Development of a method to quantify the DNA content in DNA- cationic peptide nanoparticles

Gene therapy has the potential to provide safe and targeted therapies for a variety of diseases. A range of intracellular gene delivery vehicles have been proposed for this purpose. Non-viral vectors are a particularly attractive option and among them cationic peptides have emerged as promising candidates. For the pharmaceutical formulation and application to clinical studies it is necessary to quantify the amount of pDNA condensed with the delivery system. There is a severe deficiency in this area, thus far no methods have been reported specifically for pDNA condensed with cationic peptide to form nanoparticles. The current study seeks to address this and describes the evaluation of a range of disruption agents to extract DNA from nanoparticles formed by condensation with cationic fusogenic peptides RALA and KALA. Only proteinase K exhibited efficient and reproducible results and compatibility with the PicoGreen reagent based quantification assay. Thus we report for the first time a simple and reliable method that can quantify the pDNA content in pDNA cationic peptide nanoparticles.

Unraveling the synergy between gold nanoparticles and chromium- hydrotalcites in aerobic oxidation of alcohols

The combination of gold nanoparticles (AuNPs) with chromium-substituted hydrotalcite (Cr-HT) supports makes very efficient heterogeneous catalysts (Au/Cr-HT) for aerobic alcohol oxidation under soluble-base-free conditions. The Au-support synergy increases with increasing Cr content of the support and decreasing AuNP size. In situ UV-Raman, X-ray absorption and photoelectron spectroscopic studies firmly establish that the strong Au-Cr synergy is related to a Cr ↔ Cr redox cycle at the Au/Cr-HT interface, where O activation takes place accompanied by electron transfer from Cr-HT to Au. The interfacial Cr species can be reduced by surface Au-H hydride and negative-charged Au species to close the catalytic cycle. A study of kinetic isotope effect indicates that alcohol O-H cleavage is facilitated by the presence of Cr, making a-C-H bond cleavage step more rate-controlling. Accordingly, a dual synergistic effect of Au/Cr-HT catalysts on the activation of O2 and alcohol reactants is proposed.

Plant extract: A promising biomatrix for ecofriendly, controlled synthesis of silver nanoparticles

Uses of plants extracts are found to be more advantageous over chemical, physical and microbial (bacterial, fungal, algal) methods for silver nanoparticles (AgNPs) synthesis. In phytonanosynthesis, biochemical diversity of plant extract, non-pathogenicity, low cost and flexibility in reaction parameters are accounted for high rate of AgNPs production with different shape, size and applications. At the same time, care has to be taken to select suitable phytofactory for AgNPs synthesis based on certain parameters such as easy availability, large-scale nanosynthesis potential and non-toxic nature of plant extract. This review focuses on synthesis of AgNPs with particular emphasis on biological synthesis using plant extracts. Some points have been given on selection of plant extract for AgNPs synthesis and case studies on AgNPs synthesis using different plant extracts. Reaction parameters contributing to higher yield of nanoparticles are presented here. Synthesis mechanisms and overview of present and future applications of plant-extract-synthesized AgNPs are also discussed here. Limitations associated with use of AgNPs are summarised in the present review.

Development and characterization of self-assembling nanoparticles using a bio-inspired amphipathic peptide for gene delivery

The design of a non-viral gene delivery vehicle capable of delivering and releasing a functional nucleic acid cargo intracellularly remains a formidable challenge. For systemic gene therapy to be successful a delivery vehicle is required that protects the nucleic acid cargo from enzymatic degradation, extravasates from the vasculature, traverses the cell membrane, disrupts the endosomal vesicles and unloads the cargo at its destination site, namely the nucleus for the purposes of gene delivery. This manuscript reports the extensive investigation of a novel amphipathic peptide composed of repeating RALA units capable of overcoming the biological barriers to gene delivery both in vitro and in vivo. Our data demonstrates the spontaneous self-assembly of cationic DNA-loaded nanoparticles when the peptide is complexed with pDNA. Nanoparticles were < 100 nm, were stable in the presence of serum and were fusogenic in nature, with increased peptide α-helicity at a lower pH. Nanoparticles proved to be non-cytotoxic, readily traversed the plasma membrane of both cancer and fibroblast cell lines and elicited reporter-gene expression following intravenous delivery in vivo. The results of this study indicate that RALA presents an exciting delivery platform for the systemic delivery of nucleic acid therapeutics.

Experimental design and batch experiments for optimization of Cr(VI) removal from aqueous solutions by hydrous cerium oxide nanoparticles

Hydrous cerium oxide (HCO) was synthesized by intercalation of solutions of cerium(III) nitrate and sodium hydroxide and evaluated as an adsorbent for the removal of hexavalent chromium from aqueous solutions. Simple batch experiments and a 2⁵ factorial experimental design were employed to screen the variables affecting Cr(VI) removal efficiency. The effects of the process variables; solution pH, initial Cr(VI) concentration, temperature, adsorbent dose and ionic strength were examined. Using the experimental results, a linear mathematical model representing the influence of the different variables and their interactions was obtained. Analysis of variance (ANOVA) demonstrated that Cr(VI) adsorption significantly increases with decreased solution pH, initial concentration and amount of adsorbent used (dose), but slightly decreased with an increase in temperature and ionic strength. The optimization study indicates 99% as the maximum removal at pH 2, 20 °C, 1.923 mM of metal concentration and a sorbent dose of 4 g/dm³. At these optimal conditions, Langmuir, Freundlich and Redlich–Peterson isotherm models were obtained. The maximum adsorption capacity of Cr(VI) adsorbed by HCO was 0.828 mmol/g, calculated by the Langmuir isotherm model. Desorption of chromium indicated that the HCO adsorbent can be regenerated using NaOH solution 0.1 M (up to 85%). The adsorption interactions between the surface sites of HCO and the Cr(VI) ions were found to be a combined effect of both anion exchange and surface complexation with the formation of an inner-sphere complex.

Structuring reductive media containing protic ionic liquids and their application to the formation of metallic nanoparticles

Herein, we present a facile method for the formation of monodispersed metal nanoparticles (NPs) at room temperature from M^(III)Cl₃ (with M = Au, Ru, Mn, Fe or V) in different media based on N,N-dimethylformamide (DMF) or water solutions containing a protic ionic liquid (PIL), namely the octylammonium formate (denoted OAF) or the bis(2-ethyl-hexyl)ammonium formate (denoted BEHAF). These two PILs present different structures and redox-active structuring properties that influence their interactions with selected molecular compounds (DMF or water), as well as the shape and the size of formed metal NPs in these solutions. Herein, the physical properties, such as the thermal, transport and micellar properties, of investigated PIL solutions were firstly investigated in order to understand the relation between PILs structure and their properties in solutions with DMF or water. The formation of metal NPs in these solutions was then characterized by using UV–vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and dynamic light scattering (DLS) measurements. From our investigations, it appears that the PILs structure and their aggregation pathways in selected solvents affect strongly the formation, growths, the shape and the size of metal NPs. In fact by using this approach, the shape-/size-controlled metal NPs can be generated under mild condition. This approach suggests also a wealth of potential for these designer nanomaterials within the biomedical, materials, and catalysis communities by using designer and safer media based on PILs.