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Guanosine 3'-diphosphate-5'-di(tri)phosphate (ppGpp) plays a crucial role in the gene expression, metabolism, growth, and other significant processes of microorganisms. In this work, a facile sensitive and visual strategy for the detection of ppGpp has been established by developing a colorimetric probe of copper ions (Cu 2+ )-mediated 4-mercaptobenzoic acid (4-MBA) modified gold nanoparticles (AuNPs). The sensing process was characterized by transmission electron microscopy (TEM), zeta potential, dynamic light scattering (DLS) and UV-vis spectroscopy. The strategy not only achieves desirable performance over a wide concentration range (0.05-10 μM), but also exhibits excellent selectivity over other nucleotides and biomolecules. In addition, the results could be visualized by the naked eye. We have demonstrated the determination of ppGpp in Bacillus subtilis lysate samples., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Nanotechnology is an emerging paradigm for creating functional nanoscale materials for various biomedical applications. In this study, a new nanotechnology-based drug delivery method was developed using gold nanoparticles (GNPs) as a delivery vehicle to reduce adverse drug side effects. Fludarabine Phosphate is a commercial chemotherapy drug used in cancer treatment, and has ability to kill various cancer cells. KG-1 cell, a type of acute cancer leukemia cell, was selected as a proof-of-concept target in this study. Due to the small size of GNPs, they can help Fludarabine Phosphate enter cancer cells more efficiently and better interfere with DNA synthesis in the cancer cells. To enhance targeting ability, folic acid molecules were also covalently linked to GNPs, resulting in GNP-Fludarabine-folic acid (GNP-F/f). Compared to treatments with GNP-F or drugs on its own (Fludarabine Phosphate), the GNP-F/f achieves much improved cell-killing effects. The UV-Vis spectra results also revealed that the drugs had successfully bonded covalently to the GNPs. The higher cell-killing efficiency of GNP-F/f compared with GNP-Fludarabine (GNP-F) or drugs on their own further validates the effectiveness of both the vectors (GNPs) and folic acid in enhancing the drug delivery to the cancer cells. The MTT viability tests showed that the GNPs had no cytotoxicity.

In this article, we report a new method-a sonication method to disperse iron oxide nanoparticles into smaller nanoparticles and make gold ions absorb onto the surface or trapped in the micropores of the iron oxide nanoparticles using sonication action. By using quick reduction of ascorbic acid and post-HCI solution treatment, gold covered magnetic nanoparticles (mGNPs) with spherical morphology and uniform size were synthesized in a water solution. The size of the mGNPs was found to be 20-30 nm. Some ideal mGNPs possessed a core-shell structure. The mGNPs were non-cytotoxic and mGNP-fluorescein isothiocyanate (FITC) can enter KG-1 cells when driven by an external magnetic force, which was confirmed by confocal imaging. The confocal image also showed the FITC inside the KG-1 cells was near the nucleus. The fluorescein isothiocyanate (FITC) delivery efficiency is about 100% according to the flow cytometry results.

We synthesized a novel, multi-functional, radiosensitizing agent by covalently linking 6-fluoro-6-deoxy-D-glucose (6-FDG) to gold nanoparticles (6-FDG-GNPs) via a thiol functional group. We then assessed the bio-distribution and pharmacokinetic properties of 6-FDG-GNPs in vivo using a murine model. At 2 h, following intravenous injection of 6-FDG-GNPs into the murine model, approximately 30% of the 6-FDG-GNPs were distributed to three major organs: the liver, the spleen and the kidney. PEGylation of the 6-FDG-GNPs was found to significantly improve the bio-distribution of 6-FDG-GNPs by avoiding unintentional uptake into these organs, while simultaneously doubling the cellular uptake of GNPs in implanted breast MCF-7 adenocarcinoma. When combined with radiation, PEG-6-FDG-GNPs were found to increase the apoptosis of the MCF-7 breast adenocarinoma cells by radiation both in vitro and in vivo. Pharmacokinetic data indicate that GNPs reach their maximal concentrations at a time window of two to four hours post-injection, during which optimal radiation efficiency can be achieved. PEG-6-FDG-GNPs are thus novel nanoparticles that preferentially accumulate in targeted cancer cells where they act as potent radiosensitizing agents. Future research will aim to substitute the (18)F atom into the 6-FDG molecule so that the PEG-6-FDG-GNPs can also function as radiotracers for use in positron emission tomography scanning to aid cancer diagnosis and image guided radiation therapy planning.

A facile strategy by loading luminol and secondary antibody on gold nanoparticles (Au NPs) was described in the present work. The as-prepared luminol/antibody labeled Au NPs conjugates (LAAu NPs) were used as the chemiluminescent probe for the detection of carcinoembryonic antigen (CEA) in serum. The LAAu NPs were characterized by transmission electron microscopy (TEM), UV-vis spectrophotometry (UV-vis), and chemiluminescent method. Stable and efficient chemiluminescence (CL) was obtained when luminol molecules and secondary antibodies were coimmobilized on the Au NPs by using hydrogen peroxide (H(2)O(2)) as an oxidant, horseradish peroxidase (HRP) as a catalyst, and 4-(4'-iodo)phenylphenol (IPP) as an enhancer. The LAAu NPs were further evaluated via a sandwich-type CL immunoassay of CEA in serum. In this protocol, the CEA analyte was captured by the primary antibody immobilized on the surface of magnetic beads, and then was sandwiched by the secondary antibody loaded on luminol-labeled Au NPs. The chemiluminescent intensity was proportional to the concentration of CEA over the range of 5.0x10(-10) to 5.0x10(-8) g mL(-1) and 5.0x10(-9) to 2.0x10(-8) g mL(-1) by using HRP and Co(2+) as catalysts, respectively. The present chemiluminescent immunoassay based on the luminol/antibody labeled Au NPs conjugates has offered great promise for simple, highly biocompatible, and cost-effective analysis of biological samples., (2010 Elsevier B.V. All rights reserved.)

Gold'n'beads: A chemiluminescence immunoassay for the sensitive and rapid determination of AFP has been developed, employing bromophenol blue as a novel chemiluminescence enhancer by taking advantages of easy separation by magnetic beads and signal amplification by gold nanoparticles based on a sandwich-type immunoreaction (see scheme).A novel and sensitive chemiluminescence immunoassay (CLIA) has been developed by employing a new chemiluminescence (CL) enhancer, bromophenol blue (BPB), for the determination of alpha-fetoprotein (AFP) based on magnetic beads (MBs) and colloidal gold nanoparticles (AuNPs) modified with HRP-labeled anti-AFP antibodies. BPB, as a chemical indicator, was found to act as a novel and highly signal enhancer of the peroxidase-catalyzed CL reaction of luminol with hydrogen peroxide. After optimizing the CL reaction conditions, this new luminol-H(2)O(2)-HRP-BPB CL system was applied to a sandwich-type CLIA based on the magnetic separation and the amplification feature of AuNPs as HRP labels. A linear range was obtained when the concentrations of AFP were from 0.1 to 5.0 ng mL(-1) (R=0.9997) with the detection limit of 0.01 ng mL(-1) (3sigma), which is one order of magnitude lower than that obtained without using AuNPs, and much lower than that typically achieved by ELISA. The present method was successfully applied to the determination of AFP in human serum samples. The results indicated that this proposed protocol could be quite promising for the application in immunoassays.

Gold nanoparticles (GNPs) and modified GNPs having two kinds of functional molecules, cysteamine (AET) and thioglucose (Glu), are synthesized. Cell uptake and radiation cytotoxicity enhancement in a breast-cancer cell line (MCF-7) versus a nonmalignant breast-cell line (MCF-10A) are studied. Transmission electron microscopy (TEM) results show that cancer cells take up functional Glu-GNPs significantly more than naked GNPs. The TEM results also indicate that AET-capped GNPs are mostly bound to the MCF-7 cell membrane, while Glu-GNPs enter the cells and are distributed in the cytoplasm. After MCF-7 cell uptake of Glu-GNPs, or binding of AET-GNPs, the in vitro cytotoxicity effects are observed at 24, 48, and 72 hours. The results show that these functional GNPs have little or no toxicity to these cells. To validate the enhanced killing effect on cancer cells, various forms of radiation are applied such as 200 kVp X-rays and gamma-rays, to the cells, both with and without functional GNPs. By comparison with irradiation alone, the results show that GNPs significantly enhance cancer killing.