Synthesis of Au-Ag bimetallic nanoparticles using Korean red ginseng (Panax ginseng Meyer) root extract for chemo-photothermal anticancer therapy.

Green synthesis strategies have been widely applied for the preparation of versatile nanomaterials. Gold nanospheres with an average size of 6.95 ± 2.25 nm were green synthesized by using a 70% ethanol extract of Korean red ginseng (Panax ginseng Meyer) root as a reducing agent. A seed-mediated synthesis was conducted to prepare Au-Ag bimetallic nanoparticles using gold nanospheres as seeds. Remarkably, Au-Ag bimetallic nanoparticles with an average size of 80.4 ± 11.9 nm were synthesized. Scanning transmission electron microscopy, energy dispersive X-ray spectroscopy and elemental mappings revealed bimetallic nanoparticles with Au-Ag alloy core and Au-rich shells. A face-centered cubic structure of Au-Ag bimetallic nanoparticles was confirmed by X-ray diffraction analysis. For Au-Ag bimetallic nanoparticles, the ratio of Ag/Au was 0.20 which was detected and analyzed by inductively coupled plasma-mass spectrometry. Gold nanospheres and Au-Ag bimetallic nanoparticles were functionalized by PEGylation, folic acid conjugation and grafting onto graphene oxide. Finally, docetaxel was loaded for evaluating the in vitro cell viability on cancer cells. Successful functionalization was confirmed by Fourier-transform infrared spectra. The anticancer activity of the docetaxel-loaded nanoparticles was higher than that of their non-docetaxel-loaded counterparts. The highest anticancer activity on human gastric adenocarcinoma cells (AGS) was observed in the docetaxel-loaded gold nanospheres that were functionalized by PEGylation, folic acid conjugation and grafting onto graphene oxide. Additionally, grafting onto graphene oxide and docetaxel loading induced high intracellular reactive oxygen species generation. For chemo-photothermal (PTT) anticancer therapy, cell viability was investigated using near-infrared laser irradiation at 808 nm. The highest chemo-PTT anticancer activity on AGS cells was observed in the docetaxel-loaded Au-Ag bimetallic nanoparticles. Therefore, the newly prepared docetaxel-loaded Au-Ag bimetallic nanoparticles in the current report have potential applications in chemo-PTT anticancer therapy.

Potential applications of PEGylated green gold nanoparticles in cyclophosphamide-induced cystitis.

We investigated the effect of green tea extract PEGylated gold nanoparticles (P-AuNPs) making use of its targeted and sustained drug delivery against cyclophosphamide (CYP)-induced cystitis. AuNPs were synthesized by reduction reaction of gold salts with green tea extract following the concept of green synthesis. Mostly spherical-shaped P-AuNPs were synthesized with an average size of 14.3 ± 3.3 nm. Pre-treatment with P-AuNPs (1, 10 mg/kg, i.p.) before CYP (150 mg/kg, i.p.) challenge suggested its uroprotective properties. P-AuNPs significantly reversed all pain-like behaviours and toxicities produced by CYP resulting in a decreased aspartate aminotransferase, alanine aminotransferase, C-reactive protein, and creatinine level. P-AuNPs increased anti-oxidant system by increasing the level of reduced glutathione, glutathione-S-transferase, catalase and superoxide dismutase, and reduced nitric oxide production in bladder tissue. Additionally, it attenuated hypokalaemia and hyponatremia, along with a decrease in Evans blue content in bladder tissue and peritoneal cavity. CYP-induced bladder tissue damage observed by macroscopic and histological findings were remarkably attenuated by P-AuNPs, along with reduced fibrosis of collagen fibre in bladder smooth muscles shown by Masson's trichrome staining. Additionally, alterations in hematological parameters and clinical scoring were also prevented by P-AuNPs suggesting its uroprotective effect.

Folic Acid and Chitosan-Functionalized Gold Nanorods and Triangular Silver Nanoplates for the Delivery of Anticancer Agents.

Background: Advances in the field of nanotechnology have shed light on the applications of nanoparticles for cancer treatment. Methods: Folic acid and chitosan-functionalized gold nanorods (FACS-R) and triangular silver nanoplates (FACS-T) were synthesized and their properties were elucidated by UV-visible spectrophotometry, Fourier-transform infrared spectroscopy, field emission transmission electron microscopy and high-resolution X-ray diffraction. Results: The average size of the FACS-R was determined to be a transverse length of 13.1 ± 1.8 nm and a longitudinal length of 47.2 ± 8.9 nm with an aspect ratio of 3.6. The average size of FACS-T was measured to be 31.8 ± 7.7 nm. Colloidal solutions of FACS-R and FACS-T were stable on the shelf at ambient temperature for 14 days in the dark. Anticancer agents were encapsulated in FACS-R and FACS-T. FACS-T showed a higher encapsulation efficiency with docetaxel, paclitaxel and diallyl disulfide than FACS-R. The cell viability on human gastric adenocarcinoma cells (AGS), human epithelial cervix adenocarcinoma cells (HeLa) and human colorectal adenocarcinoma cells (HT-29) after treatment with anticancer agent-encapsulated FACS-R and FACS-T was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Interestingly, paclitaxel-encapsulated FACS-R and FACS-T showed the highest percentages of early and late apoptosis on HeLa cells. A cell cycle analysis demonstrated increased G2/M arrest on HeLa cells with docetaxel and paclitaxel-encapsulated FACS-R and FACS-T. The FACS-T induced more G2/M arrest on HeLa cells than the FACS-R. To assess applications in near-infrared photothermal therapy (PTT), the cell viability on HeLa cells with the anticancer agent-encapsulated FACS-R and FACS-T was assessed in the presence or absence of 808 nm laser irradiation. The results showed that 808 nm laser irradiation significantly decreased cell viability. Conclusion: Collectively, the triangular silver nanoplates were more effective than the gold nanorods for PTT. We believe that as-prepared nanoparticles have remarkable features and will become promising future nanomedicine.

Facile Green Synthesis of Titanium Dioxide Nanoparticles by Upcycling Mangosteen (Garcinia mangostana) Pericarp Extract.

In the present report, green synthesis of titanium dioxide nanoparticles (TiO2 NPs) was performed by upcycling mangosteen (Garcinia mangostana) pericarp extract (methanol and ethyl acetate extracts). Field emission scanning electron microscopy images revealed an aggregated structure with a highly porous network of TiO2 NPs. TiO2 NPs synthesized with ethyl acetate extract (EtOAc-TiO2 NPs) exhibited more monodispersity and possessed smoother surfaces than the control TiO2 NPs (Con-TiO2 NPs) and TiO2 NPs synthesized with methanol extract (MeOH-TiO2 NPs). High-resolution X-ray diffraction patterns clearly confirmed that TiO2 NPs had a crystalline nature. A mixture of anatase and rutile was observed in Con-TiO2 NPs and MeOH-TiO2 NPs, while EtOAc-TiO2 NPs had only anatase with the smallest size (12.50 ± 1.81 nm). Ethyl acetate extract contained the highest amount of α-mangostin; thus, the surface of TiO2 NPs was functionalized with ethyl acetate extract. The functionalized TiO2 NPs synthesized with ethyl acetate extract (EtOAc-TiO2-αm) showed the highest 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH) radical scavenging activity. In vitro cell viability on mouse fibroblast cells (NIH3T3) indicated that the newly synthesized TiO2 NPs did not show any significant cytotoxicity. Therefore, the TiO2 NPs in the present report have the potential to be used in cosmetic applications such as sunscreens.

Anticancer prospects of silver nanoparticles green-synthesized by plant extracts.

Silver nanoparticles (AgNPs) were synthesized via a green strategy using fifty-eight plant extracts that originated from Vietnam and Indonesia. Among the fifty-eight AgNP samples, we selected six AgNP samples synthesized by the extracts of Areca catechu, Hypotrachyna laevigata, Ardisia incarnata, Maesa calophylla, Maesa laxiflora and Adinandra poilanei. Remarkably, these six extracts exhibited higher 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and reducing power than the other extracts. Furthermore, the contents of total phenolic compounds and reducing sugars in the six selected extracts were also higher than those in the other extracts. The six selected AgNP samples showed strong surface plasmon resonance in the range of 416-438 nm. They were all spherical shaped with an average size from 12.5 ± 1.0 nm to 21.3 ± 4.9 nm as measured by field-emission transmission electron microscopy images. The hydrodynamic sizes were measured to be 49.5-122.6 nm with negative zeta potential values. Colloidal stability was excellent on the shelf for 28 days and in cell culture medium. The cytotoxicity assessment and generation of reactive oxygen species (ROS) in A549 and HeLa cells demonstrated that the AgNP samples prepared by Ardisia incarnata, Maesa calophylla, and Maesa laxiflora showed relatively high cytotoxicity and excess ROS generation among the six selected AgNP samples. Exposure of the AgNP samples to A549 and HeLa cells resulted in cell death, which was mostly due to necrosis but slightly due to late apoptosis. Cell cycle analysis demonstrated a significant increase in the cell population in the S phase. The green-synthesized AgNPs induced cell death, suggesting anticancer prospects that may offer new insight into the development of an anticancer nanomedicine.

Diallyl disulphide-loaded spherical gold nanoparticles and acorn-like silver nanoparticles synthesised using onion extract: catalytic activity and cytotoxicity.

Onion (Allium cepa) extract was used for the green synthesis of gold and silver nanoparticles. Each colloidal solution exhibited surface plasmon resonance, with a peak at 532 nm for gold nanoparticles and 391 nm for silver nanoparticles. Microscopic results confirmed the presence of spherical shapes. The X-ray diffraction pattern demonstrated a face-centered cubic structure. Both nanoparticles had negative zeta potentials and retained colloidal stability in cell culture medium. Catalytic applications were evaluated for 4-nitrophenol reduction and methyl orange degradation reactions by monitoring with UV-visible spectrophotometry. Furthermore, the nanoparticles demonstrated no significant cytotoxicity against human pancreas ductal adenocarcinoma cells (PANC-1) and human colorectal adenocarcinoma cells (HT-29). PEGylation and diallyl disulphide loading of the gold and silver nanoparticles meaningfully reduced the cell viability of both cell lines. Furthermore, diallyl disulphide loading resulted in more cytotoxicity against PANC-1 cells than against HT-29 cells. Additionally, the gold nanoparticles were more cytotoxic than the silver nanoparticles upon diallyl disulphide loading. Interestingly, after PEGylation and diallyl disulphide loading, the silver nanoparticles exhibited acorn-like shapes, while the gold nanoparticles retained spherical shapes. This result suggested that nanoparticles green-synthesised by onion extract have possibilities as nanocatalysts and drug delivery nanocarriers for catalytic and nanomedicine applications.

Highly Selective Synthesis of Hydrazoarenes from Nitroarenes via Polystyrene-Supported Au-Nanoparticle-Catalyzed Reduction: Application to Azoarenes, Aminoarenes, and 4,4'-Diaminobiaryls.

A selective synthesis of hydrazoarene from nitroarene and its application are reported. Using polystyrene (PS) resins as solid supports for Au nanoparticles (AuNPs), polystyrene-supported Au nanoparticles (AuNPs@PS) were synthesized and characterized. In the presence of AuNPs@PS (1.0 mol %) as a catalyst, nitroarenes afforded corresponding hydrazoarenes (up to 99%) with high selectivity (up to 100%) under mild reaction conditions (NaBH4, 50% aq. EtOH, and room temperature). Depending on the reaction conditions (the amount of NaBH4, the substituent of nitroarenes, and the sequential addition of HCl), nitroarenes were converted to corresponding azoarenes (up to 95%), aminoarenes (up to 99%), and 4,4'-diaminobiaryls (up to 99%). Our easily recyclable catalytic system using a solid-phase reaction vessel provides an attractive synthetic method in an eco-friendly and sustainable manner.

Green Synthetic Nanoarchitectonics of Gold and Silver Nanoparticles Prepared Using Quercetin and Their Cytotoxicity and Catalytic Applications.

Quercetin is a flavonoid and is abundant in the plant kingdom. Green nanoparticles (gold and silver) were synthesized by using quercetin as a reductant via a green route for their potential nanoarchitechtonic applications. There were no toxic chemicals involved during the synthesis. The gold and silver nanoparticles exhibited surface plasmon resonance at 527 nm and 401 nm, respectively. Both nanoparticle solutions retained excellent colloidal shelf stability for 7 days and in cell culture medium. The crystal structure of the nanoparticles was observed by X-ray diffraction analysis. Field emission transmission electron microscopy images revealed that spherical nanoparticles were synthesized, with an average size of 20.2±4.8 nm for gold nanoparticles and 32.4±14.0 nm for silver nanoparticles. Observation of clear lattice fringes in the microscopic images suggested that both types of nanoparticles possessed a face-centered cubic structure. Catalytic activity was evaluated with respect to 4-nitrophenol reduction and methyl orange degradation. When increasing the amount of gold or silver nanoparticles used as a catalyst, the rate constant of the catalytic reaction was also increased. Cytotoxicity assessment on cancer cells demonstrated that both types of nanoparticles can be appropriate candidates for delivery vehicles of biologically active molecules, such as anticancer agents.

Sesquiterpenoids from Tussilago farfara Flower Bud Extract for the Eco-Friendly Synthesis of Silver and Gold Nanoparticles Possessing Antibacterial and Anticancer Activities.

Sesquiterpenoids from the flower bud extract of Tussilago farfara were effectively utilized as a reducing agent for eco-friendly synthesis of silver and gold nanoparticles. The silver and gold nanoparticles had a characteristic surface plasmon resonance at 416 nm and 538 nm, respectively. Microscopic images revealed that both nanoparticles were spherical, and their size was measured to be 13.57 ± 3.26 nm for the silver nanoparticles and 18.20 ± 4.11 nm for the gold nanoparticles. The crystal structure was determined to be face-centered cubic by X-ray diffraction. Colloidal stability of the nanoparticle solution was retained in a full medium, which was used in the cell culture experiment. The antibacterial activity result demonstrated that the silver nanoparticles showed better activity (two- to four-fold enhancement) than the extract alone on both Gram-positive and Gram-negative bacteria. Interestingly, the highest antibacterial activity was obtained against vancomycin-resistant Enterococci Van-A type Enterococcus faecium. Cytotoxicity on cancer cell lines confirmed that gold nanoparticles were more cytotoxic than silver nanoparticles. The highest cytotoxicity was observed on human pancreas ductal adenocarcinoma cells. Therefore, both nanoparticles synthesized with the sesquiterpenoids from T. farfara flower bud extract can be applicable as drug delivery vehicles of anticancer or antibacterial agents for future nanomedicine applications.

Shape-dependent cytotoxicity and cellular uptake of gold nanoparticles synthesized using green tea extract.

In the present report, three different shapes of chitosan-capped gold nanoparticles (nanospheres, nanostars, and nanorods) were synthesized to investigate the effects of shape on cytotoxicity and cellular uptake in cancer cells. Green tea extract was utilized as a reducing agent to reduce gold salts to gold nanospheres. Gold nanostars were prepared using an as-prepared nanosphere solution as a seed solution. Gold nanorods were synthesized using a conventional method. All three types of gold nanoparticles showed their characteristic surface plasmon resonance bands upon UV-visible spectrophotometry. In high-resolution transmission electron microscopy images, lattice structures were clearly observed in all three shapes, confirming the crystalline nature of the nanoparticles. All three colloidal solutions of gold nanoparticles retained colloidal stability in various solutions. To assess cytotoxicity, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed on four cancer cell lines. The cytotoxicity was the highest in nanorods, followed by nanostars and finally nanospheres. The cellular uptake of gold nanoparticles in human hepatocyte carcinoma cells (HepG2) was measured, and the results followed the order nanospheres > nanorods > nanostars. The outcomes of the current study may assist in the shape design of gold nanoparticles for therapeutic applications as drug delivery vehicles in the field of nanomedicine.

Green synthesis and biological activities of silver nanoparticles prepared by Carpesium cernuum extract.

The extract of Carpesium cernuum whole plant was successfully used as a green factory for the synthesis of silver nanoparticles in a one-step, one-pot process. The extract efficiently reduced silver ions to spherical silver nanoparticles. The size was measured as 13.0 ± 0.2 nm from high resolution transmission electron microscopic images. The reaction yield was determined to be 99.6% using inductively coupled plasma optical emission spectroscopy. The silver nanoparticles were highly stable for 28 days at ambient temperature without forming agglomeration or aggregation of nanoparticles. Dose-dependent antioxidant activity of the silver nanoparticles was observed in terms of the scavenging activity of 2,2-diphenyl-1-picrylhydrazyl radicals. The silver nanoparticles also exerted cytotoxicity on Mus musculus skin melanoma cells (B16F10) and human lung cancer cells (A549) in a dose-dependent manner. Specifically, the cytotoxicity of the silver nanoparticles on A549 cells was closely associated with apoptotic cell death. Cellular uptake of the silver was evaluated via inductively coupled plasma mass spectrometry, and a higher percentage of silver was taken up by A549 cells (22.6%) than by B16F10 cells (17.3%). This result indicated that higher cellular uptake of silver nanoparticles resulted in higher cytotoxicity on A549 cells. Therefore, plant extracts are capable of being valuable natural sources for the green synthesis of silver nanoparticles that exhibit potent biological activities for pharmaceutical and biomedical applications in future nanomedicine.

Assessing the antioxidant, cytotoxic, apoptotic and wound healing properties of silver nanoparticles green-synthesized by plant extracts.

We synthesized silver nanoparticles using thirty Chinese plant extracts via a green synthetic strategy. UV-visible spectra showed that the silver nanoparticles have an absorbance at 450 nm. Among the thirty extracts, seven extracts (Cratoxylum formosum, Phoebe lanceolata, Scurrula parasitica, Ceratostigma minus, Mucuna birdwoodiana, Myrsine africana and Lindera strychnifolia) exhibited the successful synthesis of silver nanoparticles. These seven extracts showed higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and reducing power than the other extracts. The silver nanoparticles synthesized using these seven extracts were mostly spherical with high colloidal stability. The cytotoxicity of these seven silver nanoparticle samples on human lung cancer cells (A549) was clearly higher than that of the extracts alone. Furthermore, the cytotoxicity was affected by the presence or absence of fetal bovine serum. Moreover, the cytotoxicity of the silver nanoparticles synthesized with Cratoxylum formosum and Mucuna birdwoodiana extracts resulted in apoptotic cell death in A549 cells. The wound healing activity observed by the cell scratch method on mouse fibroblast cells (NIH3T3) suggested that the Lindera strychnifolia extract produced silver nanoparticles with decent activity. These results provide ample and systematic information for researchers on the green synthesis of silver nanoparticles using plant extracts.

Fabrication of nanoribbons by dielectrophoresis assisted cold welding of gold nanoparticles on mica substrate.

Using alternating current electric fields, nanoribbons are fabricated from an aqueous suspension of gold nanoparticles (AuNPs) on mica substrate without resorting to further chemical functionalization of AuNPs. The potential and kinetic energies of AuNPs subjected to attractive forces from a mica substrate provide sufficient energy to pass the diffusion barrier of the gold atoms, which eventually leads to cold welding. A dielectrophoresis force exerted on polarizable particles in a non-uniform electric field contributes to the directed growth of the cold welding that occurs by adjusting the lattice structures of AuNPs. Depending on the concentration of the AuNP suspension, the frequency of the electric field, and the geometry of electrodes, various morphologies of nanoribbons are fabricated. It turns out that the welded region is nearly perfect to provide the same crystal orientation and strength as the rest of the nanostructures, which can be extensively utilized in the fabrication of various nanostructures.

Antioxidant Potential of Artemisia capillaris, Portulaca oleracea, and Prunella vulgaris Extracts for Biofabrication of Gold Nanoparticles and Cytotoxicity Assessment.

Three aqueous plant extracts (Artemisia capillaris, Portulaca oleracea, and Prunella vulgaris) were selected for the biofabrication of gold nanoparticles. The antioxidant activities (i.e., free radical scavenging activity, total phenolic content, and reducing power) of the extracts and how these activities affected the biofabrication of gold nanoparticles were investigated. P. vulgaris exerted the highest antioxidant activity, followed by A. capillaris and then P. oleracea. P. vulgaris was the most efficient reducing agent in the biofabrication process. Gold nanoparticles biofabricated by P. vulgaris (PV-AuNPs) had a maximum surface plasmon resonance of 530 nm with diverse shapes. High-resolution X-ray diffraction analysis showed that the PV-AuNPs had a face-centered cubic structure. The reaction yield was estimated to be 99.3% by inductively coupled plasma optical emission spectroscopy. The hydrodynamic size was determined to be 45 ± 2 nm with a zeta potential of - 13.99 mV. The PV-AuNPs exerted a dose-dependent antioxidant activity. Remarkably, the highest cytotoxicity of the PV-AuNPs was observed against human colorectal adenocarcinoma cells in the absence of fetal bovine serum, while for human pancreas ductal adenocarcinoma cells, the highest cytotoxicity was observed in the presence of fetal bovine serum. This result demonstrates that P. vulgaris extract was an efficient reducing agent for biofabrication of gold nanoparticles exerting cytotoxicity against cancer cells.

Upcycling of jellyfish (Nemopilema nomurai) sea wastes as highly valuable reducing agents for green synthesis of gold nanoparticles and their antitumor and anti-inflammatory activity.

Due to its tentacle poison and huge body, giant jellyfish (Nemopilema nomurai) poses challenging issues to the environment and ecosystems. Here we developed, upcycling a giant jellyfish extract as a reducing agent, a green synthetic method of gold nanoparticles (JF-AuNPs) which possess biological activities. The colloidal solutions of JF-AuNPs were blue, violet, purple and pink depending on the extract concentration. UV-visible spectra exhibited two surface plasmon resonance bands at 5 4 0 ∼ 550 nm and 810 nm. Spherical shapes with an average size of 35.2 ± 8.7 nm and triangular nanoplates with an average height of 70.5 ± 30.3 nm were observed. A face-centered cubic structure was confirmed by high-resolution X-ray diffraction. JF-AuNPs exhibited significant cytotoxic effect against HeLa cancer cells but not against normal cells such as NIH-3T3 and Raw 264.7 cells. In HeLa cells, JF-AuNPs decreased the phosphorylation of AKT and ERK, which are crucial for cell proliferation. Also, JF-AuNPs decreased NO secretion and iNOS expression levels, resulting in anti-inflammatory effects in LPS-inflamed macrophages. Collectively, we established a green synthesis of anti-tumorigenic and anti-inflammatory JF-AuNPs using the extract of jellyfish sea wastes. Thus, beneficial effects of JF-AgNPs must be weighed in further studies in vivo and it can be potent nanomedicine for future applications.

Highly stable gold nanoparticles green-synthesized by upcycling cartilage waste extract from yellow-nose skate (Dipturus chilensis) and evaluation of its cytotoxicity, haemocompatibility and antioxidant activity.

Skate (Dipturus chilensis) cartilage extract was utilized as a green reducing agent for the synthesis of spherical gold nanoparticles with an average size of 16.7 ± 0.2 nm. The gold nanoparticle solution showed a surface plasmon resonance at 543 nm with a wine-red colour. A strong X-ray diffraction pattern and clear lattice structure in high-resolution transmission electron microscopy indicated a face-centred cubic structure of the gold nanoparticles. The gold nanoparticles retained excellent colloidal stability. Gold nanoparticles showed strong antioxidant activity in terms of 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity. In vitro cytotoxicity was observed for seven cancer cells assessed by the water-soluble tetrazolium assay. Among the seven cancer cells, the highest cytotoxicity was observed for MDA-MB-231 (human breast adenocarcinoma cell) followed by HeLa (human epithelial cervix adenocarcinoma cell) and lastly by HT-29 (human colorectal adenocarcinoma cell). Furthermore, gold nanoparticles showed excellent haemocompatibility, indicating the possibility of their use as a future nanomedicine. These results strongly suggest that gold nanoparticles green-synthesized by upcycling skate cartilage waste extract will be valuable carriers or vehicles for the delivery of drugs or bioactive molecules, such as anti-cancer agents, for the treatment of cancers.

Green Synthesis, Characterization and Catalytic Activity of Gold Nanoparticles Prepared Using Rosmarinic Acid.

Green strategies to synthesize gold nanoparticles have attracted a substantial amount of attention because global sustainability is a focal issue in many research areas. In the present study, rosmarinic acid was utilized as a reducing agent to reduce gold ions to gold nanoparticles. The characteristic surface plasmon resonance of gold nanoparticles was observed at 532 nm with a pink-colored colloidal solution. High-resolution transmission electron microscopy (HR-TEM) revealed the presence of spherical nanoparticles along with triangular nanoplates. The average nanoparticle size was determined as 30.46 ± 6.25 nm from HR-TEM images, and the hydrodynamic size was measured as 31.90 nm. An evaluation of the shelf stability indicated that the colloidal solution retained an excellent stability for two weeks at room temperature. A large negative value for the zeta potential (-24.09 ±3.97 mV) also suggested the excellent stability of the colloidal solution. The face-centered cubic structure of gold nanoparticles was confirmed by the strong diffraction peaks in the high-resolution X-ray diffraction analysis. Hydroxyl and ketone functional groups in rosmarinic acid were most likely involved in the synthesis of gold nanoparticles. Catalytic activity was evaluated in 4-nitrophenol, methylene blue and methyl orange reduction reactions in the presence of sodium borohydride. The order of catalytic activity for reduction reactions was methylene blue > methyl orange > 4-nitrophenol. These three reactions were conducted at four different reaction temperatures (room temperature, 30 °C, 40 °C and 50 °C). The catalytic activity was temperature-dependent, and the highest rate constant was obtained in the methylene blue reduction reaction at 50 °C.

An aqueous extract of Nomura's jellyfish ameliorates inflammatory responses in lipopolysaccharide-stimulated RAW264.7 cells and a zebrafish model of inflammation.

The recent mass emergence of Nomura's jellyfish (Nemopilema nomurai) has caused much economic and environmental damage. However, there is no innovative strategy to dispose of or utilize these jellyfish. Some reports suggest that the jellyfish may be bioactive resources and a source of important compounds with antibacterial activity. Here, we examined the effect of an aqueous extract of Nomura's jellyfish (AENJ) on lipopolysaccharide (LPS)-stimulated Raw 264.7 macrophages and a zebrafish model of inflammation and analyzed the underlying molecular mechanisms. AENJ downregulated inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) mRNA levels in LPS-stimulated Raw 264.7 macrophages, with no apparent cytotoxic effects. However, AENJ had no effect on expression of other inflammation-related genes such as interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and MCP-1. Furthermore, AENJ reduced expression of nerve injury-induced protein 1 (Ninj1), which is an important adhesion molecule, thereby reducing cell adhesion to the extracellular matrix (ECM) in vitro. The inhibitory effect of AENJ on leukocytes was confirmed in LPS-microinjected zebrafish larvae; AENJ reduced the number of the infiltrate accumulating at the site of inflammation. In addition, AENJ suppressed the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9 in LPS-stimulated Raw 264.7 cells. Finally, AENJ blocked nuclear translocation of nuclear factor kappa B (NF-κB), a key transcription factor for inflammatory responses, in Raw 264.7 cells in a dose-dependent manner. Collectively, the data suggest that AENJ inhibits expression of COX and iNOS by blocking NF-κB signaling pathways and suppresses the activity of macrophages by downregulating Ninj1 and MMPs. Therefore, AENJ may be a useful preventive neutraceutical, or therapeutic agent against inflammatory disorders.

Anisotropic Snowman-Like Silver Nanoparticles Synthesized by Caesalpinia sappan Extract and In Vitro Antibacterial Activity.

Anisotropic snowman-like silver nanoparticles (AgNPs) were synthesized using the extract of Caesalpinia sappan heartwood as a reducing agent in the presence of cetyltrimethylammonium bromide. Two surface plasmon resonance bands of the orange solution were observed at 446 nm and 539 nm in UV-visible spectra. High-resolution X-ray diffraction analysis confirmed the face-centered cubic structure of the AgNPs. High-resolution transmission electron microscopy images clearly revealed snowman-like AgNPs with an average size of 34.36 ± 11.44 nm. The C-O functional group was most likely involved in the synthesis of the AgNPs, which was demonstrated by Fourier transform infrared spectra. Most interestingly, the snowman-like AgNPs exhibited higher antibacterial activity than the spherical AgNPs and the extract alone. Among the tested strains, the snowman-like AgNPs showed the highest activity against Staphylococcus aureus, with minimum inhibitory concentrations of 4.69 µg/mL for the extract and 0.443 µg/mL for the silver. The antibacterial activity of the snowman-like AgNPs increased 24-fold against S. aureus. These results strongly suggested that the snowman-like AgNPs synthesized from C. sappan extract have potential for treating infected disease caused by S. aureus when the antibacterial activity was combined from plant extract and AgNPs. To our knowledge, the present report is the first in which the snowman-like AgNPs synthesized using a plant extract as a reducing agent showed excellent In Vitro antibacterial activity.

Green Synthesis and Catalytic Activity of Gold Nanoparticles/Graphene Oxide Nanocomposites Prepared By Tannic Acid.

Tannic acid is a phenolic compound that is abundant in plants. Five different concentrations of tannic acid were used as a reducing agent to synthesize gold nanoparticles (AuNPs). Three kinds of AuNPs were prepared to evaluate their catalytic activity for the 4-nitrophenol reduction reaction in the presence of sodium borohydride: (i) Colloidal solutions of AuNPs synthesized using tannic acid as a reducing agent (TA-AuNPs), (ii) Nanoparticles made by centrifuging the colloidal solution of TA-AuNPs followed by re-dispersion with deionized water (cf-TA-AuNPs), and (iii) Nanoparticles made by the in situ crystallization of TA-AuNPs on graphene oxide (TA-AuNPs-GO). TA-AuNPs, cf-TA-AuNPs and TA-AuNPs-GO exhibited a characteristic surface plasmon resonance band at 527~564 nm. High resolution transmission electron microscopy images revealed spherical-shaped nanoparticles. The rate constants of 4-nitrophenol reduction reaction increased for all three types of AuNPs with decreasing tannic acid concentration used during the synthetic process. The rate constants of cf-TA-AuNPs and TA-AuNPs-GO increased 1.45~1.64-fold and 2.25~4.49-fold, respectively, compared with the rate constants of TA-AuNPs. The conversion yields from 4-nitrophenol to 4-aminophenol in the presence of the cf-TA-AuNPs catalysts were measured using reverse phase high performance liquid chromatography. The conversion yield was excellent in a range of 97.57~99.43%.