Formulation of gold nanoparticles with hibiscus and curcumin extracts induced anti-cancer activity

Gold nanoparticles (AuNPs) have shown a potential for biological applications due to their biocompatibility and high efficiency in drug delivery. Most of the times, the chemical routs are being used to synthesize the AuNPs products. In this paper, eco-friendly non-chemical rout was used to prepare AuNPs by utilizing hibiscus and curcumin extracts as reducing and stabilizing agents, and subsequently their anticancer activities were investigated. The synthesized AuNPs were characterized by using ultraviolet–visible spectroscopy (UV–Vis spectroscopy), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). UV–Vis spectroscopy analysis confirmed the characteristics absorption peak of gold, and FTIR findings were highlighted the characteristics boding. SEM and TEM analyses showed that the particles were predominantly spherical in shape. The particles were well dispersed when they were prepared under Hibiscus extracts with average size ～ 13 nm. An interesting morphology was observed when AuNPs were prepared with curcumin, where particles displayed an interconnected morphology (average size ～ 18 nm). The anticancer cell activity of AuNPs was studied against human colorectal carcinoma cells (HCT-116) and breast cancer cells (Michigan Cancer Foundation-7 (MCF-7)). The results of anticancer study showed that the treatment of cancer cells with AuNPs decreased the number of cells significantly as compared to control cells. The AuNPs -Hibiscus specimen showed a better inhibiting property than AuNPs -Curcumin, which is attributed to their uniform dispersion and small size.     

Green preparation of hollow mesoporous silica nanosphere inside-loaded gold nanoparticles and the catalytic activity

In this work, an active nano-catalyst with gold nanoparticles loaded in hollow mesoporous silica nanospheres (HMSNs/Au) was prepared by a one-pot sol-gel method, in which gold ions were loaded in hollow mesoporous silica spheres followed by sodium alginate reduction. The characterization of the HMSNs/Au were determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N₂ adsorption–desorption isotherms (BET). The high catalytic activity of HMSNs/Au, denoted as apparent turn-over frequency (TOF), was detected by UV-Vis spectrophotometer for the catalytic reduction of 4-nitrophenol (74.5 h^?1) and 2-nitrophenol (108.7 h^?1) in the presence of sodium borohydride solution due to the small gold nanoparticles size and overall exposure of active sites. It is expected that this ecofriendly approach to prepare inorganic composited nanoparticles as high active catalysts based on hollow mesoporous materials was a promising platform for loading noble metal nanoparticles.     

Eco-friendly synthesis of gold nanoparticles using fruit extracts and in vitro anticancer studies

Gold nanoparticles are biocompatible and are having several applications in biomedical Sciences and Engineering. Integration of nanoscience in medicine leads to the development of biomedical products that helps the Society in a faster and safer manner. In the present research work, bioreduction and biofunctionalization of gold nanoparticles are performed with fruit extracts of Aegle marmelos, Eugenia jambolana and soursop. The nanoparticles are characterized using UV–Vis spectroscopy, Transmission Electron Microscopy, Fourier Transform Infrared Spectroscopy and Zeta potentiometer. The qualitative phytochemical analysis of the fruit extracts shows the presence of alkaloids, amino acid, flavonoids, phenol, proteins, tannin, reducing sugars and total Sugars. The in vitro anticancer activity was confirmed by MTT assay on the human breast cancer cell line MCF-7 at different concentrations. The flavonoids present in the fruit extracts are potential reducing agent which is responsible for the formation of gold nanoparticles. Stabilization of gold nanoparticles are performed by the carboxylate group present in the proteins. Also, the nanoparticles are held apart from each other by the electrostatic repulsions that exist due to the presence of like charges surrounding the gold nanoparticles. This study proves that the fruit extracts can be used for the synthesis and stabilization of gold nanoparticles. Further, the engineered nanoparticles capped with bioactive compounds are potential anticancer agents against breast cancer cell line MCF-7.     

Nephroprotective properties of chitosan/sodium lignosulfonate/Au nanoparticles in streptozotocin-induced nephropathy in mice: Introducing a novel therapeutic drug for the treatment of nephropathy

In this study, we report the green synthesis of nontoxic, stable, and small size gold nanoparticle by using chitosan/sodium lignosulfonate hydrogel with capping/reducing ability for the synthesis of CS/NaLS/Au NPs. The prepared bio-nanocomposite were characterized by advanced physicochemical techniques like Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray spectroscopy (EDX) and X-ray Diffraction (XRD) study. It has been established that CS/NaLS/Au NPs have a spherical shape with a mean diameter from 20 to 30 nm. Diabetes was induced by administration of 60 mg/kg of streptozotocin (STZ) intraperitoneally in 100 mature male mice and they were randomly divided into 5 groups. The negative control group received normal saline and treatment groups received glibenclamide with dose 0.5 mg/kg and 10 and 40 μg/kg of CS/NaLS/Au NPs through gavage for 50 days. In addition, one group considered as positive control (in treated-diabetic). On the last day, serum levels of samples blood glucose, urea and creatinine were measured. After tissue processing, 5 μm sections of the kidneys were prepared and they were stained by periodic acid Schiff (PAS) and used for stereological analysis. In the antioxidant test, the IC50 of CS/NaLS/Au NPs and BHT against DPPH free radicals were 117 and 86 µg/mL, respectively. In the cellular and molecular part of the recent study, the treated cells with CS/NaLS/Au NPs were assessed by MTT assay for 48 h about the cytotoxicity properties on normal (HUVEC) cell line. The increased levels of blood glucose and urea were decreased (p < 0.05) significantly in CS/NaLS/Au NPs-treated groups as compared to the untreated diabetic. The kidney weight, kidney volume (Volume of cortex, medulla, glomerulus, proximal and distal tubules, collecting ducts, loop of Henle, interstitial tissues, and vessels) and kidney structures length (length of proximal and distal tubules, collecting ducts, loop of Henle, and vessels) decreased significantly (p < 0.05) after treatment with high dose of CS/NaLS/Au NPs (p < 0.05). According to the obtained results, CS/NaLS/Au NPs can regulates the levels of blood glucose and urea and inhibits from kidney damages in STZ-induced diabetic mice. This study suggested CS/NaLS/Au NPs as an antidiabetic and nephroprotective drug in the developing countries.     

Detection of flavonoids and assay for their antioxidant activity based on enlargement of gold nanoparticles

We report our findings that natural flavonoids such as quercetin, daizeol and puerarin can act as reductants for the enlargement of gold nanoparticles (Au-NPs). Consequently, the UV–vis spectra of a solution containing Au-NPs will be gradually changed, and the molecules of the natural herbs can be detected by making use of changes in the UV–visible spectra. Furthermore, we have prepared a self-assembled monolayer modified electrode by modifying cysteamine on a gold substrate electrode, which is further modified by some Au-NP seeds. When the modified electrode is immersed in a solution containing flavonoids and tetrachloroauric acid as a gold source for the growth of the Au-NP seeds, with the increase of the concentration of flavonoids, the Au-NP seeds on the surface of the modified electrode can be enlarged to varying degrees. As a result, the peak currents in the corresponding cyclic voltammograms are inversely decreased, and simultaneously the peak separation is increased. Therefore, an electrochemical method to detect flavonoids is also proposed. Compared with the optical detection method, the electrochemical method has an extraordinarily lower detection limit and a significantly extended detection range. Moreover, the optical and electrochemical experimental results can be also used to assay and compare the relative antioxidant activities of the flavonoids. Figure Enlargement of Au nanoparticles by flavonoids at cysteamine modified electrode     

One pot synthesis of polymer protected gold nanoparticles and nanoprisms in glycerol

Uniform and stable polymer protected spherical gold nanoparticles were synthesized using glycerol as reducing agent. Further it was observed that the morphology of the particles varied from spherical to triangular prismatic gold nanoparticles when the reaction was changed from normal mode of reflux condition to microwave mode (MW) of heating. Further a brief mechanism relating the formation of prisms with the orientation of polymer and nucleation period has been discussed. Formation of triangular prismatic and spherical gold nanoparticles were characterised using UV–vis spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis.     

A new organic compound for the synthesis of gold nanoparticles

2,3,5,6-Tetrakis-(morpholinomethyl)hydroquinone (1) is used for the first time in the preparation of gold nanoparticles by the reduction of HAuCl₄ in water–methanol medium without using any capping agent. Compound 1 was prepared by Mannich-type aminomethylation of hydroquinone with morpholine. It is characterized by elemental analysis, FT-IR, UV–Vis and mass spectra and finally by single crystal X-ray diffraction. The ratio of HAuCl₄ and compound 1 played a vital role in controlling the shape and size of gold nanoparticles. The samples were characterized by Transmission Electron Microscopy (TEM), XRD, FT-IR, UV–Vis measurements. With the increasing amount of gold(III) solution with respect to compound 1, two different morphologies such as self-assembled and spherical gold nanoparticles have been observed. The results indicate that the morphology of gold nanoparticles with different sizes can be controlled by changing the concentrations of compound 1 and gold(III) solution.     

Chemiluminescence detection of label-free C-reactive protein based on catalytic activity of gold nanoparticles

A novel, quantitative analytical method for measuring C-reactive protein (CRP) levels in human serum has been developed based on the catalytic activity of gold nanoparticles (GNPs) and luminol-H₂O₂ chemiluminescence (CL). The CL intensity in the presence of CRP and its ligand, O-phosphorylethanolamine (PEA), was greatly enhanced due to the aggregation of GNPs after the addition of 0.5 M NaCl. Any pretreatment steps, such as covalent functionalization of GNPs, addition of antibodies, or labeling of CRP, were not needed for CL detection. The CL enhancement was linearly proportional to CRP concentration in the range of 1.88 fM to 1.925 pM. The detection limit of CRP in serum samples was estimated to be as low as 1.88 fM. The detection sensitivity was increased more than 164 times of magnitude over that of the conventional, enzyme-linked immunosorbent assay (ELISA) method. This proposed GNP-based CL detection method offers the advantages of simplicity, rapidity, and sensitivity.     

Plant-assisted synthesis of gold nanoparticles for photocatalytic,anticancer, and antioxidant applications

The current study is the first to disclose a quick, cost-effective, and environmentally safe phytofabrication of gold nanoparticles (AuNPs) that remained stable for three months utilizing the aqueous extract of T. capensis leaves to uphold the principles of green chemistry such as less hazardous chemical syntheses, safer solvents and auxiliaries, design for energy efficiency, and use of renewable feedstocks. Several approaches were used to describe T. capensis-AuNPs, with the findings revealing the successful phytoformation of crystalline AuNPs with a dark brown color, spherical nanoparticles with a size range of 10–35 nm, a surface plasmon peak at 515 nm, and a surface charge of ? 24.5 mV. T. capensis-AuNPs showed 72% photodegradation efficacy against malachite green. The MTT experiment revealed that T. capensis-AuNPs and T. capensis extract had excellent potency in preventing the development and proliferation of human breast cancer cells (MCF7 cell line), with IC50 values of 9.6 g/mL and 23.3 g/mL, respectively. Both T. capensis-AuNPs and T. capensis extract had significant antioxidant efficacies, with DPPH scavenging percentages of 70.73% for T. capensis-AuNPs and 85.62% for T. capensis extract. Consequently, these findings suggest a new and sustainable route for the green synthesis of AuNPs using the aqueous extract of T. capensis.     

Direct electrochemical detection of kanamycin based on peroxidase-like activity of gold nanoparticles

An enzyme-free, ultrasensitive electrochemical detection of kanamycin residue was achieved based on mimetic peroxidase activity of gold nanoparticles (AuNPs) and target-induced replacement of the aptamer. AuNPs which were synthesized using tyrosine as a reducing and capping agent, exhibited mimetic peroxidase activity. In the presence of kanamycin-specific aptamer, however, the single-stranded DNA (ssDNA) adsorbed on the surface of AuNPs via the interaction between the bases of ssDNA and AuNPs, and therefore blocked the catalytic site of AuNPs, and inhibited their peroxidase activity. While in the presence of target kanamycin, it bound with the adsorbed aptamer on AuNPs with high affinity, exposed the surface of AuNPs and recovered the peroxidase activity. Then AuNPs catalyzed the reaction between H₂O₂ and reduced thionine to produce oxidized thionine. The latter exhibited a distinct reduction peak on gold electrode in differential pulse voltammetry (DPV), and could be utilized to quantify the concentration of kanamycin. Under the optimized conditions, the proposed electrochemical assay showed an extremely high sensitivity towards kanamycin, with a linear relationship between the peak current and the concentration of kanamycin in the range of 0.1–60 nM, and a detection limit of 0.06 nM. Moreover, the established approach was successfully applied in the detection of kanamycin in honey samples. Therefore, the proposed electrochemical assay has great potential in the fields of food quality control and environmental monitoring.     

各向异性金纳米粒子的制备及其在催化中的应用

尽管有关金纳米粒子催化的研究工作很多,但其中大多数都是采用传统的浸渍法将金盐负载到载体上、共沉淀或沉积-沉淀法制得负载的纳米粒子,但这些方法并未吸收最新的纳米技术。最近,金催化剂的研究者开发了在胶态悬浮液中制取金属纳米粒子,然后进行固载,从而使得单金属和双金属催化剂的催化活性和形貌控制取得较大进展。另一方面,最近十年出现了金纳米粒子合成的高级控制技术,得到了许多各向异性的金纳米粒子,且很容易制得新的形貌,可以控制纳米粒子的表面原子配位数和光学特性(可调的等离子体带),这些都与催化密切相关。这些形貌包括纳米棒、纳米星、纳米花、树枝状纳米结构或多面体纳米粒子等。除了高度关注各向异性金纳米粒子的最新开发的制备方法和性质,本综述也清楚地总结了这些纳米粒子独特的催化性能,以及通过提供更高催化性能的金催化剂、控制暴露的活性位,以及热、电和光催化的鲁棒性和可调性,从而给多相催化领域带来令人惊奇的潜在变革。     

Preparation of reversibly photo-cross-linked nanogels from pH-responsive block copolymers and use as nanoreactors for the synthesis of gold nanoparticles

Reversibly photo-cross-linkable pH-responsive block copolymer poly(ethylene oxide)-b-poly((2-(diethylamino)ethyl methacrylate-co-4-methyl-[7-(methacryloyl)oxyethyloxy] coumarin)) (PEO-b-P(DEA-co-CMA)) was synthesized via atom transfer radical polymerization (ATRP). Block copolymer nanogels could be easily prepared by first photo-cross-linking of the micelles at pH > 7 and then adjusting the solution to pH < 7. The photo-cross-linking was proved to be reversibly controlled under alternative irradiation of UV light at 365 nm and 254 nm. As a result, the cross-linking degrees and sizes of the nanogels can be easily controlled by alternatively UV light irradiation. Finally, the nanogels can serve as nanoreactors for the synthesis of gold nanoparticles. The protonated DEA units were first coordinated with HAuCl₄, and then the electrostatically bounded AuCl⁴⁻ anions were reduced to gold nanoparticles by NaBH₄. The nanogel-supported gold nanoparticles were used in chemical catalysis. The pH-responsive photo-cross-linked nanogels have been characterized using dynamic light scattering, transmission electron microscopy, UV-vis spectra and ¹H NMR spectroscopy measurements, respectively.     

Colloidal AgCl induced-growth of thorny gold nanoparticles and their SERS activity

In this paper, we exploited a unique procedure for obtaining thorny gold nanoparticles (Au NPs) with controllable length of thorns without using seeds and surfactants. The obtained Au NPs exhibited shape-determined surface-enhanced Raman spectroscopy activity toward rhodamine 6G.     

Microbial synthesis of gold nanoparticles: Current status and future prospects

Gold nanoparticles have been employed in biomedicine since the last decade because of their unique optical, electrical and photothermal properties. Present review discusses the microbial synthesis, properties and biomedical applications of gold nanoparticles. Different microbial synthesis strategies used so far for obtaining better yield and stability have been described. It also includes different methods used for the characterization and analysis of gold nanoparticles, viz. UV–visible spectroscopy, Fourier transform infrared spectroscopy, X ray diffraction spectroscopy, scanning electron microscopy, ransmission electron microscopy, atomic force microscopy, electron dispersive X ray, X ray photoelectron spectroscopy and cyclic voltametry. The different mechanisms involved in microbial synthesis of gold nanoparticles have been discussed. The information related to applications of microbially synthesized gold nanoparticles and patents on microbial synthesis of gold nanoparticles has been summarized.     

Interaction of gold nanoparticles with mitochondria

Mitochondrion is one of the most important organelles in cells with several vital responsibilities. The consequence of a deficiency in the function of mitochondrion could result with the wide range of diseases and disorders. In this study, we investigated the feasibility of utilizing surface-enhanced Raman scattering (SERS) to understand the mode of interaction of gold nanoparticles (GNPs) with mitochondria. The living lung cancer cells and the isolated mitochondria from these cells were treated with gold colloidal suspension for SERS experiments. The AFM images of the mitochondria confirmed that the treatment did not cause substantial damage to mitochondria. The localization of GNPs in living cells is investigated with confocal microscopy and found that GNPs form aggregates in the cytosol away from the mitochondria. However, SERS spectra obtained from isolated mitochondria and living cells indicate that GNPs escaped from the endosomes or entered into the living cell through another route may be in contact with mitochondria in a living cell. The findings of this study indicate that SERS can be used for mitochondrial research.     

芦丁在纳米金修饰玻碳电极上的电化学行为及其测定

采用循环伏安法将纳米金电沉积于玻碳电极表面,制备了纳米金修饰玻碳电极(NG/GCE).在pH3.29的Britton-Robinson(B-R)缓冲溶液中,用循环伏安法研究了芦丁在NG/GCE上的电化学行为.结果表明,NG/GCE对芦丁的氧化还原反应有良好的电催化作用.用方波伏安法测得芦丁的还原峰电流与其浓度在2.0×10-8～2.0×10-6mol/L范围内呈线性关系,检出限为1.0×10-8mol/L(S/N=3).     

Facile synthesis and excellent catalytic activity of gold nanoparticles on graphene oxide

For the first time,Au nanoparticles on graphene oxide（GO-AuNPs） were successfully fabricated without applying any additional reductants,just by the redox reaction between AuCl₄^-1 and GO.Their structure was characterized by transmission electron microscopy and X-ray powder diffraction.The results show that flower-like AuNPs were successfully dispersed on GO surface.Importantly,they showed a high catalytic activity for the Suzuki-Miyaura coupling reaction in an aqueous medium.     

Surface-functionalized silica-coated gold nanoparticles and their bioapplications

Monodisperse Au at SiO₂ nanoparticles has been functionalized with carboxylic groups for further bioconjugation with amino-terminated oligonucleotides. The oligonucleotide-modified Au at SiO₂ nanoprobes have been applied in the fast colorimetric DNA based on the sequence-specific hybridization properties of DNA. Self-assembling behavior of Au at SiO₂ nanoparticles was also investigated.     

Addition of gold nanoparticles to real-time PCR: effect on PCR profile and SYBR Green I fluorescence

Real-time quantitative polymerase chain reaction (qPCR) is the industry standard technique for the quantitative analysis of nucleic acids due to its unmatched sensitivity and specificity. Optimisation and improvements of this fundamental technique over the past decade have largely consisted of attempts to allow faster and more accurate ramping between critical temperatures by improving assay reagents and the thermal geometry of the PCR chamber. Small gold nanoparticles (Au-NPs) have been reported to improve PCR yield under fast cycling conditions. In this study, we investigated the effect of Au-NPs on optimised real-time qPCR assays by amplifying DNA sequences from genetically modified canola in the presence and absence of 0.9 nM Au-NPs of diameter 12 ± 2nm. Contrary to expectations, we found that Au-NPs altered the PCR amplification profile when using a SYBR Green I detection system due to fluorescence quenching; furthermore, high-resolution melt (HRM) analysis demonstrated that Au-NPs destabilised the double-stranded PCR product. The results indicate that effects on the assay detection system must be carefully evaluated before Au-NPs are included in any qPCR assay. Figure Raw amplification profiles in the presence and absence of gold nanoparticles     

A helpful method for controlled synthesis of monodisperse gold nanoparticles through response surface modeling

The interest in applying gold nanoparticles is principally based on their monodispersity. Therefore, the synthesis of monodisperse gold nanocrystals has a key role in designing nanomaterials for their specific application. However, it can represent a cutting edge for many laboratories, mainly because it requires a variety of complex techniques for properly characterizing metal nanoparticles with expensive and rugged equipment. Herein, we propose an approach to synthesize nanoparticles with controlled monodispersity that can be adjusted through the factorial experimental plan 3² using response surface modeling (RSM). The particles were characterized on the basis of visual observation, UV–visible spectroscopy, transmission electron microscopy, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDS) and statistics. Our findings illustrate how factorial design is important to providing accurate projections of nanoparticle production using sodium citrate and borohydride as reducers. The proposed method leverages facile and inexpensive routes to synthesize monodisperse gold nanocrystals without the assistance of time-consuming image-based characterization tools.