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The coupled processes of coprecipitation and ultrasonic spray pyrolysis (USP) were used to synthesize Fe3O4-Au hybrid nanostructures. The first coprecipitation method enabled the synthesis of Fe3O4 nanoparticles by mixing iron salts' ions (Fe2+ and Fe3+) and ammonia as the base, and USP was used as the coating process of the Fe3O4 nanoparticles with Au. The formatted hybrid nanostructures consist of Fe3O4 nanoparticles that have Au on their surface in the form of gold nanoparticles (AuNPs). AuNPs have a crystalline structure and range in size from 10 to 200 nm. Additional characterization techniques, including ICP-OES, TEM, SEM, EDS, DLS, zeta potential, and room temperature magnetic hysteresis loops, were used to determine the chemical, physical, and magnetic properties of the Fe3O4 nanoparticles and hybrid nanostructures. It was found that USP produces separate AuNPs too (not just on the Fe3O4 surface), suggesting a bimodal formation of AuNPs. The zeta potential of the Fe3O4 nanoparticles showed poor stability (−15 mV), indicating a high tendency to aggregate, and the zeta potential of the hybrid nanostructures was also very low (≅0), which, comparatively means even worse stability. The saturation magnetization of the Fe3O4 nanoparticles was 35 emu/g, which is relatively lower than that of bulk Fe3O4, while the saturation magnetization of the hybrid nanostructures was significantly lower (0.1 emu/g) compared to the Fe3O4 nanoparticles. [ABSTRACT FROM AUTHOR]

The present study was designed to explore the effect of gold nanoparticles on the hmgA gene expression and pyomelanin pigment production from local Pseudomonas aeruginosa isolates. Out of 162 patients suffering from ear infections, urinary tract infections, burns, wounds, cerebrospinal fluid (CSF), respiratory tract infections (RTI), and blood infection (sepsis), eight isolates identified to produce pyomelanin pigment (8.42%). All isolates were characterized using microscopical, morphological, and biochemical methods, VITEK-2 compact systems, and 16SrRNA gene, which showed that all these isolates belong to P. aeruginosa. Screening producing pyomelanin pigment was carried out by using a specific media to promote the production of pyomelanin pigment. The extracted pyomelanin pigment was purified using simple acid sedimentation followed by centrifugation to extract the crude product and purify it with HPLC. The purified pigment was positive for all major physical and chemical tests that characterize pyomelanin pigment, including UV-visible spectroscopy and Fourier transform infrared spectroscopy (FT-IR). The study also covered the preparation of gold nanoparticles using the green chemistry method, which used black tea-leaf extract. The resulting nanoparticles were positive for all significant qualitative tests used to characterize them, including UV-visible spectroscopy (FT-IR), X-ray diffraction (XRD), and SEM. The results of the SEM image showed spherical particles with a size of approximately 19nm nanoparticles. In conclusion, the effect of the prepared gold nanoparticles on the gene expression of the hmgA gene was studied at different concentrations compared to the control sample using a real-time one-step polymerization reaction, also the gene expression results showed that the gold nanoparticles significantly increased the gene expression of the hmgA gene. [ABSTRACT FROM AUTHOR]

A series of cerium-based high-entropy oxide catalysts (the ratio of CeO2 and HEO is 1:1) was prepared by a solid-state reaction method, which exploit their unique structural and performance advantages. The Ce-HEO-T samples can achieve 100% toluene conversion rate above 328°C when they were used as catalysts directly. Subsequently, the Ce-HEO-500 exhibited the lowest temperature for toluene oxidation was used as a support to deposit different amounts of Au for a further performance improvement. Among all of prepared samples, Au/Ce-HEO-500 with a moderate content of Au (0.5 wt%) exhibited the lowest temperature for complete combustion of toluene (260°C), which decreased nearly 70°C compared with Ce-HEO-500 support. Moreover, it also showed excellent stability for 60 h with 98% toluene conversion rate. Most importantly, under the condition of 5 vol.% H2O vapour, the toluene conversion rate remained unchanged and even increased slightly compared with that in dry air, exhibiting excellent water resistance. Combined with the characterizations of XRD, SEM, TEM, BET, Raman, H2-TPR and XPS, it was found that the high dispersion of active Au NPs, the special high-entropy structure and the synergistic effect between Au and Ce, Co, Cu are the key factors when improving the catalytic performance in the Au/Ce-HEO-500 catalyst. [ABSTRACT FROM AUTHOR]

The coupled processes of coprecipitation and ultrasonic spray pyrolysis (USP) were used to synthesize Fe3O4-Au hybrid nanostructures. The first coprecipitation method enabled the synthesis of Fe3O4 nanoparticles by mixing iron salts’ ions (Fe2+ and Fe3+) and ammonia as the base, and USP was used as the coating process of the Fe3O4 nanoparticles with Au. The formatted hybrid nanostructures consist of Fe3O4 nanoparticles that have Au on their surface in the form of gold nanoparticles (AuNPs). AuNPs have a crystalline structure and range in size from 10 to 200 nm. Additional characterization techniques, including ICP-OES, TEM, SEM, EDS, DLS, zeta potential, and room temperature magnetic hysteresis loops, were used to determine the chemical, physical, and magnetic properties of the Fe3O4 nanoparticles and hybrid nanostructures. It was found that USP produces separate AuNPs too (not just on the Fe3O4 surface), suggesting a bimodal formation of AuNPs. The zeta potential of the Fe3O4 nanoparticles showed poor stability (−15 mV), indicating a high tendency to aggregate, and the zeta potential of the hybrid nanostructures was also very low (≅0), which, comparatively means even worse stability. The saturation magnetization of the Fe3O4 nanoparticles was 35 emu/g, which is relatively lower than that of bulk Fe3O4, while the saturation magnetization of the hybrid nanostructures was significantly lower (0.1 emu/g) compared to the Fe3O4 nanoparticles.

This comprehensive review examines the diverse range of uses of gold nanoparticles across numerous disciplines, focusing on their distinctive characteristics in catalysis, thermal conductivity, optical properties, electrical conductivity, and biological interactions. This work emphasizes the crucial significance of gold nanoparticles in the progression of cancer treatment, demonstrating their multifunctionality in the areas of drug transport, photothermal therapy, bioimaging, and diagnostic applications. Gold nanoparticles have demonstrated their utility in improving the accuracy and effectiveness of cancer treatments, presenting innovative approaches to address clinical obstacles. Nevertheless, the research also discusses notable challenges, including apprehensions over toxicity, the influence of nanoparticle size, and potential environmental repercussions. These issues emphasize the necessity of responsible administration to fully exploit the capabilities of gold nanoparticles in the context of cancer therapy. Notwithstanding these obstacles, the review ultimately underscores the profound influence of gold nanoparticles in diverse domains such as environmental monitoring, renewable energy, catalysis, renewable energy, healthcare, cosmetics, and biotechnology. This highlights their capacity to mold the future through inventive and adaptable means.

In the present study we reported, for the first time, the gamma irradiation induced synthesis of chitosan/Au/bioactive glass (CS/Au/BG) nanocomposite. The bioactive glass (BG), with the composition 45% SiO2, 32.5% CaO, 15% Na2O, and 7.5% P2O5 wt% was synthesized through the sol–gel technique. XRD, SEM, EDX, and elemental mapping images were utilized to evaluate the structure of pure BG and CS/Au/BG nanocomposite. The antimicrobial efficacy was evaluated by zone of inhibition (ZOI), minimum inhibitory concentration (MIC), growth curve assay, and Ultraviolet irradiation effect. Investigation was carried on the antibiofilm effectiveness. Membrane leakage as well as SEM imaging were used to evaluate the antibacterial reaction mechanism. The crystallite size of CS/Au/BG nanocomposite was determined via Scherer equation as 22.83 nm. CS/Au/BG possessed the most ZOI activity against the tested microbes. The highest inhibition % of BG, and CS/Au/BG nanocomposite was investigated for S. aureus (15.65%, and 77.24%), followed by C. albicans (13.32%, and 64.75%). The quantity of protein leakage was directly-proportional after increasing the concentration of BG, and CS/Au/BG and counted to be 70.58, and 198.25 µg/mL, respectively (after applied 10 mg/mL). The promising results suggested the use of novel CS/Au/BG nanocomposite as an encourage candidate for wastewater treatment application against pathogenic microbes. [ABSTRACT FROM AUTHOR]

Self-assembled nanoparticles are an area of great research prospect as they offer switchable element for designing and creating micro-scale constructs. Self-assembly of nano-hybrids through some noncovalent interactions such as electrostatic, π-π and van der Waal interactions in different classes of composite materials provide a great prospect of utilization of these functional properties in tailor-made device applications. In this work gold nanoparticle functionalized with coumarin based fused-ring heterocyclic thiol exhibiting self-assembly is reported. The present work has been designed giving prior to pi-stacking mediated self-aggregation of nanoparticles resulting formation of larger superstructures. The work reports the coumarin-based heterocyclic fused ring having a thiol anchoring group grafted to the gold nanoparticle surface for easier electron flow between the metal nanoparticle and the aromatic ligand and study their self-assembly nature. [ABSTRACT FROM AUTHOR]

The progress in the innovative nanocrystal synthesis process by using environmentally benign and low-priced nontoxic chemicals, solvents, and renewable sources remains a challenging task for researchers worldwide. The majority of the existing synthesis techniques engage in the potentially dangerous, for either human health or the environment. Current investigation has been centered on green synthesis processes to create novel nanomaterials, which are eco-friendly as well as safer for sustainable marketable feasibility. The current work provides the green synthesis method for gold nanoparticle (GNPs) synthesis using Commiphora myrrh (C.myrrh) extract. This simple method includes 6 ml of HAuCl4·3H2O treated with 4 ml C.myrrh extract having pH 4.5 after 80 min at 25 °C temperature. In this novel method, green synthesized GNPs characterized by UV–Vis, X_ray diffraction spectroscopy (XRD), zeta potential, fourier transform infrared (FT_IR), high_resolution transmission electron microscopy (HR_TEM), energy dispersive X_ray spectroscopy (EDXA), and dynamic light scattering (DLS). During the development successful antioxidant assay, the DPPH assay was applied. The cell toxicity of green synthesized GNPs was evaluated following an MTT assay against HCT-116 (colon cancer) and MCF-7 (breast cancer).Besides molecular docking in the δ-elemene for inhibitor to VEGFR‐2 domain revealed more negative docking score (−3.976) which is an excellent binding affinity to the C.myrrh@GNP. The synthesized GNPs showed antidiabetic, antibiotic, and antibacterial properties and anti_inflammatory inhibition against inhibiting COX-1, and COX-2 enzymes. In addition, molecular docking by Lindestrene (−3.806) and Furanoeudesma-1,3-dien (−3.912) against COX1 and COX2 respectively showed strong binding affinity. The molecular docking study evidenced the anti-inflammatory and cell toxicity study.

The plasmonic resonance frequency of metal nanoparticles (NPs) strongly depend on the geometry, size, and separation between NPs. Here, a plasmonic structure is designed based on a film-coupled nanoparticle phenomenon and analytically investigated by a finite element method via COMSOL Multiphysics software tool. The optical behavior of the designed structure is studied and compared for two noble metals (gold and silver as a case study). Simulation results confirmed that structural elements such as dielectric layer thickness, metal film thickness, and metal nanoparticle separation distance significantly affect the plasmonic properties. Consequently, optimizing the dimensions of the mentioned structural elements results in a strong field enhancement in the dielectric gap layer. The simplicity of this structure, easy controlling of the dielectric gap layer thickness, strong field confinement in a limited area, and lack of incident light angle tunning are characteristic features of the proposed structure. Strong field enhancement in a limited volume makes this structure promising as plasmonic nanoantennas, SERS platforms, and sensing applications. [ABSTRACT FROM AUTHOR]

Mincong Wang,1,* Yue Meng,1,* Huifeng Zhu,1 Yong Hu,1 Chang-Peng Xu,2 Xiaomin Chao,1 Wenqiang Li,3 Chengguo Li,1 Chenglong Pan1 1Department of Joint Surgery, The Fifth Affiliated Hospital of Southern Medical University, Guangzhou, People’s Republic of China; 2Department of Orthopaedics, Guangdong Second Provincial General Hospital, Guangzhou, People’s Republic of China; 3Engineering Technology Research Center for Sports Assistive Devices of Guangdong, Guangzhou Sport University, Guangzhou, People’s Republic of China*These authors contributed equally to this workCorrespondence: Chenglong Pan; Chengguo Li Email pclgjwk@163.com; 356846516@qq.comIntroduction: Viola betonicifolia is a rich source of numerous secondary metabolites, such as alkaloids, flavonoids, tannins, phenolic compounds, saponins, triterpenoids, and so on, that are biologically active towards different potential biomedical applications. To broaden the potential use of Viola betonicifolia in the realm of bionanotechnology, we investigated the plant’s ability to synthesize gold nanoparticles (Au NPs) in a green and efficient manner for the very first time.Methods: The gold nanoparticles (VB-Au NPs) were synthesized using the leaves extract of Viola betonicifolia, in which plant’s secondary metabolites function as both reducing and capping agents. The VB-Au NPs were successfully characterized with spectroscopic techniques. The antimicrobial properties of the VB-Au NPs were further explored against bacterial and mycological species. Additionally, their antioxidant, cytotoxic, and cytobiocompatibility properties were examined in vitro against linoleic acid peroxidation, MCF-7 cancer cells, and human mesenchymal stem cells (hMSCs), respectively.Results: Results demonstrated that VB-Au NPs presented excellent antibacterial, antifungal, and biofilm inhibition performance against all the tested microbial species compared to plant leaves extract and commercially purchased chemically synthesized gold NPs (CH-Au NPs). Moreover, they also exhibited significant antioxidant potential, comparable to the external standard. The VB-Au NPs displayed good cytobiocompatibility with hMSCs and demonstrated excellent cytotoxic potential against MCF-7 cancer cells compared to CH-Au NPs. The current work presents a green method for synthesizing VB-Au NPs with enhanced antioxidant, antimicrobial, cytotoxic and biofilm inhibition efficacy compared to CH-Au NPs might be attributed to the synergistic effect of the nanoparticle’s physical properties and the adsorbed biologically active phytomolecules from the plant leaves extract on their surface.Conclusion: Thus, our study establishes a novel ecologically acceptable route for nanomaterials’ fabrication with increased and/or extra medicinal functions derived from their herbal origins.Keywords: Viola betonicifolia, gold NPs, antimicrobial, biofilm inhibition, antioxidant

[Display omitted] • This work used C.myrrh aqueous extract as a reducing and capping agent for GNPs. • The GNPs were synthesized in a single step and possessed a spherical shape. • The synthesized GNPs exhibited anti-diabetic, anti-cancer, anti-inflammation, and anti-bacterial activities. The progress in the innovative nanocrystal synthesis process by using environmentally benign and low-priced nontoxic chemicals, solvents, and renewable sources remains a challenging task for researchers worldwide. The majority of the existing synthesis techniques engage in the potentially dangerous, for either human health or the environment. Current investigation has been centered on green synthesis processes to create novel nanomaterials, which are eco-friendly as well as safer for sustainable marketable feasibility. The current work provides the green synthesis method for gold nanoparticle (GNPs) synthesis using Commiphora myrrh (C.myrrh) extract. This simple method includes 6 ml of HAuCl 4 ·3H 2 O treated with 4 ml C.myrrh extract having pH 4.5 after 80 min at 25 °C temperature. In this novel method, green synthesized GNPs characterized by UV–Vis, X_ray diffraction spectroscopy (XRD), zeta potential, fourier transform infrared (FT_IR), high_resolution transmission electron microscopy (HR_TEM), energy dispersive X_ray spectroscopy (EDXA), and dynamic light scattering (DLS). During the development successful antioxidant assay, the DPPH assay was applied. The cell toxicity of green synthesized GNPs was evaluated following an MTT assay against HCT-116 (colon cancer) and MCF-7 (breast cancer). Besides molecular docking in the δ-elemene for inhibitor to VEGFR‐2 domain revealed more negative docking score (−3.976) which is an excellent binding affinity to the C.myrrh@GNP. The synthesized GNPs showed antidiabetic, antibiotic, and antibacterial properties and anti_inflammatory inhibition against inhibiting COX-1, and COX-2 enzymes. In addition, molecular docking by Lindestrene (−3.806) and Furanoeudesma-1,3-dien (−3.912) against COX1 and COX2 respectively showed strong binding affinity. The molecular docking study evidenced the anti-inflammatory and cell toxicity study. [ABSTRACT FROM AUTHOR]

Plasmonic photocatalysts have gained more and more attention because of possible applications for solar energy conversion, environmental decontamination, and water treatment. However, the activity under visible light is usually very low, and the property-governed activity as well as the mechanisms are not fully understood yet. Accordingly, this study examines four different titania photocatalysts (anatase and rutile with fine and large crystallites) modified with gold by photodeposition. Three kinds of samples were prepared, as follows: (i) gold-modified titania (Au/TiO2), (ii) physically mixed Au/TiO2 samples (Au/TiO2(1) + Au/TiO2(2)), and (iii) Au/(TiO2(1) + Au/TiO2(2)) samples, prepared by subsequent deposition of gold on the mixture of bare and gold-modified titania. In total, twelve samples were prepared and well characterized, including diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy (STEM). The photocatalytic activity was examined in three reaction systems: (i) methanol dehydrogenation during gold photodeposition under UV/vis irradiation, (ii) oxidative decomposition of acetic acid (UV/vis), and (iii) oxidation of 2-propanol to acetone under visible light irradiation (λ > 450 nm). It was found that during subsequent deposition, gold is mainly formed on the surface of pre-deposited Au nanoparticles (NPs), localized on fine titania NPs, through the electrostatic attractions (negatively charged gold resulting from photogenerated electrons' accumulation). This gold aggregation, though detrimental for UV activity (many "naked" large titania with low activity), is highly beneficial for vis activity because of efficient light harvesting and increased interface between gold and titania (gold deposits surrounded by fine titania NPs). Moreover, it was found that rutile is more active than anatase for plasmonic photocatalysis, probably due to easier electron transfer from gold via titania to adsorbed oxygen (more negative conduction band), which might hinder the back reaction (electron transfer: Au→TiO2→Au). [ABSTRACT FROM AUTHOR]

Nanoparticles (NPs) have a tremendous potential in medicinal applications, and recent studies have pushed the boundaries in nanotherapy, including in osteoarthritis treatments. The aim of this study was to develop new poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) surfaces decorated with hyaluronic acid (HA) to enhance targeted drug specificity to the osteoarthritic knee joint. HA was selected since it binds to specific receptors expressed in many cells, such as the cluster determinant 44 (CD44), a major receptor of chondrocytes, and because of its function in the synovial fluid (SF), such as maintenance of high fluid viscosity. The PLGA polymer was grafted to sodium hyaluronate using dimethoxy-PEG (PLGA-HA) and compared with control PLGA NPs (not grafted). NPs were characterized by 1H-NMR and IR spectroscopy. Then, near-infrared (NIR) dye and gold (20 nm) were encapsulated in the formulated NPs and used to access NPs' performance in in vitro, in vivo, and ex vivo experiments. To test the NPs' CD44 receptor specificity, an antibody assay was performed. All NPs presented a size in the range viable for cell-uptake, no cytotoxicity to chondrocytes was registered. Although all the NPs had a high capacity to be absorbed by the cells, PLGA-HA NPs showed significantly higher affinity towards the chondrocytic C28/I2 cell line. In conclusion, PLGA NPs grafted to sodium hyaluronate showed increased binding to cartilage cells and tissue and enhanced accumulation at the target site. Thus, this study presents a safe drug-delivery system with improved receptor specificity, which may represent an advantageous alternative to current nanotherapies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nigella sativa seed extract as an gold nanoparticles (AuNPs) surface coating material. • Nigella sativa seed extract efficiently produced the AuNPs. • Synthesized AuNPs showed high antioxidant and antidiabetic activity. • Greener synthesis of AuNPs has high anti-diabatic property. In the present investigation, gold NPs (Au-NPs) were synthesized via seed decoction of Nigella sativa , in which, the aqueous seed extract of Nigella sativa acted as a reducing agent as well as coated on Au-NPs surface. Herein, an attempt was made to develop a rapid and biocompatible method to synthesize gold NPs by phytofabrication for anti-diabetic applications. The Nigella sativa seed extract and the Au-NPs synthesized using Nigella sativa exhibited a good antioxidant property, which was determined by the 2, 2- Diphenylpicrylhydrazyl (DPPH) scavenging activity assay. These Au-NPs exhibited 78 % of anti- diabetic property, which was confirmed by α- amylase method. The synthesized nanoparticle Au-NPs size was confirmed by using SEM and TEM. The functional groups (thymoqninone) present in the seed extract as well as Au-NPs were analysed by FTIR. The major functional group i.e. thymoquinone was confirmed by the anthraquinone test and it is responsible for the antioxidant, anti-diabetic, and anticancer properties of the Au-NPs. The phytochemical based nanoparticle prepared in this work showed efficient anti-diabetic activities and it can be considered for the medical applications. In addition, phytochemical based nanoparticle synthesis is safe, eco-friendly, biocompatible, and cost effective. [ABSTRACT FROM AUTHOR]

The plasmonic resonance frequency of metal nanoparticles (NPs) strongly depend on the geometry, size, and separation between NPs. Here, a plasmonic structure is designed based on a film-coupled nanoparticle phenomenon and analytically investigated by a finite element method via COMSOL Multiphysics software tool. The optical behavior of the designed structure is studied and compared for two noble metals (gold and silver as a case study). Simulation results confirmed that structural elements such as dielectric layer thickness, metal film thickness, and metal nanoparticle separation distance significantly affect the plasmonic properties. Consequently, optimizing the dimensions of the mentioned structural elements results in a strong field enhancement in the dielectric gap layer. The simplicity of this structure, easy controlling of the dielectric gap layer thickness, strong field confinement in a limited area, and lack of incident light angle tunning are characteristic features of the proposed structure. Strong field enhancement in a limited volume makes this structure promising as plasmonic nanoantennas, SERS platforms, and sensing applications.

Nanotechnology play vital role in the science and technology form the fabrication or synthesis, design and analysis of nano material. Nanoparticles in the desired range of nanoscale in µm and nm which are important in various fields. Amongst all nanoparticles Silver and Gold Nanoparticles were synthesized by various methods like sol-gel, precipitation, mechano-chemical. Over the all-green synthesis is the newer and better environment friendly. The present review is based on only greener or biogenic way for the synthesis of nanoparticles. Biological material like different plant parts, tea, coffee, polyphenols present in plant materials biomolecules as proteins, enzymes. Bacteria, yeast, algae and viruses were used as reducing agents and capping agents to reduce the size to prepare the NPs by ecofriendly approach. The synthesized Nanoparticles were characterized by X-ray diffraction, SEM, TEM, FTIR and UV-Vis spectroscopic methods, and data obtained for further interpretation of results. A major aim to recognize the material for nano conversion and their antimicrobial activity. Many researchers used biological materials for sizing outs. In this regard to try to critically analyze the literature of Au and Ag metals and biological material searches. The scope of paper only silver and gold metal Nanoparticles and biomolecules from natural sources by investigators. [ABSTRACT FROM AUTHOR]

In this research, we reported an environment friendly approach for the synthesis of gold nanoparticles (Au NPs) using Mentha Longifolia leaf extract. The formation of the Au NPs was characterized by UV–visible and FT-IR spectroscopy, XRD, SEM, EDX and TEM analyses. The UV–Visible spectra of gold nanoparticles showed a surface plasmon resonance peak at 512 nm. The crystalline nature of gold nanoparticles was stablished by XRD diffraction pattern. TEM revealed the spherical shape with a mean particle size of 36.4 nm. Thereafter, biological performance of those biomolecule functionalized Au NPs was investigated. To survey the anti-human breast cancer effects of gold nanoparticles, MTT assay was used on the common breast cancer cell lines i.e., breast adenocarcinoma (MCF7), breast carcinoma (Hs 578Bst), breast infiltrating ductal cell carcinoma (Hs 319.T), and breast infiltrating lobular carcinoma (UACC-3133). The conversion was achieved in short reaction time with good to excellent yields in association with outstanding turnover frequency (TOF). In addition, the nanocomposite catalyst was easily recovered and recycled for 12 successive times without noticeable decrease in catalytic activity. Gold nanoparticles had high anti-breast cancer activities dose-dependently against MCF7, Hs 578Bst, Hs 319.T, and UACC-3133 cell lines. The best result of anti-breast cancer effects was seen in the case of the UACC-3133 cell line. It looks gold nanoparticles can be used for the treatment of several types of breast cancers in human.

Plasmonic photocatalysts have gained more and more attention because of possible applications for solar energy conversion, environmental decontamination, and water treatment. However, the activity under visible light is usually very low, and the property-governed activity as well as the mechanisms are not fully understood yet. Accordingly, this study examines four different titania photocatalysts (anatase and rutile with fine and large crystallites) modified with gold by photodeposition. Three kinds of samples were prepared, as follows: (i) gold-modified titania (Au/TiO2), (ii) physically mixed Au/TiO2 samples (Au/TiO2(1) + Au/TiO2(2)), and (iii) Au/(TiO2(1) + Au/TiO2(2)) samples, prepared by subsequent deposition of gold on the mixture of bare and gold-modified titania. In total, twelve samples were prepared and well characterized, including diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy (STEM). The photocatalytic activity was examined in three reaction systems: (i) methanol dehydrogenation during gold photodeposition under UV/vis irradiation, (ii) oxidative decomposition of acetic acid (UV/vis), and (iii) oxidation of 2-propanol to acetone under visible light irradiation (λ > 450 nm). It was found that during subsequent deposition, gold is mainly formed on the surface of pre-deposited Au nanoparticles (NPs), localized on fine titania NPs, through the electrostatic attractions (negatively charged gold resulting from photogenerated electrons’ accumulation). This gold aggregation, though detrimental for UV activity (many “naked” large titania with low activity), is highly beneficial for vis activity because of efficient light harvesting and increased interface between gold and titania (gold deposits surrounded by fine titania NPs). Moreover, it was found that rutile is more active than anatase for plasmonic photocatalysis, probably due to easier electron transfer from gold via titania to adsorbed oxygen (more negative conduction band), which might hinder the back reaction (electron transfer: Au→TiO2→Au).

In this work, the encapsulated-Au nanoparticles (NPs) into the silica hollow NPs were synthesized by microwave-assisted preparation of PEG-coated Au NPs, coating them with a layer of organically modified silica and removing the PEG around the Au NPs. The structure of these encapsulated NPs was characterized by TEM, SEM, XRD, FTIR, EDX, TGA, and ICP-OES. These NPs have shown excellent activities in the aerobic oxidation of benzyl alcohol derivatives and tandem oxidative A3 coupling reactions as a catalyst and reactor in the water at room temperature. Synthesis of a new silica/gold nanoparticles as catalytic nano-reactor for carrying out A3-coupling reaction in the water at ambient temperature [ABSTRACT FROM AUTHOR]

High-intensity ultrasonic waves have great potential for the green synthesis of various nanomaterials under mild conditions and offer an excellent alternative for hazardous chemical methods. Herein a facile approach for the eco-friendly synthesis of Au-ZrO2 nanocatalyst with a high catalytic activity using a facile ultrasonic method is presented. Gold (Au) in the nanosize regime was successfully deposited on the surface of solvothermally synthesized monodispersed ZrO2 nanoparticles (ZrO2 NPs) in a very short period of time (5 min) at room temperature. Spherical shape small size Au nanoparticles that are uniformly dispersed on the surface of ZrO2 nanoparticles were obtained. Notably, in the absence of ZrO2 nanoparticles, HAuCl4 could not be reduced, indicating that nano-sized ZrO2 not only acted as support but also helped to reduce the gold precursor at the surface. The as-prepared Au-ZrO2 nanocatalyst was characterized by various techniques. The Au-ZrO2 nanocatalyst served as a highly efficient reducing catalyst for the reduction of 4-nitrophenol. The reaction time decreased with increasing the amount of catalyst. [ABSTRACT FROM AUTHOR]

This study aimed to prepare, optimise, and characterise the novel hybrid hydrogel scaffold containing atorvastatin lipid nanocapsules (LNCs) and gold nanoparticles (NPs) to improve cardiomyoblasts proliferation and regeneration of myocardium. A thermo‐responsive aminated guaran (AGG) hydrogel was prepared to encompass extracellular matrix (ECM) fetched from human adipose tissue. Emulsion phase‐inversion technique was used to obtain LNCs. Biocompatibility, tensile strength, conductivity, and proliferation of human myocardial cells of the optimised formulation were studied. The LNCs have a spherical shape, and the optimised formulation showed a mean particle size of 18.79 nm, the zeta potential of − 11.4 mV, drug loading of 99.99%, and release efficiency percent over 72 h was 18.73%. The injectable thermo‐sensitive hydrogel prepared using 1 w/v% of AGG, 35 w/w% of ECM, ∼0.5 mg/ml of gold NPs and atorvastatin loaded LNCs showed the best physical characteristics. The hybrid scaffold loaded with atorvastatin and gold NPs improved the proliferation of cardiomyoblasts more than sevenfold with enhanced cell attachment to the scaffold. The tensile strength and the conductivity of the scaffold were 300 kPa and 0.14 S/m, respectively. Injectable hybrid adipose tissue prepared by ECM and AGG hydrogel loaded with atorvastatin and gold NPs showed promising physical characteristics for myocardial tissue engineering. [ABSTRACT FROM AUTHOR]

Herein, polymethylmethacrylate (PMMA)/dextran(D) hybrid composites are prepared by reinforcement of various concentrations of in situ reduced gold nanoparticles (Au NPs). As-synthesised PMMA/D-Au nanocomposites are characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), high resolution transmission electron microscopy(HRTEM) and atomic force microscopy(AFM). It is found that, the average size of Au NPs is 30 nm. The size distributions of Au NPs are studied from dynamics light scattering studies (DLS). The incorporation of Au NPs enhances the oxygen barrier, thermal, and antimicrobial properties of the PMMA/D matrix, by which, the hybrid composites are suitable for packaging applications. [ABSTRACT FROM AUTHOR]

Understanding the uptake, distribution, and stability of gold nanoparticles (NPs) in cells is of fundamental importance in nanoparticle sensors and therapeutic development. Single nanoparticle imaging with surface-enhanced Raman spectroscopy (SERS) measurements in cells is complicated by aggregation-dependent SERS signals, particle inhomogeneity, and limited single-particle brightness. In this work, we assess the single-particle SERS signals of various gold nanoparticle shapes and the role of silica encapsulation on SERS signals to develop a quantitative probe for single-particle level Raman imaging in living cells. We observe that silica-encapsulated gap-enhanced Raman tags (GERTs) provide an optimized probe that can be quantifiable per voxel in SERS maps of cells. This approach is validated by single-particle inductively coupled mass spectrometry (spICP-MS) measurements of NPs in cell lysate post-imaging. spICP-MS also provides a means of measuring the tag stability. This analytical approach can be used not only to quantitatively assess nanoparticle uptake on the cellular level (as in previous digital SERS methods) but also to reliably image the subcellular distribution and to assess the stability of NPs in cells.

In this study, bio-ultrasound-assisted synthesized gold nanoparticles using Gracilaria canaliculata algae have been immobilized on a polymeric support and used as a glassy probe chemosensor for detection and rapid removal of Hg 2+ ions. The function of the suggested chemosensor has been explained based on gold-amalgam formation and its catalytic role on the reaction of sodium borohydride and rhodamine B (RhB) with fluorescent and colorimetric sensing function. The catalyzed reduction of RhB by the gold amalgam led to a distinguished color change from red and yellow florescence to colorless by converting the amount of Hg 2+ deposited on Au-NPs. The detection limit of the colorimetric and fluorescence assays for Hg 2+ was 2.21 nM and 1.10 nM respectively. By exposing the mentioned colorless solution to air for at least 2 h, unexpectedly it was observed that the color and fluorescence of RhB were restored. Have the benefit of the above phenomenon a recyclable and portable glass-based sensor has been provided by immobilizing the Au-NPs and RB on the glass slide using electrospinning. Moreover, the introduced combinatorial membrane has facilitated the detection and removal of Hg 2+ ions in various Hg (II)-contaminated real water samples with efficiency of up to 99%. [ABSTRACT FROM AUTHOR]

High-intensity ultrasonic waves have great potential for the green synthesis of various nanomaterials under mild conditions and offer an excellent alternative for hazardous chemical methods. Herein a facile approach for the eco-friendly synthesis of Au-ZrO2 nanocatalyst with a high catalytic activity using a facile ultrasonic method is presented. Gold (Au) in the nanosize regime was successfully deposited on the surface of solvothermally synthesized monodispersed ZrO2 nanoparticles (ZrO2 NPs) in a very short period of time (5 min) at room temperature. Spherical shape small size Au nanoparticles that are uniformly dispersed on the surface of ZrO2 nanoparticles were obtained. Notably, in the absence of ZrO2 nanoparticles, HAuCl4 could not be reduced, indicating that nano-sized ZrO2 not only acted as support but also helped to reduce the gold precursor at the surface. The as-prepared Au-ZrO2 nanocatalyst was characterized by various techniques. The Au-ZrO2 nanocatalyst served as a highly efficient reducing catalyst for the reduction of 4-nitrophenol. The reaction time decreased with increasing the amount of catalyst.

The purpose of the present work was to design a colorimetric method for the determination of 6-mercaptopurine (6-MP). 6-MP is a useful drug for the treatment of leukemia. Gold nanoparticles (NPs) are known to undergo a change in colour upon aggregation. Hence, in the present work phenylalanine-capped gold NPs were used as a colorimetric probe for the determination of 6-MP. Transmission electron microscopy (TEM) measurements revealed that the phenylalanine-capped gold NPs ranged from 6 to 9 nm in size. The UV–vis spectrophotometric measurements showed that the surface plasmon resonance (SPR) band of the metallic NPs was positioned at 516 nm. The effect of 6-MP addition on the SPR band of the gold NPs was investigated at pH 8 and 5. At pH 8, only a slight change in the position and intensity of the SPR band was observed. However, at pH 5, the SPR band of the gold NPs was broadened as well as red shifted in the presence of 6-MP. The colour of the gold NPs changed from red to dark purple. The ratio of the absorbance of the gold NPs at 600 and 516 nm versus the concentration of 6-MP was found to be linear in the range 0.2–1.8 μM. The limit of detection (LOD) of the colorimetric method for the determination of 6-MP was calculated to be 0.647 μM. [ABSTRACT FROM AUTHOR]

In the present study, we carried out a chemical synthesis and characterization of Fe3O4@PEG-Au as a core/shell nanocomposite in an aqueous solution by the chemical co-precipitation of Fe3+ and Fe2+ ions and encapsulated it by polyethylene glycol (PEG) in order to enhance hydrophilicity and biocompatibility of gold ions and immobilize them in the presence of NaBH4 as a reducing agent. The nanostructures were characterized with FT-IR, FESEM, EDS, WDX, VSM, ICP-MS, and TEM. The antimicrobial activities of the nanostructures were tested against pathogenic microorganisms, including Staphylococcus aureus, Escherichia coli, and Candida albicans by broth microdilution method according to the methods of the Clinical Laboratory Standard Institute (CLSI). The toxicity of the nanostructures was tested against animal cell line based on MTT assay. The synthesized core/shell nanostructures had a good activity against the representative microorganisms of public health concern and revealed an insignificant toxicity against animal cell line. [ABSTRACT FROM AUTHOR]

A new and promising biosurfactant extracted from corn steep liquor has been used for the green synthesis of gold and silver nanoparticles (NPs) in a one-step procedure induced by temperature. Most of the biosurfactants proposed in the literature are produced by pathogenic microorganisms; whereas the biosurfactant used in the current work was extracted from a liquid stream, fermented spontaneously by lactic acid bacteria, which are "generally recognized as safe" (GRAS) microorganisms. The reduction of a gold precursor in the presence of a biosurfactant gives rise to a mixture of nanospheres and nanoplates with distinct optical features. Moreover, the growth of nanoplates can be promoted by increasing the reaction temperature to 60 °C. In the case of silver, the biosurfactant just induces the formation of pseudo-spherical NPs. The biosurfactant plays a key role in the reduction of the metal precursor, as well as in the stabilization of the resulting NPs. Furthermore, the antimicrobial activity of the resulting silver colloids has been analyzed against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The biosurfactant stabilized NPs slightly increased the inhibition of E. coli in comparison with citrate stabilized Ag NPs. The use of this biosurfactant extracted from corn steep liquor for the synthesis of metal NPs contributes to enhancing the application of green technologies and increasing the utilization of clean, non-toxic and environmentally safe production processes. Therefore, it can help to reduce environmental impact, minimize waste and increase energy efficiency in the field of nanomaterials. [ABSTRACT FROM AUTHOR]

Mesoporous silica nanoparticles-gold nanoparticles (MSNPs/AuNPs) nanocomposite was prepared using mono-dispersed mesoporous silica as a template for gold nanoparticles without any functional group on the silica surface. The growth of gold layer over the surface of mesoporous silica nanoparticles (MSNPs) was demonstrated via scanning electron microscopies (SEM), Fourier transform infrared (FTIR) spectra, high-resolution transmission electron microscopy (HRTEM), and ultraviolet-visible (UV) adsorption spectrum. The presence of gold on the mesoporous nanoparticles gave an absorption band at 520 nm, also X-ray diffraction (XRD) indicated the crystal structure of gold NPs which has a cubic shape. Raman spectra proofed the high ability of MSNPs/AuNPs nanocomposite for removing methacrifos from water which was also confirmed by using high-performance liquid chromatography (HPLC) at room temperature where the removal rate exceeded 98 %. MSNPs/AuNPs nanocomposite has high capacity as an adsorbent which could be considered as a new eco-friendly strategy for pesticide removal and appears to be the new promising material in water treatment application. [ABSTRACT FROM AUTHOR]

In the present investigation, TiO 2 modified with a different geometry and size of gold particles, such as nanospheres (NSPs), nanostars (NSTs) and nanorods (NRs), were prepared by the immobilization method. The effect of the gold shape, size and TiO 2 matrix type (TiO 2 microspheres or rutile TIO-6_TiO 2 ) were systematically investigated. The obtained photocatalysts were thoroughly characterized by UV–vis diffuse-reflectance spectroscopy (DRS), BET surface area measurements, scanning electron microscopy (SEM), scanning transmission microscopy (TEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity under visible light (λ > 420 nm) has been estimated in phenol degradation reaction in an aqueous phase. The significantly high photocatalytic activity under visible light irradiate as demonstrated by the TiO 2 sample modified by spheres of gold. The average rate of phenol decomposition was 1.9 μmol dm −3 min −1 and was three-times higher compared to the pristine TiO 2 amorphous microspheres. On the other hand the photocatalytic activity was relatively lower and was 0.38 and 0.27 μmol dm −3 min −1 for nanorods and nanostars deposited on the amorphous form of TiO 2 microspheres, respectively. The visible light activity decreased in following order: (NSPs)> (NRs)> (NSTs). The obtained photocatalytic efficiency of samples was ascribed to the geometry and the size effect of the enhanced and the possible mechanism for this was discussed in detail. Furthermore, in this work we show the effect of calcination temperature on the structure of gold NPs, NRs and NSs before and after modification on the morphology and photocatalytic activity of Au-TiO 2 . [ABSTRACT FROM AUTHOR]

Enhancing the optical response of rare earth doped glasses for miscellaneous optical applications is challenging in materials science and technology. Influences of heat treatments in modifying the spectral features of melt-quench synthesized gold nanoparticles embedded Er 3 + -doped lead–tellurite glasses are investigated. Time of heat treatment is varied from 1 to 24 h. Modifications in physical, optical and structural parameters are ascribed to the alteration of non-bridging oxygen due to heat treatments. X-ray Diffraction patterns of all glass samples confirm their amorphous nature in the presence of crystalline peak at 28.66°. Transmission Electron Microscopic images reveal the nucleation of gold nanoparticles having average diameter in the range 1.24–8.40 nm for the heat-treated samples. The ultraviolet–visible-near-infrared spectra exhibit seven absorption bands centered at 490, 526, 551, 652, 800, 979 and 1520 nm corresponding to 4f–4f transitions of Er 3 + ions. The up-conversion emissions peaks centered at 520, 550 and 660 nm are assigned to 2 H 11/2 – 4 I 15/2 , 4 S 3/2 – 4 I 15/2 and 4 F 9/2 – 4 I 15/2 transitions, respectively. Intensity enhancement displayed by heat treated glass samples is attributed to the local field effect of gold NPs. The intensity parameters related to the radiative transitions within 4f n configuration of Er 3 + ion are determined and analyzed using Judd–Ofelt theory. [ABSTRACT FROM AUTHOR]

Abstract: Tuning the enhanced optical properties of rare earth (RE) doped inorganic glasses mediated via surface plasmon resonance (SPR) by embedding metallic nanoparticles (NPs) with controlled sizes is ever-demanding in photonics. Erbium (Er3+) doped zinc–sodium tellurite glasses containing gold NPs are prepared and spectroscopic characterization are made. The heat treatment temperature dependent variations in refractive index, density, molar volume, molar refraction and polarizability are ascribed to the alteration in bonding of non-bridging oxygen (NBO) ions originates from annealing processes between 325 and 400°C. X-ray diffraction pattern confirms the amorphous nature of the glass samples. TEM micrograph reveals the nucleation of heat treated Au0 NPs and SAED manifest their growth along the (111) crystallographic planes having average diameter in the range 7.4–10.3nm. The UV–vis spectra exhibit seven absorption bands corresponding to 4f–4f transitions of Er3+ ions. The SPR bands evidenced in the range 629–631nm validate the growth of gold NPs in the glass matrix. The glass annealed at 350°C displays maximum enhancement in the up-conversion (UC) emission intensity by a factor of 4.86 and 3.40 for green bands (2H11/2→4I15/2 and 4S3/2→4I15/2) and a strong enhancement by a factor of 4.91 for red band (4F9/2→4I15/2). The enhancement is primarily attributed to the local field effect of non-spherical NPs assisted SPR effects and the energy transfer processes between Er3+ ions and NPs. The excellent luminescence efficiency of proposed glasses nominates them potential for photonic devices and solid state lasers. [Copyright &y& Elsevier]

[Display omitted] • Facile synthesis of Au NPs on zirconia NPs by laser ablation in liquid (LAL) protocol. • A high-performance strategy for NaBH 4 -mediated degradation of MO and MB in water. • Characterization of ZrO 2 -Au nanocomposite via XRD, FTIR, SEM, EDS, XPS, BET, and MAP analyses. • The ZrO 2 -Au nanocomposite can be reused several times with almost no loss in activity. The continuous development of industrial activities and also changing climate of worldwide lead to increase water pollutants and the eradication of safe water sources. Hence, remediation of wastewater and reduction of water pollutants notably organic dyes have become a serious environmental challenge. Reducing organic pollutants by heterogeneous nanocatalysts can be employed as an efficacious manner to overcome this problem. Accordingly, a nanocomposite catalyst consisting of zirconium oxide or zirconia nanoparticles (ZrO 2 NPs) and gold (Au) NPs were made by means of a straightforward and green route. Au NPs were firstly prepared via laser ablation in liquid (LAL) method and then deposited on the ZrO 2 NPs with the size of 53–88 nm using the magnetic stirring approach. The characterization methods indicated that the ZrO 2 -Au nanocomposite was successfully fabricated. The catalytic performance of ZrO 2 -Au catalyst for the degradation of methylene orange (MO) and methylene blue (MB) was investigated. [ABSTRACT FROM AUTHOR]

Despite recent progress in localized surface plasmon resonance (LSPR) based bio-sensing, it remains challenging to achieve sensitive and high throughput LSPR detection with facilities available in common laboratories. Here we developed a wall-less LSPR array chip for facile, label-free and high throughput detection of biomolecules using a normal microplate reader. The wall-less LSPR array chip was fabricated by immobilizing plasmonic nanoparticles (NPs) on a hydrophilic–hydrophobic patterned glass slide, enabling high throughput detection. The wall-less configuration simplifies chip fabrication and sample processing, and enables miniaturization to significantly reduce sample and reagent consumption. A double-gold NPs enhanced system comprising of 13-nm-gold NPs conjugated to aptamer modified 39-nm-gold NPs on glass substrate was adopted to constitute competitive replacement assay for signal amplification in small molecule (i.e. ATP) detection. Upon enhancement, the detection sensitivity of ATP was augmented by 5 orders of magnitude from 0.01µM to 100µM measured by the laboratory microplate reader. The wall-less LSPR sensor chip can be widely applied for miniaturized and high throughput detection of a variety of targets in biomedical applications and environmental monitoring using facilities available in common laboratories. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we developed a technique for delivering genes to microorganisms via electrospray of gold nanoparticles. During the electrospray process, charged monodisperse nano-droplets (a mixture of pET30a-GFP plasmid and nano-sized gold particles) were accelerated and deposited on a thin layer of non-competent Escherichia coli cells. Via antibiotic selection, transformed cells containing green fluorescent protein appeared on the agar plates. PCR amplification and restriction enzyme analysis further confirmed that pET30a-GFP plasmid had successfully been delivered into the non-competent E. coli cells. The transformation efficiencies were optimized under different electrospray conditions. Among several electrospray buffer solutions, CaCl2 (0.01M) was found to be the best for gene delivery. Furthermore, gold nanoparticles (NPs, 50nm diameter) significantly improved plasmid transformation efficiency by 5–7 fold (up to 2×106 CFU/μg plasmid) compared with that obtained using naked plasmid. Electronic microscopy images and gel electrophoresis showed that the morphology of plasmids remained unchanged during the electrospray process, but cellular membrane integrity was reduced after being electrosprayed with gold NPs and CaCl2 buffer solutions. This gene delivery method has the potential to work for many other microorganisms. [Copyright &y& Elsevier]

Elevating the reaction temperature is an effective method to accelerate protein enzymatic digestion because it can promote protein denaturation and enzyme activities. In this study, we demonstrated a new photothermal heating method to assist protein tryptic digestion on glass slides. A glass slide coated with layer-by-layer gold nanoparticles (Glass@AuNPs), combined with the use of a near infrared (NIR) diode laser, was used to raise reaction temperature during tryptic digestion in a short period of time. The modified glass slide is capable of absorbing NIR light arising from the dipole-dipole interactions between Au NPs immobilized on the slide. The temperature of Glass@AuNPs rapidly increased when irradiated by the NIR laser, accelerating protein enzymatic digestion conducted on the slide. Thus, when performing the tryptic digestion of proteins on the Glass@AuNPs slide under NIR irradiation, 3.5 min was sufficient to carry out the tryptic digestion of proteins in solution, while less than 5 min was adequate for in-gel tryptic digestion of proteins. Matrix-assisted laser desorption/ionization mass spectrometry was used for characterization of the tryptic digestion product. On the basis of the results, the time taken to analyze proteins could be greatly reduced using this current approach. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]