Different Concentrations Of Gold Nanoparticles Research Articles

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.

Perylene Derivative Dyes Luminescence in Polysiloxane Matrix in Presence of Gold Nanoparticles.

Four perylene derivatives, including commercially available dyes Lumogen Red and Lumogen Orange, as well as 1,6,7,12-tetrachlоrоperylene-3,4,9,10-tetradicarboxydianhydride (Dye I) and 3,4:9,10-bis(1,2-benzimidazole)- 1,6,7,12-tetra(4-tert-octylphenoxy) perylene (syn/ anti-isomers) (Dye III, which was prepared from dye I through intermediate 3,4:9,10-bis(1,2-benzimidazole)-1,6,7,12-tetrachloro perylene (Dye II)) were used for preparation of polysiloxane samples (PSi) containing different concentrations of gold nanoparticles (GN). Dyes I and III demonstrate significant fluorescence intensity increase upon addition of GN independent on excitation energy. For Lumogen Red composition in PSi some increase of fluorescence intensity was observed upon addition of small concentrations of GN, while further increase of GN concentration quenches fluorescence. The increase of Lumogen Red emission intensity, which depends on energy of excitation, is probably due to the increase of radiation decay rate since excitation rate decreases. Effect of GN on Lumogen Orange provided quenching of fluorescence even at small concentrations of GN. Calculations at DFT level of approximation for dye III suggest location of GN in plane of perylene core for increase of fluorescence intensity.

Electrically conductive gold nanoparticle-chitosan thermosensitive hydrogels for cardiac tissue engineering

Injectable hydrogels that resemble electromechanical properties of the myocardium are crucial for cardiac tissue engineering prospects. We have developed a facile approach that uses chitosan (CS) to generate a thermosensitive conductive hydrogel with a highly porous network of interconnected pores. Gold nanoparticles (GNPs) were evenly dispersed throughout the CS matrix in order to provide electrical cues. The gelation response and electrical conductivity of the hydrogel were controlled by different concentrations of GNPs. The CS-GNP hydrogels were seeded with mesenchymal stem cells (MSCs) and cultivated for up to 14days in the absence of electrical stimulations. CS-GNP scaffolds supported viability, metabolism, migration and proliferation of MSCs along with the development of uniform cellular constructs. Immunohistochemistry for early and mature cardiac markers showed enhanced cardiomyogenic differentiation of MSCs within the CS-GNP compared to the CS matrix alone. The results of this study demonstrate that incorporation of nanoscale electro-conductive GNPs into CS hydrogels enhances the properties of myocardial constructs. These constructs could find utilization for regeneration of other electroactive tissues.

Application of Gold Nanoparticles of Different Concentrations to Improve the Therapeutic Potential of Autologous Conditioned Serum: Potential Implications for Equine Regenerative Medicine

The aim of this work was to evaluate the effect of different concentrations of gold nanoparticles (AuNPS) on equine platelet morphology, ultrastructure as well as secretion of bone morphogenetic protein 2 (BMP‐2), vascular endothelial growth factor (VEGF), gelsolin (GSN), and tumor necrosis factor alpha (TNF‐α). The gold nanoparticles, with an average diameter of 20 nm, were incubated with whole anticoagulated blood at 1%, 5%, and 10% w/v for 24 hours. We showed that the application of gold nanoparticles at all the tested concentrations led to platelet activation; however, 5% of AuNPS resulted in the secretion of elevated levels of GSN and VEGF, while the concentration of TNF‐α was the lowest. The data indicate that this method may be considered a promising tool for improving the currently used in clinical practice commercially available autologous conditioned serum (ACS) isolation systems for the treatment of equine osteoarthritis.

Inhibition effects of gold nanoparticles on proliferation and migration in hepatic carcinoma-conditioned HUVECs

Tumor angiogenesis is a complicated process based upon a sequence of interactions between tumor and vessel endothelial cells. Tumor conditioned medium has been widely used to stimulate endothelial cells in vitro angiogenesis. This work was aimed to investigate the effects of gold nanoparticles (GNPs) on angiogenesis in hepatic carcinoma-conditioned endothelial cells. Human umbilical vein endothelial cells (HUVECs) were cultured with conditioned medium (CM) from the human hepatocarcinoma cell line HepG2 (HepG2-CM), and then treated with different concentrations of GNPs. The effects of GNPs on the viability, migration and active VEGF level of HUVECs were investigated by MTT assay, wound healing assay and transwell chamber assay, and ELISA assay, respectively. The data showed that GNPs significantly inhibited HUVECs proliferation and migration induced by HepG2-CM, and also reduced the levels of active VEGF in the co-culture system. Then, the alterations in morphology and ultrastructure of HUVECs detected by atomic force microscopy (AFM) showed that there appeared obvious pseudopodia, larger membrane particle sizes and much rougher surface in HUVECs after HepG2-CM treatment, which were all reversed after GNPs treatment. Changes in cytoskeleton of HUVECs determined by immunocytochemistry demonstrated that GNPs treatment remarkably inhibited the activation effect of HepG2-CM on HUVECs, which was associated with the disruption of actin filaments induced by GNPs. This study indicates that GNPs can significantly inhibit HepG2-CM activated endothelial cell proliferation and migration through down-regulation of VEGF activity and disruption of cell morphology, revealing the potential applications of GNPs as antiangiogenic agent for the treatment of hepatic carcinoma.

Influence of gold nanoparticles on activation of human blood neutrophils

Activation of neutrophils in the presence of gold nanoparticles is accompanied by formation of free-radical peroxidation products, recorded as a flash of chemiluminescence. The basis for the activation mechanism has its origins most likely in the influence of the gold particles on the membrane surface potential of neutrophils. Assessment of changes in the fluorescence intensity of the negatively charged ANS probe on the surface of model membranes upon adding different concentrations of gold nanoparticles indicates a change in the membrane surface charge density, which can cause cell activation.

Influences of gold and silver nanoparticles in loop-mediated isothermal amplification reactions

Loop-mediated isothermal amplification (LAMP) performed with protein DNA polymerase Bst and DNA chains was influenced by nanoparticles in different ways. The effects of different concentrations of gold nanoparticles (AuNPs) with diameters 10 and 20 nm and silver nanoparticles (AgNPs) 1–10 nm in diameter on the amplification of the pR72H gene of Vibrio parahaemolyticus were investigated. AuNPs with a diameter of 10 nm in 0.6–60 nM concentration accelerated initiation of the LAMP reaction, 3 nM AuNPs reduced the reaction time by about 10 min, whereas 20 nm AuNPs did not, although neither size increased the yield after 60 min. AgNPs inhibited the LAMP reaction both in speed and yield at concentrations of 0.6–60 nM; the yield of amplification was reduced by 50% and 80% for 12 and 60 nM, respectively, after reaction for 1 h. This indicated that strong bactericidal effects of silver are also observed in its nanoparticles. The molecular mechanism of AuNPs and AgNPs in LAMP needs to be explored further, although their size-related electronic, magnetic and optical properties, as well as their ability to affect protein denaturation, or hydrophilic/hydrophobic effects may be involved.

Towards real-time detection of tumor margins using photothermal imaging of immune-targeted gold nanoparticles

BackgroundOne of the critical problems in cancer management is local recurrence of disease. Between 20% and 30% of patients who undergo tumor resection surgery require reoperation due to incomplete excision. Currently, there are no validated methods for intraoperative tumor margin detection. In the present work, we demonstrate the potential use of gold nanoparticles (GNPs) as a novel contrast agent for photothermal molecular imaging of cancer.MethodsPhantoms containing different concentrations of GNPs were irradiated with continuous-wave laser and measured with a thermal imaging camera which detected the temperature field of the irradiated phantoms.ResultsThe results clearly demonstrate the ability to distinguish between cancerous cells specifically targeted with GNPs and normal cells. This technique, which allows highly sensitive discrimination between adjacent low GNP concentrations, will allow tumor margin detection while the temperature increases by only a few degrees Celsius (for GNPs in relevant biological concentrations).ConclusionWe expect this real-time intraoperative imaging technique to assist surgeons in determining clear tumor margins and to maximize the extent of tumor resection while sparing normal background tissue.

SU‐GG‐J‐125: Monte Carlo Simulation of Dose Enhancement in Tumors Using Gold Nanoparticles

Purpose: In the radiation oncology setting, high atomic number (Z) nanoparticles may provide a local dose enhancement in tumors when combined with low energy x‐rays. At energies near the K‐shell edges of these materials, the mass energy absorption coefficient (μen/ρ) may be significantly higher than that of tissue. For materials such as gold, the K‐shell edge falls in the lower energy spectrum of a conventional CT scanner. Irradiating nanoparticles inside tumor with a CT scanner may provide a high dose to the tumor while sparing healthy surrounding tissue. As a first step, a simulation of gold nanoparticles in a phantom can quantify the magnitude of this effect. Methods: Monte Carlo simulations were performed for different concentrations of gold using the program MCNPX. Simulations were performed using a cylindrical phantom with a tumor having various concentrations of gold nanoparticles. Four concentrations of nanoparticles were used: no gold, 1mg/g, 5mg/g, 10mg/g. The source of radiation was modeled using the spectrum of a 140kVP CT scanner. Each scenario was run using 109 particles. Results: For all cases, the total energy deposited in the target was determined. These calculations indicate that using nanoparticles provides a sizeable increase in the energy deposited inside the target. For 1mg/g, 5mg/g, and 10mg/g nanoparticle concentration the increases were 1.13, 1.78, and 2.58 times relative to no gold. Conclusions: Monte Carlo simulations of a phantom with different concentrations of gold nanoparticles irradiated by an x‐ray source reveal a dose enhancement relative to no nanoparticle presence. Dose enhancements of over 2.5 times for nanoparticle concentrations of up to 10mg/g indicate that localizing nanoparticles in tumor may be effective at providing an improved therapeutic ratio. The results of this simulation can be used to guide measurements for confirmation of this effect. Supported by Dept of the Army — USAMRRA W91ZSQ9081N608.

Nonlinear optical properties of Au nanoparticles colloidal system: Local and nonlocal responses

Z -scan revealed thermal and electronic contributions for the nonlinear refractive index of highly stable colloid containing different concentrations of gold nanoparticles. Large enhancement factors were observed for values of n2 and dn∕dT of the colloid, due to the presence of the nanoparticles. Our results suggest that thermal effects will play an important role in the development of photonic applications involving nanostructured materials and in the investigation of nonlocal nonlinear phenomena.