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.

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%.

Vancomycin-Functionalized Gold and Silver Nanoparticles as an Antibacterial Nanoplatform Against Methicillin-Resistant Staphylococcus aureus.

The functionalization of metallic nanoparticles using antibiotics is a promising nanoplatform to combat bacterial resistance. In the current report, vancomycin was used to functionalize gold nanoparticles (Van-AuNPs) and silver nanoparticles (Van-AgNPs) through a one-step, one-pot process. The process is facile and employs a green synthetic route. Vancomycin was used as a reducing agent to generate Van-AuNPs and Van-AgNPs from gold and silver ions, respectively. Surface plasmon resonance was observed at 520 nm for Van-AuNPs and at 405 nm for Van-AgNPs. Both Van-AuNPs and Van-AgNPs were spherically shaped, with average diameters of 11.01 ± 3.62 nm and 12.08 ± 2.13 nm, respectively. Strong diffraction peaks in the X-ray diffraction profiles of both nanoparticles confirmed their face-centered cubic structures. The Van-AgNPs presented higher in vitro antibacterial activity (2.4-4.8-fold increase) than Van-AuNPs against methicillin-resistant Staphylococcus aureus (MRSA). These results suggest that AgNPs provide a more effective anti-MRA nanoplatform than AuNPs for vancomvcin functionalization.

Crystalline Silver Nanoparticles by Using Polygala tenuifolia Root Extract as a Green Reducing Agent.

Due to the emergence of multidrug-resistant bacteria, silver nanoparticles (AgNPs) have found interest as a new category of antibacterial agents. The toxicity of the chemicals involved in the commonly employed chemical methods for synthesizing AgNPs present limitations for subsequent pharmaceutical and biomedical applications. In this report, 70% aqueous ethanol extracts of Polygala tenuifolia root were used to reduce Ag+1 ions for AgNPs synthesis. The as-synthesized AgNPs were characterized via UV-Visible spectrophotometry, high resolution transmission electron microscopy, atomic force microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. A strong surface plasmon resonance band was observed at 414 nm. Images from the high resolution transmission electron microscopy and atomic force microscopy demonstrated the spherical and irregular shapes of the AgNPs were synthesized. The AgNP crystalline structure was confirmed by the strong diffraction peaks in the X-ray diffraction results and by the bright circular spots observed in selected-area electron diffraction, whose average diameter was measured to be 17.97 8.63 nm or 15.12 nm via high resolution transmission electron microscopy images or X-ray diffraction analysis, respectively. The as-synthesized AgNPs exerted the highest antibacterial activity against Escherichia coli among the tested Gram-positive and Gram-negative bacteria. The current method is eco-friendly, straightforward, cost-effective, biocompatible, and easily scaled up to produce of AgNPs for applications in the treatment of bacterial infections.

Silver Nanoparticles Synthesized Using Caesalpinia sappan Extract as Potential Novel Nanoantibiotics Against Methicillin-Resistant Staphylococcus aureus.

Silver nanoparticles (AgNPs) have been shown to be effective antibacterial agents against methicillin-resistant Staphylococcus aureus (MRSA). In this study, AgNPs were synthesized using Caesalpinia sappan extract as a reducing agent to convert Ag+ to AgNPs. Seven stabilizers (surfactants and polymers) were added during the reduction step to increase the colloidal stability and to enhance the antibacterial activity of the AgNPs. Spherical and amorphous particles were primarily observed, with estimated diameters ranging from 30.2 to 47.5 nm. X-ray diffraction confirmed the face centered cubic structures of the AgNPs. Among the employed stabilizers, the cationic surfactant cetyltrimethylammonium bromide (CTAB) exhibited the highest antibacterial activity against 19 strains of MRSA, followed by polyvinylpyrrolidone (PVP, average molecular weight of 10,000). In contrast, the anionic surfactants sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (NaDDBS) did not exhibit any significant antibacterial activity, suggesting that the cationic surfactant head group contributed to the higher antibacterial activity of the AgNPs against MRSA.

Green synthesis of gold nanoparticles using chlorogenic acid and their enhanced performance for inflammation.

Here we developed a novel green synthesis method for gold nanoparticles (CGA-AuNPs) using chlorogenic acid (CGA) as reductants without the use of other chemicals and validated the anti-inflammatory efficacy of CGA-AuNPs in vitro and in vivo. The resulting CGA-AuNPs appeared predominantly spherical in shape with an average diameter of 22.25±4.78nm. The crystalline nature of the CGA-AuNPs was confirmed by high-resolution X-ray diffraction and by selected-area electron diffraction analyses. High-resolution liquid chromatography/electrospray ionization mass spectrometry revealed that the caffeic acid moiety of CGA forms quinone structure through a two-electron oxidation causing the reduction of Au(3+) to Au(0). When compared to CGA, CGA-AuNPs exhibited enhanced anti-inflammatory effects on NF-κB-mediated inflammatory network, as well as cell adhesion. Collectively, green synthesis of CGA-AuNPs using bioactive reductants and mechanistic studies based on mass spectrometry may open up new directions in nanomedicine and CGA-AuNPs can be an anti-inflammatory nanomedicine for future applications. FROM THE CLINICAL EDITOR: Gold nanoparticles (Au NPs) have been shown to be very useful in many applications due to their easy functionalization capability. In this article, the authors demonstrated a novel method for the synthesis of gold nanoparticles using chlorogenic acid (CGA) as reductants. In-vitro experiments also confirmed biological activity of the resultant gold nanoparticles. Further in-vivo studies are awaited.

Root extracts of Polygala tenuifolia for the green synthesis of gold nanoparticles.

Traditional medicinal plants possess diverse active constituents for exerting their biological activities. Recently, the innovative applications of plant extracts have revealed their promise as 'green' reducing agents for the reduction of metal ions during the synthesis of metallic nanoparticles. Herein, we report the use of 70% ethanol extracts from Polygala tenuifolia roots as a 'green' reducing agent for the production of gold nanoparticles by reducing gold(III) chloride trihydrate. Gold nanoparticles were characterized using UV-Visible spectrophotometry, high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The gold nanoparticles had characteristic surface plasmon resonance bands at 535 nm. HR-TEM and AFM images revealed major spherical-shaped nanoparticles. The average diameter was measured to be 9.77±3.09 nm using HR-TEM images. The crystalline structure of the gold nanoparticles was confirmed through lattice fringes and circular spots within the selected area electron diffraction in the HR-TEM images along with the XRD peaks. The gold nanoparticles exhibited enhanced anticoagulant activity, as assessed by activated partial thromboplastin time. The current method is a straightforward, environmentally friendly, and inexpensive method for the production of gold nanoparticles using extracts from traditional medicinal plants.

Wound healing and antibacterial activities of chondroitin sulfate- and acharan sulfate-reduced silver nanoparticles.

For topical applications in wound healing, silver nanoparticles (AgNPs) have attracted much attention as antibacterial agents. Herein, we describe a green-synthetic route for the production of biocompatible and crystalline AgNPs using two glycosaminoglycans, chondroitin sulfate (CS) and acharan sulfate (AS), as reducing agents. The synthetic approach avoids the use of toxic chemicals, and the yield of AgNPs formation is found to be 98.1% and 91.1% for the chondroitin sulfate-reduced silver nanoparticles (CS-AgNPs) and the acharan sulfate-reduced silver nanoparticles (AS-AgNPs), respectively. Nanoparticles with mostly spherical and amorphous shapes were observed, with an average diameter of 6.16 ± 2.26 nm for CS-AgNPs and 5.79 ± 3.10 nm for AS-AgNPs. Images of the CS-AgNPs obtained from atomic force microscopy revealed the self-assembled structure of CS was similar to a densely packed woven mat with AgNPs sprinkled on the CS. These nanoparticles were stable under cell culture conditions without any noticeable aggregation. An approximately 128-fold enhancement of the antibacterial activities of the AgNPs was observed against Enterobacter cloacae and Escherichia coli when compared to CS and AS alone. In addition, an in vivo animal model of wound healing activity was tested using mice that were subjected to deep incision wounds. In comparison to the controls, the ointments containing CS-AgNPs and AS-AgNPs stimulated wound closure under histological examination and accelerated the deposition of granulation tissue and collagen in the wound area. The wound healing activity of the ointments containing CS-AgNPs and AS-AgNPs are comparable to that of a commercial formulation of silver sulfadiazine even though the newly prepared ointments contain a lower silver concentration. Therefore, the newly prepared AgNPs demonstrate potential for use as an attractive biocompatible nanocomposite for topical applications in the treatment of wounds.

Melamine nanosensing with chondroitin sulfate-reduced gold nanoparticles.

Gold nanoparticles were green-synthesized using a glycosaminoglycan, chondroitin sulfate, as the reducing agent by mixing Au3+ and chondroitin sulfate under heating. Chondroitin sulfate-reduced gold nanoparticles were characterized by UV-Vis spectrophotometry, high resolution transmission electron microscopy and atomic force microscopy. The yield of Au3+ to Au0 was measured as 80.1% by inductively coupled plasma-atomic emission spectroscopy. A mostly spherical shape, with an average diameter of 44.68 +/- 11.25 nm, was observed from the atomic force microscopy images. Using chondroitin sulfate-reduced gold nanoparticles, we developed a melamine nanosensor that provides a simplified method to detect melamine in infant formula. With an increase in the melamine concentration in the gold nanoparticle solution, the characteristic surface plasmon resonance band of gold nanoparticles at 530 nm decreased, whereas a new peak appeared at 620 nm. There was a linear relationship between the absorbance ratio (A620/A530) and the melamine concentration in the range of 0.1-10 microM. The practical use of the proposed method was verified by quantifying melamine spiked in real infant formula at concentrations as low as 12.6 ppb. The nanosensing of melamine using chondroitin sulfate-reduced gold nanoparticles can be a promising technique for quick on-site melamine screening of milk products.

Biogenic silver nanoparticles with chlorogenic acid as a bioreducing agent.

We report the synthesis of biogenic silver nanoparticles using chlorogenic acid as a bioreducing agent. Chlorogenic acid is a polyphenol compound abundant in coffee. UV-Vis spectra showed the characteristic surface plasmon resonance band at 415 nm, indicating the successful synthesis of biogenic silver nanoparticles. Spherical and irregular shaped nanoparticles were observed with an average diameter of 19.29 +/- 8.23 nm. The reaction yield from silver ion to silver nanoparticles was observed as 95.43% by using inductively coupled plasma-mass spectrometry. Fourier transform infrared spectra revealed that the -C = O groups of chlorogenic acid may coordinate or complex into silver nanoparticles. Biogenic silver nanoparticles exerted higher antibacterial activity against Gram-negative bacteria than against Gram-positive bacteria. Interestingly, a comparable antibacterial activity to a standard antibiotic was observed against two strains of Pseudomonas aeruginosa (minimum inhibitory concentration of 0.66 microg/mL). The synergistic effect of a combination of silver nanoparticles and chlorogenic acid on antibacterial activity is obvious, leading to approximately 8-fold enhancement in the case of Pseudomonas aeruginosa when compared with chlorogenic acid alone. The present report suggests that a pure compound with a plant origin is capable of being a bioreducing agent for the synthesis of biogenic silver nanoparticles with superior antibacterial activity, opening up many applications in nanomedicine and nanobiotechnology.

Green synthesis and nanotopography of heparin-reduced gold nanoparticles with enhanced anticoagulant activity.

This paper reports on the green synthesis of heparin-reduced gold nanoparticles and their nanotopography as studied with atomic force microscopy. The study also evaluated the anticoagulant activity of the newly prepared gold nanoparticles. The heparin-reduced gold nanoparticles were homogeneous, showing characteristic surface plasmon resonance bands of approximately 523-527 nm, and their shapes were mostly spherical and amorphous. The average diameter of the nanoparticles measured from atomic force microscopic images was either 20.26 +/- 3.35 nm or 40.85 +/- 8.95 nm depending on the different precursor salts and heparin concentrations. Atomic force microscopic images revealed that the topography of the heparin polymer aggregated when deposited onto mica, resembling a chain of mountains. This characteristic nanotopography of the heparin disappeared after the synthesis of the gold nanoparticles was performed. Interestingly, prolonged prothrombin time, thrombin time, and activated partial thromboplastin time were observed in the heparin-reduced gold nanoparticles when compared to a control heparin, suggesting the enhancement of anticoagulant activity in heparin-reduced gold nanoparticles. Hence, the green synthesis of gold nanoparticles with heparin using a simple reaction step could be a viable procedure for enhancing heparin's anticoagulant activity.

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.

Rational development of a selection model for solvent gradients in single-step separation of ginsenosides from Panax ginseng using high-speed counter-current chromatography.

A new model of solvent gradients selection was rationally developed for the preparative separation of target compounds. The solvent gradients were selected based on a three-stage screening process where stationary phase retention was ensured by introducing a new parameter termed as the phase ratio. The phase ratio was calculated after mixing the upper phase of a solvent system with the lower phase of a different solvent system (1:1, v/v). The developed model was applied to the one-step separation of eight ginsenosides from Panax ginseng. Three gradients were selected on the basis of new model and eight ginsenosides, Rb(1), Rb(2), Rc, Rd, Re, Rg(1), Rf, and Rh(1), were efficiently separated by high-speed counter-current chromatography coupled with evaporative light scattering detector. The structures of all compounds were characterized by electrospray-ionization mass spectrometry and nuclear magnetic resonance spectroscopy.

Antibacterial activity and increased freeze-drying stability of sialyllactose-reduced silver nanoparticles using sucrose and trehalose.

The resistance to current antibiotics results in the emergence of health-threatening bacteria. Silver nanoparticles are known to exhibit broad-spectrum antibacterial activities without the development of resistance. Herein, we developed a green synthetic method for the preparation of silver nanoparticles with sialyllactose instead of toxic chemicals as a reducing agent, which would improve its therapeutic applicability and increase its biocompatibility. Oven incubation, autoclaving and microwave irradiation methods were applied to prepare the silver nanoparticles. High resolution-transmission electron microscopy and atomic force microscopy images revealed mostly spherical and amorphous silver nanoparticles with an average diameter of 23.64 nm. Fourier Transform-infrared spectra suggest that the N-H amide of sialyllactose might be involved in the binding of silver nanoparticles. Based on thermogravimetric analyses, 2,3-sialyllactose-reduced silver nanoparticles are composed of 54.3 wt% organic components and 45.7 wt% metallic silver. Enhanced antibacterial activities of silver nanoparticles (approximately 8-fold) were observed against Pseudomonas aeruginosa, Escherichia coli and Salmonella typhimurium (minimum inhibitory concentration 16 microg/mL). Next, we employed the use of carbohydrate stabilizers to increase the stability of silver nanoparticles during a freeze-drying process. It was found that sucrose and trehalose were the most effective stabilizers. In addition, silver nanoparticles possessed excellent salt stability as well as on-the-shelf stability in the presence of these stabilizers. Derivatives of sialic acid are known to be anti-influenza agents; therefore, the newly prepared silver nanoparticles may serve as useful antibacterial and antiviral agents to cope with both pathogenic bacteria and viruses in the near future.

Artemisia capillaris extracts as a green factory for the synthesis of silver nanoparticles with antibacterial activities.

We report a green synthesis of silver nanoparticles that uses extracts from the aerial part of Artemisia capillaris. Both water and 70% ethanol extracts successfully generated silver nanoparticles. The formation of silver nanoparticles was confirmed by surface plasmon resonance bands, Fourier transform-infrared spectra, high resolution-transmission electron and atomic force microscopic images. Various shapes of silver nanoparticles were generated with an average diameter of 29.71 nm with water extract and 29.62 nm with 70% ethanol extract. An improvement in antibacterial activity (MIC 8.35-16.7 microg/mL) was observed against a total of twenty different strains of Gram-negative and Gram-positive bacteria. A remarkable enhancement (approximately 12-fold) was observed against Pseudomonas aeruginosa, Escherichia coli, Enterobacter cloacae, Klebsiella oxytoca, and Klebsiella areogenes when compared with the extract alone. Silver nanoparticles produced by the 70% ethanol extract showed slightly higher antibacterial activity than those generated with the water extract. The correlation between total flavonoid content of each extract and the antibacterial activity did not exert any significant relationships. This report suggests that plant extracts have the potential to be used as powerful reducing agents for the production of biocompatible silver nanoparticles possessing enhanced antibacterial activities.

Enhanced antibacterial activities of leonuri herba extracts containing silver nanoparticles.

We report an efficient and powerful green process to enhance the antibacterial activities of the Leonuri herba extract. Plant sources, especially leaves and herbs, are precious for the generation of gold and silver nanoparticles. Various kinds of polyphenols and hydroxyl groups are capable of processing a reduction reaction to generate metals from its corresponding salts. We have prepared gold and silver nanoparticles with 70% ethanol and water extracts. No other toxic chemicals were utilized and the extracts played dual roles as reducing and stabilizing agents. For the generation of nanoparticles, both oven incubation and autoclaving methods were applied and the reaction conditions were optimized. Surface plasmon resonance band indicated that the formation of nanoparticles was successful. Images of high-resolution transmission electron microscopy revealed mostly spherical nanoparticles ranging from 9.9 to 13.0 nm in size. A water extract containing silver nanoparticles exhibited remarkable (approximately 127-fold) enhancement in antibacterial activities against Pseudomonas aeruginosa, Escherichia coli and Enterobacter cloacae when compared with the water extract alone. In addition, antibacterial activity towards Gram-negative bacteria was greater than that against Gram-positive bacteria. The process reported here has the potential to be a new approach to improve the antibacterial activities of plant extracts.

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.

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.