Deuterium isotope effects on carbon-13 chemical shifts in 5-[2H]-isotopomeres of ten 2-substituted adamantane derivatives were determined and used for complete assignment of their carbon-13 NMR spectra. The carbon-13 NMR spectra of ten 2-substituted adamantane derivatives have been assignated by consideration of deuterium isotope effects. Some four- and five-bond downfield deuterium effects on certain chemical shifts have been measured and attributed to remote hyperconjugative interactions. 相似文献
Although photodynamic therapy is an efficient therapeutic strategy for cancer treatment, it always suffers from the low singlet oxygen (1O2) yields owing to the weak absorption in optical transparent window of biological tissues. Herein, the black phosphorus (BP) nanosheet is integrated with gold nanoparticles (AuNPs) to simultaneously enhance the singlet oxygen generation and hyperthermia by localized surface plasmon resonance (LSPR) in cancer therapy. In the design, BP nanosheet employed as two‐dimension (2D) inorganic photosensitizer is hybridized with AuNPs through polyetherimide (PEI) as bridge to form BP‐PEI/AuNPs hybrid nanosheet. Such hybridation not only significantly increases the 1O2 production of BP nanosheet through maximizing the local field enhancement of AuNPs, but also significantly enhances the light absorption of BP nanosheet to promote photothermal effect by LSPR. Accordingly, about 3.9‐fold enhancement of 1O2 production and 1.7‐fold increasement of photothermal conversion efficiency are achieved compared with BP‐PEI alone upon single 670 nm laser irradiation. As a proof‐of‐concept model, BP‐PEI/AuNPs hybrid nanosheet with simultaneous dual‐modal phototherapy functions result in effective suppression of tumor growth with minimized side effects both in vitro and in vivo, indicating the great potential of the BP‐PEI/AuNPs hybrid nanosheet as an effective strategy to enhance the cancer therapy efficiency. 相似文献
The molecular level DNA logic gates assisted by nanomaterials hold great promise for disease diagnosis applications. However, designing convenient and sensitive logic gates for molecular diagnostics still remains challenging. In this work, a DNA logic gate platform for miRNA inputs analysis based on the observation of localized surface plasmon resonance variation of gold nanoparticles (AuNPs) is fabricated. As a demonstration, two biomarkers to differentiate indolent and aggressive forms of prostate cancer, miR‐200c and miR‐605, are selected as examples of logical inputs. In addition, five DNA probes are designed according to strand displacement reaction and hybridization chain reaction which are required for DNA logical operation. Since target miRNA inputs are able to trigger DNA structural transformations, which are further used to precisely regulate salt‐induced AuNPs aggregation, miRNA inputs information can be converted to the information of AuNPs states as outputs. This developed system performs amplified detection of low‐abundant target miRNAs without the requirement of any enzymes. In addition, single base‐pair mismatched miRNAs can be effectively differentiated. High‐order logic gates can also be developed with further modifications. Therefore, the DNA AND logic gate is successfully constructed with flexible operations, which has potential in biochemical study and disease diagnosis. 相似文献
A compact bench‐top system based on a dielectric barrier plasma discharge (DBD), enables the rapid, automatable, and continuous‐flow synthesis of gold nanoparticles (AuNPs) and radioactive gold nanoparticles (198AuNPs). AuNPs are used as radiosensitizers in oncology, and 198AuNPs (half‐life: 2.7 d) have been suggested as potential cancer brachytherapy sources. Plasma applied at the surface of a liquid containing gold ions (AuCl4?) and dextran induces the production of AuNPs directly in water. This synthesis is monitored in real time by UV–visible spectrometry: the change of absorbance of the solution provides new insights on the growth dynamics of AuNPs by plasma synthesis. By balancing gold ions and surfactant molecules, particles with a diameter lying in the optimal range for radiosensitizing applications (28 ± 9 nm) are produced. The method yields a reduction of more than 99% of the gold ions within only 30 min of plasma treatment. A postsynthesis ripening of the AuNPs is revealed, monitored by UV–visible spectrometry, and quantified within the first few hours following plasma treatment. Radioactive 198AuNPs are also produced by DBD synthesis and characterized by electron microscopy and single‐photon emission computed tomography imaging. The results confirm the efficiency of DBD reactors for AuNPs synthesis in oncology applications. 相似文献
The coordination of zinc by proteins and various other organic molecules is essential for numerous biological processes, such as in enzymatic catalysis, metabolism, and signal transduction. Presence of small molecular chelants can have a profound effect on the bioavailability of zinc and affect critical Zn2+–protein interactions. Zn2+ chelators are also emerging therapeutics for Alzheimer's disease because of their preventive effect on zinc‐promoted amyloid formation. Despite the importance of zinc–protein–chelant interactions in biology and medicine, probing such interactions is challenging. Here, an innovative approach is introduced for real‐time characterization of zinc–protein–chelant interactions using gold nanoparticles (AuNPs) functionalized with a zinc‐responsive protein mimetic polypeptide. The peptide‐functionalized AuNPs aggregate extensively in the presence of Zn2+, triggered by specific Zn2+‐mediated polypeptide dimerization and folding, causing a massive red shift of the plasmon band. Chelants affects the Zn2+–polypeptide interaction and thus the aggregation differently depending on their concentrations, zinc‐binding affinities, and coordination numbers, which affect the position of the plasmon band. This system is a simple and powerful tool that provides extensive information about the interactions of chelants in the formation of Zn2+ coordination complexes, and an interesting platform for development of bioanalytical techniques, and characterization of chelation‐based therapeutics. 相似文献
Boron neutron capture therapy (BNCT) is a binary approach for cancer treatment in which boron-10 atoms and thermal neutrons need to colocalize to become effective. Recent research in the development of BNCT drug candidates focuses increasingly on nanomaterials, with the advantages of high boron loadings and passive targeting due to the enhanced permeability and retention (EPR) effect. The use of small boron-rich gold nanoparticles (AuNPs) in combination with a pretargeting approach is proposed. Small sized polyethylene glycol–stabilized AuNPs (core size 4.1 ± 1.5 nm), are synthesized and functionalized with thiolated cobalt bis(dicarbollide) and tetrazine. To enable in vivo tracking of the AuNPs by positron emission tomography (PET), the core is doped with [64Cu]CuCl2. For the pretargeting approach, the monoclonal antibody Trastuzumab is functionalized with trans-cyclooctene-N-hydroxysuccinimide ester. After proving in vitro occurrence of the antibody conjugation onto the AuNPs by click reaction and the low toxicity of the AuNPs, the boron delivery system is evaluated in vivo using breast cancer xenograft bearing mice and PET imaging. Tumor uptake due to the EPR effect can be witnessed with ≈5% injected dose (ID) cm−3 at 24 h postinjection, but with slower clearance than expected. Therefore, no increased retention can be observed using the pretargeting strategy. 相似文献
The ferrihydrite mineral core of ferritin is a semi-conductor capable of catalyzing oxidation/reduction reactions. This report
shows that ferritin can photoreduce AuCl4− to form gold nanoparticles (AuNPs). An important goal was to identify innocent reaction conditions that prevented formation
of AuNPs unless the sample was illuminated in the presence of ferritin. TRIS buffer satisfied this requirement and produced
AuNPs with spherical morphology with diameters of 5.7 ± 1.6 nm and a surface plasmon resonance (SPR) peak at 530 nm. Size-exclusion
chromatography of the AuNP–ferritin reaction mixture produced two fractions containing both ferritin and AuNPs. TEM analysis
of the fraction close to where native ferritin normally elutes showed that AuNPs form inside ferritin. The other peak eluted
at a volume indicating a particle size much larger than ferritin. TEM analysis revealed AuNPs adjacent to ferritin molecules
suggesting that a dimeric ferritin–AuNP species forms. We propose that the ferritin protein shell acts as a nucleation site
for AuNP formation leading to the AuNP-ferritin dimeric species. Ferrihydrite nanoparticles (~10 nm diameter) were unable
to produce soluble AuNPs under identical conditions unless apo ferritin was present indicating that the ferritin protein shell
was essential for stabilizing AuNPs in aqueous solution. 相似文献
A simple method for synthesis of gold nanoparticles (AuNPs) using Aspergillum sp. WL-Au was presented in this study. According to UV–vis spectra and transmission electron microscopy images, the shape and size of AuNPs were affected by different parameters, including buffer solution, pH, biomass and HAuCl4 concentrations. Phosphate sodium buffer was more suitable for extracellular synthesis of AuNPs, and the optimal conditions for AuNPs synthesis were pH 7.0, biomass 100 mg/mL and HAuCl4 3 mM, leading to the production of spherical and pseudo-spherical nanoparticles. The biosynthesized AuNPs possessed excellent catalytic activities for the reduction of 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, o-nitroaniline and m-nitroaniline in the presence of NaBH4, and the catalytic rate constants were calculated to be 6.3×10−3 s−1, 5.5×10−3 s−1, 10.6×10−3 s−1, 8.4×10−3 s−1 and 13.8×10−3 s−1, respectively. The AuNPs were also able to catalyze the decolorization of various azo dyes (e.g. Cationic Red X-GRL, Acid Orange II and Acid scarlet GR) using NaBH4 as the reductant, and the decolorization rates reached 91.0–96.4% within 7 min. The present study should provide a potential candidate for green synthesis of AuNPs, which could serve as efficient catalysts for aromatic pollutants degradation. 相似文献
Biosynthesis and characterizations of nanoparticles have become an important branch of nanotechnology. In this paper, green synthesis of gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) using the flower extract of Rosa damascena as a reducing and stabilizing agent, has been discussed. This approach is simple, cost-effective and stable for a long time, reproducible at room temperature and in an eco-friendly manner to obtain a self-assembly of AuNPs and AgNPs. The resulting nanoparticles are characterized using UV–vis, TEM, XRD and FT-IR spectroscopic techniques. A modified glassy carbon electrode using AuNPs (AuNPs/GCE) was investigated by means of cyclic voltammetry in a solution of 0.1 M KCl and 5.0×10−3 M [Fe(CN)6]3−/4−. The results show that electronic transmission rate between the modified electrode and [Fe(CN)6]3−/4− increased. 相似文献
A green method, using pulsed spark-discharge (PSD) to synthesize gold nanoparticles (AuNPs) in ethanol, is studied in this
article. Unlike conventional methods for metal nanoparticles synthesis, the PSD method does not require the addition of chemical
surfactants and stabilizers. The size of PSD–AuNPs is examined by transmission electron microscopy, with a range 5–50 nm.
The chemical compounds, crystal structure, and surface plasmon resonance of PSD–AuNPs are studied using energy dispersive
X-ray spectroscopy, X-ray diffraction, and UV–Visible spectroscopy, respectively. Zeta potential analysis shows that a negative
charge (−40 mV) on the surface of the PSD–AuNPs may be contributing to the stability of the suspension. During the gold electrodes
discharge in the ethanol, under an intensive electric field and thermal energy, bulk metallic gold and ethanol may produce
AuNPs and varieties of chemical derivatives, which are also studied by GC/MS and FTIR to investigate the suspension mechanism.
The analysis results show that there is an oxidation reaction of ethanol occurring during the PSD process to produce ethanol
derivatives, such as acetaldehyde, acetic acid, and ethyl acetate, which may modify the surface of AuNPs by coordination of
oxygen atoms. However, only acetic acid can form a negative charge by the deprotonation of the carboxylic group of surface
in ethanol, resulting in the creation of a repulsion force between the particles to form the stable colloid system. The experimental
results indicate that PSD is an alternative green process to synthesize gold nanoparticles suspension in ethanol. Moreover,
with a gold rod consumption rate of 15 mg/L, concentrations of gold nanoparticles ~9 ppm have been observed; therefore, the
net production rate is around 60%. 相似文献
Cyanazine residue poses a great threat to human health and its derivatives would remain in soils, natural waters, and other environmental domains for a long time. Herein, a simple, rapid, and ultra-sensitive analytical method for the determination of cyanazine (CZ) based on inner filter effect (IFE) of Au nanoparticles (AuNPs) on the fluorescence of CdTe quantum dots (QDs) is first described in this study. With the presence of citrate-stabilized AuNPs, the fluorescence of GSH-capped CdTe QDs was remarkably quenched by AuNPs via IFE. The fluorescence of the AuNP–CdTe QD system was recovered upon addition of CZ. CZ can adsorb on to the surface of AuNPs due to its cyano group that has good affinity with gold, which could induce the aggregation of AuNPs accompanying color change from red to blue. Thus, the IFE of AuNPs on CdTe QDs was weakened, and the fluorescence intensity of CdTe QDs was recovered accordingly. A good linear correlation for detection of CZ was exhibited from 0.05 to 9 μM, and the detection limit reached 0.1568 μM, which was much lower than the safety limit required by the USA, the UK, and China. In order to probe into the selectivity of AuNPs towards CZ over other pesticides, various frequently used pesticides were mixed with AuNPs. AuNP composite solution shows good selectivity towards CZ among other pesticides. This method was successfully carried out for the assessment of CZ in real samples with satisfactory results, which revealed many advantages such as high sensitivity, low cost, and non-time-consuming compared with traditional methods. 相似文献
A highly selective and sensitive method is developed for colorimetric detection of melamine using gold nanoparticles (AuNPs) functionalized with p-chlorobenzenesulfonic acid. The addition of melamine induced the aggregation of AuNPs, as evidenced from the morphological characterizations and the color changed from red wine to blue, which could also be monitored by the UV–visible spectrometer and even naked eyes. This process caused a significant increase in the absorbance ratio (A650nm/A520nm) of p-chlorobenzenesulfonic acid–AuNPs. Under optimized conditions, the system exhibited a linear response to melamine in the range of 6.0 × 10?7–1.5 × 10?6 mol L?1 with a correlation coefficient of 0.997, and the limit of detection can even be 2.3 nM, which was much lower than some other methods and the safe limits (20 μM in both the USA and EU, 8.0 μM for infant formula in China, 1.2 μM in the CAC (Codex Alimentarius Commission) review for melamine in liquid infant formula). More importantly, the developed method presented excellent tolerance to coexisting common metal ions such as Ca2+, Zn2+, whose concentration is 1000 times of melamine, so that it had been applied to the analysis of melamine in liquid milk and milk powder with the recovery of 97.0–101 % and 100–103 %, respectively, indicating that the proposed method is quite a highly effective means to determine melamine in milk products. 相似文献
Ultrasound and plant extract are two green approaches that have been used to synthesize gold nanoparticles (AuNPs); however, how the combination of ultrasound and citrus peel extract (CPE) affects the structure characteristics and the bioactivity of AuNPs remains unknown. Here we investigated the effects of ultrasound conditions on the particle size, stability, yield, phenolic encapsulation efficacy, and the anti-inflammatory activity of AuNPs. The results showed that temperature was positively correlated to the particle size and the anti-inflammatory activity of synthesized AuNPs. Increasing the power intensity significantly decreased the particle size, while increased the change of total phenolic content (ΔTPC) in the reaction mixture. The increase of ΔTPC caused the enhanced anti-inflammatory activity of AuNPs. The AuNPs synthesized with or without ultrasound treatment were characterized using UV–Vis, DLS, SEM, TEM, EDS, XRD, and FT-IR. The result verified the formation of negatively charged, spherical, stable, and monodispersed AuNPs. AuNPs synthesized with ultrasound (AuNPs-U) has smaller particle size (13.65 nm vs 16.80 nm), greater yield and anti-inflammatory activity (IC50, 82.91 vs 157.71 μg/mL) than its non-ultrasound counterpart (AuNPs-NU). HPLC analysis showed that hesperidin was the key reductant for the synthesis of AuNPs. AuNPs-U also inhibited the mRNA and protein expression of iNOS and COX-2 in the LPS-induced Raw 264.7 cells. Our research elucidates the relationship between the reaction conditions and the structure characteristics and the anti-inflammatory activity of AuNPs synthesized using CPE with the help of ultrasound, thereafter, provides a feasible and economic way to synthesize AuNPs that can be used to ameliorate inflammation. 相似文献
The Turkevich method has been the preferred one for synthesis of gold nanoparticles (AuNPs), owing to its apparent simplicity and facility of replacing the citrate ions on the particle surface by molecules exhibiting different functionalities. Using the most common procedure labile spherical nanoparticles are usually obtained by this method. Here, by using factorial design of experiments, we demonstrated that gold nanodiscs (AuNDs) with short aspect ratio can be generated by the Turkevich method when Au:citrate ratio is 1:1. In comparison with the CTAB capped gold nanorods (AuNR), the citrate stabilized AuNDs exhibited a more labile character, allowing fast ligand exchange reactions and easy functionalization of the nanoparticle surface. In the presence of 4-mercaptopyridine (4-mpy), the surface enhancement Raman scattering effect was 100 and 1000 times higher than the one observed for CTAB-AuNR and spherical AuNPs, respectively, increasing the 4-mpy detection limit to 2.5 × 10?9 molL?1. 相似文献
Amphiphilic gold nanoparticles (AuNPs) functionalized with mixed monolayers consisting of hydrophobic and hydrophilic ligands find widespread applications in biosensing, drug delivery, and bioimaging. One important aspect of amphiphilic AuNPs in such applications is the tuning of the surface properties of these AuNPs by modifying the composition of the ligands. In this study, well-dispersed AuNPs as individuals with mixed monolayers of hydrophobic and hydrophilic ligands were synthesized and the ratios of hydrophilic and hydrophobic ligands on the AuNP surfaces with varying ligand lengths were investigated by electrostatic titration. We demonstrated that longer hydrophobic ligands have higher affinity for the AuNP surface, and that the relative ligand length plays an important role in determining the maximum hydrophobic coverage on the AuNP surface at which the ratio of the amount of hydrophobic to that of hydrophilic ligands on the AuNP surface is the largest, for AuNPs to remain as individuals. We expect that the AuNPs synthesized with diverse ratios of hydrophobic and hydrophilic ligands on the surface can be useful in biological applications.
We report on the use of poly(allylamine) hydrochloride (PAH) as a reducing agent for the controlled formation of gold nanoparticles
(AuNPs) in the size range of 5–50 nm. The formation of AuNPs using this polymer matrix allows for the AuNPs to be imbedded
in the polymer matrix, once formed. The kinetics of AuNP formation are shown to be pseudo first-order in [HAuCl4] at room temperature. The kinetics of AuNP formation are controlled by the ratio of reducing agent to HAuCl4 as well as the overall concentration of the PAH and HAuCl4. Additionally, at low PAH:HAuCl4 mole ratios, the plasmon resonance wavelength can be controlled through the ratio of the reactants. This plamson resonance
shift is shown to be related to AuNP size by means of TEM imaging data on the AuNPs. 相似文献
The incoherent inelastic neutron scattering spectra of hexamethylene tetramine (HMT) and adamantane have been measured at high resolution between 200 and 1000 cm-1. The agreement between the frequencies of the observed spectra and the optical spectra of Mecke and Spieseche (HMT) and Bailey (adamantane) is good. The observed neutron spectra are also matched very closely by the calculated one-phonon spectra, computed from a normal-coordinate analysis. There is some additional structure in the neutron spectra which appears to be due to multiphonon scattering involving lattice modes. 相似文献