Synthesis, In Vitro Testing, and Biodistribution of Surfactant-Free Radioactive Nanoparticles for Cancer Treatment

New forms of cancer treatment, which are effective, have simple manufacturing processes, and easily transportable, are of the utmost necessity. In this work, a methodology for the synthesis of radioactive Gold-198 nanoparticles without the use of surfactants was described. The nuclear activated Gold-198 foils were transformed into H198AuCl4 by dissolution using aqua regia, following a set of steps in a specially designed leak-tight setup. Gold-198 nanoparticles were synthesized using a citrate reduction stabilized with PEG. In addition, TEM results for the non-radioactive product presented an average size of 11.0 nm. The DLS and results for the radioactive 198AuNPs presented an average size of 8.7 nm. Moreover, the DLS results for the PEG-198AuNPs presented a 32.6 nm average size. Cell line tests showed no cytotoxic effect in any period and the concentrations were evaluated. Furthermore, in vivo testing showed a high biological uptake in the tumor and a cancer growth arrest.

Retention of Activity by Antibodies Immobilized on Gold Nanoparticles of Different Sizes: Fluorometric Method of Determination and Comparative Evaluation

Antibody–nanoparticle conjugates are widely used analytical reagents. An informative parameter reflecting the conjugates’ properties is the number of antibodies per nanoparticle that retain their antigen-binding ability. Estimation of this parameter is characterized by a lack of simple, reproducible methods. The proposed method is based on the registration of fluorescence of tryptophan residues contained in proteins and combines sequential measurements of first the immobilized antibody number and then the bound protein antigen number. Requirements for the measurement procedure have been determined to ensure reliable and accurate results. Using the developed technique, preparations of spherical gold nanoparticles obtained by the most common method of citrate reduction of gold salts (the Turkevich–Frens method) and varying in average diameter from 15 to 55 nm have been characterized. It was shown that the number of antibodies (immunoglobulins G) bound by one nanoparticle ranged from 30 to 194 during adsorptive unoriented monolayer immobilization. C-reactive protein was considered as the model antigen. The percentage of antibody valences that retained their antigen-binding properties in the conjugate increased from 17 to 34% with an increase in the diameter of gold nanoparticles. The proposed method and the results of the study provide tools to assess the capabilities of the preparations of gold nanoparticles and their conjugates as well as the expediency of seeking the best techniques for various practical purposes.

Hyaluronate-Thiol Passivation Enhances Gold Nanoparticle Peritumoral Distribution When Administered Intratumorally in Lung Cancer

Biofouling is the unwanted adsorption of cells, proteins, or intracellular and extracellular bio-molecules that can spontaneously occur on the surface of metal nanocomplexes. It represents a major issue in bioinorganic chemistry because it leads to the creation of a protein corona, which can destabilize a colloidal solution and result in undesired macrophage-driven clearance, consequently causing failed delivery of a targeted drug-cargo. Hyaluronic acid (HA) is a bioactive, natural mucopolysaccharide with excellent antifouling properties, arising from its hydrophilic and polyanionic characteristics in physiological environments which prevent opsonization. In this study, hyaluronate-thiol (HA-SH) (MW 10 kDa) was used to surface-passivate gold nanoparticles (GNPs) synthesized using a citrate reduction method. HA functionalized GNP complexes (HA-GNPs) were characterized using absorption spectroscopy, scanning electron microscopy, zeta potential, and dynamic light scattering. GNP cellular uptake and potential dose-dependent cytotoxic effects due to treatment were evaluated in vitro in HeLa cells using ICP-OES and Trypan blue and MTT assays. Further, we quantified the in vivo biodistribution of intratumorally injected HA functionalized GNPs in Lewis Lung carcinoma (LLC) solid tumors grown on the flank of C57BL/6 mice and compared localization and retention with nascent particles. Our results reveal that HA-GNPs show overall greater peritumoral distribution (**p<0.005, 3 days post-intratumoral injection) than citrate-GNPs with reduced biodistribution in off-target organs. This property represents an advantageous step forward in localized delivery of metal nano-complexes to the infiltrative region of a tumor, which may improve the application of nanomedicine in the diagnosis and treatment of cancer.

Effect of Gold Nanoparticles Size on Detection of Methylphosphonic Acid Hydrolysis Product of Nerve Agent

Citrate reduction of gold (III) chloride trihydrate (HAuCl4) is commonly used method to synthesise citrate-capped gold nanoparticles (cit-AuNPs). In this study, the sequence of reagents addition was modified (“inverse” method) to synthesise smaller size of cit-AuNPs than the standard Turkevich method (“direct” method). Ultraviolet-visible spectroscopy (UV-vis) and field emission transmission electron microscopy (FETEM) confirmed the formation of cit-AuNPs. The cit-AuNPs synthesized using “inverse” method are smaller in size (14.0 ± 3.03 nm) with uniform spherical shape compared to “direct” method (23.5 ± 7.52 nm). Smaller particles size of cit-AuNPs provide higher efficiency and sensitivity for detection of methylphosphonic acid (MPA) via colorimetric incorporated with image processing with a linear range from 2.5 to 12.5 mM and a low detection limit of 6.28 mM at shorter detection period (24 to 30 s).

Specialization of the Reiterated Copies of the Heterodimeric Integration Host Factor Genes in Geobacter sulfurreducens

Integration host factor (IHF) is a widely distributed small heterodimeric protein member of the bacterial Nucleoid-Associated Proteins (NAPs), implicated in multiple DNA regulatory processes. IHF recognizes a specific DNA sequence and induces a large bend of the nucleic acid. IHF function has been mainly linked with the regulation of RpoN-dependent promoters, where IHF commonly recognizes a DNA sequence between the enhancer-binding region and the promoter, facilitating a close contact between the upstream bound activator and the promoter bound, RNA polymerase. In most proteobacteria, the genes encoding IHF subunits (ihfA and ihfB) are found in a single copy. However, in some Deltaproteobacteria, like Geobacter sulfurreducens, those genes are duplicated. To date, the functionality of IHF reiterated encoding genes is unknown. In this work, we achieved the functional characterization of the ihfA-1, ihfA-2, ihfB-1, and ihfB-2 from G. sulfurreducens. Unlike the ΔihfA-2 or ΔihfB-1 strains, single gene deletion in ihfA-1 or ihfB-2, provokes an impairment in fumarate and Fe(III) citrate reduction. Accordingly, sqRT-PCR experiments showed that ihfA-1 and ihfB-2 were expressed at higher levels than ihfA-2 and ihfB-1. In addition, RNA-Seq analysis of the ΔihfA-1 and ΔihfB-2 strains revealed a total of 89 and 122 differentially expressed genes, respectively. Furthermore, transcriptional changes in 25 genes were shared in both mutant strains. Among these genes, we confirmed the upregulation of the pilA-repressor, GSU1771, and downregulation of the triheme-cytochrome (pgcA) and the aconitate hydratase (acnA) genes by RT-qPCR. EMSA experiments also demonstrated the direct binding of IHF to the upstream promoter regions of GSU1771, pgcA and acnA. PilA changes in ΔihfA-1 and ΔihfB-2 strains were also verified by immunoblotting. Additionally, heme-staining of subcellular fractions in ΔihfA-1 and ΔihfB-2 strains revealed a remarkable deficit of c-type cytochromes. Overall, our data indicate that at least during fumarate and Fe(III) citrate reduction, the functional IHF regulator is likely assembled by the products of ihfA-1 and ihfB-2. Also, a role of IHF controlling expression of multiple genes (other than RpoN-dependent) affects G. sulfurreducens physiology and extracellular electron transfer.

The effect of N-acetylcysteine on the antibacterial capability and biocompatibility of nano silver–containing orthodontic cement

ABSTRACT Objectives To determine whether the incorporation of N-acetylcysteine (NAC) improves the antibacterial ability and biocompatibility of nano silver (NAg)–containing orthodontic cement. Materials and Methods NAg was synthesized using a sodium citrate reduction method. NAg particles were characterized using transmission electron microscopy and ultraviolet-visible absorption spectra. NAg and NAC were incorporated into a resin-modified glass ionomer cement. Enamel shear bond strength (SBS), antibacterial capability, and cytotoxicity were evaluated. Results Incorporating 0.15% NAg and 20% NAC had no adverse effect on the SBS of orthodontic cement (P > .1). Adding NAC into NAg-containing cement greatly reduced the biofilm metabolic activity and lactic acid production (P < .05) and lowered the colony unit–forming counts by approximately 1 log (P < .05). The cell viability against NAg-containing cement was improved by NAC (P < .05). Conclusions The incorporation of NAC into NAg-containing cement achieved stronger antibacterial capability and better biocompatibility, without compromising the enamel SBS. The combined use of NAC and NAg is promising to combat caries in orthodontic practice.

Conjugation of Antibody on Gold Nanoparticles for Biosensors Application

Regarding to the unique optical property and biocompatible, gold nanoparticles have been widely used to functionalize with antibodies probe for testing specificity with their antigen targets. The antibody immobilized onto gold nanoparticles which synthesized by different methods were studied. Gold nanoparticles synthesized by citrate reduction method and by using poly (ethylene) glycol (PEG) coated gold nanoparticles were immobilized with IgM antibody by physical adsorption. Gold nanoparticles before and after functionalize with antibodies were characterized with fourier-transform infrared spectroscopy (FTIR) for functional group and UV-Vis spectroscopy for absorption wavelength. Finally, a specificity test was conducted using spot of anti-IgM antibody onto nitrocellulose membrane to confirm the bioactivity of antibodies attached to gold nanoparticles.

Identification for Disperse Dyes on Single Cotton Fiber by SERS

In the present study, an application of Ag nanoparticles (AgNPs) in order to obtain Surface-enhanced Raman spectroscopy (SERS) of disperse dyes on single cotton fiber is presented. In detail, we prepared colloid Ag by use of citrate reduction method. Add one drop of the colloid on single colored fiber and then Raman spectra recorded with excitation wavelength at 785 nm were carried out on a Renishaw Raman spectrometer coupled to a 20x object lens. Cotton fibers dyed by disperse red 17 (DR17) and disperse blue 35 (DB35) are characterized and analyzed. This method was found out to be an effectively way to identify both DR17 and DB35 on single cotton fibers. Furthermore, SERS expands methods for identification disperse dyes on fibers, and provide a good method for verify colored cotton fibers.