Properties Of Gold Nanoparticles Research Articles

Gold Nanoparticles for Retinal Molecular Optical Imaging.

The incorporation of gold nanoparticles (GNPs) into retinal imaging signifies a notable advancement in ophthalmology, offering improved accuracy in diagnosis and patient outcomes. This review explores the synthesis and unique properties of GNPs, highlighting their adjustable surface plasmon resonance, biocompatibility, and excellent optical absorption and scattering abilities. These features make GNPs advantageous contrast agents, enhancing the precision and quality of various imaging modalities, including photoacoustic imaging, optical coherence tomography, and fluorescence imaging. This paper analyzes the unique properties and corresponding mechanisms based on the morphological features of GNPs, highlighting the potential of GNPs in retinal disease diagnosis and management. Given the limitations currently encountered in clinical applications of GNPs, the approaches and strategies to overcome these limitations are also discussed. These findings suggest that the properties and efficacy of GNPs have innovative applications in retinal disease imaging.

NFC-enabled photothermal-based microfluidic paper analytical device for glucose detection.

This study introduces the development of a photothermal-based microfluidic paper analytical device (PT-µPAD) integrated with near-field communication (NFC) technology and smartphone readout for enzyme-free glucose quantification in human samples. With the properties of gold nanoparticles (AuNPs) both as a nanozyme and as a photothermal substrate, there is no need for costly reagents like enzymes or a readout instrumentation for the selective and sensitive detection of glucose. In PT-µPADs, AuNPs are etched by hydrogen peroxide (H2O2) generated from glucose catalysis. Photothermal detection from the plasmonic heating of these AuNPs when illuminated by a 533nm LED light source is achieved by inserting the PT-µPAD sensor into a portable NFC platform suitable for smartphone readout. Temperature variation is directly proportional to the glucose concentration. After optimization, we acquired a linear range between 5.0 and 20.0 µmol L-1 (R2 = 0.9967) and a limit of detection (LOD) of 25.0 nmol L-1 for glucose. Additionally, while our sensor does not utilize any enzyme, it is remarkably selective to glucose with no effects from interferences. Recovery studies in various human control samples indicated a range of 99.73-102.66% with the highest RSD of 3.53%, making it highly accurate and precise. Moreover, our method is more sensitive than other methods relying on conventional µPADs for glucose sensing. By integrating the potential benefits of microfluidics, nanomaterials as nanozymes, and NFC technology for wireless readout, our sensor demonstrates great promise as an accessible, affordable, and shelf-stable device for glucose quantification. Moreover, this concept can be extended to detect other molecules of interest as a point-of-care (POC) diagnostics device.

Parametric Drug Release Optimization of Anti-Inflammatory Drugs by Gold Nanoparticles for Topically Applied Ocular Therapy.

Eye drops represent 90% of all currently used ophthalmic treatments. Only 0.02% of therapeutic molecules contained in eye drops reach the eye anterior chamber despite their high concentration. The tear film efficiently protects the cornea, reducing access to the target. Thereby, the increase in the drug bioavailability and efficiency must come from the mucoadhesion optimization of the drug delivery system. The gold nanoparticles, used as a drug delivery system in this study, already showcased ultrastable and mucoadhesive properties. The goal was to study the gold nanoparticles' ability to release two specific ophthalmic drugs, flurbiprofen and ketorolac. The parameters of interest were those involving the loading conditions, the gold nanoparticles properties, and the release experimental conditions. The drug release was measured using an in vitro model based on dialysis bags coupled with UV-visible spectroscopy. Gold nanoparticles showed an ability to release different molecules, whether hydrophobic or hydrophilic, in passive or active drug release environments. Based on these preliminary results, gold nanoparticles could represent a promising drug delivery system for ketorolac and flurbiprofen when topically applied through eye drops.

Sử dụng hiện tượng cộng hưởng plasmon bề mặt của dung dịch nano vàng để xác định amikacin trong mẫu dược phẩm bằng phương pháp quang học

A simple and highly sensitive spectrophotometric method for detecting amikacin was developed based on the change in surface plasmon resonance (SPR) properties of gold nanoparticles (AuNPs). The change in the AuNPs solution colour from red to blue in the presence of trace amounts of amikacin makes the method visible to the naked eye. Furthermore, with the addition of amikacin, in the UV-Vis spectrum appears another absorption band at 650 nm, and the AuNPs solution also gave a linear increase of optical absorption ratio A650/A520 with a logarithm of amikacin concentration in the range of 3 × 10-7 - 3.5 × 10-6 M. Under the optimum conditions, including 2.5 × 10-4 M gold nanoparticles solution, pH = 6 and 2 mM NaCl with an incubation time of 4 minutes, the proposed method achieved the low limit of detection (LOD) of 7.2 × 10-8 M, the limit of quantitation (LOQ) of 2.4 × 10-7 M, high precision (RSD < 5%). Therefore, the developed method can be applied to determine amikacin in pharmaceutical samples and in plasma and urine samples.

Dissociation reactions of hydrogen molecules at active sites on gold clusters: A DFT study

AbstractSmall gold nanoparticles (GNPs) show special catalytic activity for hydrogen (H2) dissociation reaction, which is essential and important in understanding the hydrogen oxidation reaction in hydrogen energy source. To insight on catalytic properties of GNPs, we simulated H2 dissociation paths on neutral gold clusters (GCs) Aun (n = 1–6) and positively charged GCs (n = 3–5), which are possible active sites on GNPs. The calculated results show that H2 dissociation on GCs follows a homolytic cleavage reaction process. Light irradiation and water environment are considered for H2 dissociation on (n = 3–5, δ = 0 and +1) clusters. The calculated results show that when the incident light has a low energy close to the surface plasmon resonance (SPR) region of GNPs, the light can effectively reduce the H2 dissociation barrier, and an oxidation dissociation process is found for the water‐assisted H2 dissociation reaction.

Gold Nanoparticles Disrupt the IGFBP2/mTOR/PTEN Axis to Inhibit Ovarian Cancer Growth.

By exploiting the self-therapeutic properties of gold nanoparticles (GNPs) a molecular axis that promotes the growth of high-grade serous ovarian cancer (HGSOC), one of the deadliest gynecologic malignancies with poorly understood underlying molecular mechanisms, has been identified. The biodistribution and toxicity of GNPs administered by intravenous or intraperitoneal injection, both as a single dose or by repeated dosing over two weeks are first assessed; no biochemical or histological toxicity to vital organs is found. Using an orthotopic patient-derived xenograft (PDX) model of HGSOC, the authors then show that GNP treatment robustly inhibits tumor growth. Investigating the molecular mechanisms underlying the GNP efficacy reveals that GNPs downregulate insulin growth factor binding protein 2 (IGFBP2) by disrupting its autoregulation via the IGFBP2/mTOR/PTEN axis. This mechanism is validated by treating a cell line-based human xenograft tumor with GNPs and an mTOR dual-kinase inhibitor (PI-103), either individually or in combination with GNPs; GNP and PI-103 combination therapy inhibit ovarian tumor growth similarly to GNPs alone. This report illustrates how the self-therapeutic properties of GNPs can be exploited as a discovery tool to identify a critical signaling axis responsible for poor prognosis in ovarian cancer and provides an opportunity to interrogate the axis to improve patient outcomes.

Efficacy and Immune Response Elicited by Gold Nanoparticle- Based Nanovaccines against Infectious Diseases.

The use of nanoparticles for developing vaccines has become a routine process for researchers and pharmaceutical companies. Gold nanoparticles (GNPs) are chemical inert, have low toxicity, and are easy to modify and functionalize, making them an attractive choice for nanovaccine development. GNPs are modified for diagnostics and detection of many pathogens. The biocompatibility and biodistribution properties of GNPs render them ideal for use in clinical settings. They have excellent immune modulatory and adjuvant properties. They have been used as the antigen carrier for the delivery system to a targeted site. Tagging them with antibodies can direct the drug or antigen-carrying GNPs to specific tissues or cells. The physicochemical properties of the GNP, together with its dynamic immune response based on its size, shape, surface charge, and optical properties, make it a suitable candidate for vaccine development. The clear outcome of modulating dendritic cells, T and B lymphocytes, which trigger cytokine release in the host, indicates GNPs’ efficiency in combating pathogens. The high titer of IgG and IgA antibody subtypes and their enhanced capacity to neutralize pathogens are reported in multiple studies on GNP-based vaccine development. The major focus of this review is to illustrate the role of GNPs in developing nanovaccines against multiple infectious agents, ranging from viruses to bacteria and parasites. Although the use of GNPs has its shortcomings and a low but detectable level of toxicity, their benefits warrant investing more thought and energy into the development of novel vaccine strategies.

Structural Properties of Nanometer‐Sized Gold Nanoparticles on a Silicon Substrate

Properties of gold nanoparticles supported on Si substrates, which have been the focus of recent attention, depend sensitively on the size, structure and coordination of gold nanoparticles as well as on the processes of interdiffusion and chemical bonding at the Au-Si interface. There is great need, therefore, for developing structural techniques capable of imaging such nanosystems in atomic detail. Here, we discuss how the atomic structure of nanometer-sized gold nanoparticles deposited on a silicon surface can be determined by using high-energy x-ray diffraction measurements in combination with an analysis based on atomic-pair-distribution functions and advanced reverse Monte Carlo methods. Our approach delivers simple and incisive pictures of the structure of Au clusters on Si and reveals direct structural evidence for the emergence of a gold-silicide interface following room temperature deposition of gold nanoparticles on Si. Our study will contribute to designing Au/Si nanostructures with desirable properties. This article is protected by copyright. All rights reserved.

Gold Nanoparticle Drug Delivery System: Principle and Application

In recent years, gold nanoparticles (GNPs) have gradually become a major choice of drug delivery cargoes due to unique properties. Compared to traditional bulk solid gold, GNPs have basic physical and chemical advantages, such as a larger surface area-to-volume ratio and easier surface modification. Furthermore, these have excellent biocompatibility, can induce the directional adsorption and enrichment of biological macromolecules, help retain biological macromolecule activity, and cause low harm to the human body. All these make GNPs good drug delivery cargoes. The present study introduces the properties of GNPs, including factors that affect the properties and synthesis. Then, focus was given on the application in drug delivery, not only on the molecular mechanism, but also on the clinical application. Furthermore, the properties and applications of peptide GNPs were also introduced. Finally, the challenges and prospects of GNPs for drug delivery were summarized.

Electromagnetohydrodynamic peristaltic flow of a couple stress nanofluid through a vertical annulus in the presence of Hall currents and thermal radiation

This paper investigates the electric properties of gold nanoparticles mixed with a convection dielectric couple stress fluid inside a vertical cylindrical tube with moving endoscope in the presence of Hall currents and thermal radiation. Under the long wavelength approximation and the use of appropriate conversion relationships between fixed and moving frame coordinates, the exact solutions have been evaluated for temperature distribution, gold nanoparticles concentration, electrical potential function and nanofluid pressure, while analytical solution is found for the axial velocity using the homotopy analysis method. The results show that the presence of the electric field enhances the effects of Brownian motion parameter, thermophoresis parameter, radiation parameter, Hall currents and wave amplitude ratio on the axial nanofluid velocity, while it was found that its presence reduces the effects of couple stress parameter, thermophoresis diffusion constant and Brownian diffusion constant.

Review on Gold Nanoparticles-Based Biosensors in Clinical and Non-Clinical Applications

Gold nanoparticles (GNP) acquire unique properties that have made significant contributions to clinical and non-clinical fields, specifically in the application of GNP’s for designing biosensor devices in which exhibit novel functional properties. Many properties of GNP’s are reviewed in this literature including optical properties, biocompatibility, conductivity, catalytic properties, high surface-to-volume ratio, and high density of the GNPs, that make them excellent in the application of constructing GNP-based biosensors. This literature review covers a specific comparison between the optical, electrochemical, and piezoelectric biosensors, as these are the three most common GNP-based biosensors. Optical biosensors are optimal due to their ability to cater to surface modification, which then leads to the ability for selective bonding. Furthermore, with the use of GNP and the sensor's non-invasive and non-toxic method of use, high-resolution images and signals can be formed. The sensitivity and specificity of electrochemical biosensors with the conductivity of GNPs, the electrodes of this stable biosensor can detect tumour markers in the human body. Piezoelectric biosensors are mass sensitive sensors and with the use of GNP, it amplifies the changes in mass. Through this, these sensors progress to be immunosensors which determine microorganisms and macromolecular compounds. As well, this review will conclude with an outline of present and future research recommendations for real-world application of the three GNP-based biosensors discussed.

On the Synergism of Biogenic Gold Nanoparticles and Hydroxyaluminum Phthalocyanines in the Photoeradication of Staphylococcus aureus.

Due to the unusual properties of gold nanoparticles, these structures are widely used in medicine and biology. This paper describes for the first time the synthesis of colloidal gold nanoparticles by the cell-free filtrate obtained from the Coriolus versicolor biomass and the use of these biogenic nanostructures to increase the photosensitizing efficiency of di- (AlPcS2) and tetrasulfonated (AlPcS4) hydroxyaluminum phthalocyanines in antibacterial photodynamic therapy. The obtained monodisperse particles were extremely stable, and this remarkable stability was due to the presence of phosphoprotein as a capping agent. The studied gold nanoparticles had a spherical shape, were uniformly distributed, and were characterized by a single plasmon band at wavelength of 514–517 nm. Almost 60% of the gold particles were found to be in the range of 13 to 15 nm. In accordance with the regulations of the American Microbiological Society, indicating that any antimicrobial technique must kill at least 3 log CFU (99.9%) to be accepted as “antimicrobial”, this mortality of Staphylococcus aureus was shown to be achieved in the presence of AlPcS4 + AuNPs mixture and 4.8 J cm−2 light dose compared to AlPcS4 alone, which required a light dose of 24 J cm−2. The best effect of increasing the effectiveness of combating this pathogen was observed in the case of AlPcS2 + AuNPs as a photosensitizing mixture. The light dose of 24 J cm−2 caused a lethal effect of the studied coccus in the planktonic culture.

Study of optical properties of gold nanoparticles embedded in normal, benign, and malignant breast tissues

In this work, the complex dielectric permittivity of breast tissue is calculated for different growth rates of benign and malignant tumors using the Maxwell Garnett (MG) effective medium theory. The results show a wide variability of the dielectric properties depending on the nature and the volume fraction of the cancer cells. The benign-normal and malignant-normal heterostructures are denoted respectively x-B/N and x-M/N where x is the volume fraction of cancer cells in the breast tissue. The real and imaginary parts of dielectric permittivity increases when the growth rates of benign and malignant tumors increase and decrease when the microwave frequency increases from 0.5 to 8 GHz. In the aim to use the gold nanoparticles (GNPs) in breast cancer therapy, both for a better image diagnostic and photothermal therapy (PTT), we present here a study on the optical properties of GNPs embedded in normal, benign and malignant breast tissue in the frequency range from 0.5 GHz to 8 GHz. optical band gap energy for GNP is located in [0.5eV−1.46eV](±0.06eV), [0.72eV−1.20eV](±0.04eV) and [0.11eV−0.74eV](±0.02eV) ranges for Normal, Benign and Malignant breast tissues, respectively. We use the Finite Element Method (FEM) to evaluate the spectra of the dielectric and optical parameters of GNPs namely: complex dielectric permittivity, absorption cross section, reflectivity, dielectric loss function and conductivity, the surface plasmons resonance (SPR) properties are deduced from these spectra. The obtained results show that the SPR-peak of the GNPs is located in the Visible (Vis), near infrared (NIR) and short wavelength infrared (SWIR) bands when they are embedded respectively in the normal, benign and malignant breast tissue. For these three tissues when the microwave frequency increases from 0.5 to 8 GHz, the SPR-peak position λmax shifts towards the short wavelengths. The calculations show that in the vicinity of λmax the dielectric loss function take a maximum value and the reflectivity change strongly. These results show that the absorption and dielectric loss peaks are less wide for the high microwave frequencies and very wide for the low frequencies, which also influences the difference between the asymptotic values of the real part of permittivity and of the reflectivity. These results make it possible to identify the nature of the breast tumor using the GNPs in the sensors based on the of SPR phenomenon. The optical properties of GNPs depending on their size and on the tumor growth rate in the breast tissue are also studied and discussed. The study carried out represents a feasibility proposal for the use of GNPs for determining the degree of breast tumor progression and estimate the good performance of using the GNPs for the selective destruction of breast cancer cells.

PEGylated Gold Nanoparticles Grafted with N-Acetyl-L-Cysteine for Polymer Modification

The subjects of this work were the enhancement and determination of the stability and other properties of gold nanoparticles (AuNPs) in an aqueous solution, gold nanoparticle immobilization, and further surface grafting on polyethylene naphthalate (PEN). Gold nanoparticles in PEG with a subsequent water solution addition were prepared using cathode sputtering; for the subsequent surface activation, two different solutions were used: (i) sodium citrate dihydrate (TCD) and (ii) N-acetyl-L-cysteine (NALC). The aim of this work was to study the effect of the concentration of these solutions on AuNPs stability, and further, the effect of the concentration of gold nanoparticles and their morphology, and to describe the aging process of solutions, namely, the optical properties of samples over 28 days. Stabilized AuNPs were prepared in an N-acetyl-L-cysteine (NALC) system and subsequently immobilized with NALC. The surface chemistry modification of AuNPs was confirmed using HRTEM/EDS. Gold nanoparticles were successfully immobilized with NALC. Grafting of the modified PEN from a solution of colloidal gold stabilized in the PEG–H2O–NALC system led to the polymer surface functionalization.

Design and Development of Antibody Functionalized Gold Nanoparticles for Biomedical Applications.

Antibody-functionalized gold nanoparticle constitutes a powerful interface biosystem for biomedical applications where the properties of gold nanoparticles and the specificity of antibody-antigen interactions are combined. This study provides insight into the key factors for the development of antibody functionalized gold nanoparticles focusing on the immobilization of the antibody. Here, we address an oriented antibody immobilization procedure on gold nanoparticles. It comprises chelatemodified gold nanoparticles that are designed for oriented immobilization of IgG antibodies (end on spatial orientation) through the metal-chelation to histidine-rich metal binding site in the heavy chain (Fc) of the antibody.

Studies of in vitro antioxidant and anti-inflammatory activities of gold nanoparticles biosynthesised from a medicinal plant, Commiphora wightii

ABSTRACT Green synthesis of nanoparticles is one of the recent trends nowadays owing to its reduced toxic effects. Our study is aimed at evaluating the biological potential viz., antioxidant and anti-inflammatory properties of gold nanoparticles (AuNPs) biosynthesised using an aqueous extract of Commiphora wightii. The AuNPs synthesis was preliminarily confirmed by colour change from yellow to purple. Further, AuNPs synthesis was optimised at different ratio, pH and temperature. AuNPs were characterised using spectroscopic and microscopic techniques. FTIR analysis confirmed role of biomolecules in reduction and stabilisation of AuNPs. TEM analysis revealed polydispersed nanoparticles with an average size of 20.2 ± 6.6 nm. In vitroantioxidant activity of AuNPs were evaluated using DPPH, ABTS and H2O2 assays. The AuNPs showed significant radical scavenging ability. In vitro anti-inflammatory activity was studied for inhibition of albumin denaturation, Trypsin, LOX, and hyaluronidase enzymes. The AuNPs exhibited good activity as potent anti-inflammatory agents. Further in vivo studies are needed to explore them as good therapeutic agents.

A Paper-Based Colorimetric Aptasensor for the Detection of Gentamicin.

Antibiotics are classes of antimicrobial substances that are administered widely in the field of veterinary science to promote animal health and feed efficiency. Cattle-administered antibiotics hold a risk of passing active residues to milk, during the milking process. This becomes a public health concern as these residues can cause severe allergic reactions to sensitive groups and considerable economic losses to the farmer. Hence, to ensure that the produced milk is safe to consume and adheres to permissible limits, an on-farm quick and reliable test is essential. This study illustrates the design and development of a microfluidic paper biosensor as a proof-of-concept detection system for gentamicin in milk. Localized surface plasmon resonance (LSPR) properties of gold nanoparticles have been explored to provide the user a visual feedback on the test, which was also corroborated by RGB analysis performed using Image J. The assay involves the use of a short stretch of single stranded DNA, called aptamer, which is very specific to the gentamicin present in the milk sample. The camera-based LOD for the fabricated paper device for milk samples spiked with gentamicin was calculated to be 300 nM, with a reaction time of 2 min.

Gold nanoparticles with tailored size through ligand modification for catalytic applications.

The active sites of catalysts can be tuned by using appropriate organic moieties. Here, we describe a facile approach to synthesise gold nanoparticles (AuNPs) using various Au(I) precursors. The core size of these AuNPs can be precisely tailored by varying the steric hindrance imposed by bound ligands. An interesting relationship is deduced that correlates the steric hindrance around the metal to the final size of the nanoparticles. The synthesised AuNPs are immobilised onto TS-1 zeolite (Au/TS-1) with minimal change in the final size of the AuNPs. The catalytic performance of Au/TS-1 catalyst is evaluated for the direct gas phase epoxidation of propylene with hydrogen and oxygen, an environmentally friendly route to produce propylene oxide. The results indicate that smaller AuNPs exhibit enhanced catalytic activity and selectivity. Furthermore, this synthetic approach is beneficial when tailored synthesis of gold nanoparticles of specific sizes is required.

Simulation of the optical properties of gold nanoparticles on sodium alginate

In this contribution, we report on the simulation of optical reflectance and transmittance (R&T) taken on a set of gold nanoparticles thin film, deposited on sodium alginate by magnetron sputtering. The gold layer is very thin, so that the films are not continuous and the material is arranged in nanostructured layers. R&T spectra are simulated using the Generalized Transfer Matrix method applied to the film-on-substrate model. The gold NP films are simulated using the Drude-Lorentz model, by taking into account that the optical function of nanostructured gold exhibits increased collision frequency and reduced relaxation time. Moreover, the signal of localized surface plasmon, evident in the spectra, is simulated by introducing a dedicated modified Lorentz oscillator. The experimental results are well reproduced by the applied model. All trends (amplitude and energy position of the plasmon oscillator, film thickness, relaxation time) are correlated with the deposition parameters. The procedure represents a useful tool in the characterisation of such nanoparticles thin films.

Biotherapeutic Antibodies for the Treatment of Head and Neck Cancer: Current Approaches and Future Considerations of Photothermal Therapies.

Head and neck cancer (HNC) is a heterogeneous disease that includes a variety of tumors originating in the hypopharynx, oropharynx, lip, oral cavity, nasopharynx, or larynx. HNC is the sixth most common malignancy worldwide and affects thousands of people in terms of incidence and mortality. Various factors can trigger the development of the disease such as smoking, alcohol consumption, and repetitive viral infections. HNC is currently treated by single or multimodality approaches, which are based on surgery, radiotherapy, chemotherapy, and biotherapeutic antibodies. The latter approach will be the focus of this article. There are currently three approved antibodies against HNCs (cetuximab, nivolumab, and pembrolizumab), and 48 antibodies under development. The majority of these antibodies are of humanized (23 antibodies) or human (19 antibodies) origins, and subclass IgG1 represents a total of 32 antibodies. In addition, three antibody drug conjugates (ADCs: telisotuzumab-vedotin, indatuximab-ravtansine, and W0101) and two bispecific antibodies (GBR 1372 and ABL001) have been under development. Despite the remarkable success of antibodies in treating different tumors, success was limited in HNCs. This limitation is attributed to efficacy, resistance, and the appearance of various side effects. However, the efficacy of these antibodies could be enhanced through conjugation to gold nanoparticles (GNPs). These conjugates combine the high specificity of antibodies with unique spectral properties of GNPs to generate a treatment approach known as photothermal therapy. This approach can provide promising outcomes due to the ability of GNPs to convert light into heat, which can specifically destroy cancer cells and treat HNC in an effective manner.