Concentration Of Gold Nanoparticles Research Articles

Dual-energy CT imaging of nasopharyngeal cancer cells using multifunctional gold nanoparticles.

The purpose of this study is to measure the concentration of gold nanoparticles (AuNPs) attached to folic acid through cysteamin as the linker (FA-Cys-AuNPs) and AuNPs in KB human nasopharyngeal cancer cells using dual-energy CT (DECT). In this study, nanoparticles with a size of ∼15 nm were synthesized and characterised using UV-Vis, TEM, FTIR and ICP-OES analyses. The non-toxicity of nanoparticles was confirmed by MTT assay under various concentrations (40-100 µg/ml) and incubation times (6, 12 and 24 h). To develop an algorithm for revealing different concentrations of AuNPs in cells, a corresponding physical phantom filled with 0.5 ml vials containing FA-Cys-AuNPs was used. The CT scan was performed at two energy levels (80 and 140 kVp). One feature of DECT is material decomposition, which allows separation and identification of different elements. The values obtained from the DECT algorithm were compared with values quantitatively measured by ICP-OES. Cells were also incubated with AuNPs and FA-Cys-AuNPs at different concentrations and incubation times. Subsequently, by increasing the incubation time in the presence of FA-Cys-AuNPs, in comparison with AuNPs, DECT pixels were increased. Thus, FA-Cys-AuNPs could be a suitable candidate for targeted contrast agent in DECT molecular imaging of nasopharyngeal cancer cells.

The effects of gold nanoparticles characteristics and laser irradiation conditions on spatiotemporal temperature pattern of an agar phantom: A simulation and MR thermometry study

In this paper, the effects of parameters related to gold nanoparticles (type, size, and concentration) and the laser parameters on spatiotemporal temperature pattern of an agar phantom during a photothermal therapy (PTT) procedure were modeled and then experimentally verified. Eight agar phantoms loaded by gold nanoparticles were made. An agar phantom without any nanoparticles was also considered as the control. Different sizes of two types of gold nanoparticles (spherical and silica-gold core shell) at various concentrations were studied. The phantoms were irradiated by various laser powers for 5 min. The temperature changes in each phantom was firstly calculated using COMSOL Multiphysics software. Also, each phantom was irradiated by laser and MR thermometry was performed to validate the simulation results. A reasonable correlation between simulation and MR thermometry was obtained (R = 0.92). The error interval between calculations and experiments was ranged from ±3% to ±6%. It was clearly evident that laser irradiation conditions and nanoparticle characteristics affected the temperature rise profile. Spherical 20 nm gold nanoparticles had better thermal efficiency and generated higher level of heat. The protocol suggested in this study may be appropriate to make a pre-clinical calculation and effect visualization for any nanoparticles-based PTT procedure before entrance into the clinics.

Preparation, structural analysis, morphological investigation and electrical properties of gold nanoparticles filled polyvinyl alcohol/carboxymethyl cellulose blend

Polymer nanocomposite samples have been prepared through the solution casting method utilizing a polymer blend of polyvinyl alcohol and carboxymethyl cellulose (70/30wt.%) as organic host matrix and different concentrations of biosynthesized gold nanoparticles (Au NPs) by the leaf extract of green mint (Mentha Spicata L.) as inorganic nanofiller. The structural, optical and morphological properties of these samples have been through FT-IR, XRD, UV/Vis. and SEM techniques. The FT-IR spectra confirm the blend components are miscible by the formation of Hydrogen bond interaction and show the polymer-nanoparticle interactions. The XRD analyses depict the semicrystalline structure of these samples and the crystallinity degree decrease with increase of Au NPs content within the PVA/CMC structure. The TEM micrograph of biosynthesized Au NPs indicates that shapes of these NPs are spherical NPs and triangular/hexagonal nanoplates with average size range 5–29nm. The alternating electrical conductivity, electrical impedance, complex dielectric permittivity and electric modulus spectra of prepared samples have been investigated at 25°C in the frequency range (0.1Hz–20MHz). Thus, the variations in values of conductivity, dielectric permittivity and relaxation times indicate the feasibility of these materials as flexible nanodielectric of frequency tunable permittivity for radio/audio frequency operating microelectronic/conventional devices.

Effect of Ficus carica L. leaves extract loaded gold nanoparticles against cisplatin-induced acute kidney injury

BackgroundCisplatin (CisPt) is one of the most widely used and highly effective drugs for the treatment of various solid tumors, unfortunately acute kidney injury (AKI) is considered one of its side effects through several mechanisms including production of reactive oxygen species (ROS), pro-inflammatory and pro-fibrotic cytokines. Due to the poor effect of AKI therapy, the use of nanoparticles loaded with natural extracts for delivering to the kidney molecules are desirable. AimThis study aims to investigate the effectiveness of different concentrations of gold nanoparticles (Au-NPs) as a carrier for Ficus carica L. (Fig) leaves extract against CisPt induced AKI. MethodsSeventy male albino rats were used and divided into seven groups. After the experimental period, blood was withdrawn, serum was separated for determination of urea, creatinine, homocystein (Hcy) and folic acid while reduced glutathione (GSH), nitric oxide (NO), malondialdehyde (MDA), total antioxidant capacity (TAC) and hydroxyproline content (Hyp) were evaluated in kidney tissue homogenate. ResultsCisPt induced AKI in rats and results in a significant increase in the levels of serum urea, creatinine, Hcy and kidney Hyp, lipid peroxidation along with a significant reduction of kidney GSH, NO and TAC compared to the control rats. Treatment with Au-NPs and Fig extract particularly in a ratio of (3:2) respectively was shown to improve renal functions with efficient capacity in scavenging ROS and reduced AKI severity. ConclusionAu-NPs enhanced the anti-oxidative properties of the Fig extract in targeting kidney damaged tissue and reduced oxidative toxicity induced by CisPt.

Effect of Gold Nanoparticles on Dose Enhancement in Brachytherapy Using a Polymer Gel Dosimeter

The objective of the present study was to measure and evaluate the effect of gold nanoparticles (GNPs) on dose enhancement in brachytherapy with and 192Ir source using polymer gel dosimeters. To test the dose enhancement effect of GNPs during brachytherapy using 192Ir radioisotope, we used gamma rays in the same amount to irradiate gel dosimeters containing different concentrations and sizes of GNPs to measure their doses. Radiation was applied to 10 polymer gel dosimeters and control gel dosimeters that contained GNPs with different sizes (10 nm and 100 nm) and concentrations (0.1, 0.2, 0.3, 0.4, and 0.5 mM) under the same conditions. Dose enhancement factors (DEFs) were found to be 1.011, 1.014, 1.015, 1.026, and 1.029 when the concentrations of GNP were 0.1, 0.2, 0.3, 0.4, and 0.5 mM, respectively, with the size of the GNPs at 10 nm. When the GNP size was increased to 100 nm, the DEFs were 1.070, 1.088, 1.1890, 1.212, and 1.244 when concentrations of the GNPs were 0.1, 0.2, 0.3, 0.4, and 0.5 mM, respectively, showing dose enhancements higher than those of 10-nm-sized GNPs. When GNP size was 100 nm and its concentration was 0.3 mM or higher, the DEFs were higher than 1.15. The bigger the GNP size and the higher the concentration were, the larger the dose enhancement effect was. Such a dose enhancement effect of GNPs obtained in the present study can be utilized as basic data for clinical applications to enhance treatment effects. If such data are utilized in a treatment plan system, a treatment plan taking dose enhancement effect into account can be established at the planning stage.

Dose-Dependent Cytotoxicity of Gold Nanoparticles on Human Neural Progenitor Cells and Rat Brain

Gold nanoparticles (GNPs) are utilized as diagnostic and therapeutic tools to detect and treat human disease. Researchers in the field of nanotoxicity are working to determine the physicochemical properties of nanoparticles that lead to toxicity in an effort to establish safe design rules. In this study, we performed the MTT and terminal transferase dUTP nick end labeling (TUNEL) assays to verify the cytotoxicity of GNPs on rat brain tissue and human neural progenitor cells (NPCs). As results, we observed that GNPs induced apoptosis in NPCs. NPCs were markedly damaged following the administration of 200 μM and 2 mM GNPs, whereas 2 μM GNPs showed slightly increased damage relative to that of the control. In addition, TUNEL-positive cells were densely distributed at regions surrounding the GNP injection site in the brain 7 days after the GNPs injection. During long-term GNPs exposure, TUNEL-positive cells were rarely observed in the cerebral cortex. In this study, we observed that apoptosis increased in proportion to GNP concentrations in the brain and in cultivated NPCs. These result suggest that large GNPs (<100 nm) are toxic and that the cytotoxicity increased as the concentration of GNPs increased in NPCs or in the brain.

Radio-enhancement by gold nanoparticles and their impact on water radiolysis for x-ray, proton and carbon-ion beams

Gold nanoparticle (GNP) radio-enhancement is a promising technique to increase the dose deposition in a tumor while sparing neighboring healthy tissue. Previous experimental studies showed effects on cell survival and tumor control for keV x-rays but surprisingly also for MV-photons, proton and carbon-ion beams. In a systematic study, we use the Monte Carlo simulation tool TOPAS-nBio to model the GNP radio-enhancement within a cell as a function of GNP concentration, size and clustering for a wide range of energies for photons, protons and, for the first time, carbon-ions. Moreover, we include water radiolysis, which has been recognized as a major pathway of GNP mediated radio-enhancement.At a GNP concentration of 0.5% and a GNP diameter of 10 nm, the dose enhancement ratio was highest for 50 keV x-rays (1.36) and decreased in the orthovoltage (1.04 at 250 keV) and megavoltage range (1.01 at 1 MeV). The dose enhancement linearly increased with GNP concentration and decreased with GNP size and degree of clustering for all radiation modalities. While the highest physical dose enhancement at 5% concentrations was only 1.003 for 10 MeV protons and 1.004 for 100 MeV carbon-ions, we find the number of hydroxyl () altered by 23% and 3% after 1 s at low, clinically-relevant concentrations. For the same concentration and proton-impact, the G-value is most sensitive to the nanoparticle size with 46 times more radical interactions at GNPs for 2 nm than for 50 nm GNP diameter within 1 s. Nanoparticle clustering was found to decrease the number of interactions at GNPs, e.g. for a cluster of 25 GNPs by a factor of 3.4. The changes in G-value correlate to the average distance between the chemical species and the GNPs. While the radiochemistry of GNP-loaded water has yet to be fully understood, this work offers a first relative quantification of radiolysis products for a broad parameter-set.

The Role of Gold Nanoparticles in Sonosensitization of Human Cervical Carcinoma Cell Line under Ultrasound Irradiation: An &lt;i&gt;In Vitro&lt;/i&gt; Study

Abstract:Purpose: The objective of this investigation was to evaluate the combined effects of ultrasound irradiation as a non-invasive and non-ionizing radiation with gold nanoparticles as ultrasound sensitizers on the HeLa cells.Materials and Methods: First, Gold nanoparticles (GNPs) were prepared, and the characterizations of nanoparticles were analyzed using TEM and UV-vis. Different concentrations of nanoparticles (0.2, 1, 5, 25 and 50 μg/ml) were used. Then, cytotoxicity of the GNPs was studied on HeLa cells, and finally concentrations of 0.2, 1 and 5 µg/mL were chosen for supplementary studies. The effects of nanoparticles and ultrasound irradiation with different intensities (0.5, 1 and 1.5 W/cm2) as well as the combination of ultrasound radiation with various concentrations of nanoparticles on 24, 48 and 72 h post-experiment cells’ viability were estimated by MTT and trypan blue assay.Results: Results showed that the sonosensitizing effect of nanoparticles mainly depended on the intensity of ultrasound waves and the concentration of GNPs. By increasing the concentration of GNPs and ultrasound intensity, the nanoparticle's effect of sensitizer was also increased. Moreover, as expected, the highest effect was observed at the highest intensities (1.5 W/cm2) of ultrasound wave and high concentrations (5 μg/ml) of GNPs 72 h after exposure to ultrasound irradiation.Conclusions: It is revealed that GNPs can be used as sonosensitizers of HeLa cells to ultrasound irradiation in order to produce an efficient treatment.

Fabrication of Gold Nanoparticles of Different Sizes and its Interaction in Aquatic Phase

ABSTRACTThe generation of AuNPs was realized in presence of gold chloride (Au3+), and citrate solution as reducing agent. The production of AuNPs was proved by the color change in the solution; from yellow to red wine. Purified nanostructures synthesized at citrate/Au3+ molar ratio of 1.0/10.0 evidenced an absorption peak at 526 nm attributed to the localized surface Plasmon Resonance (LSPR) which suggested the formation of small gold nanoparticles (NPs). The decrease of citrate/Au3+ molar ratio at 1.0/3.0 provoked a growing of gold nanostructures, which was evidenced by a red shift in the SPR at 546nm. High Resolution Transmission Electron Microscopy technique evidenced the spherical form and sizes for both nanoparticles at the range 10-15 nm (small NPs) and 20-25 nm (big NPs), respectively. Electron Diffraction (ED) patterns for both sizes evidenced the (111), (200), (220), (311), and (222) reflections of face centered cubic (FCC) gold nanostructures. Studies of energy-dispersive X-ray Spectroscopy indicated peaks at 1.65, 2.12, 9.71, 11.58 and 13.38 keV for both nanostructures, which suggests the presence of gold into the crystalline structure of the nanoparticles. Interaction tests were carried out in presence of marine crustaceans and different concentrations of gold nanoparticles; including a control test. Both sizes evidenced to be toxic when the concentration and exposure time were increased.

Dynamic In Vivo X-ray Fluorescence Imaging of Gold in Living Mice Exposed to Gold Nanoparticles

Dynamic in vivo biodistribution of gold nanoparticles (GNPs) in living mice was first successfully acquired by a pinhole X-ray fluorescence (XRF) imaging system using polychromatic X-rays. The system consisted of fan-beam X-rays to stimulate GNPs and a 2D cadmium zinc telluride (CZT) gamma camera to collect K-shell XRF photons emitted from the GNPs. 2D XRF images of kidney slices of three Balb/C mice were obtained within 2 minutes of irradiation per slice. 40 mg of GNPs suspended in a 0.2 mL phosphate-buffered saline was injected into the mice via a tail vein. The mice were scanned over a 60 min period after the injection of GNPs in order to acquire a dynamic biodistribution of GNPs. The concentrations of GNPs measured by the CZT gamma camera were then validated by inductively coupled plasma atomic emission spectroscopy and ex vivo L-shell XRF measurements using a silicon drift detector. The GNP concentrations in the right-side kidneys were 1.58% by weight (wt%) at T =0 min and 0.77 wt% at T=60 min after the injection. This investigation showed a dramatically reduced scan time and imaging dose. Hence, we conclude that dynamic in vivo XRF imaging of GNPs is technically feasible in a benchtop system. The developed pinhole XRF imaging system can be a potential molecular imaging modality for metal nanoparticles to emerge as a radiosensitizer and a drug-delivery agent.

On the importance of modeling gold nanoparticles distribution in dose-enhanced radiotherapy.

Purpose: To investigate the effect of precise modeling for Monte Carlo simulations of gold nanoparticles (GNPs) dose-enhanced radiotherapy, two models characterized by their distribution of GNPs in a simulated macroscopic cubic tumor were introduced. The motivation was the widely documented tendency of GNPs to localize around the cell nucleus.Methods: The introduced models composed of 2.7×107 ellipsoid cells, each of them containing a centrally located nucleus as the target for dose evaluation. In the first model, the spheres of GNP are homogeneously distributed in the whole tumor volume, and in the latter, GNPs are localized in the cytoplasms surrounded the nuclei.Results: The results achieved through applying Monte Carlo radiation transports using the Mont Carlo N-Particle eXtended code (MCNPX) show an underestimation of nuclear dose enhancement caused by homogeneous model compared with that of heterogeneous distribution. By investigating various quantities, it was found that subcellular location of GNPs strongly governs the sensitivity of dose enhancement to the number and concentration of GNPs targeted in the tumor. Other obvious differences are revealed by studying the dose enhancement curves in depth of the tumor. While the heterogeneous model predicts an approximately constant dose enhancement in depth for primary photon energies of 50 keV and more, the homogeneous model estimates an energy-dependent increase of about 11 to 30%.Conclusion: It can be concluded that defining a model in accordance with the experimental observations can effectively account for accurate prediction of macroscopic dose enhancement in the target of interest.

Emulsion Synthesis and Electrophoretic Concentration of Gold Nanoparticles in Sodium Bis(2-Ethylhexyl) Sulfosuccinate Solution in n-Decane

Organosols of gold nanoparticles are obtained by hydrazine reduction of a chloroauric acid solution in a dynamic emulsion of water in n-decane stabilized with a surfactant, sodium bis(2-ethylhexyl) sulfosuccinate. The gold nanoparticles are characterized by phase analysis light scattering, photon correlation spectroscopy, transmission and scanning electron microscopy, X-ray phase analysis, spectrophotometry, thermal analysis, and elemental analyses. The hydrodynamic diameter (≈8 nm), electrophoretic mobility (3.9 × 10–10 m2/(V s)), and electrokinetic potential (30 mV) of the synthesized particles are determined. A liquid-phase concentrate of nanoparticles is separated from the organosol by nonaqueous electrophoresis. Hydrophobic electrically conducting films with a contact angle of 115° and a specific resistance of 0.41 Ω/mm2 are obtained by the thermal treatment of the concentrate.

Dependence of a surface plasmon resonance absorption band on the concentration of gold nanoparticles in carbon-bearing matrixes

For fullerene matrixes doped by gold nanoparticles we have established experimentally a miss of a red concentration-induced shift of surface plasmon resonance absorption band maximum. Theoretical modeling has been made for spectral characteristics of carbon–bearing nanostructures. Numerical calculations of extinction factors for a spherical metallic particle in an absorbing surrounding medium were based on the Mie theory. Transmission spectra coefficients of densely packed plasmonic nanoparticles monolayers were calculated with the use of the single coherent scattering approximation modified for absorbing matrices. Thin-film Au-air and Au–C60 nanostructures have been fabricated on glass and quartz substrates by thermal evaporation and condensation in vacuum at an air pressure of 2 · 10–3 Pа. The surface mass density of Au into Au–C60 nanostructures was varied in the range (3.86–7.98) · 10–6 g/cm2. The comparison of theoretical and experimental data allowed making a conclusion that the absorbency in carbon-bearing matrix leads to the attenuation of lateral electrodynamics coupling and blocks collective plasmon resonance in densely packed gold nanostructures.

Picoliter Cuvette inside an Optical Fiber to Track Gold Nanoparticle Aggregation for Measurement of Biomolecules.

This study demonstrated a measurement approach for biomolecules at the picoliter scale, using a newly developed picoliter cuvette inside an optical fiber constructed via near-ultraviolet femtosecond laser drilling. The sensing capacity was estimated to be within 0.4–1.2 pL due to an optical path length of 3–5 microns, as measured by scanning electron microscopy (SEM). The picoliter cuvette exhibited a change in the optical extinction spectrum after addition of biomolecules such as L-cysteine, in conjunction with a gold nanoparticle (GNP) dispersion solution, following a simple measurement configuration involving a small white light source and a compact spectrometer. A linear attenuation of the spectral dip near a wavelength of 520 nm was observed as the L-cysteine concentration was increased at 4 wt% of the GNP mass concentration. The measurement resolution of the concentration using the picoliter cuvette was evaluated at 0.125 mM. The experimental results showed the difference in aggregation processes caused by a different concentration of GNPs. Moreover, they revealed the ability of the picoliter cuvette to verify whether the concentration of GNPs in the liquid sample correspondingly determines homogeneous or inhomogeneous GNP aggregation, as supported by SEM observation and numerical calculations based on Mie theory.

Numerical Examination of Gold Nanoparticles as a Drug Carrier on Peristaltic Blood Flow Through Physiological Vessels: Cancer Therapy Treatment

Cancer is one of the most serious diseases facing the humanity. Researchers are making every effort to eradicate this disease. Gold nanoparticles (GNPs) have been used to treat cancer as a result of effects of their quantum size and their large surface area, compared with other metal atoms in addition to the ability to absorb energy. The aim of this manuscript is to study the peristaltic transport of a couple stress nanofluid as a blood model containing gold nanoparticles as cancer treatment. The equations governing the flow of a couple stress nanofluid along with total mass, thermal energy, and gold nanoparticles are established and then simplified by using the assumption of long wavelength. Analytical and numerical solutions have been evaluated for velocity, temperature, and gold nanoparticle concentration. A comparison between analytical and numerical solutions is given. The obtained results may help to understand more the process of cancer treatment with help of gold nanoparticles.

Assessment of FLUKA, PENELOPE and MCNP6 Monte Carlo codes for estimating gold fluorescence applied to the detection of gold-infused tumoral volumes

Different kinds of nanoparticles have been widely studied for biomedical purposes, including applications like dose enhancement in radiotherapy treatments and contrast agent in radiological studies. Recent work suggests that gold nanoparticles can be used as contrast agents in K-edge imaging and X-ray Fluorescence Computed Tomography, mainly due to their high K-edge energy value and good biocompatibility. However, the gold X-ray fluorescence (XRF) signal obtained in these procedures is relatively week when compared with Compton or bremsstrahlung radiation emitted in the surrounding tissues, mainly because it is not possible to achieve large gold nanoparticles concentrations within biological tissues added to the XRF is attenuated by other tissues when leaving the patient body.This work presents a feasibility study on implementation of FLUKA, PENELOPE and MCNP6 Monte Carlo codes to model the detection of gold XRF emitted by a small volume containing different gold concentrations and located at different depths in a tissue-equivalent phantom. Results indicate that there is good agreement between PENELOPE and FLUKA for gold Kα and Kβ lines estimations when highly symmetric simulation scenario and kilovoltage X-ray beam were used, achieving differences lower than 2%; however, differences up to 6 times were observed between FLUKA and MCNP6 under the same conditions. In addition, remarkable differences were obtained when megavoltage X-ray beam was used, being up to 11 times between PENELOPE and FLUKA and up to 4 times between FLUKA and MCNP6 for gold Kα and Kβ lines estimations. In this regard, a suitable normalization method was proposed and implemented to perform cross-comparisons of XRF estimations obtained from the Monte Carlo codes. By means of the proposed method, FLUKA, PENELOPE and MCNP6 can be successfully implemented to assess which configuration (gold concentration and target volume depth) leads to a better detection of gold XRF, despite differences in XRF estimation between the codes.

Effect of gamma-irradiation on the structural, optical and electrical properties of PEO/starch blend containing different concentrations of gold nanoparticles

ABSTRACTBlend of polyethylene oxide (PEO)/starch (70/30 wt.%) filled with different amounts of gold nanoparticles (AuNPs) were prepared using the casting technique. X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) techniques were used to investigate the structure of polymeric samples before and after exposing to gamma irradiation at different times. XRD showed a gradual decrease in intensity of crystalline peaks with increasing the gamma dose denotes a decrease in the amount of crystalline phase in the films, while the FTIR measurement shows induced changes in chemical structure assigned to the AuNPs amount and irradiation times. The optical energy gap values (Eg) for unirradiated and irradiated samples were calculated and interpreted. The differential scanning calorimetry (DSC) which showed the miscibility between the two components of the blend. The electrical conductivity (σ) measurement was showed increased in electrical conductivity after exposure to the gamma dose. The gold nanoparticles were used as nanofiller to improve the structural and electrical properties of polymeric samples. The results showed the Gamma irradiation significantly effect on the structural and electrical properties of PEO/starch blend.

Gold nanoparticles regulate tight junctions and improve cetuximab effect in colon cancer cells.

Aim: Colon cancer (CC) is the second cause of cancer death worldwide. The use of nanoparticles for drug delivery has been increasing in cancer clinical trials over recent years. Materials & methods: We evaluated cytotoxicity of citrate-capped gold nanoparticles (GNPs) and the role they play on cell-cell adhesion. We also used GNP for delivery of cetuximab into different CC cell lines. Results: CC cells with well-formed tight junctions impair GNP uptake. Noncytotoxic concentration of GNP increases paracellular permeability in Caco-2 cells in a reversible way, concomitantly to tight junctions proteins CLDN1 and ZO-1 redistribution. GNP functionalized with cetuximab increases death of invasive HCT-116 CC cells. Conclusion: GNP can be used for drug delivery and can improve efficiency of CC therapy.

Biochemical Changes in Human Cells Exposed to Low Concentrations of Gold Nanoparticles Detected by Raman Microspectroscopy.

The toxicological implications of nanoparticles deserve accurate scientific investigation for the protection of human health. Although toxic effects involve specific organs, the events that cause them have their origin from biochemical modifications of some cellular constituents. Therefore, a first analysis to evaluate the effects due to the action of nanoparticles is achieved by investigation of in vitro cells, which allows the identification of the cellular modifications caused by nanoparticles (NPs) even at much lower doses than the lethal ones. This work evaluated the Raman microspectroscopy capability to monitor biochemical changes occurring in human cells as a consequence of exposure to a suspension of gold nanoparticles with a non-cytotoxic concentration. Human keratinocyte cells were used as a model cell line, because they are mainly involved in environmental exposure. A trypan blue assay revealed that the investigated concentration, 650 ng/mL, is non-cytotoxic (about 5% of cells died after 48 h exposure). Specific Raman spectral markers to represent the cell response to nanoparticle exposure were found (at 1450 and 2865 cm−1) in the cytoplasm spectra, with the aid of ratiometric and principal component analysis.

Dentine collagen cross-linking using tiopronin-protected Au/EDC nanoparticles formulations

ObjectiveThe aim of this study was to investigate EDC-assisted collagen crosslinking effect with different concentrations of tiopronin-protected gold (TPAu) nanoparticles on demineralized dentine. MethodsTPAu nanoparticles were fabricated from 0.31-g tetrachloroauric acid and 0.38-g of N-(2-mercaptopropionyl) glycine (2.4-mmol). Then co-dissolved using 35-mL of 6:1 methanol/acetic acid and mixed using NaBH4. EDC (0.3-M) was conjugated to TPAu nanoparticles at TPAU/EDC-0.25:1, and TPAU/EDC-0.5:1 treatment formulations ratios. Dentin specimens treated with 0.3-M EDC solution alone or left untreated were used as control. Nanoparticles formulations were characterized in term of particles morphology and size, Zeta potential, thermogravimetric analysis and small-angle X-ray scattering. Dentin substrates were characterized in term of TEM investigation, dentin proteases characterization, hydroxyproline liberation, elastic modulus measurement, Raman analysis and confocal microscopy viewing. ResultsTEM evaluation of tiopronin protected gold nanoparticles dispersion revealed nano-clusters formations in both groups. However, based on our TEM measurements, the particle-size was ranging from ˜20 to 50 nm with spherical core-shape which were almost similar for both TPAu/EDC ratios (0.5:1 and 0.25:1). Zeta potential measurements indicate negative nanoparticles surface charge. SAXS profiles for both formulations, suggest a typical profile for uni-lamellar nanoparticles. Superior dentin collagen cross-linking effect was found with the TPAu/EDC nanoparticles formulations compared to the control and EDC treated groups. SignificanceCross-linking of dentin collagen using TPAu coupled with EDC through TPAu/EDC nanoparticles formulations is of potential significance in improving the biodegradation resistance, proteases inhibition, mechanical and structural stability of demineralized dentin substrates. In addition, the cross-linking effect is dependent on TPAu/EDC ratio, whereas higher cross-linking effect was found at TPAu/EDC ratio of 0.5:1.