Green synthesis of gold nanoparticles from Sophora flavescens extract and their antibacterial effect against some pathogenic bacteria

Aims@#The current study was aimed to evaluate the antibacterial activity of biogenic synthesized golden nanoparticles from Sophora flavescens Aiton roots aqueous extract against multidrug-resistant (MDR) clinical bacterial isolates.@*Methodology and results@#The green synthesis of gold nanoparticles (AuNPs) was accomplished using S. flavescens roots aqueous extract and examined using many accepted techniques. The antibacterial activity of S. flavescens extract and the aqueous AuNPs at concentrations (7% and 9%) ppm were investigated against two clinical MDR bacteria, including Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Pseudomonas aeruginosa). The findings demonstrate inhibitory activity against the selected MDR bacterial isolates for the aqueous extract of S. flavescens and the aqueous AuNPs noted by the significant decrease in the number of bacteria after treatment with highly significant differences (P≤0.01) compared to the untreated control.@*Conclusion, significance and impact of study@#Sophora flavescens root extracts and their biosynthesized AuNPs with antibacterial activity may find broad applications in fighting MDR pathogenic bacteria and therapeutic manufacturing.

Self-therapeutic metal-based nanoparticles for treating inflammatory diseases

Inflammatory diseases are key contributors to high mortality globally and adversely affect the quality of life. Current treatments include corticosteroids or nonsteroidal anti-inflammatories that may cause systemic toxicity and biologics that may increase the risk of infection. Composite nanoparticles that bear not only the drug payload but also targeting ligands for delivery to inflammation sites at lowered systemic toxicity are established in the nanomedicine field, but their relatively large size often leads to systemic clearance. Metal-based nanoparticles with intrinsic anti-inflammatory properties represent attractive alternatives. They are not only designed to be compact for crossing biological barriers (with the nanoparticle serving as a dual carrier and drug), but also support label-free tracking of their interactions with cells. The review commences with an outline of the common inflammatory diseases, inflammatory pathways involved, and conventional drug-loaded nanoparticles for anti-inflammation. Next, the review features the emerging applications of self-therapeutic metal-based nanoparticles (e.g., gold, coper oxide, platinum, ceria, and zinc oxide) for managing inflammatory diseases in animals over the past three years, focusing on therapeutic outcomes and anti-inflammatory mechanisms. The review concludes with an outlook on the biodistribution, long-term toxicity, and clinical translation of self-therapeutic metal-based nanoparticles.

A highly sensitive bio-barcode immunoassay for multi-residue detection of organophosphate pesticides based on fluorescence anti-quenching / 药物分析学报

Balancing the risks and benefits of organophosphate pesticides(OPs)on human and environmental health relies partly on their accurate measurement.A highly sensitive fluorescence anti-quenching multi-residue bio-barcode immunoassay was developed to detect OPs(triazophos,parathion,and chlorpyrifos)in apples,turnips,cabbages,and rice.Gold nanoparticles were functionalized with monoclonal antibodies against the tested OPs.DNA oligonucleotides were complementarily hybridized with an RNA fluorescent label for signal amplification.The detection signals were generated by DNA-RNA hybridization and ribonuclease H dissociation of the fluorophore.The resulting fluorescence signal en-ables multiplexed quantification of triazophos,parathion,and chlorpyrifos residues over the concen-tration range of 0.01-25,0.01-50,and 0.1-50 ng/mL with limits of detection of 0.014,0.011,and 0.126 ng/mL,respectively.The mean recovery ranged between 80.3％and 110.8％with relative standard deviations of 7.3％-17.6％,which correlate well with results obtained by liquid chromatography-tandem mass spectrometry(LC-MS/MS).The proposed bio-barcode immunoassay is stable,reproducible and reliable,and is able to detect low residual levels of multi-residue OPs in agricultural products.

Carbohydrate-based gold nanoparticles as colorimetric sensor for cysteine

Background@#Gold nanoparticles have been studied extensively for their potential application in the detection of important analytes. Their relative ease of synthesis through numerous procedures makes possible their implementation in a variety of assays. Cysteine (cys), a thiol-containing amino acid implicated in numerous pathologies such as obstructive sleep apnea (OSA), has been routinely detected through expensive fluorometric assay kits. @*Objectives@#As such, this study aimed to develop a carbohydrate-based gold nanoparticle colorimetric assay for the convenient and straightforward detection of cys. @*Methodology@#Carbohydrate-based gold nanoparticles (c-AuNPs) were synthesized following a microwaveassisted procedure. The as-prepared c-AuNPs were used to detect cys by plotting the ratio of the absorbances of the aggregated and dispersed gold nanoparticles against the concentration of cys. @*Results@#The c-AuNP solutions were able to detect cys in the micromolar range, with the glucose-based AuNPs (glc-AuNPs) showing the widest linear range (16.7 μm to 167 μm), and the fructose-based gold nanoparticles (frc-AuNPs) exhibiting the lowest detection limit (9.0 μm) for cys. Aside from being able to detect cys, the c-AuNPs were also responsive to tyr and lys.@*Conclusion@#This study demonstrates that carbohydrate-based gold nanoparticles prepared following a microwave-assisted procedure using sugars as reducing agents and capping agents can be used successfully in the detection of cysteine.

Catalysis at gold-ligand interfaces: a frustrated Lewis pair mechanism for selective reduction reaction / Catalise na interface ouro-ligante: pares de Lewis frustrados aplicados em reações de redução seletivas

The interaction of the organic ligands with metal nanoparticle has a very important role for applications in catalysis, as well as other processes involving ligands that can activate or poison the surface of metal nanoparticles. Very little has been studied so far on the role of organic ligands used either in the preparation of nanoparticles for applications in catalysis or addition in the reaction to activate the catalyst. In this thesis, we have studied strategies for the synthesis of metal nanoparticles, their use as components for the preparation of supported catalysts and activation and deactivation processes involving the ligands used as stabilizers or purposely added to the reaction medium or support for stimulate new reactivity and selectivity in reactions of industrial interest, such as hydrogenation. Here, the concept of frustrated Lewis pairs (FLPs) has been expanded to surface-FLP analogous formed by combining gold nanoparticles (NPs) and Lewis bases, such as amines or phosphines, creating a new channel for the heterolytic cleavage of H2, and thereby performing selective hydrogenation reactions with gold. A first approach to improve the catalytic activity of gold nanoparticles was to analyze the effect of nitrogen-containing bases. The starting inactive gold nanoparticles became highly active for the selective hydrogenation of alkyne into cis-alkenes. The hydrogenation proceeded smoothly and fully selective using H2 as the hydrogen source and under relatively mild conditions (80 °C, 6 bar H2). Our studies also have revealed that the presence of capping ligands blocks the adsorption of the amine to the gold surface, avoiding the FLPs interface and thereby leading to low catalytic activity. When the capping ligands were removed from the catalyst surface and an amine ligand was added, the FLPs interface is recovered and an enhanced catalytic activity was observed. Furthermore, we have demonstrated the successful use of simple organophosphorus ligands to boost the catalytic activity of Au NPs for a range of important reduction reactions, namely, epoxides, N-oxides, sulfoxides, and alkynes. Furthermore, the choice of phosphorus-containing ligands resulted in a decrease in the amount necessary to reach high conversion and selectivity in comparison with our previous study with N-containing ligands. The ligand-to-metal ratio decreased from 100 (amine/Au) to 1 (phosphite/Au). The synthesis of gold nanoparticles supported on N-doped carbon supports was used as an alternative method for the synthesis of a heterogeneous active gold catalyst for selective hydrogenations. The main advantage with respect to previous studies was to avoid the addition of external ligands, in large excess, for the activation of gold surfaces via FLP, making the whole process environmentally and economically attractive

A interação dos ligantes orgânicos com nanopartículas de metal certamente tem um papel muito importante para aplicações em catálise, bem como outros processos envolvendo ligantes que podem ativar ou envenenar a superfície de nanopartículas metálicas. Até agora, muito pouco foi estudado sobre o papel dos ligantes orgânicos utilizados na preparação de nanopartículas para aplicações em catálise ou adição na reação para ativar o catalisador. Nesta tese, foram estudadas estratégias para a síntese de nanopartículas metálicas, seu uso como componentes para a preparação de catalisadores suportados e processos de ativação e desativação envolvendo ligantes empregados como estabilizantes ou propositalmente adicionados ao meio de reação ou suporte para estimular novas reatividades e seletividade em reações de interesse industrial, como reações de hidrogenação. Aqui, o conceito de pares de Lewis frustrados (FLPs) foi expandido para o seu análogo de superfície formado pela combinação de nanopartículas (NPs) de ouro e bases de Lewis, como aminas ou fosfinas, criando um novo canal para a clivagem heterolítica de H2 e, assim, realizando reações seletivas de hidrogenação com ouro. Uma primeira abordagem para melhorar a atividade catalítica das nanopartículas de ouro foi analisar o efeito de bases contendo nitrogênio. As nanopartículas de ouro inicialmente inativas tornaram-se altamente ativas para a hidrogenação seletiva de alquino em cis-alquenos. A hidrogenação prosseguiu foi factível e totalmente seletiva usando H2 como fonte de hidrogênio e sob condições relativamente amenas (80 °C, 6 bar de H2). Nossos estudos também revelaram que a presença de estabilizantes pode bloquear a adsorção da base na superfície do ouro, impedindo a formação da interface FLPs e, portanto, levando a baixa atividade catalítica. Quando os estabilizantes foram removidos da superfície do catalisador e um ligante foi adicionado, o FLPs é formado sendo a atividade catalítica aprimorada. Além disso, demonstramos o uso bem-sucedido de ligantes organofosforados atuando como ativadores de Au NPs em uma série de importantes reações de redução, como, epóxidos, N-óxidos, sulfóxidos e alquinos. Além disso, a escolha do ligante fosforado resultou em uma diminuição na quantidade necessária para alcançar alta conversão mantendo a seletividade inalterada. A relação ligante/metal diminuiu de 100/1 (amina/Au) para 1/1 (fosfito/Au). A síntese de nanopartículas de ouro suportadas em carbono dopado com nitrogênio foi utilizada como método alternativo para a síntese de um catalisador heterogêneo de ouro ativo para hidrogenações seletivas. A principal vantagem em relação aos estudos anteriores foi evitar a adição de ligantes externos, em grande excesso, para a ativação de superfícies de ouro via FLP, tornando todo o processo ambiental e economicamente atraente

Gold nanoparticle-directed autophagy intervention for antitumor immunotherapy via inhibiting tumor-associated macrophage M2 polarization

Tumor-associated macrophages (TAMs), one of the dominating constituents of tumor microenvironment, are important contributors to cancer progression and treatment resistance. Therefore, regulation of TAMs polarization from M2 phenotype towards M1 phenotype has emerged as a new strategy for tumor immunotherapy. Herein, we successfully initiated antitumor immunotherapy by inhibiting TAMs M2 polarization via autophagy intervention with polyethylene glycol-conjugated gold nanoparticles (PEG-AuNPs). PEG-AuNPs suppressed TAMs M2 polarization in both in vitro and in vivo models, elicited antitumor immunotherapy and inhibited subcutaneous tumor growth in mice. As demonstrated by the mRFP-GFP-LC3 assay and analyzing the autophagy-related proteins (LC3, beclin1 and P62), PEG-AuNPs induced autophagic flux inhibition in TAMs, which is attributed to the PEG-AuNPs induced lysosome alkalization and membrane permeabilization. Besides, TAMs were prone to polarize towards M2 phenotype following autophagy activation, whereas inhibition of autophagic flux could reduce the M2 polarization of TAMs. Our results revealed a mechanism underlying PEG-AuNPs induced antitumor immunotherapy, where PEG-AuNPs reduce TAMs M2 polarization via induction of lysosome dysfunction and autophagic flux inhibition. This study elucidated the biological effects of nanomaterials on TAMs polarization and provided insight into harnessing the intrinsic immunomodulation capacity of nanomaterials for effective cancer treatment.

Synthesis of Gold Nanoparticles using Bioreductants from the Aqueous Leaves Extract of Dillenia philippinensis Rolfe. (Katmon)

Background and Objectives@#Endemic plants are integral part of the ecosystem that provide innumerable benefits. Thus, emerging studies and applications using these endemic plants continue to increase globally. In this study, the preparation of gold nanoparticles (AuNPs) has been carried out by using the aqueous leaves extract of Dillenia philippinensis Rolfe. (Katmon) as the bioreductants. @*Methodology@#After the synthesis of AuNPs, the process was further subjected to optimization to assure the production of AuNPs with the best parameters. Synthesized and optimized AuNPs were characterized using FTIR, XRD, DLS, Zeta Potential, and TEM. @*Results@#Optimization results that provide the desired properties for AuNPs were a volume ratio of 1:2 (HAuCl₄: leaves extract), no significant difference (p>0.05) with the sequence of addition and reaction time, and acidic pH. The synthesized AuNPs' particles were found to contain hydroxyl and amine groups, had broad, amorphous, and spherical particles that have a mean diameter of 60.6nm, a PDI of 0.563, and a repulsion force of -13.720mV. The optimized and characterized AuNPs were then further used as a colorimetric sensing material, showing the potential applicability of AuNPs in the heavy metal analysis.@*Conclusion@#Gold nanoparticles were able to be synthesized with the use of bioreductants that are present in the aqueous leaves extract of Katmon. This concludes that endemic plants in the Philippines can be used for the synthesis of AuNPs and can be applied in the field of phytonanotechnology and other applied sciences.

Gold nanoparticles as a promising treatment for diabetes and its complications: Current and future potentials

Diabetes and its complications represent a major cause of morbidity and mortality in diabetes patients. This review is aimed to find the potential of gold nanoparticles (AuNPs) to act as therapeutic agents for diabetes and its complications. Here, we outline the literature related to the self-therapeutic effects of AuNPs. The first goal of this review is to highlight and summarize some of the existing studies (10 years ago) in terms of several parameters such as the size of AuNPs, dose, administration route, experimental model, experimental analysis, and findings. The second goal is to describe the self-therapeutic effects of AuNPs against the pathogenesis determinants of diabetic complications. AuNPs have been found to have inhibitory effects on transforming growth factor-ß, antiglycation, antiangiogenic, anti-hyperglycemic, anti-inflammatory, and antioxidant effects. AuNPs treatment effectively disrupts multiple pathogenesis determinants in an animal model of diabetes and diabetic complications. The present review provides insight into the potential applications of AuNPs, which may help reduce the incidence of diabetes and its complications

A novel test strip assay based on gold nanoparticles-labeled nucleic acid probe for rapid detection of Vibrio splendidus / 生物工程学报

Vibrio splendidus is an opportunistic pathogen in aquaculture. It can infect a variety of aquaculture animals and has caused huge losses to the aquaculture industry. In this study, a novel and efficient method for detecting V. splendidus was developed by combining the exonuclease Ⅲ amplification strategy with a nucleic acid test strip developed based on gold nanoparticles-labeled DNA probe. The results could be directly visualized by naked eyes, and this system overcame the difficulty in preparation of the monoclonal antibody used in conventional immunostrip. Upon optimization of experimental conditions, the detection limit of the strip was 5 ng/mL for the synthetic oligonucleotide DNA fragment and 10 ng/mL for the actual genomic DNA sample of V. splendidus. This test strip was more sensitive compared with the PCR method and was specific for the detection of V. splendidus. The rapid preparation of nucleic acid strip and the efficient detection of V. splendidus open a new way for the prevention and control of aquatic diseases.

Preparation and Characterization of Cinnamon Oil Mediated Gold Nanoparticles and Evaluation of Its Cytotoxicity Using Brine Shrimp Lethality Assay

Nanotechnology is an emerging science which is associated with the synthesis of nanoparticles mediated with different chemical compositions in variable sizes and its application in health science for human benefit. We wanted to synthesize cinnamon oil mediated gold nanoparticles and evaluate their cytotoxicity using Brine Shrimp Lethality Assay. METHODS1 mL of cinnamon oil was dissolved in 9 mL of distilled water and kept in a beaker. 90 mL of 1 mM Gold chloride in distilled water was added, mixed and kept in an orbital shaker for nanoparticle synthesis. Color change was noted which indicated the presence of nanoparticles. Preparation of cinnamon oil mediated gold nanoparticles was confirmed using a UV-visible spectrophotometry and the size and shape of the nanoparticles was assessed using Scanning Electron Microscope. Varying concentrations of the synthesized gold nanoparticles was added in separate wells containing live brine shrimp (Artemia salina) and left undisturbed for 24 hours, after which the number of live shrimp larvae was counted in each well to assess the cytotoxicity. RESULTSCinnamon oil mediated gold nanoparticles were synthesized. Gold nanoparticles were characterized using Scanning Electron Microscope and were 50 nm in diameter. Brine Shrimp Lethality was done and the cytotoxicity of theses gold nanoparticles was found to be increasing with increasing concentration of the administered gold nanoparticles. CONCLUSIONSThe study concludes that evaluating the safety levels is of utmost importance prior to administration of nanoparticles for therapeutic and diagnostic purposes as there was a dose dependent cytotoxicity with cinnamon oil mediated gold nanoparticles.

High antibacterial properties of green synthesized gold nanoparticles using Uncaria gambir Roxb. leaf extract and triethanolamine

The development of antibacterial agents is increasingly gaining much attention due to the expansion activity ofmulti-drug resistant bacteria in causing many diseases. Metallic nanoparticles especially gold nanoparticles in thefield of nanotechnology is one of the new and significant materials to be developed as antibacterial agents. Goldnanoparticles have been successfully synthesized using Uncaria gambir Roxb. leaf extract as a bioreducing agent andtriethanolamine as a capping agent, through reduction of Au+3 by flavonoid compound in the leaf extract. The effect oftriethanolamine and hydrogen tetrachloroaurate (III) acid concentration on the stability and size of nanoparticles wasstudied. The presence of triethanolamine 1% as a capping agent successfully maintained the stability of colloidal goldnanoparticles with a concentration of hydrogen tetrachloroaurate (III) acid at 100 ppm. X-Ray Diffraction analysisshowed peak patterns corresponding to the metallic gold standard with a crystallite size of 32.52 nm. TransmissionElectron Microscope analysis showed that particles were spherical, hexagonal, and triangular, where the smallestparticle size was 7 nm. Synthesized gold nanoparticles showed great antibacterial activity against E. coli and S. aureus.The stability and antibacterial activity of synthesized gold nanoparticles showed good potential to be developed inbiomedical applications

Estabishment and evaluation of a new method for rapid detection of CA16 hand, foot and mouth disease pathogens based on fluorescence resonance energy transfer technique / 吉林大学学报(医学版)

Objective: To establish a new method for rapid detection of Coxsachie virus A16 (CA16) hand, foot and mouth disease pathogens based on fluorescence resonance energy transfer (FRET) technique, to evaluate the detection effect and to make the method to meet the requirements of large sample size detection during the outbreak of disease. Methods: Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis and bicinchoninic acid (BCA) protein assay were used to identify the purity of CA16 chicken yolk antibody (CA16-IgY) and the protein level. Indirect enzyme-linked immunosorbent assay (iELISA) was used to detect the titer and specificity of anti-CA16 IgY antibody. The size, morphology and characterization of gold nanoparticles (AuNPs) and their biological probes (IgY-AuNPs) were determined by UV-visible spectroscopy (UV-Vis), infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The CA16 detection system was constructed based on FRET technique. The sensitivity and specificity of the detection method and clinical sample detection were evaluated by optimizing the IgY-AuNPs concentration, sodium chloride (NaCl) dosage, fluorescence recovery time and other indicators. Results: The CA16-IgY had high purity, the titer was 1:128 000, the average protein level was 12. 15 mg · L-1, and CA16-IgY had good specificity. The results of UV-Vis, FTIR and TEM of AuNPs and IgY-AuNPs showed that IgY was successfully labeled onto the surface of AuNPs, which suggested that IgY-AuNPs could specially recognize CA16 was successfully prepared by electrostatic self-assembly. The CA16 detection system was constructed based on FRET technology, after optimization of the detection system, the optimal dosage of IgY-AuNPs was determined to be 0.52 X 10-3 g · L-1, the optimal dosage of NaCl was 40 μL and the optimal fluorescence recovery time was 90 min. The standard curve of the established detection method was I525 ntu= 15. 452 IgC-9. 746, R2 = 0.993 2, the detection limit was as 1 X 104 PFU · ml-1. Compared with qRT-PCR, the agreement rate reached 93. 75%. Conclusion: A new rapid detection method for CA16 hand, foot and mouth disease pathogens is successfully established, which can be applied to laboratory and clinical tests.

Detection of Rutin in Sophorae Immaturus Flos with Electrochemical Sensor Assembled with Gold Nanoparticles/Nafion/Multi-wall Carbon Nanotube / 中国实验方剂学杂志

Objective::A new-type electrochemical sensor was developed by electrodepositing gold nanoparticle on the surface of glassy carbon electrode (GCE) modified by Nafion-multi-wall carbon nanotube (MWNTs) by the potentiostatic method, and used for the detection of rutin in practical samples. Method::The electrochemical properties of the sensor in potassium ferricyanide-potassium ferrocyanide system were studied by electrochemical impedance spectroscopy and cyclic voltammetric method, in order to explore the electrochemical performance of the sensor. The electrochemical behavior of rutin on the surface of the sensor was studied by the cyclic voltammetric method, and the factors affecting the performance of the sensor were optimized. The content of rutin was determined by differential pulse voltammetric methods. Result::The optimized conditions were -0.25 V of the deposition potential of gold nanoparticle, 20 s of the deposition time, pH 3.0, and 6 μL of 1 g·L-1 carbon nanotube. Under the conditions, a good linear relationship between reduction peak current and rutin concentration was obtained from 5.0 ×10-9 to 7.0 ×10-7 mol·L-1, and the detection limit was 3.6×10-9 mol·L-1. Conclusion::The developed sensor has a good electrical conductivity and stability, and is highly sensitive and simple for the detection of rutin, with a low detection limit. It has been successfully applied to the detection of rutin in Sophorae Immaturus Flos with the recoveries between 97.6%and 104.4%, which provides a new method for the determination of rutin and a new idea for the quality control of Chinese medicinal materials.

Biogenic synthesis of gold nanoparticles from waste watermelon and their antibacterial activity against Escherichia coli and Staphylococcus epidermidis

Background: Globally, large quantities (tonnes) of diverse sources of food wastes derived from horticulture are produced and offer a valuable renewable source of biochemical compounds. Developing new recycling and food waste utilisation strategies creates unique opportunities for producing gold (Au) nanoparticles with desirable antibacterial properties. The present study used an eco-friendly procedure for biologically synthesizing gold (Au) nanoparticle shapes from waste Citrullis lanatus var (watermelon).Methods: The green chemistry-based procedure used in this study was straightforward and used both red and green parts of waste watermelon. The generated Au nanoparticles were subsequently evaluated using several advanced characterization techniques. The antibacterial properties of the various extracts and synthesised nanoparticles were evaluated using the Kirby-Bauer sensitivity method.Results: The advanced characterization techniques revealed the Au particles ranged in size from nano (100 nm) up micron (2.5 µm) and had a variety of shapes. The red watermelon extract tended to produce spheres and hexagonal plates, while the green watermelon extract tended to generate triangular shaped nanoparticles. Both red and green watermelon extracts produced nanoparticles with similar antibacterial properties. The most favourable response was achieved using a 5:1 green watermelon-based mixture for Staphylococcus epidermidis, which produced a maximum inhibition zone of 12 mm. While gram-negative bacteria Escherichia coli produced a maximum inhibition zone of 10 mm for the same mixture.Conclusions: The study has shown both red and green parts of waste watermelon can be used to produce Au nanoparticles with antibacterial activity towards both Escherichia coli and Staphylococcus epidermidis. The study has also demonstrated an alternative method for producing high-value Au nanoparticles with potential pharmaceutical applications.

Improvement of dose distribution in ocular brachytherapy with 125I seeds 20-mm COMS plaque followed to loading of choroidal tumor by gold nanoparticles

Aims and Objectives: Brachytherapy using removable ophthalmic plaques loaded with suitable small sealed radioactive seeds adjacent to the ocular's tumor has been widely used as an effective treatment. The aim of this study was to investigate the dose distribution in a modeled eyeball followed to loading of an ocular melanoma tumor with different concentrations of gold nanoparticles (GNPs) as dose enhancement agent by Monte Carlo (MC) calculations. Materials and Methods: The MC code of MCNPX 2.6.0 was used to modeling of COMS standard eye plaque loaded with 24 125I sources (6711 model) located on the sclera of modeled eyeball with detailed structures and materials. A choroidal melanoma tumor was simulated and loaded with different concentrations of spherical gold GNPs (50 nm in diameter). Dose enhancement factors (DEFs) of ocular components were calculated. Results: The dosimetric properties of 125I source (6711 model) and dose distribution of COMS standard eye plaque were calculated successfully as recommended by TG-43U1; AAPM. Loading of tumor with GNPs increased dose to the tumor and decreased dose to the normal tissues; the DEF was increased up to 2.280 and 2.030 for tumor apex, while it was decreased to 0.760 and 0.892 for macula and for gold-tumor mixture and nanolattice distributions, respectively. Conclusion: Loading the choroidal tumor volume with GNPs improves the dose distribution by increasing dose to the tumor and decreasing dose to the health components in ocular brachytherapy with 125I seeds 20-mm COMS plaque

Green synthesis of gold nanoparticles from waste macadamia nut shells and their antimicrobial activity against Escherichia coli and Staphylococcus epidermis

Background: The study for the first time demonstrates an eco-friendly and room temperature procedure for biosynthesizing gold (Au) nanoparticles from waste Macadamia nut shells. Currently Australia contributes around 40% to the global market and generates around AUS $150 million of export revenue. However, a consequence of large nut production is the generation of large quantities of waste nut shells. The green chemistry-based method is clean, nontoxic and eco-friendly. The method presented in this study produced a variety of Au nanoparticle sizes and shapes.Methods: The straightforward green chemistry-based technique used waste Macadamia nut shells to generate Au nanoparticles, which were subsequently studied using several advanced characterization techniques. Furthermore, the Kirby-Bauer sensitivity method was used to evaluate the antibacterial properties of the extracts and synthesized gold nanoparticles.Results: Advanced characterisation revealed the Au nanoparticles were crystalline, ranged in size from 50nm up to 2µm, and had spherical, triangular and hexagonal morphology. The gram-negative bacteria Escherichia coli produced a maximum inhibition zone of 11mm, while Staphylococcus epidermidis produced a maximum inhibition zone of 9mm.Conclusions: The study has shown that waste Macadamia nut shell extracts have no antibacterial activity, but the synthesised Au nanoparticles did display antibacterial activity to both Escherichia coli and Staphylococcus epidermidis. Thus, the present work has demonstrated a waste valorisation strategy that can be used to produce high-value Au nanoparticles with antimicrobial properties for use in future pharmaceuticals.

Characterization and DNA methylation modulatory activity of gold nanoparticles synthesized by Pseudoalteromonas strain

Marine extremophiles are shown to tolerate extreme environmental conditions and have high metal reducing properties.Here, we report intracellular synthesis of gold nanoparticles (AuNP) by marine extremophilic bacteria Pseudoalteromonassp. Bac178 which was isolated from the OMZ of Arabian Sea. Preliminary observations suggest that these bacteria usedifferent pathways which may involves the membrane as well as intracellular proteins for the gold salt reduction. Characterization of the biosynthesised nanoparticles by various techniques such as Scanning electron microscopy (SEM),Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Energy-dispersive X-ray spectroscopy (EDS)confirmed the presence of crystalline gold. These biologically synthesized AuNP were investigated for cytotoxicity andoxidative stress generation in human normal fibroblast and melanoma cells (A375). As AuNP are envisaged to find manyapplications in the medical field, it was of interest to study the effect of AuNP at the epigenetic level. They were found to benon-cytotoxic, non-genotoxic and non-oxidative stress generating over a range of concentrations. Exposure to these AuNPis observed to cause alterations in global DNA methylation as well as in the expression of DNA methyltransferase (DNMT)genes. Since biosynthesized AuNP are being used in various applications and therapies, their epigenetic modulatory activityneeds careful consideration.

Preparation and characterization of multimodal hybrid organic and inorganic nanocrystals of camptothecin and gold

We demonstrate a novel inorganic-organic crystalline nanoconstruct, where gold atoms were imbedded in the crystal lattices as defects of camptothecin nanocrystals, suggesting its potential use as simultaneous agents for cancer therapy and bioimaging. The incorporation of gold, a potential computed tomography (CT) contrast agent, in the nanocrystals of camptothecin was detected by transmission electron microscope (TEM) and further quantified by energy dispersive X-ray spectrometry (EDS) and inductively coupled plasma-optical emission spectrometers (ICP-OES). Due to gold's high attenuation coefficient, only a relatively small amount needs to be present in order to create a good noise-to-contrast ratio in CT imaging. The imbedded gold atoms and clusters are expected to share the same biological fate as the camptothecin nanocrystals, reaching and accumulating in tumor site due to the enhanced permeation and retention (EPR) effect.

Red blood cell membrane-camouflaged nanoparticles: a novel drug delivery system for antitumor application

Erythrocytes (red blood cells, RBCs) are the most abundant circulating cells in the blood and have been widely used in drug delivery systems (DDS) because of their features of biocompatibility, biodegradability, and long circulating half-life. Accordingly, a "camouflage" comprised of erythrocyte membranes renders nanoparticles as a platform that combines the advantages of native erythrocyte membranes with those of nanomaterials. Following injection into the blood of animal models, the coated nanoparticles imitate RBCs and interact with the surroundings to achieve long-term circulation. In this review, the biomimetic platform of erythrocyte membrane-coated nano-cores is described with regard to various aspects, with particular focus placed on the coating mechanism, preparation methods, verification methods, and the latest anti-tumor applications. Finally, further functional modifications of the erythrocyte membranes and attempts to fuse the surface properties of multiple cell membranes are discussed, providing a foundation to stimulate extensive research into multifunctional nano-biomimetic systems.

Investigating the Sonodynamic-Radiosensitivity Effect of Gold Nanoparticles on HeLa Cervical Cancer Cells

BACKGROUND: In this article, we estimated the combined effect of radiotherapy (RT) with ultrasound (US) wave and the ability of gold nanoparticles (GNPs) to improve their combined therapeutic effects. METHODS: At first, HeLa cells received the various treatment modalities: RT (6 MV; 0.5, 1, and 2 Gy), US irradiation (1 MHz; 0.5, 1, and 1.5 W/cm2, 1 minute), and RT+US. Afterwards, the enhanced effect of US on RT was evaluated. Then, the effect of the synthesized GNPs at different concentrations (0.2, 1, and 5 µg/mL, 24 hours) was evaluated to assess the effect on HeLa cells combined with RT+US. Cell survival rates in the different treatment groups at 24, 48, and 72 hours post-treatment were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and trypan blue assays. RESULTS: Our results show US irradiation could enhance the effect of RT at the same radiation dose and could be utilized as a sensitizer agent for RT. Moreover, our findings indicate RT+US in combination with different nanoparticle concentrations could enhance the effect of RT+US so that they can improve the treatment results up to 9.93 times and act as sonodynamic-radiosensitivity. These results also indicate that the combination of RT with US along with GNPs has synergistic effects compared to RT or US alone. Cell survival results show that combining the low US waves (1.5 W/cm2), GNPs (5 μg/mL), and X-rays (2 Gy) increase the cytotoxicity on HeLa cell up to 95.8%. CONCLUSION: We concluded that GNPs could act as a good sensitizing agent in RT+US irradiation and could result in the synergistic effects.