Effect of the concentration of protein and nanoparticles on the structure of biohybrid nanocomposites

We present colloidal nanocomposites formed by incorporating magnetite Fe₃O₄ nanoparticles (MNPs) with lysozyme amyloid fibrils (LAFs). Preparation of two types of solutions, with and without addition of salt, was carried out to elucidate the structure of MNPs-incorporated fibrillary nanocomposites and to study the effect of the presence of salt on the stability of the nanocomposites. The structural morphology of the LAFs and their interaction with MNPs were analyzed by atomic force microscopy and small-angle x-ray scattering measurements. The results indicate that conformational properties of the fibrils are dependent on the concentration of protein, and the precise ratio of the concentration of the protein and MNPs is crucially important for the stability of the fibrillary nanocomposites. Our results confirm that despite the change in fibrillary morphology induced by the varying concentration of the protein, the adsorption of MNPs on the surface of LAF is morphologically independent. Moreover, most importantly, the samples containing salt have excellent stability for up to 1 year of shelf-life.     

A synthetic biology approach for the fabrication of functional (fluorescent magnetic) bioorganic–inorganic hybrid materials in sponge primmorphs

During evolution, sponges (Porifera) have honed the genetic toolbox and biosynthetic mechanisms for the fabrication of siliceous skeletal components (spicules). Spicules carry a protein scaffold embedded within biogenic silica (biosilica) and feature an amazing range of optical, structural, and mechanical properties. Thus, it is tempting to explore the low-energy synthetic pathways of spiculogenesis for the fabrication of innovative hybrid materials. In this synthetic biology approach, the uptake of multifunctional nonbiogenic nanoparticles (fluorescent, superparamagnetic) by spicule-forming cells of bioreactor-cultivated sponge primmorphs provides access to spiculogenesis. The ingested nanoparticles were detected within intracellular vesicles resembling silicasomes (silica-rich cellular compartments) and as cytosolic clusters where they lent primmorphs fluorescent/magnetic properties. During spiculogenesis, the nanoparticles initially formed an incomplete layer around juvenile, intracellular spicules. In the mature, extracellular spicules the nanoparticles were densely arranged as a surface layer that rendered the resulting composite fluorescent and magnetic. By branching off the conventional route of solid-state materials synthesis under harsh conditions, a new pathway has been opened to a versatile platform that allows adding functionalities to growing spicules as templates in living cells, using nonbiogenic nanoscale building blocks with multiple functionalities. The magnet-assisted alignment renders this composite with its fluorescent/magnetic properties potentially suitable for application in biooptoelectronics and microelectronics (e.g., microscale on-chip waveguides for applications of optical detection and sensing).     

Immobilization of HIV-1 TAT peptide on gold nanoparticles: A feasible approach for siRNA delivery

RNA interference is one of the prosperous approaches for cancer treatment. However, small interfering RNA (siRNA) delivery to cancer cells has been faced with various challenges restricting their clinical application over the decades. Since ROR1 is an onco-embryonic gene overexpressed in many malignancies, suppression of ROR1 by siRNA can potentially fight cancer. Herein, a delivery system for ROR1 siRNA based on HIV-1 TAT peptide-capped gold nanoparticles (GNPs) was developed to treat breast cancer. Besides, we introduced a new feasible method for conjugating the peptide to the nanoparticles. Since the GNPs have high affinity to the sulfur, the findings demonstrated the peptide successfully conjugated to the nanoparticles via Au–S bonds. As positively charged nanoparticles showed high cellular uptake, we could use a low concentration of nanoparticles led to high efficient gene transfection with negligible cytotoxicity that was confirmed by flow cytometry, confocal microscopy, gel retardation, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Following transfection, downregulation of ROR1 and its targeted gene, CCND1, induced apoptosis in cancer cells. In conclusion, the reported capped GNPs could be potentially utilized for delivering negatively charged therapeutic agents in particular genes.     

Nanoparticles and cancer therapy: Perspectives for application of nanoparticles in the treatment of cancers

Rapid growth in nanotechnology toward the development of nanomedicine agents holds massive promise to improve therapeutic approaches against cancer. Nanomedicine products represent an opportunity to achieve sophisticated targeting strategies and multifunctionality. Nowadays, nanoparticles (NPs) have multiple applications in different branches of science. In recent years, NPs have repetitively been reported to play a significant role in modern medicine. They have been analyzed for different clinical applications, such as drug carriers, gene delivery to tumors, and contrast agents in imaging. A wide range of nanomaterials based on organic, inorganic, lipid, or glycan compounds, as well as on synthetic polymers has been utilized for the development and improvement of new cancer therapeutics. In this study, we discuss the role of NPs in treating cancer among different drug delivery methods for cancer therapy.     

Sequential interactions of silver–silica nanocomposite (Ag–SiO2NC) with cell wall,metabolism and genetic stability of Pseudomonas aeruginosa,a multiple antibiotic‐resistant bacterium

The study was carried out to understand the effect of silver–silica nanocomposite (Ag–SiO₂NC) on the cell wall integrity, metabolism and genetic stability of Pseudomonas aeruginosa, a multiple drug‐resistant bacterium. Bacterial sensitivity towards antibiotics and Ag–SiO₂NC was studied using standard disc diffusion and death rate assay, respectively. The effect of Ag–SiO₂NC on cell wall integrity was monitored using SDS assay and fatty acid profile analysis, while the effect on metabolism and genetic stability was assayed microscopically, using CTC viability staining and comet assay, respectively. Pseudomonas aeruginosa was found to be resistant to β‐lactamase, glycopeptidase, sulfonamide, quinolones, nitrofurantoin and macrolides classes of antibiotics. Complete mortality of the bacterium was achieved with 80 μg ml^?1 concentration of Ag–SiO₂NC. The cell wall integrity reduced with increasing time and reached a plateau of 70% in 110 min. Changes were also noticed in the proportion of fatty acids after the treatment. Inside the cytoplasm, a complete inhibition of electron transport system was achieved with 100 μg ml^?1 Ag–SiO₂NC, followed by DNA breakage. The study thus demonstrates that Ag–SiO₂NC invades the cytoplasm of the multiple drug‐resistant P. aeruginosa by impinging upon the cell wall integrity and kills the cells by interfering with electron transport chain and the genetic stability.

Significance and Impact of Study

Although the synthesis, structural characteristics and biofunction of silver nanoparticles are well understood, their application in antimicrobial therapy is still at its infancy as only a small number of microorganisms are tested to be sensitive to nanoparticles. A thorough knowledge of the mode of interaction of nanoparticles with bacteria at subcellular level is mandatory for any clinical application. The present study deals with the interactions of Ag–SiO2NC with the cell wall integrity, metabolism and genetic stability of Pseudomonas aeruginosa, which would contribute substantially in strengthening the therapeutic applications of silver nanoparticles.     

A 5q12.1–5q12.3 microdeletion in a case with a balanced exceptional complex chromosomal rearrangement

Complex chromosomal rearrangements are very rare chromosomal abnormalities. Individuals with a complex chromosomal rearrangement can be phenotypically normal or display a clinical abnormality. It is believed that these abnormalities are due to either microdeletions or microduplications at the translocation breakpoints or as a result of disruption of the genes located in the breakpoints. In this study we describe a 2-year-old child with mental retardation and developmental delay in whom a de novo apparently balanced exceptional complex chromosomal rearrangement was found through conventional cytogenetic analysis. Using both cytogenetic and FISH analysis, the patient's karyotype was found to be: 46,XY,der(5)t(5;7)(p15.1;7q34),t(5;8)(q13.1;8q24.1)dn. A large, clinically significant deletion which encompassed 887.69 kb was detected at the 5q12.1–5q12.3 (chr5:62.886.523–63.774.210) genomic region using array-CGH. This deleted region includes the HTR1A and RNF180 genes. This is the first report of an individual with an apparently balanced complex chromosomal rearrangement in conjunction with a microdeletion at 5q12.1–5q12.3 in which there are both mental-motor retardation and dysmorphia.     

Magnetic fields suppress Pseudomonas aeruginosa biofilms and enhance ciprofloxacin activity

Due to the refractory nature of pathogenic microbial biofilms, innovative biofilm eradication strategies are constantly being sought. Thus, this study addresses a novel approach to eradicate Pseudomonas aeruginosa biofilms. Magnetic nanoparticles (MNP), ciprofloxacin (Cipro), and magnetic fields were systematically evaluated in vitro for their relative anti-biofilm contributions. Twenty-four-hour biofilms exposed to aerosolized MNPs, Cipro, or a combination of both, were assessed in the presence or absence of magnetic fields (Static one-sided, Static switched, Oscillating, Static + oscillating) using changes in bacterial metabolism, biofilm biomass, and biofilm imaging. The biofilms exposed to magnetic fields alone exhibited significant metabolic and biomass reductions (p < 0.05). When biofilms were treated with a MNP/Cipro combination, the most significant metabolic and biomass reductions were observed when exposed to static switched magnetic fields (p < 0.05). The exposure of P. aeruginosa biofilms to a static switched magnetic field alone, or co-administration with MNP/Cipro/MNP + Cipro appears to be a promising approach to eradicate biofilms of this bacterium.     

Silver colloidal nanoparticles: antifungal effect against adhered cells and biofilms of Candida albicans and Candida glabrata

The aim of this study was to evaluate the effect of silver nanoparticles (SN) against Candida albicans and Candida glabrata adhered cells and biofilms. SN (average diameter 5 nm) were synthesized by silver nitrate reduction with sodium citrate and stabilized with ammonia. Minimal inhibitory concentration (MIC) tests were performed for C. albicans (n = 2) and C. glabrata (n = 2) grown in suspension following the Clinical Laboratory Standards Institute microbroth dilution method. SN were applied to adhered cells (2 h) or biofilms (48 h) and after 24 h of contact their effect was assessed by enumeration of colony forming units (CFUs) and quantification of total biomass (by crystal violet staining). The MIC results showed that SN were fungicidal against all strains tested at very low concentrations (0.4–3.3 μg ml^?1). Furthermore, SN were more effective in reducing biofilm biomass when applied to adhered cells (2 h) than to pre-formed biofilms (48 h), with the exception of C. glabrata ATCC, which in both cases showed a reduction ～90%. Regarding cell viability, SN were highly effective on adhered C. glabrata and respective biofilms. On C. albicans the effect was not so evident but there was also a reduction in the number of viable biofilm cells. In summary, SN may have the potential to be an effective alternative to conventional antifungal agents for future therapies in Candida-associated denture stomatitis.     

Isoniazid-induced cell death is precipitated by underlying mitochondrial complex I dysfunction in mouse hepatocytes

Isoniazid (INH) is an antituberculosis drug that has been associated with idiosyncratic liver injury in susceptible patients. The underlying mechanisms are still unclear, but there is growing evidence that INH and/or its major metabolite, hydrazine, may interfere with mitochondrial function. However, hepatic mitochondria have a large reserve capacity, and minor disruption of energy homeostasis does not necessarily induce cell death. We explored whether pharmacologic or genetic impairment of mitochondrial complex I may amplify mitochondrial dysfunction and precipitate INH-induced hepatocellular injury. We found that INH (≤3000 μM) did not induce cell injury in cultured mouse hepatocytes, although it decreased hepatocellular respiration and ATP levels in a concentration-dependent fashion. However, coexposure of hepatocytes to INH and nontoxic concentrations of the complex I inhibitors rotenone (3 μM) or piericidin A (30 nM) resulted in massive ATP depletion and cell death. Although both rotenone and piericidin A increased MitoSox-reactive fluorescence, Mito-TEMPO or N-acetylcysteine did not attenuate the extent of cytotoxicity. However, preincubation of cells with the acylamidase inhibitor bis-p-nitrophenol phosphate provided protection from hepatocyte injury induced by rotenone/INH (but not rotenone/hydrazine), suggesting that hydrazine was the cell-damaging species. Indeed, we found that hydrazine directly inhibited the activity of solubilized complex II. Hepatocytes isolated from mutant Ndufs4^+/− mice, although featuring moderately lower protein expression levels of this complex I subunit in liver mitochondria, exhibited unchanged hepatic complex I activity and were therefore not sensitized to INH. These data indicate that underlying inhibition of complex I, which alone is not acutely toxic, can trigger INH-induced hepatocellular injury.