Gold Bulletin最新文献

Protein oligomerization contributes to Alzheimer’s disease development (AD). A nanoparticle that can speed up the oligomerization of proteins is generally considered harmful. Gold nanoparticles (AuNPs) have been reported to be making headway in biological platforms, but they may also have the capacity to stimulate protein oligomerization. Our goal herein was to investigate the neurotoxicity and oligomerization of amyloid-β-1-42 (Aβ_1-42) in the presence of AuNPs. The precipitation approach was used to create AuNPs, which were then analyzed using transmission electron microscopy (TEM), ThT, Congo red, and CD spectroscopy. The results demonstrated that the 50-nm-sized fabricated AuNPs guided acceleration in Aβ_1-42. In addition, cytotoxicity studies on PC 12 cells showed that Aβ_1-42 with AuNPs were less toxic than untreated oligomers Aβ_1-42 in terms of inducing cell death, oxidative apoptosis, stress, and membrane leakage. In conclusion, our investigation sheds light on how AuNPs stimulate the development of cytotoxic oligomers by binding to proteins in Alzheimer’s disease.

In this study, carbon quantum dots (CQDs) were first synthesized using a hydrothermal method, and then, Au@SiO₂ core-shell nanomaterials were synthesized using layer-by-layer assembly. CQDs were adsorbed on the surface of Au@SiO₂ nanoparticles through self-assembly to form Au@SiO₂/CQDs nanocomposite materials. Transmission electron microscopy and X-ray diffraction were used to characterize the size, shape, element composition, and structure of nanocomposites; ultraviolet-visible absorption spectroscopy and fluorescence spectroscopy were used to analyze the optical properties of nanocomposites. The results show that Au@SiO₂/CQD nanomaterials have a core-shell structure with good morphology and exhibit excellent luminescence characteristics. The electrochemical performance of nanocomposites was characterized using electrochemical means, and a hydrogen peroxide sensor was constructed for the sensitive detection of hydrogen peroxide, thus realizing the rapid and sensitive detection of hydrogen peroxide at levels as low as 0.2 mM. The electrode GCE modified with Au@SiO₂/CQDs exhibits good selectivity and stability in the detection of hydrogen peroxide.

This study encompasses the synthesis of gold nanoparticles (GNPs) captured on nanofibrous vinyl brushes (NVBs) using sepiolite nanoclay as a matrix. The diameter of GNPs was found to be 2–8 nm investigated by a particle-size analyzer. Due to the high surface reactivity, GNPs are more susceptible to agglomeration which reduces their efficacy as catalyst. A suitable support could be employed to arrest the discrete gold particles on its surface. The distinct textural morphology of sepiolite allows it to be a promising choice as support. Silanol groups on the surface of sepiolite nanofibers were consumed to graft vinyl brushes using hydrolyzed vinyl triethoxy silane. This grafting was characterized by FT-IR spectroscopy. Morphological studies of developed nanocomposites (AuNVBs) were conducted by TEM and FESEM revealing evidently the incorporation of well-distributed GNPs. XRD diffractograms have validated the connectivity of GNPs on NVBs surface. GNPs immobilized on the surface of NVBs are commendable candidates as catalyst to enhance the reaction rate for the conversion of 4- nitrophenol to 4- aminophenol.

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Conventional techniques for microbial detection are time-consuming, expensive, and unsuitable. The use of nanoparticles is a valuable technique for the detection of bacterial as well as viral DNA. Gold nanoparticles (gold NPs) have been used as a promising detector for rapid and low-cost identification of microbes with high sensitivity. In this study, gold nanoparticles-probes were used to identify Pseudomonas aeruginosa and Acinetobacter baumannii genomic DNA. Thiol-functionalized probes were attached to gold NPs. Hybridization of the probe with the amplified product of Oprl and glta genes resulted in accumulation of gold nanoparticles in a cross-linked manner, caused a color change of the reaction mixture, which indicated the presence of Pseudomonas aeruginosa and Acinetobacter baumannii in the sample. To study the sensitivity, the polymerase chain reaction product with different bacteria was used, and results were compared. The gold nanoparticle-based colorimetric assay can be used as a direct and rapid method with high sensitivity for specific identification of these pathogens in clinical and food samples.

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Abstract

The high enhancement activity of litchi-like gold nanoparticles (Au NPs) is prepared in deep eutectic solvent (DES), and the prepared Au NPs as SERS active substrate exhibits excellent sensitivity when rhodamine 6G (R6G) is used as a probe molecule for detection. The enhancement factor (EF) is calculated to be about 1.8 × 10¹², and the minimum detected concentration is outstanding in R6G aqueous solution at 10⁻¹² M. In addition, the microtrace determination of penicillin G sodium (PG) in camel milk powder produced in Xinjiang was successfully achieved by using the prepared Au NPs. This work provides an environmentally friendly, simple, and rapid method to prepare efficient and sensitive surface-enhanced Raman scattering (SERS) materials. Meanwhile, it also uncovers a new possibility for the development of various nanoparticles with SERS prepared using DES as reactive solutions.

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Abstract

Abstract

Healthy dairy products should be free of any substances that threaten human health. However, the use of antibiotics for the treatment of lactating animals can be a risk to human health, as their residues and metabolites can be transferred into milk. Various methods are used to ensure the purity of milk. In this study, a kit based on a specific penicillin aptamer bonded to gold nanoparticles was designed to measure penicillin in milk, and its measurement was performed using ELISA colorimetric method. After synthesis of gold nanoparticles, the molarity of gold nanoparticles was calculated by UV spectrophotometer, and its synthesis was confirmed by FTIR. Salt concentrations were also optimized to bind aptamer to gold nanoparticles. The gold nanoparticles were then bonded to the specific aptamer of penicillin, and the concentration of penicillin G in the milk sample was measured by a biosensor designed by ELISA. The choice of biosensor was also examined in the presence of similar antibiotics.