interaction of telomeric G-quadruplexes with gold nanoparticles generated via the green route.

Plasmonic Interaction of Gold Nanoparticles with the Anti-hypoglycemic Medicament Metformin

Plasmonic Interaction of Gold Nanoparticles with the Anti-hypoglycemic Medicament Metformin

Anomalous Gold Concentrations in Hypersaline Wetland Sediments (Laguna Honda, South Spain) Caused by Nanoparticles Used in Agricultural Practices: Environmental Transformation.

Illite-rich sediments from the Laguna Honda wetland, an eutrophicated hypersaline wetland with waters enriched in Mg and Ca surrounded by olive groves in the Guadalquivir Basin River (South Spain), are polluted by elevated concentrations of gold (up to 21.9 ppm) due to agricultural practices. The highest gold contents appear in the shore sediments of the lake, where up to 20 µm homoaggregates of fused gold nanoparticles (AuNp) are found. Small nanoaggregates of up to six fused gold nanoparticles and very few isolated nanoparticles around 1 nm in size can also be observed to form heteroaggregates of AuNp-mica, especially in the deeper sediments in the central part of the wetland, where Au concentrations are lower (up to 1.89 ppm). The high nanoparticle concentration caused by the inappropriate application of pesticides favors nanoparticle collision in the wetland's Mg- and Ca-rich waters and the fast coagulation and deposition of Au homoaggregates in the gold-rich shore sediment of the lake. The interaction of gold nanoparticles with the abundant illite particles in the wetland's hypersaline waters promotes the simultaneous formation of low-density Au-illite heteroaggregates, which are transported and deposited in the less-rich-in-gold sediments of the central part of the lake. The small sizes of the isolated AuNp and AuNp-fused contacts of the aggregates suggest modifications in the original nanoparticles involving dissolution processes. The presence of bacterial communities resistant to heavy metal stress (Luteolibacter and Maricaulis), as well as the activity of sulfate-reducing bacteria (SRB) and particularly sulfur-oxidizing bacteria (SOB) communities from the shore sediments, favored the high-Eh and low-pH conditions adequate for the destabilization and transport of AuNp.

Doxorubicin Conjugated γ-Globulin Functionalised Gold Nanoparticles: A pH-Responsive Bioinspired Nanoconjugate Approach for Advanced Chemotherapeutics.

Developing successful nanomedicine hinges on regulating nanoparticle surface interactions within biological systems, particularly in intravenous nanotherapeutics. We harnessed the surface interactions of gold nanoparticles (AuNPs) with serum proteins, incorporating a γ-globulin (γG) hard surface corona and chemically conjugating Doxorubicin to create an innovative hybrid anticancer nanobioconjugate, Dox-γG-AuNPs. γG (with an isoelectric point of ~7.2) enhances cellular uptake and exhibits pH-sensitive behaviour, favouring targeted cancer cell drug delivery. In cell line studies, Dox-γG-AuNPs demonstrated a 10-fold higher cytotoxic potency compared to equivalent doxorubicin concentrations, with drug release favoured at pH 5.5 due to the γ-globulin corona's inherent pH sensitivity. This bioinspired approach presents a novel strategy for designing hybrid anticancer therapeutics. Our study also explored the intricacies of the p53-mediated ROS pathway's role in regulating cell fate, including apoptosis and necrosis, in response to these treatments. The pathway's delicate balance of ROS emerged as a critical determinant, warranting further investigation to elucidate its mechanisms and implications. Overall, leveraging the robust γ-globulin protein corona on AuNPs enhances biostability in harsh serum conditions, augments anticancer potential within pH-sensitive environments, and opens promising avenues for bioinspired drug delivery and the design of novel anticancer hybrids with precise targeting capabilities.

Three-body interaction of gold nanoparticles: the role of solvent density and ligand shell orientation.

Molecular dynamics simulations are used to study the effective interactions of alkanethiol passivated gold nanoparticles in supercritical ethane at two- and three-particle levels with different solvent densities. Effective interaction is calculated as the potential of mean force (PMF) between two nanoparticles, and the three-body effect is estimated as the difference in PMFs calculated at the two- and three-particle levels. The variation in the three-body effect is examined as a function of solvent density. It is found that effective interaction, which is completely repulsive at very high solvent concentrations, progressively turns attractive as solvent density declines. On the other hand, the three-body effect turns out to be repulsive and increases exponentially with decreasing solvent density. Further, the structure of the ligand shell is analyzed as a function of nanoparticle separation, and its relationship with the three-body effect is investigated. It is observed that the three-body effect arises when the ligand shell begins to deform due to van der Waals repulsion between ligand shells. The study provides a deep insight into good understanding of the solvent evaporation-assisted nanoparticle self-assembly and can aid in experiments.

Effects on molecular interactions of hollow gold nanoparticles and antibody for sensitizing P24 antigen determination.

In recent years, with the rapid development of point-of-care testing, the application of lateral flow immunochromatography assay (LFIA) has become increasingly widespread. The key to the success of these detection technologies is the effective binding with diagnostic materials and detection antibody proteins. Although many researchers have tried to optimize antibody binding, a universally accepted strategy that can provide maximum performance has not been determined. In this study, the HIV infection P24 antigen was selected as the detection biomarker. Then the binding mechanism between hollow gold nanoparticles as diagnostic materials and detection antibodies was explored through dynamic light scattering, Fourier transform infrared spectroscopy, circular dichroism spectroscopy, and other methods. It was found that the binding efficiency is related to the change in protein secondary conformation during binding, hydrogen bonding, and van der Waals force maintain the binding mechanism between antibodies and nanoparticles. The main forces of particle complexation and the main binding site of the antibody were discussed and analyzed. Finally, an immunochromatographic system was constructed to evaluate the significant advantages of this platform compared to the common colloidal gold immunochromatographic system.

High-Precision Optical Excited Heaters Based on Au Nanoparticles and Water-Soluble Porphyrin

Gold nanoparticles are widely used as local heaters under optical excitation. Hybrid molecular-plasmon nanostructures based on gold nanoparticles and water-soluble porphyrin have been developed. A colloidal solution of gold nanoparticles was obtained by laser ablation of metallic gold in water, ensuring its highest chemical purity. The hybrid nanostructures formation was performed due to the Coulomb interaction of cationic porphyrin and gold nanoparticles. The revealed functional properties of hybrid nanostructures make them promising for controllable nano-heater applications (for example, photothermal therapy). Gold nanoparticles act as heaters, whereas porphyrin serves as a fluorescent thermometer with a single optical excitation.

Controlling plasmonic suprastructures through self-assembly of gold nanoparticles with hybrid copolymer-lipid vesicles

Hybrid lipid membranes incorporating amphiphilic copolymers have gained significant attention due to their potential applications in various fields, including drug delivery and sensing. By combining the properties of copolymers and lipid membranes, such as enhanced chemical tunability and stability, environmental responsiveness, and multidomain nature, novel membrane architectures have been proposed. In this study, we investigated the potentialities of hybrid membranes made of two distinct components: the rigid fully saturated phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and the soft copolymer poly(butadiene-b-ethyleneoxide) (PBD-b-PEO). The objective was to explore the interaction of citrate-coated gold nanoparticles (AuNPs) and the hybrid membrane, aiming at constructing AuNPs-hybrid vesicles suprastructures with controlled and adjustable plasmonic properties. A series of experimental techniques were employed to investigate hybrid free-standing and supported membranes. The results revealed that the incorporation of the copolymer into the lipid membrane promotes AuNPs clustering, demonstrating a distinctive aggregative phenomenon of citrate-coated AuNPs on multidomain membranes. Importantly, we show that the size and morphology of AuNPs clusters can be precisely controlled in non-homogeneous membranes, enabling the formation of hybrid suprastructures with controlled patch properties. These results highlight the potential of lipid-copolymer hybrid membranes for designing functional materials with tailored plasmonic properties, with potential applications in nanomedicine and sensing.

Tightly focused linearly and radially polarized beam effect on the LSPR peak with varying particle size

Interactions of gold and silver spherical nanoparticles (NPs) of a wide range of radius size with tightly focused beams are investigated for a wide range of wavelengths. The scattering of tightly focused beams with a single NP of varying size is examined using a generalized Mie theory and average intensity enhancement in the near-field due to localized surface plasmons is examined for different tightly focused beams. A multipole expansion approach is used to observe the contribution of modes in shaping the scattered light intensity. Influence of particle size and tightly focused beam on intensity enhancement factor is investigated and a shift in localized surface plasmon resonance (LSPR) peak towards higher wavelength is observed with increasing particle size. Maximum intensity enhancement factor due to scattering of different incident beams by a metallic NP is theoretically examined and reported. Gold and silver NP having radius size ranging from 30–60 nm and 1–15 nm respectively showed a maximum intensity enhancement factor in different media. A significant enhancement for the tightly focused radially polarized beam is observed for gold and silver NPs of radius size between 50 nm and 100 nm. Variation towards higher wavelength in LSPR peak due to involvement of higher order of multipoles, and the surrounding medium are also examined in detail.

Synthesis and characterization of gold nanoparticles using Brevibacterium casei (SOSIST-06) isolated from Southern Ocean water samples and their in vitro and in silico anti-WSSV activity

The worldwide shrimp aquaculture business, which is expanding and producing food, has experienced significant economic losses due to a variety of disease outbreaks. One of the main viral pathogens for the global shrimp aquaculture sector is the white spot syndrome virus (WSSV). There have been several attempts to eradicate the virus in shrimp, but none of them have been successful in the long-term effectiveness. In the present work, we establish the isolated strain identified as Brevibacterium casei SOSIST-06 from the Southern Ocean water sample and its capacity for green synthesis of gold nanoparticles. The nanoparticles were characterized using UV–vis spectroscopy, X-ray diffraction, and Transmission electron microscopy. The morphology of nanoparticles is most spherical and there are a few triangles with an average size ranging from 9.5 to 52.3 nm. In vitro anti-wssv activity was carried out using hybrid cell line PmLyo-Sf9 cells, and the synthesized gold nanoparticles were shown to inhibit the virus infection (attachment inhibitory and virucidal activity) with a dose-dependent effect. Further, the interaction of gold nanoparticles and VP28 envelope protein was confirmed using in silico approach. To our knowledge, this is the first study to identify that an actinobacterium, Brevibacterium casei synthesized gold nanoparticles could fight against the white spot syndrome virus. These findings do point the way towards creating potent antiviral or therapeutic techniques for aquaculture that utilize gold nanoparticles.

On the interaction and nanoplasmonics of gold nanoparticles and lipoproteins

The extracellular space is nanostructured, populated by heterogeneous classes of nanoparticles, e.g., extracellular vesicles and lipoproteins, which “made by cells for cells'' mediate intercellular, inter-organ, cross-species, and cross-kingdom communication. However, while techniques to study ENP biology in-vitro and in-vivo are becoming available, knowledge of their colloidal and interfacial properties is poor, although much needed. This paper experimentally shows, for the first time, that the aggregation of citrate-capped gold nanoparticles (AuNPs) triggered by lipid vesicle membranes and the related characteristic redshift of the plasmonic signature also applies/extends to lipoproteins. Such interaction leads to the formation of AuNP-lipoprotein hybrid nanostructures and is sensitive to lipoprotein classes and AuNP/lipoprotein molar ratio, paving the way to further synthetic and analytical developments.

Adsorption of gold nanoparticles on illite under high solid/liquid ratio and initial pH conditions

AbstractAdsorption of nanoparticles on minerals affects the fate and transport of nanoparticles directly and is of great significance to many fields, including research into ore deposits, geochemistry, the environment and mineral materials. Whereas many previous studies have been conducted under the equilibrium pH and low solid (mineral) to liquid (nanoparticle suspension) ratio conditions, adsorption processes under initial pH and high solid/liquid ratio conditions may represent many important yet underexamined complex scenarios. To fill in this research gap, the adsorption of gold nanoparticles on illite was investigated experimentally at a relatively high solid/liquid ratio of 5 g L–1 and the effects of initial pH, ionic strength, citrate concentration, temperature and illite particle size were evaluated. The adsorbed amount of gold nanoparticles (from <5% to nearly 100%) increased with increasing ionic strength, temperature and citrate concentration and decreased with increasing pH and illite particle size. The presence of illite resulted in the dynamic evolution of the pH of the suspension, which, along with solution chemistry parameters, controlled the electrostatic interaction of illite and gold nanoparticles. The adsorption results, scanning electron microscopy observations and surface properties of illite suggest that the negatively charged gold nanoparticles were adsorbed predominantly on the positive illite edges through electrostatic interaction. The electrostatic attraction between illite and gold nanoparticles appeared to be strong, supported by the minor amount of desorption. These research findings are expected to provide a valuable reference regarding many critical issues in the geosciences as well as for industrial applications.

Biophysical interaction of gold nanoparticles with model biological membranes: Investigation of the effect of geometry on cellular uptake and photothermal performance

Gold nanoparticles (AuNPs) with different geometry have been demonstrated to provide significant advantages in enhancing cellular uptake and improving the efficacy of photothermal therapy (PTT). In this study, we synthesized spherical (AuNSs), cube-shaped (AuNCs), and rod-shaped (AuNRs) using the seed-mediated growth method in which cetyltrimethylammonium bromide (CTAB) was used as stabilizing agent. To investigate the impact of nanoparticle geometry on their potential for PTT and their ability to interact with and penetrate cell membranes, we employed two different model membranes, 1,2-dipalmitoyl-sn-glycero-3-phosphocoline (DPPC) and endothelial model membrane (EMM). The biophysical interaction between the AuNPs having different geometry and model membranes was investigated using 2D model. Similarly, we evaluated the efficiency of cellular uptake for these AuNPs and found that AuNRs exhibited greater cellular uptake than the other shapes, despite the initially higher interaction of AuNCs with the DPPC monolayer due to stronger electrostatic interactions. Furthermore, when utilizing a more realistic model membrane (EMM), we observed highly successful biophysical interactions of AuNRs regarding cellular uptake extent. Collectively, our findings suggest that the surface charge and geometry of AuNPs play a crucial role in determining their photothermal therapy potential and cellular uptake efficiency. Moreover, AuNRs are promising candidates for PTT and drug delivery applications.

Noncovalent Adsorption of Single-Stranded and Double-Stranded DNA on the Surface of Gold Nanoparticles

Understanding the patterns of noncovalent adsorption of double-stranded nucleic acids (dsDNA) on gold nanoparticles (GNPs) was the aim of this study. It was found that the high-affinity motifs in DNA can and do act as an “anchor” for the fixation of the whole molecule on the GNP (up to 98 ± 2 single-stranded (ss)DNA molecules per particle with diameter of 13 ± 2 nm). At the same time, the involvement of an “anchor” in the intramolecular DNA interaction can negatively affect the efficiency of the formation of ss(ds)DNA–GNP structures. It has been shown that the interaction of GNP with DNA duplexes is accompanied by their dissociation and competitive adsorption of ssDNAs on GNP, wherein the crucial factor of DNA adsorption efficiency is the intrinsic affinity of ssDNA to GNP. We propose a detailed scheme for the interaction of dsDNA with GNPs, which should be taken into account in studies of this type. Researchers focused on this field should accept the complicated nature of such objects and take into account the many competing processes, including the processes of adsorption and desorption of DNA on gold as well as the formation of secondary structures by individual DNA strands.

Directional movement of gold nanoparticles on the silicon substrate due to the Laplace pressure: A molecular dynamics simulation study

Due to superior ductility, oxidation resistance, and conductive properties, gold nanoparticles are widely used in semiconductor devices. From printing inks to electronic chips, gold nanoparticles are widely used as conductors. Nowadays, with the size of electronic chips getting smaller, gold nanoparticles have become an essential component in chip design. For example, they can connect resistors, conductors, and other electronic chip components. However, interactions of gold nanoparticles with curved substrates at high temperatures have rarely been studied. In our study, we simulated interactions of gold nanoparticles at high temperatures on a curved silicon substrate. It is observed that at above the metlting point, gold nanoparticles moved directionally under the effect of curvature gradients, and the curved surface can be used to control the coalescence of gold nanoparticles. The size, temperature of gold nanoparticles, and curvature gradients of the substrate are altered to observe their effects on gold nanoparticle movement. According to the results, we conclude that surface curvature gradients induce the Laplace pressure, and the Laplace pressure drives liquid gold nanoparticles to move directionally.

Preparation of Au/ZnO/Fe3O4 Composite for Degradation of Tartrazine under Visible Light

Zinc oxide has been shown to be a potential photocatalyst under UV light but its catalytic activity is limited under visible light due to its wide bandgap energy and rapid recombination of electrons and holes. Besides the catalytic recovery is a challenging issue because of its dispersion in solution. Previous work has shown that the interaction of gold nanoparticles with ZnO can reduce the band gap energy (Eg) and plasmon resonance (SPR) as well as the formation of the Schottky barrier in Au/ZnO composite can reduce the recombination of electrons and holes. In this study, Au/ZnO/Fe3O4 (AZF) composites were prepared by a simple mixing method using polyvinyl alcohol (PVA) as a binder. As-prepared composites were characterized by Scanning Electron Microscope (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffraction (XRD), UV-Vis Diffuse Reflectance (UV-Vis-DR), and Fourier Transform Infra Red (FT-IR). The catalytic efficiency of as-prepared samples was evaluated through the decomposition of tartrazine (TA), a colorant that is difficult to decompose in wastewater and has harmful effects on human health. The effects of reaction parameters such as the content of PVA, solution pH, and oxidizing agents (O2 and H2O2) on the catalytic efficiency were studied. The AZF at PVA of 0.0125 g showed the highest performance among as-prepared samples. With the presence of 12 mM H2O2 in the catalyst system, the degradation efficiency and reaction rate of TA in composite increased to 81.5% and 0.020 min−1, respectively. At this condition, photocatalysis and Fenton system catalysis occurred together. The catalytic mechanism of Tartrazine (TA) on composite was proposed and the reaction of TA was studied by the first-order kinetic model. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Interaction of Gold Nanoparticles with Cyanine Dyes in Cholesteric DNA Submicroparticles: Impact of the Way of Their Introduction into the System

Interaction of Gold Nanoparticles with Cyanine Dyes in Cholesteric DNA Submicroparticles: Impact of the Way of Their Introduction into the System