Biocompatible AuNPs Research Articles

Apoptotic Induction by Biosynthesized Gold Nanoparticles Using Phormidesmis communis Strain AB_11_10 against Osteosarcoma Cancer.

Phormidesmis communis strain AB_11_10 was isolated and identified using microscopy and 16s rRNA sequencing, and its phytochemical constituents were determined using liquid chromatography-quadrupole time-of-flight mass spectrometry. The isolate had a segmented filamentous shape with a blue-green color. Many biomolecules, including organic compounds, amino acids, and fatty acids, were detected. P. communis strain AB_11_10 was used to synthesize gold nanoparticles (Ph-AuNPs) by adjusting the optimum reaction conditions. The concentration, algal/precursor ratio, temperature, reaction time, and pH significantly influenced the synthesis of the Ph-AuNPs. Mixing 1 mL of 0.5 mM of HAuCl4 with 1 mL of algal extract and exposing the mixture to 100 °C for 30 min at pH 5.6 were the optimum conditions for the biosynthesis of Ph-AuNPs at a wavelength of 524.5 nm. The Ph-AuNPs were characterized using TEM, SEM, EDX, and mapping Zeta sizer and FTIR. The Ph-AuNPs had quasi-spherical to triangular shapes with an average diameter of 9.6 ± 4.3 nm. Ph-AuNPs composed of 76.10 ± 3.14% of Au and trace amounts of carbon and oxygen were detected, indicating that the P. communis strain AB_11_10 successfully synthesized Ph-AuNPs. The hydrodynamic diameter of the Ph-AuNPs was 28.5 nm, and their potential charge was -17.7 mV. O-H, N-H, C=C, N-O, C-H, and C-O were coated onto the surfaces of the Ph-AuNPs. These groups correspond to algal phytochemicals, which may have been the main reducing and stabilizing substances during the Ph-AuNP synthesis. The therapeutic activity of the Ph-AuNPs against osteosarcoma cancers was examined in MG-63 and SAOS-2 cell lines, while their biocompatibility was tested against Vero cell lines using a sulforhodamine B assay. The Ph-AuNPs had potent antitumor activity against the MG-63 and SAOS-2 cells, with a low toxicity toward Vero cells. Flow cytometry and cell cycle arrest analyses revealed that the Ph-AuNPs enhanced the apoptotic pathway and arrested the cell cycle in the MG-63 and SAOS-2 cells. P. communis strain AB_11_10 provides a new source to synthesize small, stable, and biocompatible AuNPs that act as apoptotic enhancers in osteosarcoma.

Interactions of Turmeric- and Curcumin-Functionalized Gold Nanoparticles with Human Serum Albumin: Exploration of Protein Corona Formation, Binding, Thermodynamics, and Antifibrillation Studies.

In order to better understand the bioavailability and biocompatibility of polyphenol-assisted surface-modified bioengineered nanoparticles in nanomedicine applications, here, we address a series of photophysical experiments to quantify the binding affinity of serum albumin toward polyphenol-capped gold nanoparticles. For this, two different gold nanoparticles (AuNPs) were synthesized via the green synthesis approach, where curcumin and turmeric extract act as reducing as well as capping agents. The size, surface charge, and surface plasmon bands of the AuNPs were highly affected by the adsorption of human serum albumin (HSA) during protein corona formation, which was investigated using dynamic light scattering (DLS), ξ-potential, ultraviolet-visible (UV-vis) spectroscopy, and transmission electron microscopy (TEM) measurements. Fluorescence-based methods, absorbance, and SERS experiments were carried out to evaluate the binding aspects of AuNPs with HSA. We found that the AuNPs show moderate binding affinity toward HSA (Kb ∼ 104 M-1), irrespective of the capping agents on the surface. Hydrophobic association, along with some contribution of electrostatic interaction, played a key role in the binding process. The binding interaction was more toward the subdomain IIA region of HSA, as indicated by the competitive displacement studies using site-specific binders (warfarin and flufenamic acid). Because of the large surface curvature of small-sized AuNPs, the secondary structural conformations of HSA were slightly altered, as revealed by circular dichroism (CD), Fourier transform infrared (FT-IR) spectroscopy, and surface-enhanced Raman scattering (SERS) measurements. Additionally, the findings of the binding interactions were re-evaluated using molecular dynamics (MD) simulation studies by determining the root-mean-square deviation (RMSD), root-mean-square fluctuation (RMSF), radius of gyration (Rg), and changes in the binding energy of HSA upon complexation with AuNPs. To determine the tentative evidence for pharmacokinetic administration, these biocompatible AuNPs were applied to inhibit the amyloid fibril formation of HSA and monitored by using the thioflavin T (ThT) assay, ANS fluorescence assay, fluorescence microscopic imaging, and FESEM. AuNPs were found to show better resistance toward fibrillation of the adsorbed protein.

Gold Nanoparticles Functionalized with 2-Thiouracil for Antiproliferative and Photothermal Therapies in Breast Cancer Cells.

Nanoparticles have been used to transport drugs to various body parts to treat cancer. Our interest is in gold nanoparticles (AuNPs) since they have the capacity to absorb light and convert it to heat, inducing cellular damage. This property is known as photothermal therapy (PTT) and has been studied in cancer treatment. In the present study, biocompatible citrate-reduced AuNPs were functionalized with a biologically active compound, 2-thiouracil (2-TU), of potential anticancer activity. Both the unfunctionalized (AuNPs) and functionalized (2-TU-AuNPs) were purified and characterized by UV-Vis absorption spectrophotometry, Zeta potential, and Transmission Electron Microscopy. Results showed monodispersed, spherical AuNPs with a mean core diameter of 20 ± 2 nm, a surface charge of -38 ± 5 mV, and a localized surface plasmon resonance peak at 520 nm. As a result of functionalization, the mean core diameter of 2-TU-AuNPs increased to 24 ± 4 nm, and the surface charge increased to -14 ± 1 mV. The functionalization of AuNPs and the load efficiency were further established through Raman spectroscopy and UV-Vis absorption spectrophotometry. The antiproliferative activities of AuNPs, 2-TU and 2-TU-AuNPs were examined by a 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay in the MDA-MB-231 breast cancer cell line. It was established that AuNPs significantly enhanced the antiproliferative activity of 2-TU. Furthermore, the irradiation of the samples with visible light at 520 nm decreased the half-maximal inhibitory concentration by a factor of 2. Thus, the 2-TU drug concentration and its side effect during treatments could be significantly reduced by synergistically exploiting the antiproliferative activity of 2-TU loaded onto AuNPs and the PTT effect of AuNPs.

Waste fruit peel – Mediated green synthesis of biocompatible gold nanoparticles

Gold nanoparticles (AuNPs) have many applications in biomedical science due to their small size, large surface area, inertness, stability, high dispersity, and biocompatibility. However, the preparation of biocompatible and non-toxic AuNPs is very important issue. Biological synthesis of AuNPs presents to be simple, cost-effective, and non-toxic, which is unlike the chemically synthesized AuNPs. The aim of this study was to synthesize biocompatible AuNPs using waste fruit peel. We developed green method for AuNP synthesis by reducing gold (III) chloride trihydrate (HAuCl 4 ) with an aqueous fruit peel extract of Ananas comosus (pineapple) and Passiflora edulis (passion fruit). Such fruit peels are usually considered a waste material but contain many chemical components including proteins, minerals, lipids, vitamin, phenolic compounds, flavonoids and carotenoid, which act as reductants and nanoparticle stabilizers. Gold nanoparticles obtained using pineapple peel (Pi-AuNPs) and passion fruit peel extracts (Pa-AuNPs) exhibit a characteristic red coloration and UV–visible spectral absorption maximum around 545 nm attributable to surface plasmon resonance. TEM imaging confirmed that the AuNPs were spherical, with XRD patterns indicating that the gold atoms adopt a face-centered cubic structure. Cell viability assays in normal African green monkey kidney epithelial cells (Vero) and breast cancer cells (MCF-7) imply that the synthesized AuNPs have no biological cytotoxicity, even at high concentration (400 μg/mL). This study thus highlights the potential benefit of employing fruit peel extracts as reducing and stabilizing agents for the synthesis of non-cytotoxic AuNPs, with the greenness of the production process being particularly important for their utility in biomedical applications.

Gold-Based Nanoplataform for the Treatment of Anaplastic Thyroid Carcinoma: A Step Forward.

Simple SummaryAnaplastic thyroid carcinoma (ATC) is a subtype of thyroid cancer that generally does not respond to the available treatments, making it one of the most lethal cancers known. As an alternative, Photothermal Therapy (PTT) can be considered a promising strategy. In this case, gold nanoparticles (AuNPs) are activated when irradiated by light, enhancing the local temperature, resulting in cell death. Thus, this study aims to formulate AuNPs specifically for targeting PTT to ATC. For this, biocompatible AuNPs were designed and functionalized with ATC-specific ligands (holo-transferrin, epidermal growth factor (EGF), and lapatinib), showing optimal physicochemical properties. Safety, efficacy, and ATC specificity were determined in vitro. Holo-transferrin functionalized-AuNPs were the most effective for PTT against ATC. Safety and biodistribution were studied in vivo, proving that the formulation was safe for intratumoural administration. So, taking these results all together, AuNPs-mediated-PTT seems to be a promising hint to find a viable treatment for ATC.Anaplastic thyroid carcinoma (ATC) is a very rare subtype of thyroid carcinoma and one of the most lethal malignancies. Poor prognosis is mainly associated with its undifferentiated nature, inoperability, and failing to respond to the typically used therapies for thyroid cancer. Photothermal Therapy (PTT) entails using light to increase tissues’ temperature, leading to hyperthermia-mediated cell death. Tumours are more susceptible to heat as they are unable to dissipate it. By using functionalized gold nanoparticles (AuNPs) that transform light energy into heat, it is possible to target the heat to the tumour. This study aims to formulate ATC-targeted AuNPs able to convert near-infrared light into heat, for PTT of ATC. Different AuNPs were synthetized and coated. Size, morphology, and surface plasmon resonances band were determined. The optimized coated-AuNPs were then functionalized with ligands to assess ATC’s specificity. Safety, efficacy, and selectivity were assessed in vitro. The formulations were deemed safe when not irradiated (>70% cell viability) and selective for ATC. However, when irradiated, holo-transferrin-AuNPs were the most cytotoxic (22% of cell viability). The biodistribution and safety of this formulation was assessed in vivo. Overall, this novel formulation appears to be a highly promising approach to evaluate in a very near future.

Nano gold incorporated into Aerva javanica chitosan hydrogels disrupting agents against infections of burn wound

ABSTRACT S. aureus (SA) and P. aeruginosa (PA) contaminations in thermally hurt patients have controlled invasive illness producing humanity. Gold nanoparticles (AuNPs) engaged in behaviour have limits owed to their oxidative damage. Current examinations demonstrated the biosynthesis of highly biocompatible AuNPs from rich antioxidant of aqueous cutting of Aerva javanica (A. javanica). The cell viability of the biosynthesised AuNPs was examined by cancerous cell lines (MCF-7 and MDA-MB-231) and non-cancerous cell lines (HUVECs), which displayed the high biocompatibility in all the cell lines. We developed the encapsulation with chitosan hydrogels to the AuNPs for the burn wound infections created by the Sprague Dawley rats. Remarkable burn wound reduction in the chitosan hydrogels was found. The histological analysis also suggested the burn wound contracting without causing any damages. The outcomes indicated that AuNPs incorporate to the chitosan hydrogels are promising burn wound dressing resources for the treatment for wound healing.

Utilization of Morchella esculenta-mediated green synthesis golden nanoparticles in biomedicine applications

This study aimed to synthesize gold nanoparticles (AuNPs) by hot water extract in room conditions using edible Morchella esculenta (ME) and investigate the bioactive properties of the synthesized Morchella esculenta-based gold nanoparticles (ME-AuNPs). The characterization of the biologically synthesized ME-AuNPs was made using the ultraviolet–visible spectrophotometry, X-ray crystallography, scanning electron microscopy, Fourier transforms infrared spectroscopy, and energy dispersive X-ray spectrum methods. The ME-AuNPs, with a particle size of 16.51 nm, were found to have strong bioactive properties. The antioxidant activity of the ME-AuNPs attempted by metal chelating activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity and the β-carotene linoleate model system. The activities at 10 mg/mL were 82, 85, and 77% for the chelation of ferrous ions, DPPH scavenging, and β-carotene linoleate tests, respectively. The ME-AuNPs also showed strong antimicrobial activity against various pathogen microorganisms and strong cytotoxic activity in the A549 and HepG2 cell lines. This study demonstrated the possibility of using a cheap and nontoxic fungal extract as a reducing and stabilizing agent for the synthesis of size-controlled, large-scale, and biocompatible AuNPs that could be used in future diagnostic and therapeutic applications.

Characterization of Biocompatible Gold Nanoparticles Synthesized by using Curcuma xanthorrhiza and their Catalytic Activity

Background: Based on various distinguished physical and chemical properties of gold nanoparticles, they have far wide applications in several areas of industry and medicine, such as catalysis, bio-sensor and drug delivery. Compared to a chemical method, biological synthesis is an economical and less toxic process, thus it is a better alternative for nanoparticle synthesis. In this study, an environmentally friendly method was chosen to produce AuNPs using Curcuma xanthorrhiza. Methods: Alkaline aqueous extract of C. xanthorrhiza rhizomes, which acts as a reducing and stabilizing agent was used to produce AuNPs by bio-reduction of HAuCl4. The formation of AuNPs was periodically monitored by UV-visible spectroscopy. The obtained AuNPs were characterized by Xray diffraction, energy dispersive spectroscopy, scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared (FTIR) spectroscopy. Catalytic activity and toxicity of the AuNPs were evaluated. Results: The AuNPs obtained from this study mostly were spherical in shape with approximately 15 nm in size. The presence of functional groups derived from C. xanthorrhiza rhizome extract involved in the gold bio-reduction process was confirmed by the spectrum of FTIR spectroscopy. The biosynthesized AuNPs at the concentration of 0.5 μg/ml had catalytic activity in dye degradation of Congo red. The results showed that this biogenic AuNPs did not cause any toxicity to zebrafish embryos and all tested cell lines. Conclusion: The biocompatible AuNPs with catalytic activity were successfully fabricated with C. xanthorrhiza rhizome extract by simple eco-friendly and inexpensive method. This catalytic activity of the obtained AuNPs is potentially useful for industrial applications as well as nanoscience and nanotechnology.

Investigating the effect of gold nanoparticles on hydatid cyst protoscolices under low-power green laser irradiation.

Various scolicidal agents are applied for the destruction of protoscolices in cysts media. Undesirable complications of the scolicidal agents limit the techniques to treat the cyst disease. Therefore, new non-toxic scolicidal agents are needed. Upon laser light irradiation, the photothermal gold nanoparticles (AuNPs) convert the absorbed laser light into heat through photothermal effect which kills the surrounding protoscolices by rising the temperature of the cysts media. In this study, we introduced biocompatible AuNPs as a non-toxic scolicidal agent to cure liver hydatid cysts. The protoscoleces were collected from the livers of naturally infected sheeps. In each experimental group, 1.5 mL suspensions of hydatid liquid containing protoscolices were added to test tubes. The test tubes were divided into five groups. Control, AuNPs only, Green laser only, High-dose AuNPs + laser and Low-dose AuNPs + laser groups. Two concentrations (0.4 and 0.8 mL) of AuNPs and three laser powers (30, 50, 150 mW) were applied for 30, 60 and 120 minutes to the groups. Then the ciysts liquid assessed under a light microscope and determined the viability of protoscoleces. Protoscolices in high-dose AuNPs group were destructed up to 89.30% deaths under 150 mW laser power for 120 minutes. However, negligible cell deaths were observed in cases where only AuNPs added or only laser irradiated groups. Increasing the dose of AuNPs or laser power or duration of aplication increased the protoscolosidal death rate. In the study, we have successfully demonstrated that the AuNPs are an effective therapeutic and scolicidal agent to cure hydatid cyst disease under laser irradiation.

Study of gold nanoparticle transport by M13 phages towards disease tissues as targeting procedure for radiotherapy applications

This work introduces an innovative new method to transport gold nanoparticles (Au-NPs) toward specific organs using as transporter the M13 filamentous phage. The aim is to improve the radiotherapy efficiency by injecting gold nanoparticles in the tumor tissues in order to increase the effective atomic number and, consequently, to produce higher locally deposited doses. The biocompatible Au-NPs can be bonded to the phage surface for their transport in the biological fluids and tissues. M13 phages can be prepared to arrive in specific tissues and organs depending on their biochemical preparation and functionalization. Evidence about the real attachment of spherical Au-NPs, 10 nm in diameter, to the M13 phages is obtained using different microscopies. Other analyses have been also performed to evaluate the number of gold nanoparticles that can be transported by M13 phages inside the organism. Our results on the study of the spherical Au-NP size distribution, deduced by AFM, EFM, and TEM analyses, have indicated that in average, 2 couples of Au-NPs are attached to each phage. Moreover, the size of the NPs ranges between 10 and 30 nm, demonstrating a little aggregation of the nanoparticles, which remain usefully sized to be vehicled with the blood flux towards specific organs.

Synthesis of AuNPs using plant polyphenols and their potential treatment for age-related macular degeneration

The primary idea behind this study is to synthesize Saudi Origanum vulgare L. extract mediated AuNPs and to investigate their efficacy in significantly treating AMD. The biocompatible AuNPs were tested for their radical scavenging efficiency in vitro. Also, The effects of AuNPs in suppressing the angiogenic protein expression and inflammatory cytokine levels were analyzed in ARPE-19 (human retinal pigment epithelium-19) as well as and human umbilical vein endothelium cell lines in vitro. From the ORAC findings, it was evident that the bio synthesized AuNPs have presented momentous anti-oxidative activity in reducing the apoptosis in H2O2 treated ARPE-19 cell lines. In addition, the biocompatible AuNPs exhibited significant potential in suppressing the LPS stimulated inflammatory reaction in ARPE-19 cell lines while demonstrating inhibitory expression of growth factor in ARPE-19 as well as in umbilical vein endothelium cell lines. The experimental findings in this study have suggested that the synthesized AuNPs are biocompatible with significant potential in defending against angiogenesis, apoptosis, and generation of pro-inflammatory cytokines in AMD disease.

Synthesis and characterization of biocompatible acetaminophen stabilized gold nanoparticles

Gold nanoparticles (AuNPs) are extensively used in the field of biological and biomedical research. The non-toxic, biocompatible AuNPs are widely used in both in vivo and in vitro studies. The toxicity of AuNPs are varied and dependent on the reducing agent, synthesizing method, size and shape. The present study describes the synthesis and characterization of gold nanoparticles using acetaminophen through the bright sunlight mediated photochemical method and the biocompatibility of synthesized gold nanoparticles were analysed through the in vitro studies. The AuNPs synthesis was carried out in 20 min at biological pH 7.4. The physicochemical properties of acetaminophen stabilized gold nanoparticles (A-AuNPs) were analyzed by the ultraviolet (UV)-visible spectroscopy, high resolution transmission electron microscopy (HR-TEM), dynamic light scattering (DLS), zeta potential, fourier-transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) techniques. The maximum surface plasmon resonance absorption spectrum of acetaminophen stabilized gold nanoparticles was obatained at 529 nm. The electron microscopic observation of A-AuNPs showed spherical shape with the average particle size of 16.5 nm. The in vitro hemocompatibility of A-AuNPs was evaluated by hemolytic assay and erythrocyte sedimentation rate (ESR) estimation. The hemolysis was 2.54% and ESR was 11 mm h−1 at a maximum tested concentration of 250 μg ml−1 on human red blood cells (RBCs). The biocompatibility of A-AuNPs was tested on normal Vero and A549 lung cancer cell lines by MTT assay, lactate dehydrogenase (LDH) leakage assay and apoptosis analysis by acridine orange/ethidium bromide (AO/EtBr) fluorescence staining. The viability of Vero and A549 cells were 86.24% and 90.44% respectively on treatment with 250 μg ml−1 concentration of A-AuNPs. The LDH assay showed 16.12% and 15.0% leakage from Vero and A549 cells in maximum concentration. Further, the results of apoptosis analysis strongly supported the biocompatibility of A-AuNPs. In summary, the cost effective, one-step synthesized A-AuNPs have good hemocompatibility and biocompatibility prpoperty, therefore they can be safely used in biological applications.

Elucidation of synergistic effect of eucalyptus globulus honey and Zingiber officinale in the synthesis of colloidal biogenic gold nanoparticles with antioxidant and catalytic properties

Natural ingredients including plants and biological materials can be used in the synthesis of colloidal gold nanoparticles (AuNPs) to fulfil the needs of safe, biocompatible AuNPs for life science applications. Despite many attempts on green synthesis of AuNPs, stable biogenic AuNPs has yet to be mass produced in the market due to the aggregation of the particles. This study provides a simple one-pot method in synthesising colloidal AuNPs using eucalyptus globulus honey and Zingiber officinale (ginger) as reducing and stabilising agents. The synthesised colloidal AuNPs exhibited well-dispersed spherical morphology with average diameter of 14.5 nm and 14.1 nm for honey-reduced colloidal AuNPs (H6) and honey-reduced/ginger-stabilised colloidal AuNPs (H6G5) respectively. Significant increase in DPPH and hydroxyl radical scavenging activities were found in H6G5 compared to H6 which indicate a prominent antioxidant property of the colloidal AuNPs. The reduction of 4-nitrophenol with the aid of the colloidal AuNPs recorded a reaction time of 28 min and 62 min for H6G5 and H6 respectively compared to 240 min of reaction without the addition of catalyst. The excellent properties of these colloidal AuNPs suggest a simple method for biogenic synthesis. Hence, the synthesised colloidal AuNPs can be further exploited for biomedical and life science applications.

Enhancing the radiotherapeutic index of gamma radiation on cervical cancer cells by gold nanoparticles

Nanotechnology has the impending ability to improve the therapeutic potential of drugs and radiation-based treatment approaches for reducing cancerous cell death while curtailing collateral toxicity to non-cancerous cells. Among all metal nanomaterials, gold nanoparticles (AuNPs) are establishing themselves as an excellent radiosensitizer and serve as a multimodal modality due to their unique physicochemical properties. The primordial purpose of the work is to evaluate the synergistic effect and molecular level interaction of gamma (γ) radiation on human cervical cancer cell (HeLa) in the presence of AuNPs. Biocompatible AuNPs in combination with γ-radiation were found to exhibit elated cytotoxic effects on cancer cells as evidenced by cell-based assays. The implication of AuNPs facilitates the minimization of radiation dose employment on cultured cells. As per our experimental evaluation, the modus operandi of dual effectors ascertained that a higher amount of reactive oxygen species (ROS) plays a key role in cellular functionality collapse. In that scenario, it can be concluded that AuNP-mediated radiosensitization proved to be the plausible candidate for preclinical testing in nanoparticle-based radiotherapy.

Biocompatible, small-sized and well-dispersed gold nanoparticles regulated by silk fibroin fiber from Bombyx mori cocoons

Biocompatible, small-sized but well-dispersed gold nanoparticles (Au NPs) remain a major challenge for their synthesis. Here a convenient solution impregnation technique is developed to prepare such Au NPs under the regulation of degummed silk fibroin fibers (SFFs) extracted from Bombyx mori cocoons. SFFs play multiple roles in the formation of Au NPs such as reactive substrate to capture AuCl4- ions by the chelation of -C = O, reducing agent for Au(0) by the reduction of -OH, and modifiers to render biocompatible Au NPs by some functional groups and biomolecules. The as-prepared Au NPs with a size of 7–10 nm are embedded in the solid SFF substrate, and can disperse well in the liquid system by the disintegration of SFFs into silk fibroin (SF) in a certain CaCl2 solution. The biocompatible Au NPs exhibit uniform small size and distribute stably in both solid and solution states, which have distinctive properties and functional advantages, and bring great convenience to their storage and transportation.

One-pot ligand-free synthesis of gold nanoparticles: The role of glycerol as reducing-cum-stabilizing agent

The synthesis of gold nanoparticles (AuNPs), especially by green methods, has attracted great attention due to their unique size-dependent optical properties, biocompatibility and diverse applications in various fields. The formation of stable AuNPs with control of size and shape often requires the use of a surfactant or some surface stabilizing ligands. Unfortunately, these stabilizing agents may hinder the catalytic activity and adversely affect the biocompatibility of the surfactant/AuNPs assembly. In this article, we report a one-pot, green synthesis of ligand-free AuNPs employing the eco-friendly glycerol both as reducing agent and stabilizing agent, thereby, greatly simplifying the synthesis process. The effect of glycerol:water (G:W) ratio, pH, temperature, dilution, ionic strength and aging on the stability and particle size distribution was studied. Stable AuNPs with reasonably good size distribution (8 ± 2 nm) were obtained which, at room temperature, showed no significant agglomeration or size change up to 04 days and only slight changes were seen after 08 days. The stability and size distribution of the particles was found to be dependent on the G:W ratio, temperature and pH of the reaction media. Owing to their clean surface, the synthesized ligand-free AuNPs exhibit advantage of lower energy requirement for glycerol electro-oxidation when compared to bulk Au and AuNPs-PVP materials. Such surfactant-free biocompatible AuNPs prepared using the eco-friendly glycerol may find useful applications in catalysis and biomedical applications.

Successful Green Synthesis of Gold Nanoparticles using a Corchorus olitorius Extract and Their Antiproliferative Effect in Cancer Cells.

A facile bottom-up “green” synthetic route of gold nanoparticles (Au NPs) is described, using a leaf extract of the Malvaceae plant Corchorus olitorius as a reducing and stabilizing agent. The size and shape of the obtained nanoparticles were modulated by varying the amounts of the metal salt and the broth extract in the reaction medium. Only one hour was required for the complete conversion to Au NPs, suggesting that the reaction rate was higher or comparable to those of nanoparticles synthesized by chemical methods. The obtained nanoparticles were characterized by UV–visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, and thermal gravimetric analysis (TGA). While infrared spectroscopy was employed to characterize the various functional groups in the organic layer that stabilized the particles, TEM images were used to optimize the conditions for NPs growth. A low concentration of the C. olitorius extract yielded mixed triangular and hexagonal shapes; in contrast, quasi-spherical shapes of Au NPs with an average size of 37–50 nm were obtained at a higher extract broth concentration. The Au NPs displayed Surface Plasmon Resonance (SPR) bands at 535 nm. An in vitro cytotoxic assay of the biocompatible Au NPs revealed a strong cytotoxic activity in three human cancer cell lines, namely, colon carcinoma HCT-116, hepatocellular carcinoma HepG-2, and breast adenocarcinoma MCF-7. In-silico bioactivity, drug-likeness, and ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) predictions were conducted in order to examine the pharmacokinetic behavior of the compounds present in the C. olitorius extract.

Intracellular accumulation of gold nanoparticles by multipotent bone marrow-derived mesenchymal stem cells

Gold nanoparticles formed by mesenchymal stem cells have tremendous diagnostic and therapeutic potential in cancer. Bone marrow-derived mesenchymal stem cells (BM-MSCs) grown to ∼90% confluency exhibited intracellular gold nanoparticles (AuNPs) accumulation when incubated in 1 mM auric chloride in phosphate buffered saline (PBS) at pH 7.4 for 28 days. Scanning electron microscopy (SEM) and elemental mapping confirmed the growth and distribution of AuNPs within cells and on cell membranes, respectively. Transmission electron microscopy (TEM) of ultrathin-microtome sections of BM-MSCs incubated in auric chloride solution showed the accumulation of AuNPs throughout cells, especially on cell membranes, and within cytoplasm (especially vesicles) and nuclei. Raman spectroscopy showed the interaction of accumulated AuNPs with intracellular proteins, fatty acids, and nucleic acids, and results suggested that these AuNPs could, by enhancing Raman signals, be used to monitor cellular process. The results obtained demonstrated for the first time, the ability of BM-MSCs to bioreduce Au(III) and produce biocompatible AuNPs in cytoplasm and nuclei. This synthesis of gold nanoparticles in BM-MSCs, as intracellular accumulations, without using any added reducing or capping/stabilizing agent is potentially useful for several nano(bio)technological and biomedical applications.

Origanum vulgare mediated green synthesis of biocompatible gold nanoparticles simultaneously possessing plasmonic, antioxidant and antimicrobial properties.

PurposeThe leaves and flowering stem of Origanum vulgare contain essential oils, flavonoids, phenolic acids and anthocyanins. We propose a new, simple, one-pot, O. vulgare extract (OVE) mediated green synthesis method of biocompatible gold nanoparticles (AuNPs) possessing improved antioxidant, antimicrobial and plasmonic properties.Materials and methodsDifferent concentrations of OVEs were used to reduce gold ions and to synthetize biocompatible spherical AuNPs. Their morphology and physical properties have been investigated by means of transmission electron microscopy, ultraviolet–visible absorption spectroscopy, photon correlation spectroscopy and Fourier transform infrared spectroscopy, whereas their plasmonic properties have been tested using surface-enhanced Raman spectroscopy (SERS). The antioxidant properties of nanoparticles (NPs) have been evaluated by 2,2-diphenyl-1-picrylhydrazyl radical scavenging assay, and the antimicrobial tests were performed using the disk diffusion assay. Their cytotoxicity has been assessed by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.ResultsThe experimental results confirmed the successful synthesis of biocompatible, spherical, plasmonic NPs having a mean diameter of ~40 nm and an outstanding aqueous stability. This new class of NPs exhibits a very good antioxidant activity and presents interesting inhibitory effects against Staphylococcus aureus and Candida albicans. Due to their plasmonic properties, AuNPs are used as SERS substrates for the detection of a test molecule (methylene blue) up to a concentration of 10−7 M and a pharmaceutical compound (propranolol) in solution. Cytotoxicity assays revealed that AuNPs are better tolerated by normal human dermal fibroblast cells, while the melanoma cancer cells are more sensitive.ConclusionThe biocompatible AuNPs synthetized using OVEs showed significant bactericidal and antimycotic activities, the most sensitive microorganisms being S. aureus and C. albicans, both commonly involved in various dermatological infections. Moreover, the significant antioxidant effect might recommend their use for protective and/or preventive effect in various skin inflammatory conditions, including the reduction in side effects in dermatological infections. Meanwhile, the as-synthesized biocompatible AuNPs can be successfully used as SERS substrates for the detection of pharmaceutical compounds in aqueous solutions.

Biologically Synthesized Gold Nanoparticles Ameliorate Cold and Heat Stress-Induced Oxidative Stress in Escherichia coli.

Due to their unique physical, chemical, and optical properties, gold nanoparticles (AuNPs) have recently attracted much interest in the field of nanomedicine, especially in the areas of cancer diagnosis and photothermal therapy. Because of the enormous potential of these nanoparticles, various physical, chemical, and biological methods have been adopted for their synthesis. Synthetic antioxidants are dangerous to human health. Thus, the search for effective, nontoxic natural compounds with effective antioxidative properties is essential. Although AuNPs have been studied for use in various biological applications, exploration of AuNPs as antioxidants capable of inhibiting oxidative stress induced by heat and cold stress is still warranted. Therefore, one goal of our study was to produce biocompatible AuNPs using biological methods that are simple, nontoxic, biocompatible, and environmentally friendly. Next, we aimed to assess the antioxidative effect of AuNPs against oxidative stress induced by cold and heat in Escherichia coli, which is a suitable model for stress responses involving AuNPs. The response of aerobically grown E. coli cells to cold and heat stress was found to be similar to the oxidative stress response. Upon exposure to cold and heat stress, the viability and metabolic activity of E. coli was significantly reduced compared to the control. In addition, levels of reactive oxygen species (ROS) and malondialdehyde (MDA) and leakage of proteins and sugars were significantly elevated, and the levels of lactate dehydrogenase activity (LDH) and adenosine triphosphate (ATP) significantly lowered compared to in the control. Concomitantly, AuNPs ameliorated cold and heat-induced oxidative stress responses by increasing the expression of antioxidants, including glutathione (GSH), glutathione S-transferase (GST), super oxide dismutase (SOD), and catalase (CAT). These consistent physiology and biochemical data suggest that AuNPs can ameliorate cold and heat stress-induced oxidative damage in E. coli. Our results indicate that AuNPs may be effective antioxidants. However, further studies are needed to confirm the role of AuNPs as antioxidative agents, as well as their mechanism of action.