Interaction Of Gold Nanoparticles Research Articles

Intracellular Localized Surface Plasmonic Sensing for Subcellular Diagnosis

This paper proposes a method for diagnosing intracellular conditions and organelles of cells with localized surface plasmonic resonance (LSPR) by directly internalizing the gold nanoparticles (AuNPs) into the cells and measuring their plasmonic properties through hyperspectral imaging. This technique will be useful for direct diagnosis of cellular organelles, which have potential for cellular biology, proteomics, pharmaceuticals, drug discovery etc. Furthermore, localization and characterization of citrate-capped gold nanoparticles in HeLa cells were studied, by hyperspectral microscopy and other imaging techniques. Here, we present the method of internalizing the gold nanoparticles into the cells and subcellular organelles to facilitate subcellular plasmonic measurements. An advanced label-free visualization technique, namely hyperspectral microscopy providing images and spectral data simultaneously, was used to confirm the internalization of gold nanoparticles and to reveal their optical properties for possible intracellular plasmonic detection. Hyperspectral technology has proved to be effective in the analysis of the spectral profile of gold nanoparticles, internalized under different conditions. Using this relatively novel technique, it is possible to study the plasmonic properties of particles, localized in different parts of the cell. The position of the plasmon bands reflects the interactions of gold nanoparticles with different subcellular systems, including particle-nucleus interactions. Our results revealed the effect of the different intracellular interactions on the aggregation pattern of gold nanoparticles, inside the cells. This novel technique opens the door to intracellular plasmonics, an entirely new field, with important potential applications in life sciences. Similarly, the characterization of AuNP inside the cell was validated using traditional methods such as light microscopy and scanning electron microscopy. Under the conditions studied in this work, gold nanoparticles were found to be non-toxic to HeLa (cervical cancer) cells.

Spectroscopic Study of the Interaction of Carboxyl-Modified Gold Nanoparticles with Liposomes of Different Chain Lengths and Controlled Drug Release by Layer-by-Layer Technology.

In this article, we investigate the interactions of carboxyl-modified gold nanoparticles (AuC) with zwitterionic phospholipid liposomes of different chain lengths using a well-known membrane probe PRODAN by steady-state and time-resolved spectroscopy. We use three zwitterionic lipids, namely, dipalmitoylphosphatidylcholine (DPPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), and 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), which are widely different in their phase transition temperatures to form liposome-AuC assemblies. The steady-state and time-resolved studies indicate that the AuC brings in stability toward liposomes by local gelation. We observe that the bound AuC detach from the surface of the liposomes under pH ≈ 5 due to protonation of the carboxyl group, thus eliminating the electrostatic interaction between nanoparticles and head groups of liposomes. The detachment rate of AuC from the liposome-AuC assemblies is different for the aforementioned liposomes due to differences in their fluidity. We exploited the phenomena for the controlled release of a prominent anticancer drug Doxorubicin (DOX) under acidic conditions for different zwitterionic liposomes. The drug release rate was further optimized by coating of liposome-AuC assemblies with oppositely charged polymer (P), polydiallyldimethylammonium chloride, followed by a mixture of lipids L (DMPC:DMPG) and again with a polymer in a layer-by-layer fashion to obtain capsule-like structures. This system is highly stable for weeks, as confirmed by field-emission scanning electron microscopy (FE-SEM) and confocal laser scanning microscopy (CLSM) imaging, and inhibits premature release. The layer coating was confirmed by hydrodynamic size and zeta potential measurements of the systems. The capsules obtained are of immense importance as they can control release of the drug from the systems to a large extent.

Interaction of Colloidal Gold Nanoparticles with Protein

Interaction of Colloidal Gold Nanoparticles with Protein

Exploring gold nanoparticles interaction with mucins: A spectroscopic-based study

The interaction between two mucin types (mucin from porcine stomach – PGM and mucin from bovine submaxillary glands – BSM) and gold nanoparticles (GNPs) of various size (5, 20 and 40 nm) and functionalization (with cysteamine or thioglycolic acid) was studied under physiological conditions, in order to investigate the affinity of the nanoparticles to the proteins.Different methods are employed to monitor the interactions: UV–vis and fluorescence spectroscopy, fluorescence lifetime, circular dichroism and transmission electron microscopy. These studies have shown the formation of a complex between GNPs and both PGM and BSM.This aspect could be of great importance for the use of gold nanoparticles for biomedical purposes in those diseases where qualitative and quantitative mucin anomalies play an essential role in mucus composition and rheology.

Interaction of polymer-coated gold nanoparticles with cellobiose dehydrogenase: The role of surface charges

Studying the interaction of functional proteins such as enzymes and nanoparticles (NPs) includes the important topic of investigating any possible changes in stability and function of enzymes in nanostructured environments. The effects of NPs on the enzyme activity and stability are governed by their physical and chemical properties such as structure, shape, size, surface chemistry and their surface charges. In this study, the influence of negatively and positively charged AuNPs are investigated on the activity of immobilized Myriococcum thermophilum cellobiose dehydrogenase (MtCDH) and its electron transfer rate with graphite electrodes modified with positively and negatively AuNPs. The MtCDH modified graphite electrode premodified with positively charged AuNPs showed an alkaline shift in the pH of maximum activity from pH5.5 to 8. No change in the pH of maximum activity was observed when MtCDH graphite electrodes were premodified with negatively charged AuNPs. The results clearly demonstrated the effect of surface charge of AuNPs on the activity of the enzyme. The catalytic current density and the KMapp value for MtCDH graphite electrode premodified with positively charged AuNPs were enhanced with up to 66 and 8 times, respectively. Two spectroscopic assays were also performed in solution to investigate the influence of the presence of positively or negatively charged AuNPs on the activity of MtCDH in homogeneous solution. The results clearly demonstrated that not only the rate of the heterogeneous electron transfer between the immobilized MtCDH and the electrode but also the rate of the homogeneous electron transfer between soluble MtCDH and the acceptor was highly dependent on the type of surface charge of the AuNPs.

A colorimetric study of the interaction of cationic and anionic surfactants with anionic gold nanoparticles

The interactions of citrate-capped 10-nm gold nanoparticles with a cationic model surfactant, CTACl, and an anionic one, SDS, are explored. Results show that for CTACl, values of the c.m.c. close to those reported in the absence of nanoparticles can be obtained by simple colorimetric measurements. For SDS, its interaction with the same-charge nanoparticles is explored through the use of an indirect colorimetric method involving NaCl addition, and a surfactant-nanoparticle interaction model is postulated in this basis. C.m.c. measurements for SDS in the presence of AuNPs show that, despite both substrates being anionic, SDS micelle formation is actually promoted in the presence of gold nanoparticles.

Interaction of silver and gold nanoparticles in mammalian cancer: as real topical bullet for wound healing— A comparative study

The present study evaluates in vitro cytotoxic effects and the mode of interaction of biologically synthesized Ag and Au nanoparticles (NPs) using Brassica oleracea L. var. capitata f. rubra (BOL) against HT-1080 cancer cells and bacterial cells as well as their wound healing efficacy using a mouse model. UV-visible spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray analysis have ascertained the formation of nano-sized Ag and Au particles. Fourier transform infrared analysis has confirmed that polyphenol and amide groups in BOL act as capping as well as reducing agents. The free radical scavenging activity under in vitro conditions is found to be higher for the Ag NPs when compared to the Au NPs. Acridine orange-ethidium bromide dual staining and comet assay have indicated that the cytotoxic effects are mediated through nuclear morphological changes and DNA damage. The intracellular localization of Ag and Au NPs in HT-1080 cells and their subsequent effect on apoptosis and necrosis were analyzed by flow cytometry while the mode of interaction was established by scanning electron microscopy under field emission mode and by bio-transmission electron microscopy. These methods of analysis clearly revealed that the Ag and Au NPs have easily entered and accumulated into the cytosol and nucleus, resulting in activation of inflammatory and apoptosis pathways, which in turn cause damage in DNA. Further, mRNA and protein expression of caspase-3 and caspase-7, TNF-α, and NF-κB have provided sufficient clues for induction of intrinsic and extrinsic apoptosis and inflammatory pathways in Ag NP- and Au NP-treated cells. Evaluation of wound healing properties of Ag and Au NPs using a mouse model indicates rapid healing of wounds. In addition, no clear toxic effects and no nuclear abnormalities in peripheral blood cells are observed. Ag NPs appear to be a better anticancer therapeutic agent than Au NPs. Nonetheless, both Ag NPs and Au NPs show potential for promoting topical wound healing without any toxic effects. Graphical abstract Schematic representation of biological synthesis of Ag and Au NPs and its application on cancer and wound healing.

Individual and simultaneous voltammetric determination of ascorbic acid, uric acid and folic acid by using a glassy carbon electrode modified with gold nanoparticles linked to bentonite via cysteine groups

A voltammetric sensor for both the individual and the simultaneous determination of ascorbic acid (AA), uric acid (UA) and folic acid (FA) is described. It is based on a glassy carbon electrode (GCE) that was modified with bentonite (Bnt) that was first functionalized with cysteine (Cys) to which gold nanoparticles were linked. The resulting material (referred to as Au-Cys-Bnt) and the other materials were characterized by UV-vis spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray analysis and electrochemical methods. The XRD peak positions of bentonite and Cys-functionalized bentonite prove the incorporation of Cys into bentonite. The XPS spectrum of Au-Cys-Bnt confirms the interaction of gold nanoparticles with the thiol group of Cys. The modified GCE displays high electrocatalytic activity for the oxidation of AA, UA and FA, typically at 0.19, 0.41, and 0.73 V (vs. SCE), respectively. Differential pulse voltammetric data show a linear response that covers the 1 μM to 25 mM concentration range for AA, the 1 to 200 μM concentration range for UA, and two linear ranges for FA, one from 5 to 100 μM and one from 100 μM to 1.5 mM. The sensor was applied to the determination of AA, UA and FA in (spiked) multi-vitamin syrup, bird serum and milk samples.

Shape-dependent interaction of gold nanoparticles with cultured cells at laser exposure

Laser optoporation of cells by local heating of plasmonic gold nanoparticles (GNPs) was proven as a favorable delivery method of molecules into cells. The optoporation efficiency depends on the laser beam intensity and GNP properties. Here, we evaluate the membrane optoporation in vitro in terms of fluorescent dye permeability under treatment of a multi-pulsed nanosecond 1064 nm laser with a sharply-focused beam. Anisotropic GNPs, such as nanorods and nanostars, were fabricated to achieve the optimal GNP-cell interaction. Nanostars demonstrated highest optoporation efficacy with more than 80% of permeabilized cells within the illuminated area. By contrast to common laser techniques, the laser beam scanning method results in cell optoporation within a controllable programmed in advance irradiated area.

Interactions of Renal-Clearable Gold Nanoparticles with Tumor Microenvironments: Vasculature and Acidity Effects.

The success of nanomedicines in the clinic depends on our comprehensive understanding of nano-bio interactions in tumor microenvironments, which are characterized by dense leaky microvasculature and acidic extracellular pH (pHe ) values. Herein, we investigated the accumulation of ultrasmall renal-clearable gold NPs (AuNPs) with and without acidity targeting in xenograft mouse models of two prostate cancer types, PC-3 and LNCaP, with distinct microenvironments. Our results show that both sets of AuNPs could easily penetrate into the tumors but their uptake and retention were mainly dictated by the tumor microvasculature and the enhanced permeability and retention effect over the entire targeting process. On the other hand, increased tumor acidity indeed enhanced the uptake of AuNPs with acidity targeting, but only for a limited period of time. By making use of simple surface chemistry, these two effects can be synchronized in time for high tumor targeting, opening new possibilities to further improve the targeting efficiencies of nanomedicines.

Effect of the electric potential on the interaction of gold nanoparticles deposited on a graphite substrate with molecular hydrogen

Hydrogen interaction with gold nanoparticles deposited on the surface of a highly oriented pyrolytic graphite is determined by the external potential ϕ of the sample with respect to the ground. It is demonstrated that, at ϕ > +1 V, molecular hydrogen does not practically interacts with hydrogen, whereas at ϕ ≤ 0 V, such interaction is possible.

Exploring gold nanoparticle interactions with proteins and the tumor microenvironment in biological systems.

Gold nanoparticles (AuNPs) have been widely studied as a theranostics agent, especially in the field of cancer treatment and diagnosis, due to their versatile physical and chemical properties (1). Their physical properties make them a good imaging enhancer under different modalities, including x-ray and computed tomography. Their surface plasmon resonance enables them to be combined with newer technologies, including photoacoustic imaging and thermal ablation. Their versatility in synthesis means that AuNPs can be different sizes and shapes, including colloidal gold nanoparticles, nanorods, nanostars, and nanoshells. Common surface modifications are achieved via gold-thiol bond conjugation, and this is a widely applied method of delivering anticancer drugs.

Gold nanoparticle interactions in human blood: a model evaluation

In this study, we investigated gold nanoparticle (AuNP) interactions in blood using thromboelastography as a rapid screening tool to monitor their influence on blood coagulation. 1.2 nM colloidal AuNPs ranging from 12 to 85 nm have no effect in the blood, however, 5 nM AuNPs demonstrate pro-thrombogenic concentration dependent effects with a reduction in clot formation. Size effects exhibit a non-linear trend with 45 and 85 nm particles resulting in a faster pro-thrombotic response. Clot strength decreased with AuNP size with the greatest reduction with 28 nm particles. We assessed AuNP interactions in the blood focusing on their biological activity. AuNP-RGD possessed pro-coagulant activities, while PEG-thiol, human fibrinogen and clopidogrel prevented blood clot formation and influenced platelet activity, and were more efficient when bound to nanocarriers than unbound ligands. Such tests could fill the knowledge gaps in thrombogenicity of NPs between in vitro test methods and predict in vivo haemocompatibility.

Interaction of gold and silver nanoparticles with human plasma: Analysis of protein corona reveals specific binding patterns

Determining how nanomaterials interact with plasma will assist in understanding their effects on the biological system. This work presents a systematic study of the protein corona formed from human plasma on 20nm silver and gold nanoparticles with three different surface modifications, including positive and negative surface charges. The results show that all nanoparticles, even those with positive surface modifications, acquire negative charges after interacting with plasma. Approximately 300 proteins are identified on the coronas, while 99 are commonly found on each nanomaterial. The 20 most abundant proteins account for over 80% of the total proteins abundance. Remarkably, the surface charge and core of the nanoparticles, as well as the isoelectric point of the plasma proteins, are found to play significant roles in determining the nanoparticle coronas. Albumin and globulins are present at levels of less than 2% on these nanoparticle coronas. Fibrinogen, which presents in the plasma but not in the serum, preferably binds to negatively charged gold nanoparticles. These observations demonstrate the specific plasma protein binding pattern of silver and gold nanoparticles, as well as the importance of the surface charge and core in determining the protein corona compositions. The potential downstream biological impacts of the corona proteins were also investigated.

Biomolecular Interaction and Photohemolytic Effect of Gold Nanoparticles

Biomolecular Interaction and Photohemolytic Effect of Gold Nanoparticles

Gold nanoparticle interactions with endothelial cells cultured under physiological conditions.

PEGylated gold nanoparticles (AuNPs) have an extended circulation time after intravenous injection in vivo and exhibit favorable properties for biosensing, diagnostic imaging, and cancer treatment. No impact of PEGylated AuNPs on the barrier forming properties of endothelial cells (ECs) has been reported, but recent studies demonstrated that unexpected effects on erythrocytes are observed. Almost all studies to date have been with static-cultured ECs. Herein, ECs maintained under physiological cyclic stretch and flow conditions and used to generate a blood-brain barrier model were exposed to 20 nm PEGylated AuNPs. An evaluation of toxic effects, cell stress, the release profile of pro-inflammatory cytokines, and blood-brain barrier properties showed that even under physiological conditions no obvious effects of PEGylated AuNPs on ECs were observed. These findings suggest that 20 nm-sized, PEGylated AuNPs may be a useful tool for biomedical applications, as they do not affect the normal function of healthy ECs after entering the blood stream.

Photo-Modulated Therapeutic Protein Release from a Hydrogel Depot Using Visible Light.

The use of biomacromolecular therapeutics has revolutionized disease treatment, but frequent injections are required owing to their short half-life in vivo. Thus there is a need for a drug delivery system that acts as a reservoir and releases the drug remotely "on demand". Here we demonstrate a simple light-triggered local drug delivery system through photo-thermal interactions of polymer-coated gold nanoparticles (AuNPs) inside an agarose hydrogel as therapeutic depot. Localized temperature increase induced by the visible light exposure caused reversible softening of the hydrogel matrix to release the pre-loaded therapeutics. The release profile can be adjusted by AuNPs and agarose concentrations, light intensity and exposure time. Importantly, the biological activity of the released bevacizumab was highly retained. In this study we demonstrate the potential application of this facile AuNPs/hydrogel system for ocular therapeutics delivery through its versatility to release multiple biologics, compatibility to ocular cells and spatiotemporal control using visible light.

Colorimetric sensing of silver ion based on anti aggregation of gold nanoparticles

A colorimetric assay with excellent selectivity is reported for detecting silver ion in aqueous solutions. The system works based on the competitive interaction of gold nanoparticles (AuNPs) and Ag+ with tris(hydroxymethyl) aminomethane (tris). The sensing strategy is quite simple, fast, convenient and the detection is by the naked eye. The aggregation of AuNPs with tris was inhibited in the presence of Ag+ ions resulting in a significant hypsochromic spectral shift of the surface plasmon resonance (SPR) of AuNPs and a color change from blue to red. The interaction between tris and Ag+ ion was investigated with cyclic voltammetry. The effect of Ag+ concentration on the aggregation of AuNPs by tris was monitored by UV–vis spectroscopy with the dynamic range of 1–9μM and detection limit of 0.41μM. The recovery analysis of river water and wastewater samples proved that this colorimetric sensor is successfully operational in environmental monitoring.

Gold nanoparticles in combination with megavoltage radiation energy increased radiosensitization and apoptosis in colon cancer HT-29 cells

Purpose: Gold nanoparticles (GNP) act as a radiosensitizer in radiation therapy. However, recent studies have shown contradictory evidence in terms of radiosensitization in the presence of GNP combined with X-ray megavoltage energy (MV) on different cell types. In this study, the effect of GNP on radiosensitization enhancement of HT-29 human colorectal cancer cells at MV X-ray energy was evaluated.Materials and methods: The cytotoxicity and radiosensitization of GNP were evaluated in HT-29 human colorectal cancer cells by MTS-assay and multiple MTS-assay, respectively. Cellular uptake was assayed using graphite furnace atomic absorption spectrometry (GFAAS). Apoptosis and cell cycle progression were determined by an Annexin V-FITC/propidium iodide (PI) kit and PI/RNase solution with flow cytometry, respectively.Results: Results showed that the cell viability of the HT-29 cells was not influenced by exposure to different concentrations of GNP (10–100 μM). GNP alone did not affect the cell cycle progression and apoptosis. In contrast, GNP, in combination with radiation (9 MV), induced more apoptosis. The interaction of GNP with MV energy resulted in a significant radiosensitization enhancement compared with irradiation alone.Conclusion: It was concluded that GNP may work as bio-inert material on HT-29 cancer cells and their enhancement of radiosensitization may be due to increase in the absorbed irradiation dose.

Covalent and Non-Covalent DNA-Gold-Nanoparticle Interactions: New Avenues of Research.

The interactions of DNA, whether long, hundred base pair chains or short-chained oligonucleotides, with ligands play a key role in the field of structural biology. Its biological activity not only depends on the thermodynamic properties of DNA-ligand complexes, but can and often is conditioned by the formation kinetics of those complexes. On the other hand, gold nanoparticles have long been known to present excellent biocompatibility with biomolecules and are themselves remarkable for their structural, electronic, magnetic, optical and catalytic properties, radically different from those of their counterpart bulk materials, and which make them an important asset in multiple applications. Therefore, thermodynamic and kinetic studies of the interactions of DNA with nanoparticles acting as small ligands are key for a better understanding of those interactions to allow for their control and modulation and for the opening of new venues of research in nanomedicine, analytic and biologic fields. The interactions of gold nanoparticles with both DNA polymers and their smaller subunits; special focus is placed on those interactions taking place with nonfunctionalized gold nanoparticles are reviewed in the present work.