Absence Of Gold Nanoparticles Research Articles

All-dielectric double-layer honeycomb tunable metamaterial absorber with integrated gold nanoparticles

The optical regulation strategy of gold nanoparticles can significantly improve the performance of terahertz devices. We designed an all-dielectric double-layer honeycomb metamaterial absorber (MA) to demonstrate the broadband terahertz absorption characteristics in the presence or absence of gold nanoparticles. When it does not contain gold nanoparticles, MA exhibits a peak absorption efficiency of over 99% within the bandwidth range of ∼486 GHz. In particular, gold nanospheres (AuNPs), gold nanobipyramids (AuNBPs), and gold nanorods (AuNRs) are used to modulate the optical coupling effect of metamaterial absorbers, which improves their modulation performance. In the simulation, the effective medium theory (EMT) was applied to quantitatively calculate the optical response of a metamaterial absorber with an integrated gold nanoparticle equivalent gold layer. The integrated gold nanoparticle equivalent gold layer can achieve modulation enhancement of one order of magnitude. In the experiment, our process is compatible with CMOS technology, which may contribute to the development of terahertz detectors. In addition, the tunability and modulation enhancement characteristics demonstrated are beneficial for creating dynamic functional terahertz devices, such as THz modulators and switches.

A simulation study on the effect of penetration of gold nanoparticles in the cytoplasm of healthy eye organs on dose enhancement of brachytherapy

Purpose Special properties and recent advances in the synthesis and biomolecular functionalization of gold nanoparticles (GNPs) have led to the evolution of their use in biomedical applications such as photon radiotherapy. Simulation-based studies on the effect of various parameters that govern the dose enhancement due to utilizing GNPs have facilitated the progress of knowledge in this field. Due to their flexibility and easier accessibility compared with experimental works, simulations have the potential to be considered for pre-clinical tests and, therefore, should be close to the realistic conditions as much as possible. Materials and methods To this aim, the present work investigates the effect of the presence of GNPs that are accumulated in the cytoplasm of the constituent cells in healthy tissues of a human eye phantom, inspired by the published experimental results which report that non-target tissues also receive the drugs containing GNPs. The GNPs’ concentrations are assumed to decrease by moving from the tumor toward the depth of the phantom through a suggested pattern. The MCNPX Monte Carlo code is used for the simulations. Results The results show that for four concentrations tested, the dose enhancement factor in the shallower layer reaches 6, and decreases to 1.2 in the last layer. The dose enhancements are also examined for critical structures of the iris, cornea, sclera, and lens, showing maximum deviations of about 3 to 200% compared with the absence of GNPs in the healthy tissue. Considering the reported doses to the lens by clinical institutions, the effect of penetration of GNPs to deep layers on treatment time is also investigated. Conclusions The results show that the penetration of GNPs from the tumor toward healthy tissues strongly controls the dose enhancement over the various eye structures and emphasizes the importance of modeling the GNPs’ distribution in the medium on the overall dose enhancement. Considering the current challenges in the clinical use of GNPs, more effort needs to be made to reach an effective endpoint in treatment.

Indirect effects of interference of two emerging environmental contaminants on cell health: Radiofrequency radiation and gold nanoparticles

BackgroundThe global need for wireless technologies is growing rapidly. So, we have been exposed to a new type of environmental pollution: radiofrequency radiation (RFR). Recent studies have shown that RFR can cause not only direct effects but also indirect or non-targeted effects such as the bystander effect (BE). In this study, we investigated the BE induced by RFR in the present of gold nanoparticles (GNP). Moreover, we studied the expression of cyclooxygenase-2 (COX-2). MethodsNon-toxic dose of 15-nm GNP was used to treat the Chinese Hamster Ovary (CHO) cells. After 48 h of incubation, cells were exposed to 900 MHz GSM RFR for 24 h. Then we collected the cell culture medium of these cells (conditioned culture medium, CCM) and transferred it to new cells (bystander cells). Cell deaths, DNA breaks, oxidative stress and COX-2 expression were analyzed in all groups. ResultsThe results showed that RFR increased metabolic death in cells treated with GNP. Inversely, the colony formation ability was reduced in bystander cells and RFR exposed cells either in the presence or absence of GNP. Also, the level of reactive oxygen species (ROS) in GNP treated cells showed a significant reduction compared to those of untreated cells. However, RFR-induced DNA breaks and the frequencies of micronuclei (MN) were not significantly affected by GNP. The expression of COX-2 mRNA increased in RFR GNP treated cells, but the difference was not significant. ConclusionOur results for the first time indicated that RFR induce indirect effects in the presence of GNP. However, the molecular mediators of these effects differ from those in the absence of GNP. Also, to our knowledge, this is the first study to show that COX-2 is not involved in the bystander effect induced by 900 MHz RFR.

Synthesis and Biological Evaluation of Substituted Fused Dipyranoquinolinones

New methyl-substituted, and diphenyl-substituted fused dipyranoquinolinones are prepared in excellent yields via the triple bond activation and 6-endo-dig cyclization of propargyloxycoumarin derivatives by gold nanoparticles supported on TiO2 in chlorobenzene under microwave irradiation. In the absence of gold nanoparticles, the methyl-substituted propargyloxycoumarin derivatives resulted in fused furopyranoquinolinones through Claisen rearrangement and 5-exo-dig cyclization. The intermediate propargyloxy-fused pyridocoumarins are prepared by propargylation of the corresponding hydroxy-fused pyridocoumarins. The methyl-substituted derivatives of the latter are synthesized in excellent yield by the three-component reaction of amino hydroxycoumarin with n-butyl vinyl ether under iodine catalysis. The diphenyl-substituted derivatives of hydroxy-fused pyridocoumarins are obtained, also, by the three-component reaction of amino hydroxycoumarin with benzaldehyde and phenyl acetylene catalyzed by iron (III) chloride. Preliminary biological tests of the title compounds indicated lipoxygenase (LOX) (EC 1.13.11.12) inhibitory activity (60–100 μM), whereas compound 28a, with IC50 = 10 μM, was found to be a potent LOX inhibitor and a possible lead compound. Only compounds 10b and 28b significantly inhibited lipid peroxidation.

Magnetic Nanoparticles for Drug Delivery through Tapered Stenosed Artery with Blood Based Non-Newtonian Fluid

Nanoparticles play an essential role in biomedical applications. A most promising area in nanomedicine is drug targeting which is done with the aid of magnetized nanoparticles. In this study, the hemodynamics of hybrid nanofluid flow with gold and copper nanoparticles suspended in it is investigated. This research primarily focuses on magnetic drug delivery which is propagated through a tapered stenosed artery under three situations, including converging, diverging, and non-tapering arteries. To explore the rheological characteristics of blood, a Sutterby fluid, which is a non-Newtonian fluid, is postulated. The energy equation also incorporates the effects of the magnetic field and joule heating, as well as the viscous dissipation function. Lubrication theory provides a mathematical framework for model formulation. The hypothesized modeling is simplified to a set of nonlinear differential equations that are then solved using a perturbation method up to the second order of approximation. Graphs are used to describe the outcomes of different evolving parameters. The Sutterby fluid parameter opposes the flow negligibly, whereas the Hartmann number and thermal Grashof number strengthen the flow field. Copper nanoparticles (in the absence of gold nanoparticles) are observed to deplete the thermal profile substantially more than gold nanoparticles. Nevertheless, the thermal profile is enhanced by the presence of both nanoparticles (hybrid nanofluids). For greater values of the Sutterby fluid parameter, the wall shear stress has been observed to rise considerably, whereas the inverse is true for the Hartmann number and the thermal Grashof number. The present results have been improved to give significant information for biomedical scientists who are striving to study blood flow in stenosis situations, as well as for those who will find the knowledge valuable in the treatment of different diseases.

The effect of ultrasound hyperthermia with gold nanoparticles on retinoblastoma Y79 cells

The purpose of this study was to evaluate the possible synergistic effect of gold nano-therapy (Au-NPs) on Y79 cells treated with ultrasonic hyperthermia. The cells in the presence and absence of gold nanoparticles were subjected to ultrasonic irradiation (3 MHz, 1 W/cm2, 40% pulse mode). Gold nanoparticles with an average diameter of 60 nm were synthesized. The cell viability of the Y79 cells was evaluated 48 h after performing 0.5–11 min hyperthermia with and without Au-NPs using the MTT assay. There was no cytotoxicity with 1.7 μg/mL Au-NP concentration. Moreover, the results revealed a significant difference in the cell viability between the control group and the groups with a hyperthermia period of more than 4 min. The results indicated that with increasing the concentration of Au-NPs (1.75, 3.5, 7, 14, 28 and 56 μg/mL), the cytotoxicity increased. The Y79 cell viability of 50% was caused for 9 min hyperthermia time alone and 4.5 min hyperthermia time in the presence of gold nanoparticles. The cell viability of the Y79 cells for a 0.5 to 11 min hyperthermia time, compared with the control group, was 93 to 27% and 95 to 32% with and without Au-NPs, respectively. It is concluded that the cells are more sensitive to hyperthermia induced by ultrasound irradiation in the presence of Au-NPs.

Wide dynamic range and ultrasensitive detection of hydrogen peroxide based on beneficial role of gold nanoparticles on the electrochemical properties of prussian blue

This paper reports the beneficial effects of gold nanoparticles (GNPs) on the deposition, electrochemistry and electrocatalysis of Prussian Blue (PB) on a glassy carbon electrode modified with a bucky gel (BG) consisting of carbon nanotubes (CNTs) and ionic liquid (IL). The electrodeposition of PB nanoparticles was accomplished on the BG/GC electrode in the absence and presence of GNPs and the effect of GNPs on the electrochemical properties of PB was investigated. The PB-GNPs/BG/GC electrode showed a higher PB surface concentration and lower formal potential, as compared with the PB/BG/GC electrode. The calculated surface concentration value of PB was 1.1 × 10−8 mol cm−2, showing that the deposition efficiency of PB was enhanced by 2.7 fold, and the formal potential decreased from 0.198 to 0.183 V. The apparent diffusion coefficient of K+ (2.28 × 10−10 cm2 s−1) was enhanced by a factor of ~15 compared with that in the absence of GNPs. Although electron transfer rate (ks) of the PB-GNPs/BG/GC modified electrodes (1.60 s−1) decreased by 30%, the sensitivity toward H2O2 reduction was greatly increased (about four times) and the dynamic range for H2O2 detection was prolonged over three orders of magnitude. On the other hand, GNPs improved the stability of the PB modified electrode. Compared to other H2O2 sensors, the PB-GNPs/BG/GC electrode could detect H2O2 in a wide dynamic range of 9.16 × 10−6 to1.43 × 10−1 M with a very high sensitivity.

Divalent ion-induced aggregation of gold nanoparticles for voltammetry Immunosensing: comparison of transducer signals in an assay for the squamous cell carcinoma antigen.

A method is described for the electrochemical determination of squamous cell carcinoma (SCC) antigen, and by testing the effect of 30nm gold nanoparticles (GNPs). Three comparative studies were performed in the presence and absence of GNPs, and with agglomerated GNPs. The divalent ion Ca(II) was used to induce a strong agglomeration of GNPs, as confirmed by colorimetry and voltammetry. Herein, colorimetry was used to test the best amount of salt needed to aggregate the GNPs. Despite, voltammetry was used to determine the status of biomolecules on the sensor. The topography of the surface of ZnO-coated interdigitated electrodes was analyzed by using 3D-nano profilometry, scanning electron microscopy, atomic force microscopy and high-power microscopy. The interaction between SCC antigen and antibody trigger vibrations on the sensor and cause dipole moment, which was measured using a picoammeter with a linear sweep from 0 to 2V at 0.01V step voltage. The sensitivity level was 10 fM by 3σ calculation for the dispersed GNP-conjugated antigen. This indicates a 100-fold enhancement compared to the condition without GNP conjugation. However, the sensitivity level for agglomerated GNPs conjugated antibody was not significant with 100 fM sensitivity. Specificity was tested for other proteins in serum, namely blood clotting factor IX, C-reactive protein, and serum albumin. The SCC antigen was quantified in spiked serum and gave recoveries that ranged between 80 and 90%. Graphical abstractSchematic representation of SCC (squamous cell carcinoma) antigen determination using divalent ion induced agglomerated GNPs. Sensitivity increment depends on the occurrence of more SCC antigen and antibody binding event via GNPs integration. Notably, lower detection limit was achieved at femto molar with proper orientation of biological molecules.

Radiation-Induced Mitotic Catastrophe Enhanced by Gold Nanoparticles: Assessment with a Specific Automated Image Processing Workflow.

In recent years, the use of gold-based nanoparticles in radiotherapy has been extensively studied, and the associated radiosensitization mechanism has been evaluated in a variety of in vitro studies. Given that mitotic catastrophe is widely involved in radiation-induced cell death, we evaluated the effect of gold nanoparticles on this key event. Most of the methods currently used to visualize and quantify morphological changes and multinucleation are manual. To circumvent this time-consuming step, we developed and optimized an image processing workflow (based on freely accessible software and plugins) for the automated quantification of mitotic catastrophes. We validated this approach in three cell lines by comparing the number of radiation-induced mitotic catastrophes detected using the automated and manual methods in the presence and absence of nanoparticles. With the Bland-Altman analysis, the automated and manual counting methods were found to be fully interchangeable. The ultimate goal of this work was to determine whether mitotic catastrophe was critically involved in radiationinduced cell death after prior exposure to gold nanoparticles. In the radioresistant U87 cell line, exposure to gold nanoparticles was associated with a shorter time course for the events related to mitotic catastrophe, which peaked at 96 h postirradiation. Mitotic catastrophe was dose-dependent in both the presence and absence of gold nanoparticles. These results demonstrate that cell exposure to gold nanoparticles led to an increase in mitotic catastrophe events, and confirm the marked radiosensitizing effect observed in clonogenic assays.

Layer-by-Layer Films of Graphene Nanoplatelets and Gold Nanoparticles for Methyl Parathion Sensing

The wide use of pesticides in agriculture makes necessary the development of cost-effective, easy, and rapid methods aiming for environmental and health protection. We propose the fabrication and investigation of layer-by-layer (LbL) films composed of reduced graphene oxide stabilized in polyelectrolytes in the presence and absence of gold nanoparticles (AuNPs) toward methyl parathion (MP) detection. In addition to the film assembly and sensing application, we performed a systematic investigation of the influence of MP distribution on the limit of detection and linear range of the sensor. Indium tin oxide (ITO) electrodes modified with the LbL films were applied by differential pulse voltammetry achieving an LOD and a linear range of 0.226 ppm and 0.25–40 ppm in the absence of AuNPs, while in the their presence, a wider linear range was achieved (0.5–60 ppm, with LOD of 0.770 ppm). Real sample analysis indicated potential application in water, ground, and vegetables, with recovery varying from 92% to 113%.

The contribution of hydrogen peroxide to the radiosensitizing effect of gold nanoparticles.

Plasmid DNA in aerated aqueous solution is used as a probe to determine whose of the reactive oxygen species (ROS) generated after absorption of ultra-soft X-rays (USX) take part in biomolecule damage in the presence and in absence of Gold Nano-Particles (GNP) and specific scavengers. Citrate-coated GNPs with core sizes of 6, 10 and 25 nm are synthetized and characterized, especially in terms of plasmon band shift, ζ-potential and hydrodynamic radii (respectively 9, 21 and 30 nm). We confirm the radiosensitizing effect of GNP and show that the SSB number per plasmid increases when, for a same mass of gold element, the core size of the gold nanoparticles decreases. Hydroxyl radicals (OH) are scavenged using the positively-charged 2-amino-2-hydroxymethyl-1,3-propanediol (TRIS) and the neutral dimethyl sulfoxide (DMSO) molecules. Due to both negatively-charged environments of DNA and GNP, at identical scavenging capacity, TRIS is more effective at quenching OH than DMSO. The strong radiosensitizing effect of hydroxyl radicals is confirmed. Methanoate anions are then used to transform OH into hydrogen peroxide; the latter being known to be non-aggressive regarding DNA in the absence of easily oxidable metallic ions (Fenton reactions). Surprisingly, in the presence of GNP, high DNA damage yields are observed even though hydrogen peroxide might not be hold as responsible. Conversely, the radiosensitizing effect of GNP is not observed anymore when H2O2 is scavenged using pyruvate ions. We demonstrate that hydrogen peroxide constitutes quite unexpectedly a hidden stock of OH which are activated at the surface of the GNP by decomposition of H2O2 molecules.

GNP enhanced responses in microdosimetric spectra for 192Ir source

The potential radiosensitizing effects of gold nanoparticles (GNPs) in radiation therapy have been extensively studied. GNPs loaded in the tumor produce a large number of low-energy secondary electrons which contribute to the local dose enhancement and elevate the relative biological effectiveness (RBE). Thus GNP enhanced responses in 192Ir, a widely used brachytherapy source, are the subject of interest. These radiosensitizing effects can be examined through comparisons between microdosimetric spectra of secondary electrons resulting from the 192Ir in the presence and absence of GNPs in cells. Measurements of single-event lineal energy spectra give indications of a relative therapeutic advantage. In the present work, a mini tissue equivalent proportional counter (TEPC) was constructed to measure the microdosimetric spectra in cells containing and without GNPs for 192Ir source. A plug, either contained a 50 nm-thick gold foil coated on its inner surface or without the foil, was inserted into the TEPC wall during measurements. Analyses of the measured un-normalized and normalized dose lineal energy spectra provided information on the enhancements in absorbed dose and RBE. The dose enhancement was 1.27 and 1.37 for 1 and 0.5 μm-diameter sites, respectively. The increase in dose enhancement with decreasing site diameter revealed the sharp fall-off in the local dose enhancement. Applying the biological weighting function method, the RBE enhancement was 1.32 based on the lineal energy spectra of 1 μm site.

Gold nanoparticles as a potent radiosensitizer in neutron therapy.

The purpose of this study was to investigate the potential of gold nanoparticles as radiosensitizer for use in neutron therapy against hepatocellular carcinoma.The hepatocellular carcinoma cells lines Huh7 and HepG2 were irradiated with γ and neutron radiation in the presence or absence of gold nanoparticles. Effects were evaluated by transmission electron microscopy, cell survival, cell cycle, DNA damage, migration, and invasiveness.Gold nanoparticles significantly enhanced the radiosensitivity of Huh7 and HepG2 cells to γ-rays by 1.41- and 1.16-fold, respectively, and by 1.80- and 1.35-fold to neutron radiation, which has high linear energy transfer. Accordingly, exposure to neutron radiation in the presence of gold nanoparticles induced cell cycle arrest, DNA damage, and cell death to a significantly higher extent, and suppressed cell migration and invasiveness more robustly. These effects are presumably due to the ability of gold nanoparticles to amplify the effective dose from neutron radiation more efficiently.The data suggest that gold nanoparticles may be clinically useful in combination therapy against hepatocellular carcinoma by enhancing the toxicity of radiation with high linear energy transfer.

Enhancement of Cisplatin Efficacy by Gold Nanoparticles or Microwave Hyperthermia? An In Vitro Study on a Melanoma Cell Line

Purpose: Chemotherapy-resistance of melanoma has led to poor prognosis and decreased survival in the patients. Therefore, the addition of adjuvant therapies to the conventional chemotherapy regimens has been taken into consideration to improve the clinical treatments efficiency. In this study, the effect of microwave (MW) Hyperthermia has been evaluated on the toxicity of cisplatin on the MM200 cell line in the presence and without gold nanoparticles (GNPs). Methods: Cells incubation was performed with and without cisplatin in the presence and absence of GNPs. To induce hyperthermia, the cells were immediately placed under MW irradiation for 25 and 30 minutes (41- 43°C) following the addition of the drug and GNPs, then they were incubated for 24 hours. Finally, cell survival was determined by MTT assay. Results: GNPs (up to 6.6 µg/mL) showed no toxicity. GNPs at the concentration of 13.2 and 26.4 µg/mL caused 13% and 20.7% drop in cell survival rate, respectively. IC50 of cisplatin decreased from 4 to 2 µg/mL in the presence of GNPs. Hyperthermia (43°C) plus chemotherapy (2 µg/mL) resulted in no significant enhancement in cisplatin cytotoxicity relative to chemotherapy alone whereas by adding GNPs, an increase in cell mortality up to 15-fold in comparison to cisplatin alone was observed. Conclusions: There is a synergistic effect between cisplatin and GNPs, this could be due to the facilitated entrance of cisplatin in the presence of GNPs. MW exposure improves the efficacy of cisplatin therapy in the presence of GNPs on MM200 cells.

Structure and effects of gold nanoparticles in bacterial cellulose–polyaniline conductive membranes

Bacterial cellulose (BC) and poly(aniline) (PANI) composites were successfully synthesized by in situ polymerization of aniline by ammonium persulphate (APS) in the presence and absence of gold nanoparticles.

Elucidating the Influence of Gold Nanoparticles on the Binding of Salvianolic Acid B and Rosmarinic Acid to Bovine Serum Albumin

Salvianolic acid B and rosmarinic acid are two main water-soluble active ingredients from Salvia miltiorrhiza with important pharmacological activities and clinical applications. The interactions between salvianolic acid B (or rosmarinic acid) and bovine serum albumin (BSA) in the presence and absence of gold nanoparticles (Au NPs) with three different sizes were investigated by using biophysical methods for the first time. Experimental results proved that two components quenched the fluorescence of BSA mainly through a static mechanism irrespective of the absence or presence of Au NPs. The presence of Au NPs decreased the binding constants of salvianolic acid B with BSA from 27.82% to 10.08%, while Au NPs increased the affinities of rosmarinic acid for BSA from 0.4% to 14.32%. The conformational change of BSA in the presence of Au NPs (caused by a noncompetitive binding between Au NPs and drugs at different albumin sites) induced changeable affinity and binding distance between drugs and BSA compared with no Au NPs. The competitive experiments revealed that the site I (subdomain IIA) of BSA was the primary binding site for salvianolic acid B and rosmarinic acid. Additionally, two compounds may induce conformational and micro-environmental changes of BSA. The results would provide valuable binding information between salvianolic acid B (or rosmarinic acid) and BSA, and also indicated that the Au NPs could alter the interaction mechanism and binding capability of drugs to BSA, which might be beneficial to understanding the pharmacokinetics and biological activities of the two drugs.

Gold Nanoparticles‐enhanced Chemiluminescence Determination of Fenfluramine

AbstractA simple and sensitive chemiluminescence method was developed for the determination of fenfluramine. The chemiluminescence signal arising from the reaction between alkaline luminol and N‐bromosuccinimide was found to be greatly enhanced by fenfluramine in the presence of gold nanoparticles. But fenfluramine alone slightly inhibited the CL signal of N‐bromosuccinimide‐luminol in the absence of gold nanoparticles. The experimental parameters that affected the chemiluminescence signal were thoroughly investigated. Under the optimum experimental conditions, the enhanced chemiluminescence intensity was proportional to the concentration of fenfluramine in the range of 0.005‐1.0 mg/L. The detection limit was 0.9 μg/L fenfluramine with a relative standard deviation of 2.5% for 0.1 mg/L fenfluramine solution (n = 11). The method was applied to the determination of fenfluramine in some weight‐reducing tonics and in spiked human urine. A possible CL reaction mechanism was proposed.

Monitoring of transient cavitation induced by ultrasound and intense pulsed light in presence of gold nanoparticles

One of the most important challenges in medical treatment is invention of a minimally invasive approach in order to induce lethal damages to cancer cells. Application of high intensity focused ultrasound can be beneficial to achieve this goal via the cavitation process. Existence of the particles and vapor in a liquid decreases the ultrasonic intensity threshold required for cavitation onset. In this study, synergism of intense pulsed light (IPL) and gold nanoparticles (GNPs) has been investigated as a means of providing nucleation sites for acoustic cavitation. Several approaches have been reported with the aim of cavitation monitoring. We conducted the experiments on the basis of sonochemiluminescence (SCL) and chemical dosimetric methods. The acoustic cavitation activity was investigated by determining the integrated SCL signal acquired over polyacrylamide gel phantoms containing luminol in the presence and absence of GNPs in the wavelength range of 400–500nm using a spectrometer equipped with cooled charged coupled devices (CCD) during irradiation by different intensities of 1MHz ultrasound and IPL pulses. In order to confirm these results, the terephthalic acid chemical dosimeter was utilized as well. The SCL signal recorded in the gel phantoms containing GNPs at different intensities of ultrasound in the presence of intense pulsed light was higher than the gel phantoms without GNPs. These results have been confirmed by the obtained data from the chemical dosimetry method. Acoustic cavitation in the presence of GNPs and intense pulsed light has been suggested as a new approach designed for decreasing threshold intensity of acoustic cavitation and improving targeted therapeutic effects.

Cysteine‐capped gold nanoparticles suppress aggregation of proteins exposed to heat stress

Gold nanoparticles show a lot of promise as potential agents for drug delivery and disease diagnosis. Because of this, it is important that the interaction between gold nanoparticles and biomolecules be well characterized to avoid undesirable consequences. In this study, gold nanoparticles were synthesized by the reduction of gold salt by sodium borohydride in the presence of cysteine as the capping agent. The physical features of the nanoparticles were analyzed using Ultraviolet-Visible spectrophotometry and transmission electron microscopy. The interaction between gold nanoparticles and the following proteins: bovine serum albumin, citrate synthase, malate dehydrogenase, and human heat shock protein 70 was investigated by UV-Vis spectrophotometry. The stability of the proteins against heat stress was assessed by monitoring their aggregation at 48 °C, either in the presence or absence of gold nanoparticles. The gold nanoparticles were capable of suppressing the heat-induced aggregation of the proteins. Furthermore, apart from possessing independent protein-aggregation suppression function, the AuNPs also augmented the chaperone function of human heat shock protein 70. Findings from this study demonstrate that cyteine-coated gold nanoparticles exhibit chaperone-like activity and have the capability to stabilize proteins to which they may be conjugated.

Gold nanoparticles decorated polylactic acid-co-ethyl cellulose nanocapsules for 5-fluorouracil drug release

The present work describes the synthesis and characterisation of PLA-co-EC copolymer from lactic acid and ethyl cellulose by azeotropic dehydration, under reduced pressure, at 140°C for eight hours. The synthesised PLA-co-EC copolymer was used for controlled drug release systems with gold nanoparticles. Fluorouracil (5-Fu) containing PLA-co-EC nanocapsules were prepared in the presence and absence of gold nanoparticles via solvent evaporation method. The drug entrapped nanocapsules were characterised by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The average diameter of gold nanoparticles was found to be in the range of 18–20 nm and size of the nanocapsules was found to be in the range of 230–260 nm. The controlled drug release of anticancer drugs entrapped nanocapsules were carried out in 0.1M HCl and 0.1M phosphate buffer (pH-7.4). Results indicated that the drug release for gold nanoparticles incorporated PLA-co-EC nanocapsules was controlled and slow compare to Fu incorporated PLA-co-EC nanocapsules. This may be due the interaction between the gold nanoparticles and fluorouracil in PLA-co-EC nanocapsules.